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NATURAL HISTORY OF ARTHROPODS.

E. A. BIRGE, Ph.D. L. O. HOWARD.

J. H. COMSTOCK. J. S. KINGSLEY.

GEORGE DIMMOCK, Ph.D. A. S. PACKARD, Ph.D.

HENRY EDWARDS. C. V. RILEY, Ph.D.

C. H. FERNALD. P. R. UHLER.

S. W. WILLISTON, Ph.D.

Eupuyuriis bemhardus, hermit crab.

THE STANDARD

NATURAL HISTORY.

EDITED BY

JOHN STERLING KINGSLEY.

VOL. II.
CRUSTACEA AND INSECTS.

Ilhistvated

BY SIX HUNDRED AND SIXTY-SIX WOOD-CUTS AND TWENTY

FULL-PAGE PLATES.

B astern:

S. E. CASSINO AND COMPANY.

1886.

Copyright by
S. E. GASSING AND COMPANY,

1884.

no

C. J. PETERS AND SON,
STEREOTYPEKS AND ELECTROTYPERS,

145 lib, 11 STREET.

CONTENTS.

PAGE

BRANCH VII. ARTHROPODA 1

CLASS I. CRUSTACEA . 6

SUB-CLASS I. CIRRIPEDIA . .12

ORDER I. APODA 17

ORDER II. ABDOMINALIA . .17

ORDER III. RHIZOCEPHALA 18

ORDER IV. THORACICA 19

SUB-CLASS II. ENTOMOSTRACA .22

ORDER I. COPEPODA 22

ORDER II. SIPHONOSTOMATA .... . .26

ORDER III. OSTRACODA 29

ORDER IV. CLADOCERA 31

ORDER V. PHYLLOPODA . .36

SUB-CLASS III. PODOPHTHALMIA 42

ORDER I. PHYLLOCARIDA 42

ORDER II. SCHIZOPODA 43

ORDER III. DECAPODA 44

SUB-ORDER I. MACRURA .... 48

SUB-ORDER II. BRACHYURA 58

ORDER IV. STOMATOPODA 65

ORDER V. CUMACEA . .67

SUB-CLASS IV. EDKIOPHTHALMIA 68

ORDER I. ISOPODA . .69

ORDER II. AMPHIPODA 72

SUB-ORDER I. L^EMODIPODA . . .... 72

SUB-ORDER II. AMPHIPODA GENUINA . . ,73

ARTHROPODA OF DOUBTFUL POSITION 78

PYCNOGONIDA 78

TARDIGRADA 80

GlGANTOSTRACA ' 81

TRILOBITA 81

MEROSTOMATA 82

PCECILOPODA 86

EURYPTERIDA 86

PENTASTOMIDA 87

CLASS II. INSECTA 89

SUB-CLASS I. MALACOPODA . . .96

CONTENTS.

SUB-CLASS II. ARACHNTDA 98

ORDER I. ACARINA . .... 99

ORDER II. ARANEINA . 103

SUB-ORDER I. DIPNEUMONIA ug

SUB-ORDER II. TETRAPNEOIONIA 120

ORDER III. ARTHROGASTRA 121

SUB-ORDER I. OPILIONEA 121

SUB-ORDER II. PEDIPALPI 122

SUB-ORDER III. SOLIFUG.E 123

SUB-ORDER IV. PSEUDOSCORPII 124

SUB-ORDER V. SCORPIODEA 125

SUB-CLASS III. MYRIAPODA 127

ORDER I. CHILOGNATHA . 127

ORDER II. PAUROPIDA 128

ORDER III. CHILOPODA 128

SUB-CLASS IV. HEXAPODA 131

ORDER I. THYSANURA . 135

SUB-ORDER I. COLLEMBOLA ]35

SUB-ORDER II. SYMPHYLA 136

SUB-ORDER III. CINURA 137

ORDER II. DERMATOPTERA 139

ORDER III. PSEUDONEUROPTERA 140

SUB-ORDER I. PLATYPTERA 140

SUB-ORDER II. ODONATA 147

SUB-ORDER III. EPHEMERINA 151

ORDER IV. NEUROPTERA 155

ORDER V. ORTHOPTERA 167

ORDER VI. HEMIPTERA 204

SUB-ORDER I. PARASITA 209

SUB-ORDER II. HOMOPTERA 212

SUB-ORDER III. HETEROPTERA 249

ORDER VII. COLEOPTERA 297

SUB-ORDER I. CRYPTOTETRAMERA 310

SUB-ORDER II. CRYTOPENTAMERA 313

SUB-ORDER III. HETEROMERA 345

SUB-ORDER IV. PENTAMERA 354

ORDER VIII. DIPTERA .... .403

SUB-ORDER I. ORTHORHAPHA 407

SUB-ORDER II. CYCLORHAPHA . 423

ORDER IX. APHANIPTERA 434

ORDER X. LEPIDOPTERA . 435

SUB-ORDER I. HETEROCERA 435

SUB-ORDER II. EHOPALOCERA . 469

ORDER XI. HYMENOPTERA 503

SUB-ORDER I. TEREBRANTIA . 506

SUB-ORDER II. ACULEATA . 516

LIST OF PLATES.

PAGE

HERMIT CRAB Frontispiece

METAMORPHOSES OF CRAB 4

EXTERNAL ANATOMY OF A LOBSTER . . 6

LOBSTER AND SPINY LOBSTER 54

GREEN CRAB 62

UPPER AND UNDER SURFACE OF GARDEN SPIDER 104

SPIDERS . 118

BIRD SPIDER . 120

HARVESTMEN 122

CARRION BEETLES AND FLIES 132

A SWARM OF MAY FLIES . . 152

MOLE CRICKETS 180

TROPICAL HEMIPTERA 224

LONG-ARMED BEETLE 326

HERCULES BEETLE, MALE AND FEMALE . 368

SCARAB.EID BEETLES 374

CARABID BEETLES 400

SILKWORM MOTHS 456

AMERICAN BUTTERFLIES 486

PALM WASP 534

NATURAL HISTORY OF ARTHROPODS.

BRANCH VII.- -ARTHROPOD A.

CUVIER, in his great divisions or branches of the animal kingdom, recognized a
group Articulata characterized by having a bilaterally symmetrical body, composed of
a series of rings or segments serially arranged. An excellent example of the arrange-
ment of these rings can be seen in the common earth or angleworm. These rings
make a hardened external skeleton, which at once forms a framework for the attach-
ment of muscles, and also a protection for the internal organs. Typically, there is
found in each segment a portion of each of the more important organs of the body.
Just under the dorsal surface is found an elongated dorsal vessel, which represents the
heart ; the intestine lies in the median line of the body, which it usually traverses from
end to end, while the nervous system, consisting of a series of enlargements, called
ganglia, connected by nervous cords, extends along the floor of the body. This
group of Articulata was still further divided into three classes : Worms, Crustacea, and
Insects.

This classification was long prevalent, and even at the present time it is found in
use in a few text-books, though when naturalists came to study more thoroughly the
principles upon which animals should be grouped, and especially upon applying the rev-
elations of embryology, it was seen that the class of Worms contained the most hetero-
geneous elements, and that while certain members of it were possibly closely related to
Crustacea and Insects, the great majority had no such affinity, and that the features
uniting them were of not so much importance as many others. Hence, as we have seen
in the preceding volume, the group of Articulata has been dismembered and dropped
from use, and even the class of worms is far from being a natural one.

According to the majority of the naturalists of the present day, the Crustacea and
the Insects are together considered as forming a sub-kingdom, ARTHROPODA (a^jjo*', a
joint, and novg, 71066$, a foot), but the tendency of scientific thought at the present time
is toward the discarding of this group, and toward the belief that the Crustacea and the
Insects are generically no more closely related to each other than they are to the
worms, and that each should be raised to the dignity of branches. The reasons for
such a course are many, but for convenience, in the present work, the prevailing classi-
fication will be retained.

The Arthropoda have the following features in common, some also being common
to many worms : The body is (except in a few forms, the result of adaptation), bilater-
ally symmetrical, one side being a repetition of the other ; and is made up of a varying
number of rings (called segments, somites, or arthromeres) arranged one after another,
and each ring theoretically bearing a pair of appendages, which in turn are jointed to

S3

VOL. II. 1

2 NATURAL HISTORY OF ARTHROPODS.

admit of a freedom of motion. In many cases, as in most insects, it is found that all
traces of these appendages have disappeared from some of the body segments, though
where we examine the larvae or immature stages, we find that the generalization is fully
justified, and that in the most generalised types each of these segments also bears a pair
of limbs. This segmentation of the body and appendages is almost entirely confined
to the external portions, the nervous system alone exhibiting a similar character, and,
though constant throughout the group, it seems to be a secondary feature, and the re-
sult of a provision for movement rather than a fact of great morphological importance.
This external envelope of the body is of cutaneous origin, and is rendered firm and
hard by a peculiar organic substance known as chitine. This chitine, first made known
by Odier, resembles the cellulose of plants in not being dissolved in caustic potash, but
it differs essentially from it in containing nitrogen. In addition to this chitine there
are frequently present in the exo-skeleton salts of lime, calcic-phosphate and carbonate,
which render it much harder, and consequently more of a protection to the animal.

The rings of the body and the appendages which they bear, are variously modified
according to the parts they have to protect and the functions they have to perform.
Some of the appendages are adapted for walking, some for swimming, some for the
seizure and mastication of food, Avhile others play a part in the respiration, and still
others give support to organs of sense. Of these appendages and their structure we
shall speak more in detail in the succeeding pages.

In their internal structure the Arthropoda agree in many important particulars, but
it is to be noted that in many respects these characters are common to other groups of
Invertebrata, a fact which renders them of less weight in defining the Branch Arthro-
poda. The heart is usually an elongate tube on the dorsal surface of the body, is usu-
ally provided with valves, and serves for the propulsion of the blood, generally in a
direction from behind forward. The arteries have proper walls, but the venous system
consists merely of spaces or lacunce between the various organs. The blood is usually
colorless, but occasionally is yellow or red, or even purple, but the color belongs to the
fluid itself, not to the contained globules.

The principal nervous system consists of a series of ganglia, or nervous centres,
normally one to each segment, connected by a double longitudinal cord. This corre-
spondence of ganglia and segments is the most evident instance of a segmentation of
the internal organs. The first ganglion or "brain "lies in front of the mouth, and

O O O

from it arise the nerves going to the eyes and antennae. The two nervous cords con-
necting it with the rest of the nervous system pass one on either side of the oesophagus
and enter the first of the series of infra-oesophageal ganglia. Thus we see that the ali-
mentary canal passes through the nervous system, a feature which has its analogies, if
not homologies, in other groups of the animal kingdom, and notably among most of the
worms and molluscs. The posterior portion of the chain lies on the floor of the body-
cavity, and, as has been said, normally consists of a series of ganglia, one to each seg-
ment, but frequently some of the ganglia are fused together, and where, theoretically,
there should be several ganglia but one compound one is found. Each ganglion gives
off nerves to the adjacent organs, and where we find two or more ganglia united, the
nerves usually remain separate, thus clearly showing just what has taken place. A sec-
ondary nervous system is frequently well developed, analogous to the sympathetic
system of the Vertebrata, and with a somewhat similar distribution.

The alimentary canal is usually nearly straight, traversing nearly the entire length
of the body, and for the greater part of its course lying between the nervous and cir-

INTRODUCTION.

dilatory centres. The mouth is on the lower anterior surface of the body, and is sur-
rounded by the " mouth-parts " (the appendages of the adjacent segments, variously
modified for the purposes of eating). These are sometimes adapted for crushing and
biting, at others for piercing and sucking. Usually these mouth-parts are capable of
motion, but they move in a horizontal plane, from side to side, and not vertically, as do
the jaws of vertebrates. From the mouth the oesophagus passes upward and backward
through the nervous system, as has been described, and terminates in the Crustacea at
the stomach, in the insects at the crop or ingluvies. The rest of the course of the
alimentary canal presents so many variations that it is best to resume the subject
in connection with the different groups, and to close our account of it here with
the statement that in many forms the canal is a simple tube with no well-defined
divisions.

In the Arthropods two types of eyes are found, simple and compound, both some-
times occurring together in the same animal.
These eyes have recently been made the sub-
ject of very exhaustive studies by Grenacher
and others, but their accounts are too long for
detailed insei'tion here. The simple eyes consist
of a thickening of the outer integument, forming
at once a refractive lens and an organ of defense.
Beneath this lens the cells of the hypodermis be-
come elongated. In the outer cells pigment is
deposited, but the inner are transparent, and the
lower ones, which are in connection with filaments
of the optic nerve, form a retina. Various modi-
fications of this structure are found, all, however,
being reduceable to this type. In most cases the
anterior portion of the retinal cells become elon-
gated into a " rod," while the anterior transparent cells frequently break up into a cor-
responding number of highly refractive bodies, known as crystalline cones. Each of
these cones has its base placed against the corneal lens, while its tip is connected with
a rod, and thus with the optic-nerve.

The compound eyes differ from the simple ones by having a large number of cor-
neal lenses, each conveying the light to a single rod and cone. In some (Fig. 3) the
crystalline cones are well developed, in others {Fig. 2) they are represented by cells
but little modified. Concerning the physiological action of the eyes of Arthropods,
there have been several theories, but the one which at present is most in vogue is the
" mosaic theory," which supposes that each retinal cell perceives but a portion of the
picture, and that by the action of the brain the various parts are put together so that
the whole is seen, as a veritable optical mosaic. There are certain difficulties connected
with this theory, but our space forbids their discussion.

As a rule the eyes are confined to a Avell-defined region, that of the head, there
being, however, one conspicuous exception, the crustacean JZuphausia, where on the
thorax and abdomen occur organs which are interpreted as having visual functions.
In many of the Crustacea simple eyes are found in the young, but all traces of them
disappear in the adult.

The auditory organs are far less constant in their position, as can be seen from a few
examples. In the Decapod Crustacea they occur on the basal-joint of the inner an-

FIG. 1. Section of simple eye of Dytlscus
larva, greatly enlarged. I. Lens. c. Crystalline
body, not yet broken up into cones, r. Rods.
rt. Retina, n. Optic nerve.

NATURAL HISTORY OF ARTHROPODS.

tennse ; in the closely allied Mysis^ on the posterior pair of appendages. In the Acri-
didse (grasshoppers) the ears are found on the base of the abdomen, while in the Locus-
tidre (locusts) the auditory organs are on the first pair of legs. In the Crustacea the
ear, when found, consists of a sac, more or less completely closed by a membrane, and
containing small sand-like particles (otoliths) suspended in a mucous fluid. The inner
wall of the sac bears a row of numerous fine hairs, each connected Avith the extremity
of a nerve fibrile. A sound causes the membrane of the sac to vibrate, this in turn sets
the granular contents in motion, and these, touching the hairs, convey the impression
to the nerves and thence to the brain. In the common grasshopper the ear is of a
different type. On either side of the first segment of the abdomen is found a large

rl

FIG. 2. Section of part of eye of tipula. c. Crystalline
cells, ct. Cuticula. 1. Corueal lenses, n. Nerves.
p. Pigment cells, r. Kods. rl. Retinula.

FIG. 3. A. Section of eye of cray-fish. B. A single
corneal lens, with corresponding cone, rod, and retin-
ula, greatly enlarged.

membrane, roughly corresponding to the tympanic membrane of the Vertebrates. At-
tached to the inner surface of this are two horny processes. A large tracheal vessel is
distributed over the inner side of the membrane, and between its walls and the latter a
nerve passes to the region occupied by the processes above referred to, and there
enlarges into a ganglion, the outer face of which, beset with numerous glassy rods,
arranged side by side, is in contact with the tympanic membrane. In the crickets and
locusts the ears have an essentially similar structure. In other insects great uncer-
tainty as yet exists regarding the auditory organs. Professor Mayer thinks that the
fine hairs on the antennas of the mosquito have acoustic functions, but this is far from
proved.

Regarding the other organs of sense in the Arthropoda, our knowledge is very
slight, and all statements are largely a matter of speculation. The hairs which are
found disti'ibuted over the surface of the body, are frequently concerned in the sense
of touch, and possibly sometimes in smell, taste, and hearing as well. The difficulty
which attends any attempt at experiment in this direction is the chief cause of this
uncertainty.

All Arthropods further agree in the fact that in the ripening of the egg (except in
a very few forms) no polar globules are known to be formed. They have also a com-
mon mode of egg segmentation ; but neither of these points are to be regarded as of

FIG. 5. Megalops of Neptunus.

FIG. 6. Young Neptunus produced from the above by a single moult.

INTRODUCTION.

great importance when viewed from a systematic standpoint. Beyond the maturation
and segmentation of the egg the Arthropod have but very few embryological features
in common ; on the other hand, the evidence presented by the development of the
insects and Crustacea is such as to be almost conclusive of the distinctness. We have,
however, one feature to note in connection with their growth. As we have seen, the
Arthropoda are enclosed in a chitinized integument, which forms a firm investment for
the body, without provision for any increase in size, to correspond with the natural
growth of the animal, and hence, at intervals more or less frequent, according to the
size and rapidity of growth, the integument, or rather its outer hardened portion, is
shed, and then the underlying skin produces a new and larger external skeleton, to be
shed in turn when further increase in size renders it necessary. In connection with
this growth in size and consequent shed-
ding of the skin or exuviation most of the
Arthropods undergo marked metamorphoses,
the result being to produce forms widely
differing from the younger stages. Some-
times the changes are effected gradually,
slight differences being noticeable at each
moult, at other times the differences be-
tween two moults being enormous, as shown
in Plate I, which repi-esents the changes
produced by a single moult in the edible
crab (Neptunus hastatus) of the Atlantic
coast. The only other example which need
here be instanced is that presented by the
Butterflies, familiar to all, in which a worm-
like larva hatches from the egg, eats and
grows, occasionally casting its skin to accom-
odate its increase in size, but without much
changing its general appearance, until at
last, by a single moult, it passes suddenly into

a chrysalis, which presents but a very slight resemblance to the previous larval condi-
tion. A period of apparent inaction now intervenes, in our climate frequently lasting
through the winter, but beneath the skin of the chrysalis great changes are in progress,
and in due season the skin is shed again and for the last time, and the perfect form, the
butterfly, is the result. In the pages of this volume many examples of these metamor-
phoses will be found.

The Arthropoda are usually divided into two classes, Crustacea and Insects, but in
nature we do not find such exact classifications as are to be found in books, and there
exist many groups of Animals which do not readily fit in any of the accepted classifi-
cations. Among the Arthropoda we find such forms, whose position is by no means cer-
tain, and which have alternately been regarded as belonging to the Crustacea and to
the Insects. Owing to this unsettled condition of our knowledge and opinions, in the
present work the Horse-Shoe Crabs and Trilobites, the Water-bears, Sea-spiders, and
Linguatulina are placed between the Insects and Crustacea, where it is possible they
really belong.

J. S. KlNGSLEY.

EIG. 4. Ear of grasshopper, from within, a. Thick-
ened rim of (6) tympanum, c. Muscles, d. Spir-
acle, e. Conical process, fc. Triangular chamber.
/. Auditory nerve, m. Auditory ganglion.

6 NATURAL HISTORY OF ARTHROPODS.

CLASS I. CRUSTACEA.

The Crustacea as a group are essentially aquatic, and although some of the members
live on the land, all require the presence of moisture for the purposes of respiration.
Nine-tenths of the known species live in the sea, while the majority of the remaining
forms inhabit fresh water, only a very few being adapted for life on the land. In size
they vary from forms only to be seen with the microscope to the giant Macrocheira of
the Japanese Seas, whose legs w r ill occasionally embrace a distance of twenty feet and
even more, and the lobster of our own coast, specimens of which have been taken
weighing forty pounds. No very reliable or accurate estimates have been made as to
the number of existing species, but probably ten thousand is within the limits. This
number is much larger than the one usually assigned, but when we recollect that there
are about eight hundred species of Decapoda alone described from North America and
the West Indies, it will readily be seen that our estimate for the class is certainly within
bounds.

The body of the Crustacea is almost universally enveloped in a more or less
hardened chitinous integument, in which, in the Barnacles and the higher groups,
carbonate and phosphate of lime are deposited, giving this external skeleton much
greater firmness. This, though a character of but slight morphological importance, has
nevertheless given the name to the class in allusion to the crustaceous character of the
body walls. Were this external skeleton solid and firm all motion would be impossible,
but this is provided for by joints in which no lime is deposited, and which are there-
fore softer and more flexible. As in all Arthropoda, we can reduce the body to a series
of rings or somites, arranged one after another, and each typically bearing a pair of
jointed appendages. So far this corresponds with the structure of the insects, but it is
to be noticed that in the Crustacea each appendage consists of a basal joint (basiopt-
odite) attached to the body, and from this arise two jointed branches, the inner being-
called the endopodite, the outer the exopodite, the inner and outer feet. In the adult
forms of many of the Crustacea but one of these branches persists in some of the limbs
of the adult, though in the young the bifurcate character is almost always plainly to be
seen. By following through the development we find that it is the outer branch which
has disappeared in the adult. In the anterior portion of the body the rings are fre-
quently so completely coalesced that it would be difficult to ascertain their number
were it not for the morphological law first propounded by the eminent French natural-
ist, J. C. Savigny, that each segment of the arthropod body bears but one pair of
appendages ; a law to which, however, there are several exceptions. The number of
segments in the Crustacea varies widely, from the three indicated segments of the larva?
of some forms to twenty segments in the Decapoda, and forty-seven in Apus, one of
the Phyllopods, which, by the way, affords one of the exceptions to Savigny's law, it
having twenty-seven thoracic segments bearing sixty pairs of limbs.

As has been said, it is frequently difficult in certain portions of the crustacean
body to make out the limits of some of the segments, and especially of those in the
anterior part. This is due to two causes : the segments are frequently coalesced so
that the sutures are almost obliterated, and partly to the fact that certain segments are
so hypertrophied that atrophy of parts of the adjacent somites of a necessity follows.

7)1

EXTERNAL ANATOMY OF A LOBSTER.

C, Carapax; I- VII, Abdominal segments; e, eye; y, gill; TO, metastoma; w, endopodite; p, epipodite; a', exopodite;
1, antennula; 2, antenna; 3, mandibles; 4, 5, maxilla'; C, 7, 8, maxillipeds; 9, big pincer; 10-13, walking feet.

CRUSTACEA.

A striking case of this occurs in the lobster, which viewed from above shows the an-
terior portion of the body covered by a large shield, the carapax, with a transverse
line. On careful study it is found that this anterior portion, to anticipate a little our
account, represents the dorsal portions of the mandibular and second antenna! segments,
and the impressed line represents the nearly obliterated suture between the two
somites. This carapax covers more than the two segments mentioned, and if the seg-
ments covered are examined it will be found that the rings are not complete, the
upper portion being absent, its place being supplied by the carapax. It is frequently
attempted to divide the anterior portion of the body of the Crustacea into head and
thorax, corresponding to the same portions of insects, but without any great success, as
in nature no such division exists, and the attempts to homologize the appendages of the
insects with those of the Crustacea are never productive of any very satisfactory
results. Still, the divisions are very convenient, and in this
work will be used with functional limits, the head containing
those segments connected with the senses and with eating, the
thorax, those whose appendages are principally locomotive, while
the abdomen embraces the segments behind the thorax. Thus,
in the Decapoda the line between head and thorax will come
between the eighth and ninth segments ; in the Tetradecapoda
between the sixth and seventh, etc.

Returning now to the limbs or appendages which we left
for the moment, we find other things for consideration. Besides
the two branches, exopodites and endopodites, which we have
mentioned, the limbs frequently bear a third, the epipodite or
flabellum, and the gills or respiratory organs, of which more
anon. The form of the limbs is subject to great variation
according to the functions they have to perform, some being
the supporters of organs of sense, those around the mouth taking
part in the capture and preparation of food, the next group in
walking or swimming, while still others play a subordinate part
in the perpetuation of the species, either as intromittent organs
or as supporters of the eggs. The two anterior pairs of appen-
dages, the antennulce and antennae are always in advance of the
mouth, and seem to be chiefly sensory, the ear in many forms
occurring on the basal joint of the antennula. The mandibles,
the first pair of appendages behind the mouth, come next, and
are succeeded by two pairs of maxillce, and then the maxillipeds,
of which in the Tetradecapoda there is but a single pair, in the
Decapoda three pairs. Beyond this point in any account of the
limbs of the Crustacea as a whole it is difficult to go, and the
reader is referred to the portions upon the special groups for in-
formation upon this point.

Strange as it may at first sight seem, a true heart is not in-
variably present in all Crustacea ; in certain forms the blood is
propelled merely by the motions and consequent changes in the
shape of the body, and no central propelling organ exists. When
present, the heart consists either of an elongate tube or a short sac directly beneath
the integument of the back. From the heart the blood is carried in arteries to

FIG. 8. Internal structure
of lobster, half natural
size. b. Brain, e. Eye. g.
Gills, h. Heart, ha. He-
patic artery, i. Intestine. I.
Liver, m. Muscles, o. Oph-
thalmic artery, s. Stom-
ach, pa. Posterior artery.

8 NATURAL HISTORY OF ARTHROPODS.

all parts of the body, and is then collected in venous sinuses (spaces between the
various organs and muscles, there being no true veins), goes to the gills, and then back
to the heart. The blood is either colorless or of a pale yellowish or reddish hue, which
is due to the fluid portion and not to the few colorless corpuscles.

With the Crustacea the appendages near the mouth, as has been already indicated,
are usually modified for the capture and the comminution of food. After being torn
into sufficiently small bits to obtain a ready entrance to the mouth, the substances
eaten pass through a short oesophagus into that portion of the digestive tract called the
stomach, which in the higher groups is divided into two portions. In the anterior are
found three hardened, bony teeth which, moved by appropriate muscles, meet together
and thoroughly grind the food. When in a sufficiently fine condition it passes into the
posterior and smaller chamber, the passage of the larger particles being prevented by
a strainer of stiff bristles. From the stomach the partially digested food passes into a
long and straight intestine terminating at the posterior end of the body. A liver,
which is always very large with the Crustacea, pours its secretions into the intestine.
This slight description of the digestive tract applies to the higher forms, and between
them and the degraded Rhizocephala, in which the digestive tract entirely disappears,
almost every gradation can be traced. A few of the Crustacea live upon vegetable
food, some are parasitic, and draw their sustenance directly from the fluids of the body
of their host, Avhile the great majority of the class are scavengers, living on decaying
animal matter. The immense amounts of animal tissues which these Crustacea will
devour almost surpasses belief. The flesh of a large fish when placed in the sea will
wholly disappear in a few hours, all being eaten by these useful forms.

In their manner of respiration the Crustacea present a marked difference from the
insects, in that moisture is always necessary. In the lower groups the aeration of the
blood occurs at the surface of the body, no specialized organs being developed, while in
the higher forms gills are present, and there the principal portion of the oxygenation
of the blood takes place. These gills, which are always expansions of the integument,
are either borne upon the limbs or the walls of the body immediately adjacent to them,
or are limbs themselves, modified so as to expose a large surface to the water. In
some cases the gills hang freely in the water, but more generally they are enclosed in
special respiratory chambers, which in the Isopoda are formed beneath the hinder seg-
ments of the body, and are enclosed by a pair of modified legs which shut together
like folding-doors. In the Decapoda the gill-chambers are two in number, there being
one on either side of the anterior half of the body. If we examine a lobster, crayfish,
or crab, we find that the portion of the carapax immediately above the walking legs
is not the wall of the body, but that between it and the true envelope there exists a
cavity into which the gills project. This cavity is nearly closed, and in it the gills
would have but little chance for exercising their functions were it not for an in-
teresting contrivance for constantly renewing the water in the chamber. At the
anterior end of the chamber there is a thin, leaf-like organ which in life is in constant
motion, thus forcing the water forward, while fresh water enters from behind. This
organ is really the exopodite of the second maxilla, and has received the name scaph-
ognathite, or the bailing jaw. In a land crab from the East Indies (Birgus latro),
Dr. Semper found that by a long life upon the land the gills had become much
reduced in size through disuse, and to afford a means of respiration there had devel-
oped in the upper portion of the branchial cavity numerous ramified tufts w r ell supplied
with afferent and efferent blood vessels, and which can be interpreted only as func-

CRUSTACEA.

9

N

tional lungs. In other land crabs no such pulmonary organs are developed, and yet it
is possible to drown them by a prolonged submergence in the water. We shall recur
again to this subject in treating of the Decapods.

The nervous system of the Crustacea, like that of all Arthropoda,
usually consists of a large anterior ganglion, or " brain " (supra-oesophageal
ganglion), from Avhich two nervous cords or commissures arise, and which,
passing back, one on either side of the resophagus, connect the brain with
a series of similar but smaller ganglia lying on the floor of the body, there
being typically a single ganglion for each segment of the body ; but occa-
sionally we find two or more of these secondary brains united, and the
cords which should connect them obliterated. From the supra-oesophageal
ganglion nerves go to the eyes and the antenna, in which the organs of
sense are most specialized, and hence, as it is through this portion of the
nervous system that the animal receives the larger portion of its knowledge
of the external world, the supra-oesophageal ganglion may be dignified
with the name of the brain. From the other ganglia nerves arise which pass
to the muscles, organs, and limbs of the corresponding portions of the body.
The foregoing account applies to the majority of the Crustacea, but various
modifications are found, and in the adults of some of the parasitic forms
no trace of a nervous system has as yet been found.

One of the most interesting subjects connected with the Crustacea is
their reproduction, a field which has already furnished many valuable re-
sults, but which, nevertheless, has scarcely begun to be worked. A few
general features only will be mentioned here, the variations in the differ-
ent groups being described in their proper place in the succeeding pages.

The eggs of the Crustacea are almost invariably carried by the mother,
either attached to some portion of the body (usually the abdominal legs)
or covered in a brood-pouch usually attached to some portion of the thorax.

The eggs after fertilization segment more or less completely,
there usually being a central portion of the yolk which does
not divide. A portion of the resulting cells soon invaginate,
and are destined to form the lining cells of that portion of
the alimentary tract known as the mesenteron. The place
where this invagination took place soon closes up, and on
either side the appendages are seen to bud out. These
appear at first as simple buds, the pair which are to form the
antenna first being seen, and very soon after the antennula3
and mandibles arise simultaneously,

and then after them, in varying order, the other appendages.
These appendages increase in length and become divided
into a series of joints, and each, except the first, acquires a
two-branched condition. The mesenteron, formed as we have
seen, for a time exists without any connection with the ex-
terior, but soon there is a pushing in at each end of the body,
and the tubes thus formed unite with that already existing,
forming the completed alimentary canal.

The stage of growth at which the embryo hatches from FIG. 11. Gastruia of crayfish.

i . -i /. a - Abdomen, m. Mesenteron.

tne egg varies even among closely allied forms, there being p. Proctodeum. s. stomodeum.

FIG. 9. Ner-
vous system
of lobster.

FIG. 10. Section of segmented
egg of shrimp.

10

NATURAL HISTORY OF ARTHROPODS.

An

several distinct types of development, which, omitting several exceptions, may be
here briefly described. The barnacles, Entomostraca, and a few examples of other

groups, hatch when but three pairs
of legs are developed. This stage
of the young is known as the JVaii-
plius (Fig. 12), this term having
been applied to one of these larval
forms by Otto Fabricius Miiller, a
Danish naturalist, under the im-
pression that it was an adult.
From this the use has extended,
until now a larval crustacean with
three pairs of limbs, the two pos-
terior two-branched, a single median
eye, a large upper lip, and gener-
ally an unsegmented body is im-
plied by this term. In another type
the young crustacean hatches in
the form known as a Zoea (Fig.
13), named by Bosc, with the same
impression as that to which we owe
the term nauplius. The zoea is
characterized by the presence of a
FiG.i2.-Nau P imsofran^ ca^ s . A. Antenna!*. . Anus. lar S e carapax, sometimes armed

u53!u? o. oc E eiiu s pod ; te stomachr 0podite - ^ Labrum ' with lon S 8 P ines - The abdominal

segments are well developed, but

FiGS. 13 and 14. Front and side view of zoea of Neptunus. a. Abdomen. A. Antennulse. An. Antennae, c.
Carapax. d. Dorsal spine. E. Eye. L. Labrum. I. Lateral spine, rnp 1 . First maxilliped. mp-. Second
maxilliped. r. Rostrum, t. Telson.

CRUSTACEA. U

without appendages, while the seven anterior pair of cephalic appendages are present,
most of them biramous in character. In the higher Decapoda the zoea frequently
gives rise to a Megalops (PL I., Fig. 5), with very large, stalked eyes, and the com-
plete number of appendages, from which, by a series of moults, the adult form is pro-
duced.

In the third type which we have to consider, the young undergo all of these
changes within the egg, and when hatched more or less closely resemble the adult, the
full number of appendages being formed.

On hatching from the egg the young crustacean usually begins to eat, and with the
assimilation of food an increase in size occurs. Now the larva is enclosed in a hard-
ened integument, and so to accommodate this growth, the skin is periodically shed.
This exuviation is accomplished in different ways ; the skin or shell either splits across
between the segments or down the back, and the animal withdraws himself through
the opening thus presented. At first the new skin is very soft, but it gradually
becomes harder, at last acquiring its proper condition. In the young these ecdyses
are very frequent, and are often accompanied by the great changes in the shape and
appearance of the larva just described, but as the animal approaches the adult condition
the exuviations are less frequent, and the changes less marked.

The classification of the Crustacea has not yet reached a satisfactory condition,
but for our purposes the following grouping of the sub-classes may prove convenient :
Sub-class I., Cirripedia ; II., Entomostraca; III., Podophthalmia; IV., Edriophthalmia.

The Phyllopod division of the Entomostraca seems to represent the central stem
around which the other groups are arranged, and with which they are phylogenetically
related, though as yet our knowledge is not sufficient to clearly show the hues of descent
and the degrees of relationship of the various forms.

12

NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS I. CIRRIPEDIA.

The Barnacles derive their scientific name, Cirripedia, from the appearance of their
feet, which, as thrust from the living shell, present a marked resemblance to a lock or
curl of hair. Regarding their common name, barnacles, some doubt exists, though it
probably was derived from the Latin perna, a ham ; diminutive pernacula, from whence
the transition is easy to the now current form. Closely connected with the barnacles,
in a now extinct folk-lore, are the barnacle geese, and Professor Max Miiller has traced

out the myth in its various phases,
clearly showing that it arose from a
similarity of vernacular names of the
bird and of the crustacean. The bird
derived its name from its occurrence
in Ireland (Hibernia), whence the old
form Anas hiberniculce. Then the
" hi " was dropped, as is frequently the
case among Latin words which find their
way into the Romanic tongues, and we
have bernicula. So, as the names were
identical, it most conclusively follows
that the animals are one and the same,
and so arose the myth, which was cur-
rent for five centuries, that the barna-
cles when ripe opened their valves and
out came the young barnacle goose,
Some of the old accounts may prove of
interest.

Bellenden, Archdeacon of Murray,
quoting from a Latin history of Scot-
land (1527), gives this description of
" geis genesit of the see, namit clakis " :
" All treis that are cassin in the seis be
proces of tyme first worme etin, and in
the small boris and hollis thairof growis
small wormis. First they schaw their
held and feit, and last of all they schaw
their plumis and wyngis."

Gerarde, in the Appendix to his
" Herball or generall Historic of
Plantes" (1633), not only describes,

but gives a picture of the whole process, which we reproduce. His description, with
a few omissions, is as follows : " We are arrived to the end of our Historic, think-
ing it not impertinent to the conclusion of the same to end with one of the marvels
of this land (we may say of the world). There are founde in the north parts of

FIG. 15. Gerarde's figure of Barnakles producing geise.

CIRRIPEDIA.

13

Scotland, and the islands adjacent, called Orchades, certain trees whereon doe growe
certaine shell fishes, of a white colour, tending to russet, wherein are conteined
little living creatures ; which shells, in time of maturities do open, and out of them
grow those little living foules, whom we call Barnakles, in the north of England Brant
Geise, and in Lancashire tree geise ; but the other that do fall upon the land do perish
and come to nothing." He then goes on to describe in detail the various transforma-
tions which he witnessed, saying, "But what our eies have seene and hands have
touched we shall declare." He tells us that when the bird is formed in the shell, the
latter gapes, the legs hang out, the bird grows larger, until at length it only hangs by
the bill, and finally drops into the water, " where it gathereth feathers and groweth to
a foule bigger than a mallard and lesser than a goose." In Walton's " Complete
Angler" we find the same idea in poetical form, and, finally, in the "Philosophical
Transactions of the Royal Society" (1677) Sir Robert Moray has published " a relation
concerning barnacles," embodying the same curious idea. These extracts show that
the myth had a strong life, for, although contradicted by Albertus Magnus and
Roger Bacon, still, so the story runs, the barnacle goose was allowed to be eaten during
Lent and on fast days, since coming from the barnacle, a fish, the goose could not be
flesh, and hence was not prohibited by the laws of the church.

It was not till 1828-29 that J. V. Thompson showed by their embryology that
the barnacles should be classed with the Crustacea. Previous to that time they had
been universally considered as belonging to the mollusks, from the fact that they
possessed a shell. Even Cuvier, who dissected them, failed to be struck with their
articulate characters. Thompson's discoveries were soon published, and at first met
much opposition, though their accuracy was soon established.

We may take for our type of the group Lepas fas-
cicularis Ellis and Solander, which is well represented
in Fig. 16. In this form we have a short, stout, fleshy
stalk or peduncle by which the animal attaches itself, and
a larger " head " or capitulum, in which we find the prin-
cipal organs of the ciriped. Occasionally, instead of
being attached to some marine object, this species of bar-
nacle secretes a float from the cement glands of the pe-
duncle, and thus, free from every other object, is drifted
about by the waves. The capitulum is flattened and en-
closed by five calcareous valves connected by a tough
membrane. On one edge there is an opening through
which the feet and the mouth can be protruded at will,
but when the animal is disturbed, in go the feet, and
by the aid of a muscle connecting the valves of the shell, all is made close and
tight. Removing the valves from one side (Fig. 17) we can see the body, irregularly
oval in form, with six pairs of long, feathery feet, each pair being divided in twain
nearly to the base. In life these twenty-four feet are in constant motion, creating
currents in the waters, by which food is brought to the mouth, which is situated
on a sort of prominence nearer the peduncle. On either side of the body are
several " filamentary appendages," whose function is not known, though they are
supposed to be respiratory, or partially so. On opening the animal we find that the
alimentary canal is but little more than a simple tube, the limits between oesophagus
stomach, and intestine being very indistinct. The mouth is furnished with three pairs

FIG. 16. Lepas fascicularis.

14

NATURAL HISTORY OF ARTHROPODS.

of delicate mouth-parts, and over the outside of the stomach occur numbers of simple
glands, which are supposed to represent the liver. The nervous system (Fig. 17, C) is
upon the regular arthropodal type and needs no special description. Its principal
features can be made out from the figure, and its general relations are the same as in
other Crustacea. One thing, however, is of interest. For a long time the barnacles
were supposed to be without organs of vision, but in 1848 the eminent anatomist, Dr.
Joseph Leidy of Philadelphia, found the eyes in the Acorn Barnacle, JZalanus, and since
that time they have been found in many other species. In the form now under
discussion there is but a single eye present, and this is found as a small, dark spot in

front of the mouth, and
completely covered by the
integument of the body.
Although to a superficial
glance this eye seems
single, it is in reality com-
posed of two, as is seen
from the fact that it re-
ceives a nerve on either
side (Fig. 17, C e). Of
course an eye of this simple
character and so enclosed
bv the skin cannot be of

m

use in distinguishing ob-
jects, but since the tissues
of the body are very trans-
lucent, this eye can recog-
nize the differences be-
tween light and shade.

^j

Of this ability, a ready
proof is attainable ; go to
some tidal pool where the
little white acorn barnacles

FIG. 17. Anatomy of Lepas fascicularis. A. General anatomy: a. anus;

c. cirri ; d. dorsal sinus ; e. adductor muscle ; f. filamentary ap- abound, and there watch

pendages ; h. hepatic openings ; i. intestine ; 1. liver ; m. mouth ;

o. ovary ; p. penis ; s. stomach ; t. testis : v. vas deferens ; v.c. the delicate and feathery

carina ; v.s. scutum ; r.t. tergum. It. Mouth-parts. C. Nervous

anatomy : a. antennal nerve ; c. nerves to cirri ; e. eye ; o. optic movements OI the C11T1, and

ganglia; ce. CEsophageal commissure; s. supra-oesophageal ganglion.

then suddenly pass the

hand between them and the source of light, and instantly every foot will be withdrawn,
only to be put out again after some considerable time has elapsed.

The barnacles are peculiar, in that they have no heart, and even distinct blood-
vessels are wanting. The blood Hows around between the different organs and
muscles, and is kept in motion by the movement of the various parts of the body.
There exists a large cavity in the dorsal region, which may be supposed to represent
the heart, but no distinct Avails are found and no traces of valves exist. In their
respiration the barnacles are equally degraded, the whole surface of the body aiding in
the aeration of the blood.

The reproductive organs of the barnacles are, in comparison to the rest of the body,
very large. In each individual are to be found both male and female parts. The
former form finely lobular masses on either side or the body, communicating by fine

CIRRIPED1A.

15

branching tubes with a long intromittent organ arising below the vent, at the base of
the sixth pair of feet. The ovaries are situated in the peduncle, and superficially
resemble the spermogenous organs. The eggs when ripe pass out into the capitulum
and there are impregnated. Leaving the egg for the present we will consider a highly
interesting subject connected with the reproduction of these animals.

As has been said, the greater portion of the barnacles are hermaphroditic, that is,
in each individual are combined the organs of both sexes. Now, one would think that
these animals were peculiarly adapted for self-fertilization, but this, so far as our
knowledge goes, is not the case. Large numbers of plants have both stamens and
pistil (male and female organs) existing in the same flower, and in the older botanical

works, especially those with a teleological ten-
dency, attention was called to the adaptations
which these flowers exhibited for fertilizing
themselves. But subsequent observations
show that another interpretation can be placed
upon the structure of these organs, and to-day
it is clearly proved that in many plants self-
fertilization is impossible, and that pollen of
another flower is absolutely necessary for the

FIG. 18. Scnlpellum regium, with complemental
males attached at a.

FIG. 19. Complemental male of Scalpellum regium,
greatly enlarged.

fertilization of the ovule and the development of the seed. So with the barnacles. When
we study more closely their habits, their anatomy, and the relations of the individuals to
each other, we see that there exists a striking adaptation for cross-fertilization. In Lepas
fascicuZaris, as in the majority of the barnacles, the individuals occur in colonies placed
in close juxtaposition to each other, and so the moderate-sized intromittent organ can
be inserted into the shell of the adjoining specimen. In Acasta, a form which is found on
certain corals, the different individuals are usually a little distant from each other, and
here we find the intromittent organ extremely elongated, several times the length of
the body, so that it can extend from one specimen to its neighbor. Certain barnacles
are always found semi-parasitic on larger animals. One species, Anelasma squaZicota,
makes a sort of burrow in the skin of sharks, and has a seeming provision for cross-
fertilization the animals occur in pairs. There is still a more peculiar condition. The

16

NATURAL HISTORY OF ARTHROPODS.

two genera, Ibla and Scalpettum are generally solitary ; but in these genera we have
a queer assortment of sexes. First, we have the normal hermaphrodites ; secondly,
forms similar in appearance but which are only females, the testicular tissue and the
intromittent organ being absent ; third, males which are attached to the females, and
others (complemental males) which are found only in the hermaphrodites. These
males show a great imperfection of development, and always are found living like
parasites. In some the mouth and alimentary canal is entirely lacking, some have a

peduncle, others none. The male generative
organs are always developed, but the intro-
mittent organ when present is very short.
These forms are found just within the valves,
there being sometimes ten complemental males
found within the capitulum of a single her-
maphrodite. Upon the theory that cross-fer-
tilization is a necessity, the existence of these
different forms is readily understood; upon
every other it seems to be inexplicable. Nor
is our knoAvledge of cross-fertilization wholly
theoretical. Both Dr. Fritz Mtiller and Mr. R.
Bishop have published accounts of witnessing
the very act, and the writer would also add
his testimony, having seen the operation in the
common white acorn barnacle, JBalanus bala-
noides.

We have noticed the curious life-histories
which the older writers connected with the
FIG. 20. Naupiius of Baianus baianoides, the Barnacles, but scarcely less marvellous is

frontal horns not fully extended ; greatly enlarged. , i i i p -i mi,

the true embryology of the group. The fer-
tilized eggs, which we left inside the capitulum, there undergo an unequal segmenta-
tion, some of the cells growing around others which are destined to form the
alimentary canal. Soon three pairs of legs bud out, the two posterior becoming
birarnous, and the young barnacle hatches in the form known as a Naupiius, This
nauplius is characterized by the presence of two frontal horns, a single eye on the
under surface of the head, and a long upper lip. All cirriped nauplii have these points
hi common, but otherwise they present many prominent points of difference in the

different groups. In some there is a great develop-
ment of spines. With its growth the nauplius moults
several times, and finally it passes by a single moult
into the Cypris stage (so called from its resemblance
to the adult condition of one of the Ostracoda). The
dorsal shield is then replaced by a bivalve shell,
hinged above and kept closed by a transverse muscle
just below the mouth ; a compound eye appears on
either side of the primitive single ocellus. A fourth pair of appendages arise behind the
mandibles, and behind these are found the rudiments of six pairs of feet. The second pair
of antennas disappear, while on the first pair is developed a sucking disc, in the centre
of which is the opening of the cement gland. With succeeding moults the posterior feet
increase in size, and are used in swimming. The free-swimming cypris stage is not of

FIG. 21. Cypris stage of Baianus,
enlarged.

CIRRIPEDIA. 17

long duration ; the animal attaches itself by the sucking disc on the antennae, while the
cement gland pours out a secretion which more firmly fixes the larva. The succeeding
moults are each accompanied with changes in structure, which, slight when considered
singly, in the aggregate produce important modifications in the form of the body,
resulting at last in the adult condition.

Having now a general idea of the structure and growth of one cirriped we may
pass to a consideration of the various forms, noting their differences from the type
chosen. We may divide the cirripeds into four orders, APODA, ABDOMIKALIA, RHIZO-
CEPHALA, and THORACICA, all of which, with the exception of the Rhizocephala, are
treated in Mr. Darwin's masterly monograph.

ORDER I. CIRRIPEDIA APODA.

This group is represented by the singular genus, Proteolepas of Darwin, which
leads a parasitic life upon one of the higher barnacles, Alepas cornuta. Externally
it strongly reminds one of an insect larva fastened by two threads (the antennas) to
the host. All traces of the cirri are absent. The body is composed of eleven
segments, while the mouth is suctorial and so projects from the rest of the body as to
give one the impression that it constitutes a distinct segment. Inside of this proboscid-
iform mouth are the mandibles, which serve not only as a means of cutting the skin of
the host, but as hooks to anchor the parasite firmly in position. From the mouth can
be traced a short oesophagus, but all other portions of the alimentary tract are absent,
there being no stomach, no intestine, no anus. The nervous system is also apparently
absent, and the whole cavity of the body is occupied with the reproductive organs. The
antenna?, however, possesses the same structure as in the other barnacles. Of the
development of the single known species, Proteolepas bivincta, nothing is known.

ORDER II. CIRRIPEDIA ABDOMINALIA.

This order is scarcely richer in species than the preceding, but three forms belong-
ing to distinct genera being known, Cryptophialus of Darwin, Alcippe of Hancock,
and Kochlorine of Noll. The body has eleven segments, and three pairs of cirri are
present, but unlike all other cirripeds these are borne upon the
abdominal segments. The labrum or upper lip is very long and
capable of independent movement. The lower end of the oesophagus
is armed with internal teeth, reminding one of the gizzard of the

O O

cricket; the stomach is well developed, while the anus is at the
end of the last thoracic segment, just in front of the cirri. The whole
body is enveloped in a flask-shaped sac. It was the study of Cryp-
tophialus minutus (Fig. 22), which bores into the shells of Conch-
olepas peruviana, which first led Mr. Darwin to the study of the
cirripeds. This form, as its name indicates, is very small, the largest
being not a tenth of an inch in length.

While in many groups of animals the females of widely different
families closely resemble each other, and we have to resort to the males for classificatory
characters, in the Cirripedia the reverse is the case, for when males exist they are always
of an extremely rudimentary character and always live as parasites upon the females.
Such is the case with the Abdominalia, where several males are attached to the mouth

VOL. II. 2

18

NATURAL HISTORY OF ARTHROPODS.

of the female, those of Cryptophialus minutus closely resembling those of Alcippe, which
was formerly placed among the Thoracica, and showing far more resemblance to those
of Ibla and Scalpellum than do the females.

But little is known of the embryology of this group. Alcippe hatches as a true
nauplius and subsequently passes into the pupa state, closely resembling that of the
Thoracica, while in the other forms a free nauplius stage is absent. The embryo is at
first oval, but soon two anterior processes, the rudimentary antennas, appear. The larva
next passes into the free cypris stage, creeping about freely within the mantle of
the mother. The subsequent stages are not known.

The known species of Abdominalia have the following distribution : Cryptophalius
comes from the Chonos Islands, Southern Chili ; Alcippe from the English coast, and
Kochlorine from the Mediterranean.

OHDER III. - - CIRRIPEDIA RHIZOCEPHALA.

These degraded Cirripeds, in their adult condition, live as external parasites upon
the abdomen of the higher Crustacea, and by degeneration have so completely lost
every trace of an articulate structure that were we ignorant of their development, their
affinities with the Crustacea would not be suspected. In shape they are sack-like, more
or less modified in form by pressure between the thorax and abdomen of the host.
From one side arises a tubular process which penetrates the host and frequently divides
up into numerous root-like branches. This tube is in reality the mouth, and through it
the juices of the crab pass into the body of the parasite. Nearly opposite the mouth
is an opening through which the eggs pass out. The whole body is enclosed in a
thick muscular mantle, which is never calcified. The internal organs are principally
reproductive, the animals being hermaphroditic, while the digestive organs are fre-
quently entirely absent. No traces of a nervous system have as yet been found.

When we study the embryology of the group we recognize
at once its affinities. From the egg there hatches a nauplius
resembling that of the true barnacle in having frontal horns,

O O '

while the hinder end of the body ends in two points and the
mouth and alimentary canal are Avanting. After several moults
the cypris stage is reached and the larva after swimming freely
for a while attaches itself to the abdomen of some crab, and
there undergoes the retrograde metamorphosis which results in
the degraded adult. The Rhizocephala are usually regarded
as the lowest of the Crustacea, but Kossmann, whose account we
are following, places them as they are here classified.

Six genera and about forty species of Rhizocephala have
been described, but the distinctions between the various forms frequently seem unim-
portant, and the characteristic which is most emphasized in the diagnoses
is the host, it being assumed that the parasites of different species of
crabs must of necessity be distinct. Several forms occur in North
American waters, but they have not been studied. We figure two
species : Peltogaster pagiiri (Fig. 23), which, as its name indicates,
is parasitic upon the hermit crabs, and Lernceodiscus porcellance (Fig.
24), as attached to the abdomen of a porcelain crab. The roots, which FIG. 24.
are well shown in the former figure, are said to have the power of growth

FIG. 23. Peltogaster pag-
uri, showing root-like
mouth - parts. En-
larged.

CIRRIPEDIA.

19

when separated from the rest of the body, and Fritz Muller says that a parasitic isopod
frequently eats the body of the root barnacle and then settles down and draws his
nourishment through the roots, which under this stimulus continue their growth. The
effect of the root barnacles upon their host is to entirely prevent the normal action of
the reproductive organs.

ORDER IV. CIRRIPEDIA THORACICA.

These forms agree, in having six thoracic segments, usually bearing six pairs of
appendages, the abdomen being absent or rudimentary, the
body enveloped in a carapax, which is frequently stiffened by
a deposit of salts of lime, and are either sessile or mounted on a
fleshy stalk or peduncle. This order embraces the great majority
of forms and is readily divided into three families : the Lepadidae,
Verrucidae, and Balanidae.

FAMILY LEPADIDAE. -These Barnacles are characterized by
the possession of a fleshy stalk or peduncle which in some is
very short, in others sometimes over a foot in length. The
capitulum is always flattened and the two sides are drawn to-
gether by a single transverse muscle. The general characters
of the family have already been mentioned in connection with
the account of Lepas fascicularis, and need not be repeated
here. Most of the Lepadidas are attached only by the tip of the
peduncle, the rest of the body hanging freely in the water, but
in the genus Lithotrya a different habit is noticed. The
species of this genus, which are mostly tropical, bore holes in
shells, corals, or calcareous rocks, in which they live. These
holes are excavated by horny spines and calcified beads upon
the extremity of the peduncle, and so far as the evidence goes
the boring is simply a mechanical action. One species, L.
dorsalis, inhabits the Carribean region, the rest living in the
eastern seas.

Pollicipes seems to be the most generalized type of Barna-
cles, a fact which is in full accord with its geological history, it
being the oldest genus. The calcareous valves are very numer-
ous, varying in number from eighteen to over one hundred.
Two species occur on the western coast of our continent,
P. polymerus being the common California form. Of Ibla
and Scalpellum we have already had occasion to speak in
connection with the reproduction of the Barnacles. A single
species of Scalpellum, S. /Stromei, has been found in the deep
waters off the New England coast. There are several genera
of Lepadidae in which the calcareous valves of the capitulum
are very small or wanting, of which we can only mention Coit-
choderma aurita, which has two tubular earlike appendages
on the capitulum, which possibly are of use in respiration,
while the more common C. virgata is without such append-

ages.

The specimen figured (Fig. 25) is attached to a Penella,

PIG. 25. A Barnacle, Con-
choderma virgata, attached
to a sea pen, Penella filosa,
which in turn was parasitic
on a sun-fish.

20 NATURAL HISTORY OF ARTHROPODS.

one of the siphonostomous Crustacea (to be referred to further on), which in turn was
parasitic upon the large sunfish, Mola rotundata. Lepas, the typical genus of this
family, is almost invariably attached to floating objects, and, hanging down in the
water, sometimes reaches a length (in L. anatifera, Fig. 26) of sixteen inches. These
are the most common forms in collections, and the species have a world-wide distri-
bution.

FIG. 26. Lepas anatifera, attached to floating pumice-stone.

FAMILY VEBRUCID^E. -This family, containing but the single genus Verruca,
closely resembles the next in being sessile, but differs in having a very symmetrical
shell, and the valves closely resemble those of the Lepadidas.

FAMILY BALANID^E. The acoi-n barnacles are the most numerous in species and
specimens, and we may take the common form of the Northern Seas, Balanus balan-
oides, as our type. This species, which is found encrusting rocks and piles between
tide-marks, in form is a white calcareous pyramid, made of six immovably-united
pieces, forming an irregular oval ring with the centre filled with four movable valves,
between which the animal protrudes the cirri. Inside of the shell we find the animal
closely resembling that part of a Lepas which is embraced within the capitulum, but
with an additional muscle for pulling down the occludent valves and thus more com-
pletely protecting it. Bdlanus psittacus, is the largest species, sometimes reaching a

CIRRIPEDIA. 21

length of nine inches, and in one case three and one-half inches in diameter. It is con-
sidered, both by the natives of the west coast of South America and the travellers
who have eaten it, a delicious article of food.

Chelonobia is a flattened form which is usually found attached to turtles or
Crustacea in tropical seas, the tortoise-shell turtle almost invariably having several
attached to his carapax. Coronula,
with its three species, diademia (Fig.
27), regina, and balcenaris, always
occurs imbedded in the skin of whales,
a habitat which is shared by Tubici'n-
ella, while Xenobalanus affects the
shell of Tortoises and skin of Black-
fish.

Of the Cirripeds the Thoracica
alone have been found fossil. The

Lepadidae appeared first, Pollicipes, FIG. 27. Coronula diademia, one-third natural size.

the oldest genus, appearing in the

Lias, while the family attained its culmination in the Cretaceous Period. Verruca
appears in the Cretaceous, while the Balanidae belong to the Tertiary and Recent times,
Balanus occurring in the Eocene of Europe and America. Many species have been
described by Lea, Conrad, Morton, Holmes, and others from American strata, but from
the fact that the opercular valves are usually wanting, it becomes very difficult to rec-
ognize the affinities of the species mentioned. The geological history, the structure,
and the development as far as known all point to the idea that Pollicipes is the ances-
tral form of the Thoracica, and from it have developed on one side the rest of the
Lepadida3, and on the other the sessile Balanidae and Verrucidae.

J. S. KlNGSLEY.

22 NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS II. ENTOMOSTKACA.

BETWEEN the Cirripedia, or barnacles, which we have just left, and the Podoph-
thalmia, or stalk-eyed crustaceans, there are placed, in all systematic treatises, a large
number of Crustacea, mostly of minute size, the large majority of them being so small
as to require the compound microscope in their study. Beyond the fact that they
occupy the intermediate position just mentioned, authorities do not completely agree
in their classification. But this difference of opinion arises chiefly from the fact that
some consider the divisions Cladocera, Copepoda, etc., as sub-classes equivalent in rank
to the Cirripedia and Podophthalmia, while others regard these groups as only of
ordinal value, a view which we are inclined to adopt.

In the Entomostraca the abdomen is almost always devoid of appendages, and,
further, is frequently itself reduced to a mere rudiment. But three pairs of morpho-
logical limbs function as mouth-parts, while the true limbs show an almost endlessly
varied series of form, and the variations in number are nearly as great, all being lacking
in the adults of some parasitic forms, while in some of the Phyllopoda the number
of appendages exceeds sixty. Some of the Entomostraca have specialized respiratory
organs, in others all traces of organs of circulation and respiration are wanting. The
Entomostraca almost always hatch from the egg as nauplii. Beyond these few points
it is difficult to go ; for there is so much variation in the different orders and indi-
viduals that but few statements will apply to the sub-class as a whole.

From an economic standpoint the Entomostraca are important only as they
indirectly affect human interests by furnishing food for fishes, or, by the parasitic
habits of some forms, tending to injure the quality and growth, or even destroy the
life, of this valuable source of food. The larger forms are somewhat rare, compara-
tively speaking ; but the smaller forms, especially in the ocean, exist in unnumbered
millions. No one who has never drawn a surface net in some sheltered bay has any
idea of the myriads of Entomostraca in the sea ; and should this " surface skimming "
be perfonned on a still night, the phosphorescence adds not a little to the interest of
the occasion. While in tropical seas large numbers of animals produce this light,
on the New-England coast the greater part is the result of the Entomostraca, though
jelly-fishes and Infusoria furnish their share.

In the succeeding account each order of Entomostraca is mentioned, but only the
most important families are enumerated.

ORDER L COPEPODA.

This order embraces many of our commonest fresh-water Entomostraca, as well as
very numerous salt-water forms. In number of species, and in economic importance
as well, it stands first. In range of habitat, and in reproductive power, the group
surpasses all others among the Crustacea. The animals are mostly small, but are
very active; better fitted for locomotion and for a predatory life than are the
Cladocera, and so find all waters and all localities suited to one or more of their many
species.

ENTOMOSTRACA.

23

Turning to the technical characters, we have to note that the anterior segments
of the body are covered with a carapax ; the feet are few in number, not exceeding
five pairs ; a single eye is present, and the segments
of the body are well marked. Like most of the En-
tomostraca, the Copepoda hatch from the egg in the
nauplius stage, from which the growth to the adult is
gradual, no startling metamorphoses being introduced
with the moults.

Of all the Copepoda none is more widely dis-
tributed or better known than Cyclops, the type
of the family CYCLOPID^E. It is found in ponds
and slow streams all over the world, and is the
most common crustacean inhabitant of our drink-
ing-water.

It has a body of a long-oval or pear shape, with
a large anterior shield, to which succeed four large seg-
ments, followed in turn by four smaller joints, forming
a tail, which is terminated by two projections armed
with bristles.

In front of the animal appears the small com-
pound eve, the primitive crustacean eye, which is
found in a rudimentary form in so many of the higher
members of the Crustacea, where it has been func-
tionally replaced by a larger and more perfect com-
pound eye. The reten-
tion of this relatively

imperfect sense-organ as the only organ of sight is one
among several features which mark this as one of the
most primitive groups of Crustacea.

The large, straight intestine, usually filled with food
and kept in constant motion, occupies most of the body
cavity. By its churning action it keeps the blood in
motion, and thus fills the place of a heart, an organ
wanting in this genus, though present in other Copepoda.
At the proper season the large ovary may also be seen,
and often numerous fat globules, sometimes aggregated
into large masses.

Of the appendages the antennules are functionally
the most important. They are long, stout, many-jointed,
and serve as most vigorous organs of locomotion. The

fj *j

antennaa are much smaller, and the mouth parts, man-
dibles, and pairs of maxilla are fitted for biting. There
are four pairs of large, two-branched legs, which are used

a

FIG. 28. Cyclops fluviatilis.

in swimming.

FIG. 29. Cyclops canthocarpoides.
a. Antennulse. b. Eyes. c. Oviduct.
d. Carapax. n. Ovisac.

These Copepoda have various methods of locomo-
tion. Most frequently they ply their antennules like a
pair of oars, and assist their progress by strokes of the
tail, using it as a sort of sculling oar. The exact style of

24

NATURAL HISTORY OF ARTHROPODS.

motion depends upon the size of the antennules. In Cyclops they are of moderate size,
and are actively used in swimming, though the tail is employed for sudden leaps, and
often aids ordinary progress. In the CALANID.E the antennulae are very long often

FIG. 30. Calanus pavo.

longer than the animals and moved by muscles of corresponding strength. Single
strokes propel the animal to a considerable distance. This power, and the relatively
large size of these members of the Copepoda, give a sort of dignity to their movements.
They remain quietly at rest for some minutes, flapping the wing of the maxilla in order

to keep up a current of water for respiration, and perhaps to
bring small bits of food to the mouth ; then suddenly dart a
little way, probably to seize some victim, and then return once
more to rest. Their vigor is well seen on trying to catch
one with the dipping-tube. As soon as the animal feels the
rush of ascending water it darts off with a single powerful
stroke of the antennules, and so escapes repeated attempts at
capture.

At the other end of the series from Calanus, so far as re-
gards locomotion, stands Canthocamptus^ a member of the
family HARPACTID.E (Fig. 31), whose antennules are very
short, and their action aided by a constant wiggling of the
body in locomotion making their motion almost worm-like.

Cyclops, both in structure and habits, stands between these
extremes. It is usually found, like Calanns, in the free water,
though, like Canthocamptus, it may burrow in among weeds
and vegetable debris. Often it lies suspended in the water,
at rest save for the fluttering of the maxilla, or it may rest by
FIG. 31. - Canthocamptus clinging to some support. It may move slowly and steadily

cavernarum. -TIC. / T i

by rapid strokes of its thoracic feet, or dart an inch or more

by sudden strokes of its antennules. These movements seem to catch the prey,
which consists of rotifers, Infusoria, other Crustacea, in short, any animal not too large

ENTOMOS TRA CA. 25

or too active to escape its attack. The intestine is often filled with vegetable matter,
but this appears to be eaten mainly if not wholly for the sake of the animals it contains.
The cellulose seems to be unchanged by the intestinal juices of the animal. It not
only eats these minute creatures in the mass, but can single out and hunt down its
prey. An interesting study may be made of a Cyclops placed in a glass containing, say,
JParamoecia. The Copepod may hurry about, darting from spot to spot, surprising
its prey, or it may stealthily swim about by means of its thoracic feet, and so creep up
within reach of its food. For minutes together it will remain at rest, until the smaller
animals are collected about it, then pounces upon one and quietly devours it, and looks
for new prey. But it does not depend solely on hunting. It will, especially in confine-
ment, buiTow in decaying vegetable matter, and there seek its food ; and a decaying
animal is always haunted by these Crustacea, though probably more for the Protozoa
collected about it than for the decaying flesh itself, although that may be eaten.

The development of Cyclops and its allies shows their primitive nature, indicated
also by their eye, carapax, segmentation, and appendages. They hatch from the egg,
as a nauplius, a tiny creature with oval, unsegmented body, a straight intestine, a
median eye, like that of the adult Cyclops, and three pairs of locomotor appendages
representing respectively the antennulas, antennae, and mandibles of the adult. This
larval form is of great interest because of its constant recurrence among the Crustacea.
No equal group in the animal kingdom combines so great diversity of form with unity
of fundamental structure and development as does the class of Crustacea. The
nauplius larva is one of the great bonds of union in the class. Barnacles, Cladocera,
Copepoda, prawns, and many other diverse forms have the egg at this stage, and in
other groups it is clearly indicated as a stage in the development of the egg.

The changes in passing from nauplius to adult in the Cyclops are of the simplest
character. New segments and appendages are added to the rear of the nauplius, and
their front appendages are modified to serve their permanent uses. These changes are
effected by very numerous moultings.

Small as the Copepoda are individually, they are of no little economic importance.
This importance they reach through their enormous reproductive powers. An old
Cyclops may produce forty or fifty eggs at once, and may give birth to eight or ten
broods of children, living five to six months. As the young begin to reproduce at an
early age, the rate of multiplication is astonishing. The descendants of one Cyclops
may number, in one year, nearly 4,500,000,000, or more than three times the total
population of the earth ; provided that all the young reached maturity, and produced
the full number of offspring.

These animals thus appear in immense numbers, and their multitude compensating
for their small size, they are of great value as a fish-food. They form the main food
of most of our fresh-water fishes while young ; and some adult forms, like the Coregoni,
feed mainly on them. The shiners, too, which serve as food for so many larger fish,
derive much of their nourishment from these Crustacea. Insect Iarva3, too, find them
an important item in the bill of fare.

In the sea the Copepoda are of still greater importance. Hundreds of square miles
of water in the Atlantic Ocean have been seen colored red by these innumerable
swarms. At such times the fish gather in great numbers to feed on the Crustacea ;
and even whales find abundant nutriment from these tiny creatures, whose numbers
more than make up for their minuteness. Whalers are sometimes warned of the prob-
able presence of their game by the appearance of these swarms of Crustacea.

26 NATURAL HISTORY OF ARTHROPODS.

A connection still more important exists between these Crustacea and the herring
and mackerel fishery of the coasts of Scotland and Xorway. The appearance of these
fish on the coasts has been found to accompany the presence of innumerable multitudes
of the Calanus and other genera of these Copepoda. Xo other order of Crustacea can
therefore compare in economic importance with this. The smallest pools and ditches
swarm with them. Wherever life may find a lodging in the water there they are
found, ready to become the prey of all higher animals ; ready, too, by their surprising
rapidity of reproduction to keep their number full. Without them the life of the
JYesh-water fishes would be almost impossible ; and, lacking their innumerable swarms,
the- schools of herrings and other sea-fish would hardly be able to exist.

A few forms of this group demand special notice in addition to those already

named.

One of the marine genera, ftapphirina, belonging to the CORTC^EID^:, is among the
most beautiful of animals. It is large, nearly a quarter of an inch
long, and is broad and flat in shape. Below the transparent cuticle
it possesses a layer of cells from which it gives off flashes of light.
This power it shares with numerous other animals, surpassing them
in the brilliancy of the light, and in the variety of the colors. While
most such animals shine by night, Sapphirina shines by day. As
OIK- looks into the calm sea he may catch sight of brilliant flashes
of color in the water beneath him, purple, sapphire blue, gold, or
green, or other hues. The brilliancy may also vary from the softest
to the intensest and most vivid tint. Imagine a diamond shining
M ith its own light, and flashing all colors at will, and one may get
a faint conception of this jewel of the sea. Like so much of the
beauty of the living world, this power of light-emission is connected

FIG. 32. Sapphirina. with the mutual attraction of the sexes, and is possessed by the

males alone.
The families of Copepoda are some twelve in number, and embrace a total of about

four hundred species, as at present known. But the field is far from exhausted.

Almost nothing is known of any except the European species. The American forms

have scarcely been touched, while of the rest of the world the Copepoda are an

unknown quantity. No field to-day will afford the investigator more novelties than

this group of Copepoda.

ORDER II. SIPHONOSTOMATA.

By far the greater majority of parasitic animals belong to the Arthropoda. Land
animals are infected with parasitic insects, and the aquatic vertebrates are abundantly
supplied wilh guests and parasites from the class of Crustacea.

The parasitic Crustacea, like the insects, mainly belong to one order. A few
parasites an- known among the barnacles, and a few scattered forms from other
groups; but the Siphonestomata are all parasites, in the broad sense of the word, and
the group contains very numerous forms of these unbidden guests.

The grades of parasitism in the order are very various. Some species are commensals,
living in digestive tract or gill-sac, but feeding only on the food of the host, not on his
tissues. Others, though true parasites, are locomotive, attaching themselves to their
prey and sucking his blood, but not permanently residing upon him. Others still are

ENTOMOSTRACA.

27

more permanent ictoparasites ; still others are endoparasites, living imbedded in the
body-cavity or tissues of the host, and living on his blood and lymph. Such forms
are often distorted in growth far from the ordinary crustacean type.
Nothing can remind one less of a crab, or the nearest allies of the
Siphonostomata, the Copepoda, than the misshapen forms of the
Lernceocera or Hceinobaphes. Other forms are less widely sepa-
rated from the usual type of Crustacea, and remind one of dis-
torted and ill-shaped monstrosities ; while the temporary parasites
are possessed of well-developed appendages, and in all respects
conform to the usual type. We have, then, all grades of struc-
ture, all the modifications which can be induced by a parasitism here
displayed on a scale, and with a completeness which no other
group in the animal kingdom affords. The parasitic insects are
too little altered in structure, the parasitic worms are all too pro-
foundly modified to give the range of this order. Again, develop-
ment here shows the connection of the various forms. However
unlike the crustacean form the adult may be, the larva always
belongs to the nauplius type, and thus indicates the real affinities
of its parents.

The hosts of these parasites are as various as their forms.
Fishes of all kinds, whales, mollusks, worms, and ascidians are all
provided with these guests. As on land almost every species of
bird or mammal has its own parasitic insects, so in the water
almost every species of fish or larger invertebrate has its para-
sitic Siphonostomata. Numerous varieties of parasites often infest
a single host. The haddock, for instance, has more than a dozen
kinds of parasites, some attached to the skin, others to the fins,
others still to the gills, or to the skin of the mouth, or imbedded
in the muscles. Other fishes have nearly as many forms ; and
careful study would, no doubt, vastly extend the number for all
sorts of fishes. They attach themselves to the skin of worms or Crustacea, -- to the
gills of the latter group, burrow in the flesh of sea-snails, and suck the blood of the
cuttle-fishes. Some forms live in the gill-sac of ascidians, either as commensals or as
true parasites ; and, finally, star-fishes, jelly-fishes, and corals are not exempt from these
omnipresent pests.

From these parasitic habits these forms have acquired the vulgar name of "fish-
lice," and the order itself is called, by some authors, Epizoa, for obvious reasons.
Though closely allied to the preceding order, and, in fact, by some authors united with
it, the Siphonostomata seem to be sufficiently distinct to be entitled to a distinct order.
Forms like Caligus closely resemble the Copepods ; but the more typical species of
these parasites have undergone a most marvellous retrograde metamorphosis, losing
almost everything which could be used as proof of their proper position in any scheme
of classification were the adults, and especially the females, studied, the larval stages
and the males being ignored.

We will begin the series of parasites with A/rgulus, a temporary parasite, living
on the blood-plasma of fishes drawn from the blood-vessels of the gills, but capable of
leaving one host for another, and of maintaining an independent life for a considerable
time, living apart from the host as long as a week or ten days after it has filled itself

FIG. 33 Dinematoura
ferox.

28

NATURAL HISTORY OF ARTHROPODS.

FIG. 35. tfogasus
latrelllei.

FIG. 34. Panda-
rus.

with blood. Indeed, if one may judge from specimens kept in aquaria, it seems to
prefer the free life except when hungry. Argulus (the type of the Family ARGULID.E
through which the Siphonostomata are connected with the Phyllopoda and Ostracoda)
has a flat body, oval in outline, Avith a bilobed abdomen, four pairs of two-branched
swimming legs, besides the antennae and mouth-parts. On each side of the mouth is a
large round sucker, by Avhose aid they attach themselves to the skin and gills of the
fishes on Avhich they prey. They possess pointed mandibles, through
Avhich they obtain the blood, and have, besides, a median needle-shaped
organ, probably connected Avith poison-glands, by which they may
pierce the skin of the host, and by the poison stimu-
late the flow of blood. There are two large eyes, and
the antennae are present. So highly organized an
animal one so Avell fitted for an independent life
is hardly a true parasite. It is parasitic at times,
and when its sacculated intestine is filled Avith blood
may or may not return to a free life.

A second group of the Siphonostomata contains
the CALIGID.E. Here belong A r ery numerous species of
fish-lice. These have still Avell-developed appendages,
but they are fitted for clinging to the host rather than
for swimming, and the forms of C aligns and allied
genera are sessile though capable of locomotion.
They haA r e a sucking proboscis, Avhich encloses the
mandibles. They live, mainly attached to the gills of various fishes,
on whose blood they live. They may often be found by separating the lamellae of
the gills. Here also belong the genera Pandarus and " Nogasus" which Av r e illus-
trate. The latter genus is very doubtful, the individuals being in all probability the
males of forms assigned to other genera. Both forms are parasitic on
fishes, the individuals figured being attached to Atwood's shark (Car-
char odon aticoodi).

In Dichelesthium and its allies, which form the family DICHELES-
THIID^E, degradation is carried a step further. The limbs are often
aborted so that locomotion is possible only by bending the body. Their
habits are much the same as those of the preceding group.

In the family LERIOEIIXE (Lernea, Lernceonema, Penetta, Jfcemob-
aphes, and related forms) the effects of parasitism are carried much fur-
ther. The segmentation of the body is scarcely marked,
the limbs are stumpy projections, and the head is armed
with projections which aid in fixing the animal to its host.
They are rather worm-like than crustacean in appearance.
They live attached to the skin or gills of fishes of all kinds,
or in some of their species buried in the muscles of their
victim. The males are not parasitic, and are of the usual
crustacean form, and the young are Cyclojys-like. The
distorted form of the adult female is reached after the
parasitic life is begun.

In the LERis^EOPODiDyE, the last familv AVC haA r e to

_ T -F-v. 7 77 FlG. 37. eTOE-

mention, embracing JL,ernceopoaa, Diocus, and Ancnoreua, onema radiata.

FIG. ZG.-Hmno-

ENTOMOSTRA CA.

29

creatures
are, they

the degradation of form is still further carried. These misshapen, distorted
resemble nothing but the uncanny figures of a nightmare. Small as they
arouse in the spectator an involuntary feeling of disgust that
such abortions should be found in the group of animals. By
what law of nature it follows that parasites should pay for their
habits by their loss of beauty and symmetry of form, it is per-
haps hard to say, but the fact is undoubted. Wholly apart
from a knowledge of their habits, these and most other para-
sitic forms of animals awaken feelings of disgust. Very few
are even neutral aesthetically ; fewer still are even moderately
beautiful, and those are of the less truly parasitic forms.

In many of these parasitic Crustacea the males are much
smaller than the females, so-called pigmy-males, and are far
less numerous. The females, as is the case in most parasites,
produces enormous numbers of eggs.

The development for a time is essentially similar to that
of the preceding order. The eggs are carried in egg-pouches
(shown in the figures of Dinematoura, Pandarus, Hcwtiobaphes,
and Lernoeonema), and from them hatch true nauplii. After
hatching, the young pursues a type of development peculiar to
the family to which it belongs ; but in all cases it is the female
which undergoes the most extensive metamorphosis, the males
diverging but little from the normal crustacean type.

OKDER. III. OSTRACODA.

As in many another group of minute animals, we have to
turn to Europe and European forms for a knowledge of the
one now before us, for the reason that these forms have been
almost entirely neglected by our own observers, who have had
larger, but no more interesting, animals to study and describe.

The Ostracoda are generally very small, and have hard (and
frequently calcified) bivalve shells, which often are so opaque
that only the most indistinct views can be had of the internal
structure without the aid of the somewhat delicate operation
of dissection. This bivalve shell is usually ornamented, and
by the peculiarity of this ornamentation, as well as the structure
of the internal portions, are the species recognized. In the
fossil forms the former group of characteristics alone can be
used. Some of these markings are produced by the attachments
of strong adductor muscles, which pass from one valve to the other, and which by
their contraction close the shell.

The shells of the Ostracoda are usually lenticular or reniform, and frequently one
end is a little larger than the other. On removing one of the valves the internal
structure can be made out with little difficulty. Only seven pairs of appendages are
present ; the two pairs of antennae are large, extending beyond the valves, and with
their long fringes of hairs are well adapted for purposes of locomotion, in which they
are the principal organs. The mandibles are strong, and the mandibular palps are well

FIG.

ing a barnacle, Conchoder-
ma virgata (see also p. 19).

30

NATURAL HISTORY OF ARTHROPODS.

FIG. 39. Ci/pris fusca, enlarged, a 1 . Antennula.
a 2 . Antenna, 'c. Telson. d. Maxillse. e. Eggs.
f 1 . First pair of feet. f 2 . Second pair of feet.
g. Gill. in. Mandible.

developed. The four remaining appendages are one or two maxilla?, and three or four
ambulatory limbs. These variations in number are due to the fact that one of the

members functions as a second maxilla in
some forms (e. g. Cyprus), while in others, as
Cythere, the same member appears as one of
the locomotive series.

The various divisions of the alimentary
tract are not well marked. In the anterior
portion there is a gastric mill slightly resem-
bling that of the lobster and other decapods,
but more strongly recalling the somewhat

Cj / d7

similar structure in the Isopoda. Behind
this mill arise a pair of tubes to which has
been ascribed a hepatic function. Some
forms are without a heart, while in others
that organ is short, and has three apertures.
The nervous system, so far as it has been
studied, consists of supra and infra-oesophageal
ganglia, and a chain of four thoracic ganglia,
from which the ambulatory limbs and genitalia are innervated.

The food may be either animal or vegetable, the latter being taken as well for the
animals entangled in it as for the protoplasm of the plant, for the cellulose is here, as
elsewhere, unaffected by the digestive juices.

The complete protection afforded by the shell confers peculiar habits upon the
Ostracoda. They scramble about clumsily but rapidly, when undisturbed. Their heavy
shells are somewhat of an impediment to graceful locomotion, while the small antennas
are not strong enough to prevent a kind of wobbling in the gait, which sometimes has
a ludicrous effect. When disturbed they make no attempts at resistance or escape, but
the feet and antenna? are quickly drawn in, the valves close, and the animal, relying on
the protection afforded by its hardened shell, sinks to the bottom.

The Ostracoda have about the same value, in an economic way, as any other group
of Entomostraca, but their comparatively small size and numbers make them less
important than the Copepoda. They seem able to maintain themselves when other
Crustacea fail to do so. At least it frequently happens that they are the sole crustacean
inhabitants of a small pool, and a great number of Osti'acoda usually means a paucity
of other forms, while other similarly situated puddles may support a more varied
entomostracan fauna.

The living forms are mostly small, averaging about a twentieth of an inch in length,
though a few members of the group are larger, reaching a length of a quarter of an
inch. The fossil forms sometimes acquire greater dimensions, many being as large as
a good-sized bean, and some even measuring three inches in their greatest dimensions.

As will be seen from the foregoing, there is no group among the Entomostraca, with
the exception of the Siphonostomata, which departs more widely from the regular
crustacean type than does this order of Ostracoda. The bivalve shell gives the animal
a very molluscan appearance, and the animals, especially the fossil forms, were long
referred to that group.

There are six well-marked families in the order, the first two of which have the
antenna? simple, the remaining four families having them two-branched.

ENTOMOS TEA CA. 31

The first family which we will mention is the CYPRIDID.E, so called from its most
prominent genus Cypris. The family is readily distinguished from the next by having
two pairs of ambulatory feet and two pairs of maxillae ; the heart is absent, the eyes
simple (in Bairdia they are absent). The species are found in both salt and fresh
water, and are distributed in all parts of the globe. Cypris is a small form scarcely
exceeding a twentieth of an inch in length ; but, notwithstanding its minuteness, it has a
highly creditable ancestry, for forms usually referred to that genus are found in the
Silurian rocks. The animal swims by means of its antennae, which are protruded from
the shell for that purpose, but as frequently the same organs are used in a mode of
locomotion best described by the term scrambling. The antennas are aided in the
latter method by the hind legs and by the abdomen, which is forked at the extremity,
and is used as a lever to push the animal forward. The smaller antennae have chiefly
sensory functions, while a membranous portion of the maxillae by a constant motion
keeps up a continual current of water through the valves, thus aiding in respiration.
-Bairdia, another genus of this family, extends back to Silurian times.

The family CYTIIERID.E likewise lacks a heart ; the shell is thicker and stouter than
is the case with the Cyprididae, while there is but one pair of maxillaa and three pairs
of ambulatory feet. About twenty genera, with numerous species, are known.

The four remaining families are less important, and may be dismissed with the mere
mention of their names : HALOCYPRID.E, with three genera, CYPRIDINID^E, with nine
and POLYCOPID.E and CYTHERELLIDJE, with a single genus in each.

The young Ostracoda hatch from the egg as a modified nauplius with three pairs
of appendages, but possessing the bivalve shell of the adult.

ORDER IV. CLADOCERA.

This group includes mostly small fresh-water Crustacea, which are enveloped in
a bivalve shell, and which have the antennae fitted for locomotion. Few salt-water
forms are known, but almost every body of fresh water supports its myriads. Open
lakes, ponds, the weedy margins of ponds and streams, marshes, muddy bottoms of
waters, and temporary pools, all have their population largely made up of members
of the Cladocera, whose structure is frequently modified to correspond with the habitat.

We can best arrive at a knowledge of the structure of this group by a study of the
anatomy of Daphnia, one of the most common forms in fresh water.

Anatomically Daphnia is divided into a head and a body, the latter being enclosed
in a large bivalve shell. In the head lie the brain, liver-tubules, and eye, the latter organ
with its large body of pigment being the
most conspicuous structure. The eye is
freely movable by means of three pairs
of muscles, and is connected with the
optic ganglion by numerous nerves. To
the sides of the head are attached the
large two-branched antennae, from which
the order gets it scientific name, the an-
tennaa being compared to the branches
of a tree (xAciJoc, a branch, and xec, a

i \ mi i t. it, FIG. 40. Anatomy of Daplmia pulex. a. Antenna, e.

horn). The surface Avlnch these antennae Eggs. A. Heart, i. intestine; t. Telson. 1,2,3,4,5.
present to the water is greatly increased Five pairs of legs.

32 NATURAL HISTORY OF ARTHROPODS.

by the long plumose hairs with which they are covered. The style of motion of the
various species of the Cladocera largely depends upon the size and mode of handling
these organs. In the Daphnidae, where they are large, the animal usually moves in a
somewhat dignified manner by the slow strokes of the antennae; in the Lynceidae,
where they are small and moved by powerful muscles, the motion is either a hurried,
toddling scramble, curiously suggestive of indecision, or, in the smaller and more
active forms, it becomes a rapid and decisive darting about. Each genus is charac-
terized by its own style of locomotion, and the motion is often varied with the species,
so that the experienced observer can frequently identify the forms in an aquarium with
the naked eye, even when but a fiftieth or even a hundredth of an inch in length.

Resuming our anatomical account, the head also bears the antennulae, fringed with
sense-hairs. These organs are brought down to the edges of the valves, so that they
may take cognizance of whatever passes into the shell cavity. The large shell is but
an enormous development of the integument of the back of the head, and consists of
two layers, between which there is provision for an extensive circulation of the blood.
The upper portion of the shell cavity serves as a brood cavity, while the adjacent
portion of the valves develops the ephippium, to be described further on. The shell
is marked with lines and dots, the pattern varying with the species.

The slender body terminates in an abdomen which is bent forward and ends in two
claws, and is further provided with a row of spines on each side. This terminal joint
is very useful to the animal ; it keeps the valves free from extraneous matter, kicking
out any unwelcome particle which may have obtained entrance, and serves as a
powerful lever in case the animal be caught. To the under side of the body are
attached five pairs of legs, all completely covered by the shell. These are broad, flat,
and leaf-like, composed of several lobes and furnished with numerous hairs. The
largest lobe of the first four pairs is scoop-shaped, with the convexity forward, and
with the outer edge thickly set with long hairs, which reach to the inner surface of the
valves. These legs move together, backward and forward, and so keep up a constant
current of water through the valves, which serves for respiration, and also brings the
food. The fifth pair of legs is of a different shape, and is attached to each other
along the middle line, and flap like a pair of wings, but in reverse direction to the other
legs. The use of this arrangement will appear when the mouth-parts have been
described.

The mouth lies just within the edge of the valves. It is guarded below by the
long, tongue-shaped lower lip, which is normally pressed up against the lower side of
the body. Here are the two mandibles, whose grinding surfaces are rubbed together
to triturate the food. Just behind them are a pair of maxillae, short, hand-shaped
organs, which serve to thrust the food between the mandibles.

The mode of obtaining the food is as follows : The first four pairs of legs flap
vigorously, and propel a current of water through the shell cavity from front to rear.
Just at the edge of the valves lie the small antennae, which take notice of any large or
unwelcome particle. When such an intruder is perceived, the valves close and the
motion of the legs stops. The fifth pair of legs, working in a direction opposite to that
of the others, creates a sort of whirl in the water, and directs a current upward, which
passes between the legs forward to the mouth. The particles of food are thus stored
up in this space until the mouth is ready for them, when the lower lip is depressed, the
mouth opens, and the maxillae push a quantity of food between the mandibles. In a good
locality a large amount of food will be seen as a dark mass between the legs awaiting

ENTOMOSTRACA.

33

its turn to be eaten. These creatures are omnivorous. Infusoria, rotifers, eggs, and
embryos of small animals, diatoms and other algas, vegetable debris of all kinds are
acceptable. The sole
condition is that the
food shall not be too
large to enter into the
cavity of the shell. The
animals are not without
taste, as may be seen by
feeding them with car-
mine. At first your
Daphnid seems to re-
joice in the abundant
food-supply, flaps its legs
vigorously, and accumu-
lates a mighty supply
between them ; but as
soon as it has tasted
the unaccustomed viand
its mood changes. It
works its oesophagus
backward, reverses the
action of its jaws, spits
out the food, and with
the terminal claws on
the tail carefully scrapes
out and kicks from the
shell cavity the carmine,
and even cleans out its
mouth with the same implements; then sulks and refuses to draw in a current of
water laden with such particles.

The Cladocera have an extraordinarily great power of reproduction. All through
the summer they produce brood after brood of " summer-eggs," which are simply buds
detached while still in the condition of a single cell, and resembling eggs in all
external particulars. They develop, however, without fertilization, while the true
egg will not do so. These buds or summer-eggs are carried in a brood chamber

oo OO

formed by the dorsal part of the valves. This varies greatly in size and shape in
different genera. In the Lynceidre it is small and imperfectly closed, and rarely con-
tains more than two large eggs. In the Daphnias there are often a dozen or more
eggs, sometimes as many as forty or fifty, which are enclosed in a much more
perfectly closed brood chamber, and nourished by fluids excreted by the mother into
this cavity. The young develop directly, without metamorphosis, and hatch in the
form of the parent. They remain for a day or two in the cavity after hatching, while
the shell hardens and the muscles gain strength. They are at this time quite active,
and cause much trouble to the parent in keeping the numerous brood in the cavity.
Some lively young one must always be kicked back being too hasty in his attempts
to see the world for himself. These broods of summer eggs are produced in rapid
succession, and as the young begin to reproduce when only a few days old, the rate of
multiplication is very great.
VOL. II. 3

FIG. 41. Acanthocercus, enlarged.

34

NATURAL HISTORY OF ARTHROPODS.

I have seen pools of water red with Daphnias, giving the appearance of bloody
water. Such phenomena used to be terrible portents to European peasants, foretelling

any sort of coming disaster. The water becomes
fairly thick with the animals, and all these thousands
and millions of beings come into life in a very few
weeks.

When the the pools begin to dry up, or, in perman-
ent bodies of water, when winter approaches, a new
mode of reproduction comes in. Instead of what may
be called neu-
ter-females, true
males and fe-

FIG. 42. Ephippium of Acanthocercus.

males are produced from the summer-eggs, and
from the female are produced two true eggs.
These are enclosed in a hardened part of the
shell, called the ephippium or saddle. This con-
sists of the dorsal and lateral parts of both
valves, which become hardened and opaque,
and when the moult takes place these separate
from the rest of the shell and unite their free

FiG.44.Lepto(h>rahyaiina. a '. Antennuise. a". An-

tennse. e. Eggs. h. Heart, s. Shell, st. Stomach.

i, 2, 3, 4, 5. Legs (sixth pair not shown).

, enlarged. g . Brain, n. Heart.

edges to enclose the eggs. In this case
the eggs lie until spring or wet weather
causes them to develop. The parent does
not necessarily die on producing these
eggs, but may return to the formation of
summer-eggs. The deep or open water
forms of Cladocera live, as a rule, through
the winter, while the shallow water forms,
and those inhabiting temporary pools, de-
pend on the winter-eggs for the preserva-
tion of the species from year to year.

This order is divided into two sub-
orders, Gymnomera and Calyptomera.
The first is characterized by a small shell,
not enclosing the limbs, the legs small,
the respiratory appendages rudimentary.
It embraces the families PODONTID.E, with
two genera, in which the abdomen is short
and enclosed in the shell, while the an-
tennulas lie close to the head ; POLYPHEM-
ID^E, which has the abdomen elongate and
free, and the antennula? exsert and free ;
and the LEPTODORID^;, which has six pairs
of ambulatory feet (the other families
having but four pairs), the abdomen
greatly elongate and segmented, while the
respiratory organs are absent. Leptodora

. , J

is one of the most outre of the Cladocera.

ENTOMOSTRACA.

35

FIG. 45. Bosmina striata.

A rudimentary shell is present only in the female. It grows to be more than an

inch in length, and is found in the open water of our great lakes as well as in Europe.
In the second sub-order, Calyptomera, the shell is well-developed, enveloping the

limbs, and the ambulatory feet are broad, lamellar, and indistinctly segmented. The

lowest family is the LYNCEIDJE, which has a short oval heart, a long, slender, convoluted

intestine, very large antennae, both branches of which are three-jointed; and the legs,

of which there are four or five pairs, are dissimilar, the hinder pair being the broadest.

There are about nine or ten genera, the species of which are very small, few attaining

a length of a twenty-fifth of an inch. They are

mostly inhabitants of weedy shores and bottoms of

the shallower parts of lakes and ponds. They are

far less abundant than the Daphnice in temporary

pools a fact, probably, due to their less perfect

ephippium. But favorable localities swarm with

them, swimming from weed to weed, burrowing

about in vegetable debris, or rapidly whirling

about on the calm surface.

In the DAPHNID^E the heart is the same as in

the last family, the intestine is short and straight,

one branch of the antennae is three-jointed, the

other four, while the pairs of ambulatory feet vary

in the different genera, of which there are nearly twenty, from three to six. Of

Daphnia, the typical genus, we have already spoken at considerable length. Bos-
mina is a form closely allied to
Daphnia. It is a beautiful genus,
having the antennulaa very large
and firmly attached to the head,
curving downward and backward
like the tusks of a walrus. The
species are very small and un-
usually transparent, so that the
microscope reveals at once their
whole anatomy. Hyaleodaphnia
is characterized by having the
front of the head greatly pro-
duced.

The last family is the SIDID^E,
which has an elongate heart, a
short, straight intestine, and six
pairs of similar, lamellar legs. It

contains eight genera, of which Penilia, Sida, and Latona are the most prominent.
The economic value of the Cladocera rests upon their astonishing fertility. Their

numbers make up for their minute size, and they form no unimportant element in the

food of our fresh-water fishes the smaller feeding greedily upon them, and as these

in turn furnish food for the larger forms, the importance of the Cladocera and the

Copepoda can readily be seen.

E. A, BIEGE.

FIG. 46. Hyaleodaphnia kerusses.

36 NATURAL HISTORY OF ARTHROPODS.

ORDER V. PHYLLOPODA.

It is seldom that an ordinal name is more appropriate and more descriptive than
that applied to the group now to be discussed, for the term Phyllopoda, leaf-footed, is
at a o-lauce seen to be applicable in the highest degree to these beautiful and interesting
forms. Frequently they are considered as a sub-order of an order Branchiopoda, the
other divisions of which are the Ostracoda and Cladocera.

In all the Phyllopoda except the Branchipodidse the body bears a large earapax,
which in the Apodida? covers the anterior portion of the body in a manner strongly
susi^estive of that found in the lobster and higher Crustacea, while in the Limnadi-

ada? this armature takes the form of a bivalve shell, the two
halves being united by a hinge and closed by an adductor mus-
cle, as in the Ostracoda. This bivalve shell, into which all the
members can be drawn, closely resembles that of certain fresh-
water molluscs belonging to the genera Sphtrriion and Pist'Jiuin.
Morphologically this earapax is but the o-reatlv expanded dorsal

FIG. 47 -Shell of Esthtna - ' / -,-. i

beifragei, enlarged three portion ot the mandibular or a post-mandibular segment, and

forms a good illustration of the hypertrophy of parts to which

we have alluded on page 7. The two pairs of antenna? are present, but in some of
the Apodida? the first pair is small and the second is occasionally absent. The mouth-
parts are a pair of mandibles, two pairs of maxilla?, and in AJ:>HS and its allies a pair
of maxillipeds. The locomotive feet are foliaceous and membraneous, giving the name
to the order, and as portions of them (the exopodites) have respiratory functions, the
name Branchiopoda (gill-footed) is also appropriate. The feet vary largely in number,
there being fourteen in Ximnetis and sixty in some species of Apia*. There is no
distinction to be drawn between the thorax and abdomen, while the number of seg-
ments in these portions shows nearly the same variability as is exhibited by the loco-
motive members, there being twelve in Ximnetfs and twenty-seven in Esther ia and
forty-two in Aps. The abdomen terminates in a telson, which bears a pair of
appendages in all the genera except Thanmnocepha^us.

The internal anatomy, as a whole, follows the usual crustacean type, and only the
modifications peculiar to the order need be mentioned. The heart, which occupies
the usual position, is a more or less elongated tube, partially divided into a series of
chambers by annular constrictions. The alimentary canal is a simple tube, sometimes
lined with glandular bodies of uncertain function. The liver is large, and, contrary
to the usual rule in Crustacea, is placed in the anterior portion of the body, in front
of the oesophagus and beginning of the stomach. The brain or supra-cesophageal
ganglion is very small, and is connected with the ventral chain in the usual manner.
Of this ventral nervous cord nothing need be said, but the brain possesses a peculiar
interest. In the higher Crustacea, so far as our knowledge goes, the brain is composed
of two or more oran^lia fused together, and from it arise the nerves supplying the eves,

i J. * C* *

and both pairs of antenna?, but in the Phyllopoda the brain consists of but a single
ganglion, and the nerves which arise from it supply only the optic organs.

Attractive as they are in form, habit, and structure, the Phyllopoda possess a
higher interest when we study their development and the many curious features con-
nected therewith. The young Phyllopoda leave the egg in the nauplius stage, which,
however, presents several differences from the larva? of other Crustacea to which the

ENTOMOSTRACA.

37

same name is applied. In some the first pair of appendages are absent, in others they

are well developed. Some have the segments of the body behind the mandibles well

indicated, w T hile in others no indication of segmentation

is visible. From this point the development is more or

less direct, no startling metamorphosis being introduced.

With succeeding moults new segments are introduced, and

new limbs appear, until the adult condition is reached.

In the Limniadiadge at an early age the carapax of the

nauplius becomes folded so as to form the bivalve shell

of the adult. It is uncertain whether all of this shell is

moulted, but the evidence adduced seems to us to indicate

that at least in Estheria it is not wholly cast, and that

the concentric lines upon the outside are in reality lines

of growth, like those so familiar among the Mollusca.

An interesting feature of the eggs of the Phyllopods
is their ability to withstand dessication; in fact, the only
species so far as known whose ova have not this power is
Lepidurus productus of Europe. This power is not, how-
ever, confined to this group, but is possessed by Cypris, Cypridinia, Daplmia, and
many Copepoda. It is apparently a necessary provision for the perpetuation of these

forms, for the puddles in which they dwell
usually become dry in the summer, and
were it not for this peculiarity of the
eggs the species would soon disappear.
When the mud is wet again by the spring
thaw the eggs hatch, but it is not neces-
sarily the ova deposited by last year's
brood which people the puddle, for Dr.
Semper found that mud which was taken
from a pond in which he had found Apus
gave no young the first year, and but few
the second ; but in succeeding years he was
able to hatch out nauplii in great numbers.
In 1872 Professor Zittel collected mud in
the oasis of Dahel, which was sent to Pro-
fessor von Siebold, and produced nauplii
of Artemia in 1877, but none in previous
years. A still further peculiarity is the fact
that, at least in several species, it is neces-
sary that the mud containing the ova should
become dry in order that the eggs may
hatch. So far as known a single species of
Chirocephalus is the only form in which
this dessication is not an absolute essential ; and further, the researches of Professor
Brauer show that the eggs of several Phyllopoda develop most rapidly, and, perhaps,
only, when they have previously been exposed to a temperature near the freezing
point. The length of time required for hatching and development varies here, as in
other groups, with the temperature. Branchipus and Apus eggs require several weeks at

FIG. 49. Lepidurus productus.

38

ATURAL HISTORY OF ARTHROPODS.

a temperature of 60 to 65, but at 85 the nauplii appear in less than twenty-four hours.

This power of withstanding the effects of dessication has enabled naturalists to

study the habits and development of these
interesting Crustacea in places far from their
original habitat. Thus Professor Glaus, in
Vienna, found it easy to investigate the an-
atomy of Daphnia atkinsoni, from Jerusa-
lem ; Professor Siebold, at Munich, was en-
abled to study the habits of Artemia gracilis,
hatched from mud brought from Great Salt
Lake ; and Dr. Gissler, in Brooklyn, studied
the embryology of Apus lucusanus, from eggs
obtained in the same manner from Kansas.
The figure we give of the nauplius of Apus
was drawn by Dr. Gissler from one of these
specimens.

There are three well-marked families of
Anten- Phyllopoda, all of which are represented
in North America. The first family, LIMNI-

FIG. 50 Nauplius of Apus lucasanus. a',
nulse. a". Antennae, m. Mandible.

;, has the body enclosed in a bivalve shell, the antennulae small, the antennae
large and well developed ; from ten to twenty-seven pairs of swimming feet. In the
male one or two of the first pairs of feet are provided with a pincer, while in the
females they are simple. The telson is large, and bears a pair of appendages. The
genera are four in number, Limnetis, Estheria, and
Limnadia being the most prominent. Compared
with the other families the Limniadiadas possess but
few points of popular interest.

The family APODID^E contains but two genera,
Apus and Lepidurus. In these the anterior portion
of the body is flattened, and covered with a broad
and somewhat ovate carapax, from beneath which
the abdominal segments project behind, giving the
animal, at the first glance, a somewhat striking re-
semblance to the horse-shoe or king-crab, .Limulus,
with which, indeed, they were originally classed by
Otto F. Mttller. As in the preceding family, the
compound eyes are sessile. The antennae are small,
the second pair sometimes being absent ; the post-
oral appendages usually number sixty-three pairs,
some of the segments bearing as many as six pairs
apiece. The eleventh pair are modified to form the
egg-sacs in the female. The terminal segment of
the body bears two long-jointed appendages, and ter-
minates either abruptly (Apus) or in a long paddle-
like outgrowth (Lepidurus). The family has its best
representation on our western plains and in the Rocky Mountains, where six species
occur, while from all the rest of the world less than twenty species are known. In
America, outside these limits, but three forms are known, one in Greenland, one in

FIG. 51. Apus cequalis, natural size.

ENTOMOSTRACA.

39

the West Indies, and the third in Lower California. None are known in the United
States east of the Mississippi River. The Apodidae frequent shallow pools, where
they sometimes occur in countless myriads, swimming, like
the members of the next family, upon their backs, with a
graceful motion, or burrowing in the soft ooze of the bot-
toms of the puddles, somewhat like a lAmulus^ in search of
food, which, so far as is known, is of an animal nature.

The most interesting feature in connection with Apus is
its parthenogenetic reproduction, which also occurs in Lepi-
durus, Limnadia, and Artemia among the Phyllopoda, as
well as elsewhere in the Arthropoda. In plain English, par-
thenogenesis means a reproduction by means of unfertilized
eggs, the influence of the male element being unnecessary.
The investigations of this interesting subject are mainly the
work of Professor Siebold, of" Munich. He was led to study
by the fact that at that time (1856) no males of Apus cancri-
formis were known. In 1858 males were discovered, "and
Siebold received specimens from various localities. He thus
learned to distinguish with perfect facility the two sexes, and

was able to convince himself that with Apus broods occur which are entirely desti-
tute of males, and go on reproducing parthenogenetically, w T hile other broods occur
in which both sexes are present." "On one occasion, he had the whole contents
of a little pond removed with the greatest care, so as to feel sure that he had
obtained every Apus present. He obtained on this occasion 5,796 specimens of
Apus, every one of which, being carefully examined, proved to be a female." After-
ward he experimented with Artemia, using every care to exclude males and sperma-
tozoa, and demonstrated beyond a question that virgin females will deposit eggs
from which, unfertilized by any male sperm, a brood can develop. How far either
Apus or Artemia can continue reproducing parthenogenetically has not yet been
determined.

The BRANCHIPODID^E, the highest family of the order, lacks the carapax, so char-
acteristic of the other two, though the homologues of the shell glands persist in a rudi-

FIG. 52. Dorsal and side
views of Lepidurus couesii,
natural size.

FIG. 53. Branchinecta coloradensis. a. Male. b. Female, c. Front of head of male, showing claspers.

mentary condition in the adults of at least some species. The head is small, and the
compound eyes are placed upon a stalk similar to that in the Podophthalmia (to be
discussed further on), while the median ocellus (the eye of the natiplius) persists in

40

NATURAL HISTORY OF ARTHROPODS.

the adult. Both pairs of antennae occur, the second being modified in the males to
produce clasping organs. The locomotive feet are eleven in number, the only excep-
tion being nineteen in the Siberian genus, Polyartemia. The distinction between the
cephalo-thorax and abdomen is better marked than in the other families, and the abdo-
men bears two simple unjointed appendages. In many forms the front of the head is
prolonged into a peculiar appendage, which varies much in shape in the different
species.

The genus Branchipus is, in the eastern parts of the United States, the most com-
mon of the Phyllopods, and the species known as _Z?. vernalis is one of the most familiar
fresh-water forms. Like others of the Phyllopoda, it inhabits temporary pools, those
formed by the melting snow in the early spring being favorite localities. Here they
may be found swimming on their backs in the most graceful manner imaginable, their
beautiful shades of red, flesh color, white, and greenish adding not a little to their
beauty. It is just these features which render it impossible for one to make any draw-
ing or illustration which will in any way compare with the originals.

Artemia is a salt-water, or rather brine inhabiting, form, illustrated in North America,
according to the latest authority, by but a single species, Artemia gracilis. This is
found in immense numbers in Great Salt Lake and Mono Lake, and in brine pools
elsewhere in the country. They are frequently found in the salt water which is kept
in tubs on the railroad bridges across the heads of bays and similar places along the

sea-coast. The food is apparently vegetable.

In technical characters this and the next genus differ as
follows : Artemia has eight abdominal segments without ap-
pendages ; the second antennal claspers of the male have their
second joint flat and triangular, while the ovisac is short. In
JBranchinecta the abdomen has nine segments, the male claspers
are simple and cylindrical, and the ovisac is long and slender.
Under ordinary circumstances these would be considered as
of generic value, but what shall we say when we know the
results of the observations and experiments of the Russian
naturalist, Vladimir Schmankewitsch ? Condensed from his
account these were as follows: In 1871 the spring flood broke
down the barriers separating the two different lakes of the
salt-works near Odessa, diluting the water in the lower portion
to 8 Beaume, and also introducing into it a large number of
the brine shrimp, Artemia salina. After the restoration of
the embankment the water rapidly increased in density, until
in September, 1874, it reached 25 of Beaume's scale, and be-
gan to deposit salt. With this increase in density a gradual
change was noticed in the characters of the Artemice, until,
late in the summer of 1874, forms were produced which had
all the characters of a supposed distinct species, A. muehlhaus-
enii. The reverse experiment was then tried. A small quantity
of the water was gradually diluted, and, though conducted for
FIG. 54. a. Branchinecta only a few weeks, a change in the direction of A. salina was

qrubei, male. b. Female, nat- . . , ... ,

iirai size. c. Artemia salina, very apparent. Led by these experiments he tried still others :

Taking Artemia salina, which lives in brine of moderate
strength, he gradually diluted the water, and obtained as a result a form which is known

ENTOMOSTRACA. 41

as Branchinecta schcrfferi, the last segment of the abdomen having become divided
into two. Nor is this change produced by artificial means alone. The salt pools near
Odessa, after a number of years of continued washing, became converted into fresh-
water pools, and with the gradual change in character Artemia salina produces first a
species known as Branchinecta spinosus, and at a still lower density Branchinecta ferox,
and another species described as B. medius. We have already referred to partheno-
genesis in this genus.

There are only two other genera of this family which need to be mentioned,
Chirocephalus and Thamnocephalus. In these genera the frontal process, which is
small in Branchipus, acquires a great development, branching in the latter genus,
which is peculiar to America, in a manner recalling the limbs of a tree, whence the
scientific name of the genus, bushy head. Thamnocephalus also differs from all the
other genera of Phyllopoda in the absence of appendages to the telson.

Several species of Phyllopoda are known in a fossil condition, four being found in
American strata. Estheria occurs in the Devonian of Europe, while Leaia, a more or
less problematical form, occurs in the lower carboniferous of both Great Britain and
Pennsylvania. Apus first appears in the Triassic, while Branchipus dates back to the

Eocene.

J. S. KINGSLEY.

42 NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS III. PODOPHTHALMIA.

This division receives its name from the fact that the eyes are situated upon mov-
able peduncles ; and while this feature of itself is of slight importance, arid, moreover,
is not found in all members of the group, and, on the other hand, exists among the
Tanaidae, which have a doubtful position among the Isopoda, and the Phyllopods, still the
character is so nearly universal that we may be permitted to employ the name for the
group. The name Decapoda, which we have employed to designate a single order, is
frequently used as synonymical with Podophthalmia, but it is even more inappropriate
than that term for the whole group.

The general characters of the order are a body of twenty segments, as in the Edrioph-
thalmia, a carapax which extends over some, if not all, of the thoracic somites ; the
two pairs of antenna are always present, the eyes (except in Cumacea and one or two
aberrant forms) are well developed, and placed on jointed peduncles. Respiration is
effected by well-developed gills, and in their development the Podophthalmia usually
pass through a more or less complicated metamorphosis, in which, in contradistinction
to the lower sub-classes, a nauplius stage is rare.

Though this sub-class has been the subject of more study than any other group of
Crustacea, its classification is as yet in a very unsatisfactory condition. For our present
purposes the following grouping, which fairly represents our knowledge of the subject,
may answer: Order I., Phyllocarida ; Order IL, Schizopoda; Order III., Decapoda;
Order IV., Stomatopoda ; Order V., Cumacea.

ORDER I. - - PHYLLOCARIDA.

This group, which is represented on the eastern coast of North America by two
species of JVebalia, a northern JV. bipes and an as yet undescribed species from
Florida, is of very uncertain position, some classing it with the Phyllopoda, others with
the Podophthalmia, while Dr. Packard prefers to con-
sider it as distinct from both. With this uncertainty
it may be well to allow it for the present to remain
near Mysis, to which it is evidently closely allied.
Nebalia has a compressed body. The rostrum is
articulated to the carapax. The second pair of an-
temuB are nearly as long as the body. Three pairs of
mouth-parts are present, and following them are eight
pairs of short leaf-like feet with respiratory functions. Next come four large and
two small pairs of abdominal feet (the latter inadvertently omitted in the cut). The
last abdominal segment terminates in two large spines.

As has been said, the development closely resembles that of Mysis, and the animal
hatches with all of its appendages outlined, although there exists a time, while the
embryo is within the egg, when the features of the nauplius are hinted at, followed
by another which recalls the zoea of the Decapoda. Doubtless Dr. Packard is correct
in following S alter and Huxley in regarding the fossil forms which occur in the strata

PODOPHTHALMIA.

43

from the Lower Silurian to the Carboniferous, as representing on a, grand scale (Dithyro-
caris being over a foot in length) the Nebalia, half an inch in length, of the present
day.

ORDER II. - - SCHIZOPODA.

The name of this order means cleft feet, and was given in allusion to the biramous
or two-branched character of the thoracic appendages of the adult, both exopodite and
endopodite being present and well developed. This schizopodal character of the
appendages, which remains as a permanent feature in this group, is found only as a
transitory feature among the larvae of most of the Decapod a, thus clearly showing the
higher position of the latter order. The number of pairs of these functionally thoracic

feet varies from six in My sis
to eight in Thysanopoda,
the increase in number over
that to be noticed in the
Decapoda being produced
by the transfer of mouth-
parts to the locomotive
series. The abdomen is
relatively very large, being
frequently mere than twice
the length of the cephalo-

FiG. 56. My sis stenolepis, opossum shrimp, enlarged. thorax. Gills, when pres-

ent, are attached to the

thoracic feet, but instead of being enclosed in a gill-chamber hang freely in the water.
In a few forms it has been observed that the posterior extremity of the digestive tract
plays a part in respiration, it being richly supplied with blood-vessels, while water is
drawn into and then forced out from the anus. It may be interesting in this connec-
tion to note that a somewhat similar feature exists in some fishes. Cobitis fossilis and
several Brazilian forms swallow small bubbles of air, which, in passing through the
intestine, aerate the blood, while similar habits among the Invertebrata, - - insects,
worms, and holothurians, are numerous. Several species of Mysis and allied genera
are common on our eastern coasts, forming a prominent portion of the food of many of
our shore fishes. We figure Mysis stenolepis.

In their development two types are exhibited by the Schizopoda, that furnished by
Mysis and that observed in Euphausia. Euphausia leaves the egg as a true nauplius
with its three pairs of appendages, a
mouth being present, though the ali-
mentary tract is not open at the pos-
terior end. With the succeeding
moults new appendages are formed
and the carapax outlined, while the
abdomen does not make its appear-
ance, except in a very rudimentary
condition, until six appendages are
outlined. A modified zoeal condition
now ensues, from which the adult condition is gradually produced by a series of
successive moults. In Mysis the eggs and young are carried in an incubatory

FIG. 57. Later nauplius of Euphausia, enlarged.
I, II, VI. Appendages.

44 NATURAL HISTORY OF ARTHROPODS.

pouch beneath the thorax, from which the common name of these forms, " opossum
shrimps," is derived. The floor of the pouch is formed from plates arising from the
bases of the legs in a manner similar to that found in the Edriophthalmia. When the
nauplius stage of the young is reached, the egg of Mysis hatches, but as a free life does
not begin until much later, the nauplius skin is not at once thrown off, and the subse-
quent changes are effected within it.

ORDER III. - - DECAPODA.

This group embraces the largest, most interesting, and most useful forms of Crustacea,
and although the general structure is the same, the variation of the different parts in
size and proportion is such as to produce a great diversity in appearance. At first
sight the contrast between the shrimps, whose length is frequently ten times their
breadth, and Ixa, three times as broad as long, renders it difficult to realize that the
two are in any way related, though hi reality every homology can be traced between
the two. Almost every part is essentially the same in each, the difference being only
in the "mode of expression," to use a term which belongs to the science of forty
years ago.

The Decapoda, like all of the Podophthalmia, have twenty segments of the body,
each, with the exception of the hinder one, bearing at some period of life a pair of
appendages. Of these, the two anterior (antennuloe and antenna) are especially devoted
to the senses ; next come six pairs which play a part in eating, followed by five pairs
of feet (ten in all), which are of use in locomotion. On the abdomen are six pairs of
small feet in the lower forms, while in the higher groups, in the males, these are mostly
aborted, and in the females are used only as supports for the eggs. As was stated on
a previous page, the terms head, thorax, and abdomen, when used in reference to the
Crustacea, imply functional and not morphological regions of the body ; and so, in treat-
ing of the Decapoda, the cephalic appendages extend from the antennulae to the ex-
ternal maxilliped ; the thoracic members are the five large pairs used in locomotion,
while the abdominal legs embrace those on the seven last segments of the body.

Going more into details, we will now discuss the various modifications of these
appendages and their functions. The anterior pair, the antennula?, are always small,
and bear the ear on the basal joint. In some cases these antennula? terminate in a
single flagellum, while in others they are two, or even three-branched. The antenna?
usually are mxich larger, and in the higher forms are unbranched, the exopodite dis-
appearing with development. In the lower forms it, however, remains as a scale or
inconspicuous spine. On the basal joint is the external opening of the "green gland,"
an organ supposed to be renal or depuratory in function. Both the antenna? and
antemuilre are fringed with hairs, and are the special seat of feeling, and possibly of
smell as well. Of the mouth-parts the most anterior are the mandibles, a pair of
powerful organs which play a part in the comminution of food, preparing it for
entrance into the mouth, Avhich lies between them. The mandibles usually bear a
jointed continuation, the palpus, which in life assists in cleaning the cutting surfaces,
a crustacean tooth-brush, it might be called. Two pairs of delicate, leaf-like maxilla?
come next, the first being without exopodite, while the second has this branch greatly
developed, foraaing the scaphognathite or gill bailer, to which reference was made on
a preceding page. In life this appendage is kept in constant motion, ptimping water
over the gills. The next three pairs, maxillipeds by name, have the exopodite well
developed.

POD OPH THA LMIA .

45

The thoracic feet in some of the lower groups retain, even when adult, the exopo-
dite, though in a very rudimentary condition. In the higher forms it always entirely
disappears. One or more of these thoracic feet usually terminate in a pincer or chela,
which can be used in grasping or crushing. In the lobster these pincers acquire a
great development, and no mention is necessary of the strength with which they can
pinch. At first sight it would appear as if, in order to form the pincer, the end of the
leg was split, but a little examination shows that in reality the chela is produced by
the last joint of the leg meeting a prolonged portion of the preceding joint, and in
some forms (e. g. Crangori) intermediate stages can be seen where this inner angle is
not produced so far, and the terminal joint has to bend at right angles in order to
meet the palm.

Among the abdominal feet the amount of variation is but slight, and when present,
all, except the first pair, which are modified for reproductive purposes, are biramous ;
the last pair in the Macrura uniting with the last segment of the body, the telson, to
form the powerful caudal fin which the animal uses in swimming backward through
the water. As will be seen when we come to the subdivisions of the Decapoda, the
abdomen shows a good deal of variation in size and development, which need not here
be discussed.

We have already referred to the position of the mouth, which is situated between
the mandibles. In front w r e have a fleshy upper-lip, and below an under-lip, which in
every way, both in structure and development, appears to be an appendage homologous
with the others, but which, until the present decade, has never been so considered.
Respiration is effected (with a very few exceptions) by gills, which are always present,
and are attached to the basal joints of the thoracic limbs and a few of the mouth-
parts, and extend up into the gill-chamber already described. The heart is a strong,
small, and compact organ, situated in the middle of the upper part of the thorax.
From it arise five arteries ; one supplying the eyes, one the upper surface of the
abdomen, one goes down to the lower surface of the body, and there dividing, supplies
the appendages, while the two remaining arteries, one on each side, convey the blood
from the heart to the viscera.

The eggs of the Decapods, after exclusion from the genital organs, pass back, and
are attached to the abdominal feet of the mother, where they undergo a portion of
their development. The eggs of the Decapods have a regular segmentation, but, owing
to the fact that the protoplasm has a perpheral distribution, the planes of cleavage do
not pass completely through the egg. When the segmentation is completed, a small
patch of the blastoderm invaginates to form the primitive stomach, and the opening or
blastopore soon closes. By similar imaginations the anterior and posterior portions of
the digestive tract are formed, each pushing in until it meets the first invagination.

C3 / J. ^j j

Anticipating for a moment our account, we will say that here, as in all Crustacea, the
primitive stomach, or mesenteron of embryologists, foi-ms but a very small portion of
the alimentary tract, and that from the anterior invagination, the stomodeum, as it is
called, the stomach with its complicated mill is developed. Hence it is that when the
animal casts its skin, the lining of the stomach is also shed. Returning now to our
egg, the next feature seen is a small prominence, the future abdomen, and then the
first three pairs of appendages appear nearly simultaneously, giving rise to the
nauplius stage. Lucifer (which presents an exception to the other Crustacea, in hav-
ing a total segmentation and in the formation of a true segmentation cavity) and Peneus
leave the egg at this point, and we will follow their further development at another

46 NATURAL HISTORY OF ARTHROPODS.

place. All other Decapods remain awhile longer in the egg, and usually a free life
begins with a zoeal condition, which, however, is subject to various modifications,
which will be mentioned in their proper place.

So far as the writer is aware, all Decapods follow two modes of casting the shell. In
the Macrura the carapax splits longitudinally down the back, and the body is withdrawn
through the opening thus produced. In the Brachyura, on the other hand, the splitting
of the shell, though still dorsal, is transverse, and takes place between the last segment
of the thorax and the first of the abdominal series. As a preparation for casting the
shell Dr. Braun describes in the crayfish a series of hairs, developed at about the time of
moulting, on the surface of the hypodermis, which serve to lift up the old and hardened
integument. Before the time of moulting there is developed on either side of the
stomach an oval mass of carbonate of lime, which is usually regarded as a supply stored
up for the calcification of the new integument. From the fact that in the crayfish
these " crab-stones " weigh but about two grains, Professor Huxley is disposed to ques-
tion this explanation, that small amount being but slight in proportion to the animal.
In the lobster, and in other forms, these stones are much larger, and there the objec-
tion of insufficiency would hardly apply.

Connected with the moulting is the reparation of injuries. When a crustacean
loses a leg, or suffers an injury in any part, with the succeeding moults the damages
are repaired, but not always perfectly. Some interesting observations on this point
have recently been made by Dr. Faxon, especially on the claws of the lobster. Fre-
quently when the claw is injured, instead of acquiring its former shape, there is a ten-
dency toward the formation of another pincer ; the two jaws are formed, their inner
margins become armed with teeth, but the apparatus cannot answer for a pincer, for
the joint allowing it to be closed is never formed, and the two parts are never able to
come together. This tendency of nature to reproduce parts forms a very interesting
subject for investigation, for Avhich, aside from a meaningless jingle of words, no ex-
planation has yet been given.

Many Crustacea have the power of producing a noise, but whether these sounds are
employed as calls, the evidence as yet presented, does not *enable us to decide. In
many forms, as Gelasimiis, Ocypoda, and Palinurus, these sounds are produced by
rubbing together two parts of the hardened integument, and frequently stridulating
organs for this purpose are well developed. A description of that in Ocypoda w T ill
suffice. In all the species of this genus there occurs in the inside of one of the large
pincers a row of closely set granules, which can be rubbed across a corresponding ridge
on the carapax, producing a noise closely resembling that which results from rubbing
some hard substance over a coarse file. In many species of the genus Alpheus, the
movable finger of the large claw is armed with a strong tooth, which fits into a corre-
sponding socket in the immovable thumb. By opening the claw and drawing the tooth
from the socket these small Crustacea are able to produce a noise similar to that pro-
duced by snapping the finger-nails together.

It has been stated several times in the preceding pages that the Crustacea are
essentially an aquatic group, but there are some which always live on land, only re-
pairing to the water for the purposes of reproduction. So far have these forms become
accustomed to a terrestrial life and an atmospheric respiration, that Fritz Mtiller has
proved by actual experiment that it is possible to drown a sand crab (Ocypoda) by a
prolonged immersion in water, and we can do no better than to reproduce here some
of his remarks upon the respiration of other terrestrial Decapoda, quoting from the

PODOPHTHALMIA. 47

excellent translation by Mr. Dallas of " Fur Darwin," and using to a large extent the
exact words, though that fact is not indicated by quotation marks.

Among the numerous facts in the natural history of Crustacea, there is one which
appears of particular importance, namely, the character of the branchial cavity in the
air-breathing crabs. In the frog-crab (Hanina) of the Indian Ocean, which, accord-
ing to Rumphius, loves to climb up on the roofs of the houses, the anterior entrant
orifice to the branchial cavity is entirely wanting, according to Milne Edwards, and
the entrance of a canal, opening into the hindmost parts of the branchial cavity, is
situated beneath the commencement of the abdomen. The case is most simple in some
of the Grapsoidea, as in Aratus pisonii, a charming, lively crab, which ascends the
mangrove bushes and gnaws their leaves. By means of its short but remarkably acute
claws, which prick like pins when it runs over the hand, this crab climbs with the
greatest agility upon the thinnest twigs. Once, when one of these animals was sitting
on my hand, I noticed that it elevated the hinder portion of its carapax, and that, by
this means, a wide fissure was opened upon each side, above the last pair of feet,
through which I could look far into the branchial cavity. I have frequently repeated
the same observation upon another animal of the same family (apparently a true
Grapsus), which lives abundantly upon the rocks of our coast [Southern Brazil].
Whilst the hinder part of the carapax rises, and the above-mentioned fissure is formed,
the anterior part seems to sink, and to narrow or entirely close the anterior entrant
orifice. Under water the elevation of the carapax never takes place. The animal,
therefore, opens its branchial cavity in front or behind, accordingly as it has to breathe
water or air.

I have also observed the same elevation of the carapax in some species of the allied
genera, Sesarma and Cydograpsus, which dig deep holes in marshy ground, and often
run about in the wet mud, or sit, as if keeping watch, before their burrows. One
must, however, wait for a long time with these animals, when taken out of the water,
before they open their branchial cavity to the air, for they possess a wonderful arrange-
ment, by means of which they can continue to breathe water for some time when taken
from that element. The* orifices for the egress of the water which has served for res-
piration are situated in these, as in most crabs, in the anterior angle of the buccal
frame, while the entrant fissures of the branchial cavity extend from its hinder angles
above the first pair of feet. Now, that portion of the carapax which extends at the
sides of the mouth between the two orifices appears in our animals to be divided into
small, square compartments. This appearance is caused partly by small wart-like
elevations, and partly and especially by curious geniculated hairs, which, to a certain
extent, constitute a fine net or hair-sieve extended immediately over the surface of the
carapax. Thus, when a wave of water escapes from the branchial cavity, it imme-
diately bedomes diffused in this network, and then is again conveyed back to the
branchial cavity by vigorous movements of the appendage of the outer maxilliped,
which works in the entrant fissure. While the water glides in this way over the cara-
pax, in the form of a thin film, it will again saturate itself with oxygen, and may then
serve afresh for the purposes of respiration. In very moist air the store of water con-
tained in the branchial cavity may hold out for hours, and it is only when this is used
up that the animal elevates its carapax in order to allow the air to have access to its
branchiao from behind.

In the Sand Crabs ( Ocypoda) a peculiar arrangement on the third and fourth pairs
of feet has long been known, although its connection with the branchial cavity has not

48 NATURAL HISTORY OF ARTHROPODS.

been suspected. These two pairs of feet are closer together than the rest, and the
adjoining surfaces of their basal joints are smooth and polished, and their margins bear
a dense border of long, silky, and peculiarly formed hairs. Milne Edwards, who com-
pares these surfaces as to appearance with articular surfaces, thinks that they serve to
diminish the friction between the two feet. In considering this interpretation the
question could not but arise, why such an arrangement for the diminution of friction
should be necessary in these particular crabs, and between these two feet, leaving out
of consideration the fact that the remarkable brushes of hair, which, on the other hand,
must increase friction also remain unexplained. But, upon bending the feet of a large
sand crab to and fro in various directions, in order to see in what movements of the
animal friction occurred, at the place indicated it was noticed, when the feet were
stretched widely apart, there was in the hollow between them a round orifice of con-
siderable size, through which air could be blown into the branchial cavity, and a small
rod might even be introduced. While in Grapsus the water reaches the branchias
only in front, in Ocypoda it flows in through this orifice. A somewhat similar struc-
ture is found in two species of fiddler crabs, and our author is disposed to regard the
hairs mentioned as possibly organs of smell.

It may not be amiss to state in this connection the reasons why most gill-bearing
animals die when taken from the water. Although the amount of oxygen present in
the air greatly exceeds that in water, the gills, usually soft in character, so mat to-
gether when the supporting influence of the water is withdrawn, that the extent of
surface available for respiration is not sufficient for the needs of the animal, and hence
suffocation ensues.

The Decapoda are usually divided into Macrura or long-tailed crabs, Brachyura or
short-tailed crabs, and a third group, Anomura, standing between the two first men-
tioned, and to a certain extent combining the characters of each. When, however,
we come to study the embryology it is seen that the members of the Anomura should
be divided among the two groups first mentioned ; and further, that the usually
adopted arrangement of the divisions of the Brachyura does not represent their true
relationships. So, following the hints afforded us by the development, which, when
properly interpreted, are in full accord with those furnished by comparative anatomy,
we will divide the Decapoda into two sub-orders, Macrura and Brachyura, each in turn
containing several distinct sub-divisions.

SUB-ORDER I. MACRURA.

The Macrura, embracing the shrimps, prawns, lobsters, crayfish, and hermit crabs,
are characterized by the possession of an elongate body, the abdomen being very large
and not habitually folded under the thorax. The carapax is frequently long and
cylindrical. Both pairs of antenna are long and filiform ; the inner pair are never
folded away in little pits, as in the Brachyura ; the outer pair frequently bear a lamellar
appendage at the base, the modified exopodite. The buccal area is not margined in
front, while the external maxillipeds are strongly pediform. Attached to the abdomen
are usually six pairs of appendages, the sixth pair uniting with the last segment of the
body to form the powerful caudal fin, so useful to these animals in locomotion. With
the exceptions of the Penaeidea and Astacidea, whose development will be men-
tioned further on, the Macrura hatch from the eggs as zoeas, in which the first eight
appendages (ending with the external maxillipeds) are present, while all of the thoracic

PODOPHTHALMIA. 49

and abdominal feet are usually absent. These zoeas differ from those of the Brachyura
in that the enormous defensive spines, so characteristic of the larvae of that sub-order,
are here but very slightly developed, thus enabling one at the first glance to say to
which group any larva belongs. From the zoea a J/ysts-like stage is produced, in
which, the thoracic and finally the abdominal feet appear, the thoracic feet exhibiting
as a temporary character the schizopodal form, which is retained in the adult opossum-
shrimp. From this the change to the adult condition is gradual. To this one ex-
ception may be noted ; in the hermit crabs (Paguridea) and Thalassinidea, so far as
known, the My sis stage has disappeared.

For our purposes we may divide the Macrura into the groups Penandea, Caridea,
Astacidea, Thalassinidse, Galathaeidea, and Paguridea, the two latter embracing a por-
tion of the old group Anomura, each in turn being divisible into several families.

The PEN^EIDEA, with its two families PEN.EID^E and SERGESTIDAE, though a
well-marked group, is not easily defined in words, if we rely upon characters derived
wholly from the adult, but the three genera, whose development has been studied,
Lucifer, Sergestes, and Penceus, all leave the egg in the nauplius condition, and are thus
in strong contrast to all the other Decapods. Aside from their development, a slight
account of which will be given, the whole group possesses but few points of interest.
Of Lucifer, a small transparent form, one species of Avhich is found on our southern
coast, we have, thanks to that able naturalist, Dr. Brooks, one of the most complete

life-histories yet published. The eggs, contrary to
those of most Crustacea, are almost entirely com-
posed of protoplasm, and undergo a total segmenta-
tion, followed by the formation of a true segmentation
cavity. From the egg there hatches a true nauplius,
which, by two moults, produces a protozoea with
an elongate but unsegmented abdomen, and a well-

x developed carapax. Seven pairs of appendages are

FIG. 58. -Nauplius of Lucifer. now P^ent, while the segments of the body cor-

responding to the third maxilliped and the three

first thoracic limbs are outlined. The heart is formed, and Dr. Brooks thinks that
water was drawn in and expelled from the posterior portion of the intestine, a feature
which would remind us of the intestinal respiration already mentioned in connection
with My sis on a preceding page. With three moults, during which nearly all of the
thoracic and abdominal segments appeal-, while the compound eyes are developed (in
a manner which, if we rightly interpret the text and drawings of Dr. Brooks, lends not
the slightest countenance to the idea that they are homologically jointed appendages),
the zoea is reached. From this point the development is much more gradual, the
larva passing through a My sis stage, and reaching essentially the adult form when
about half an inch long.

The development of Penceus, so far as known, corresponds in a general way with
that of Lucifer, while in Sergestes some of the larval stages are characterized by very
peculiar branching spines.

The species of Penceus, all of which have the three anterior pairs of feet chelate,
are very numerous in the warmer seas of the globe, and form an important article
of food. In the Southern States large numbers of Penceus braziliensis are sold under

O

the name of shrimp.

The only other form of Penaeoid which needs mention is the curious Spongicola

VOL. II. 4

50

NATURAL HISTORY OF ARTHROPODS.

FIG. 59. Lucifer (natural size, of an inch in length).

which is frequently found in that beauti-
ful sponge from the Philippines {Euplec-
tella), which has received the name of
"Venus' flower-basket." It was formerly
supposed that these small shrimps were in-
serted in the sponge, and the opening then
skilfully closed by those ingenious people
of the East to whom we owe so many
" curios," from mermaids to curious carved
balls of ivory, one within the other. Such,
however, is not the case. Not only has no
one yet been able to discover the openings
which would be necessary for such an
operation, but every specimen thus im-
prisoned belongs to the same species,
a fact which would hardly be probable
were we indebted to man for the arrange-
ment.

The next group in order is the
CARIDEA, which is represented in all
seas by many species, some also occurring
in fresh water. In North America alone,
including the West Indies, about one hun-
dred distinct forms occur. In these forms
the antennas have a large basal scale, the
carapax is not joined at its inferior margin
to the mandibular and antennal segments,
while at the most only the two anterior
pairs of thoracic feet terminate in a pincer,
while frequently but a single pair (either
the first or second) has such a termination.
In Nika an interesting modification takes
place, only one foot of the anterior pair
is chelate, the other being monodactylous.
Another feature, which is common to many
genera, is the breaking up of the carpal
(antipenultimate) joint of one pair of legs
into a long series of annuli, affording great
freedom of motion, though the pincers
borne on these feet are always so small
as to render it difficult to see what can
be the gain to the animal by this struc-
ture.

In the eastern United States the
Caridea are of but slight economic im-

portance, but in other parts of the world, under the names of shrimps and prawns
(German Garneelen, French crevette), they are largely used as an article of food.
The shrimp of England is the Crangon vulgaris of science, while the term prawn

PODOPHTHALMIA.

51

FIG. 60. Crangon vulgaris, natural
size.

FIG. 61. Panda/us montagui,
slightly reduced.

is applied indiscriminately to species of Palcemon, Pandalus, and Hippolyte. Cran-
gon vulgaris is common to tlie shores of Europe
and both coasts of North America. In color it is
a dirty white, finely speckled with black, presenting
a close resemblance to the sandy shores on which
it dwells, and thus afford-
ing a certain protection,
for almost every shore
fish is fond of the delicate
crustacean. In England
and on the adjacent shores
of the continent a common
way of catching shrimps is
by "horse-power,"- -ahorse
dragging behind him a large
net is made to walk np and
down through the shallow
water, and the Crustacea
are held in the meshes.
Shrimps are prepared for
the table by boiling. In
California the shrimp fish-
eries are almost entirely in
the hands of the Chinese,

and the following account taken from the Bulletin of
the Fish Commission tells their method of preparation :

" That part of each day's catch which is not sold is carried to the Chinese quarter,
and there put at once into boiling brine. The shrimps are then spread out to dry upon
level plats of smooth, bare ground. After four or five days they are crushed under
large wooden pestles, or trod upon by the Chinese in wooden shoes, for the purpose of
loosening the meats from the outer chitinous covering; after which the entire mixture
is put through a fanning mill, for the actual separation of the meats from the shells.
About 200,000 pounds of shrimps are sold annually in San Francisco, and the annual
exports of shrimp-meats to China and the Sandwich Islands are valued at about
$100,000. The meats are eaten by all classes in China, but they are cheaper and less
esteemed than the native shrimps, which are said to be comparatively scarce."

Of the habits and details of structure of the Caridea but little of general interest
can be said. The families are founded upon the character of the mandibles, while the
maxillipeds and thoracic feet afford a means of division into genera. The genus
Pakemon contains a large number of species, and occurs both in salt and in fresh
water, one form (Palcemon ohionis), as its name indicates, being found in the Ohio
and Mississippi Rivers. Some of the East Indian species acquire a great size, Palcemon
carcinus, from the tip of the chelipeds to the end of the telson, sometimes measuring
nearly two feet, while our own Palcemon jamaicensis is nearly as large. The genus
Alpheus, with about sixty species distributed over the warmer seas of the world,
usually leads a burrowing life, some of the Floridan species living in sponges. In
these forms the carapax has grown forward so as to completely cover the eyes, Avhile
the anterior pair of feet present an interesting peculiarity. These feet are both ter-

52

NATURAL HISTORY OF ARTHROPODS.

FIG. 62. Alpheus heterocheles, twice natural size.

minated with pincers, one being small while the other is enormously developed, being
as large as the cephalothorax.
This genus is almost exclus-
ively marine, but some species
are occasionally found in fresh
water as well. In one of
these from Florida (Alpheus
minus) the marine forms are
very small, while specimens
obtained from fresh water,
belonging to the same species,
were nearly three times as
large.

None of the Caridea are
true parasites, though a few
are commensals, that is, they
are closely associated with
other animals. Thus some species of Alpheus and Pontonia live within the shells
of certain molluscs.

The ASTACOIDEA is a much more important group than the one that we have
just left, embracing as it does many large species possessing an alimentary interest.
Without entering into the characters limiting this group, we may proceed to divide it
into three families, Astacida?, Loricata, and Thalassinida'.

The ASTACID^E, in their shape show a close approximation to the Caridea, but are
distinguished from them by having the epistome united to the carapax, as it is in all
the higher forms, while on the dorsal surface of the carapax is a transverse suture
(wanting in the Caridea), which, as we have seen, is the remains of the joint between
the antennal and mandibular somites. All three (and in the Eryoninas four or five)
of the anterior pairs of thoracic feet are terminated by a pincer, the first pair being very
large, and forming the well-known " claw " of the lobster.

The Astacidae, so far as is known, differ from the rest of the Decapods in leaving
the egg in nearly the adult condition, the zoeal stage being suppressed, the youngest
larva being in the Mysis stage in the case of the lobster, while in the fresh-water cray-
fish the young differs in only unimportant details from the adult. The genera, of
which about fifteen have been described, are distributed about equally between marine
and fresh-water forms, and may be divided into two sub-families, the Eryoninae and
Astacinaa. The former, as has been stated, being characterized by four or five pairs of
chelate feet, the latter by three. The Eryoninae were long considered as an entirely
extinct group, but recent deep-sea dredgings have brought to light several forms which
have been described under the generic names of Polycheles, Pentacheles, and Witte-
moesia. The genus Eryon occurs fossil in the Solenhofen lithographic stone (Upper
Oolite). The sub-family is exclusively marine.

The Astacinas contains the crayfish and lobsters, or fresh and salt-water forms.
Though several genera have been described, only Cambarus, Astacus, and Homarus,
need here be mentioned. Cambarus and Astcwus, our types of crayfish, differ from
each other in only unimportant details ; but the distribution of our American species
presents an interesting feature. The genus Astacus occurs on the Pacific slope
(and in Europe as well), while the waters which flow into the Atlantic contain only

PODOPH THA LMIA .

53

individuals of the genus Cambarus. Many of our species, which have been described
by Dr. Hagen, have burrowing habits, and are thus productive of considerable damage
in mill-dams, and especially in the levees of the Mississippi. In Europe the crayfish
are extensively used for food, as they are to a certain extent in our Southwestern
States. In France there are several large farms for their propagation and cultivation,
and when desired for the market they are captured by sinking in the water bundles of
brushwood, in which the individuals become entangled and are brought to the sur-
face. An interesting form is Cambarus
pellucidus, the blind crawfish of Mammoth
Cave and the neighboring caverns of Ken-
tucky and Indiana. In these forms the eye-
stalks remain, but the optical portions have
almost entirely disappeared, a good ex-
ample of the effects of disuse, for in the total
darkness of the subterranean streams the
use of an organ of vision would be ex-
tremely slight. Dr. Packard has recently
described a fossil crawfish from the Tertiary
of our Western States.

To the New Englander the lobster is

*z?

by far the most important member of the
whole class of Crustacea, The genus Homa-
rus, to which it belongs, contains three spe-
cies, vulgaris of Europe, capensis from the
Cape of Good " Hope, and the americanus
ranging from Labrador to New Jersey, and
possibly even further south, Dr. Coues hav-
ing found a single specimen near Beaufort,
N.C. It frequents rocky bottoms, hiding
among the stones, or occasionally varying
its habitat for sandy or gravelly regions.
Lobsters are very fond of decaying animal
matter, and the nets and traps employed
in capturing them are usually baited Avith
fish offal. Two methods of lobster fish-
ing are in vogue. In one a large net, with the bait fastened in the centre, is
lowered to the bottom, and after a sufficient time is hauled to the surface so
rapidly that the lobsters have no chance to escape. The more usual means of
catching these animals is by " lobster-pots." These are wooden frames usually
constructed of laths with netting ends. In one or both ends is a small circular
opening, through which the lobster passes to reach the bait on the inside of the
pot. These pots are sunk in promising spots, their position being marked by a wooden
float. Weather permitting, the pots are visited every day and hauled to the surface by
means of the rope connecting the float to the pot. Frequently, when the character of
the bottom permits, the pots are attached together in trawls, each end of the trawl line
being marked by a float. The number of pots set by each fisherman varies, few using
as many as one hundred. Possibly the average may be forty or fifty.

The lobster industry is very large, and we gather from the pages of Mr. Rath-

FIG. 63. Cambarus pvllucidus, blind crawfish of
Mammoth Cave, natural size.

54

X AT URAL HISTORY OF ARTHROPODS.

bun the following statistics : In 1880 the total catch on the Maine coast amounted to

~

14,234,000 pounds, valued at $268,000, fishermen's prices ; in Massachusetts 4,315,000
pounds, valued at $158,000. Of the Maine catch the larger proportion was canned,
the twenty-three canning establishments in that State taking about 9,500,000 pounds ;
while the Provincial factories put up an even larger amount. The quantity of lobsters
handled by the several large fresh markets during 1880 was as follows: Boston,
3,637,000 pounds ; New York, '2,500,000 pounds, and Portland, 2,000,000 pounds.

All of the interested States, with the exception of New Jersey, have passed more or
less stringent laws regulating the time of catching and the size of the lobsters caught,
those of Maine being the most lax. For several years past the average size of the
lobsters caught has been decreasuig, a specimen weighing four pounds being compara-
tively rare. Lobsters, however, are occasionally found much larger in size, there being
one in the Museum of the Peabody Academy of Science at Salem, Mass., which
weighed thirty-nine pounds.

The lobster, when about to moult, seeks some secluded spot under the shelter of a
large stone, and there sheds his old shell. As a preparation for this act the lime salts
in certain parts of the integument are absorbed, and then the carapax splits down the
back, and through this opening the animal withdraws itself. As it would be impos-
sible for the enormously developed claws to pass through the rigid joints of the arm,
there is an absorption of the lime salts in these joints, and thus the claw is readily
withdrawn. Together with the old shell, the lobster, like all Crustacea, sheds the lin-
ing of the stomach and of the posterior portion of the intestine. After moulting the
lobster's skin is very soft, and the flesh soon becomes poor, watery, and flabby ; but in
a short time, by a deposition of calcic carbonates and phosphates, the new integument,
which is larger than the old one, regains its former firmness, and in a few days the
flesh acquires its former solidity and indigestibility.

The breeding season varies according to

the locality. In Long Island Sound the eggs
are laid sometimes as early as the last of
April or the first of May. In Massachusetts
Bav the season extends from about the first

/

of June to the first of August, w T hile Pro-
fessor S. I. Smith found at Halifax females
with newly-laid eggs in September. For a
knowledge of the development of our lobster
we are indebted to Professor Sydney I. Smith,
Mr. G. O. Sars having performed a similar
work for the European species. The eggs,
which for Crustacea are very large, are of a
dark green color, and at the time of hatching,
the embryo strongly resembles a My sis, all
of the thoracic feet being two-branched, while
the external maxillipeds play a part in loco-
motion. At the next stage the abdominal feet appear, and at each succeeding
moult the young approaches more nearly the adult, retaining, however, their free-
swimming habits until about half an inch in length.

The LORICATA differ anatomically from the group we have just left, by the
absence of a scale on the basal joint of the antennae, and in having the anterior pair of

FIG. 64. Embryo lobster some time before hatch-
ing, natural size above, o. Yolk. b. Margin
of carapax. c. Eye. </. Antemmla. e. \n-
teniia. (j to i. Thoracic feet. k. Intestine. /.
Heart, m. Telsou.

PODOPHTHA LMIA.

55

FIG. 65. Phyllosoma, glass crab, the larva of Palinurus, natural size.

feet monodactyle, that is, not ending with a pincer, but in their development they pre-
sent marked differences, the young forming the "glass crabs," which formerly, under
the name Phyllosoma, were
regarded as adults. These
larvae are flattened, hardly
thicker than a sheet of
paper, and in life are per-
fectly transparent, present-
ing not the slightest resem-
blance to the parents. The
two families, SCYLLARID.E
and PALINUBID^E, are found
in tropical seas, and are
among the largest Crustacea.
All of the feet, except the
posterior pair in the female
Scyllaridae, are monodactyle,
while the antennal scale is
always lacking. The Palin-
nridae are nearly cylindrical,
while the Scyllaridae are
greatly flattened, the sides of the body being very thin. Both families are repre-
sented in our warmer waters by the genera Palinurus and Panulirus, Scyllarus,
Ibaciis, Evibacus, ftnd Arctus.

The THALASSINIDEA, represented in our waters by several genera, are a bur-
rowing group, the individuals of which, except from a scientific standpoint, are of but
slight importance. While in the majority of forms the respiratory apparatus is of the
normal character, it is said that in Callianidea (of which one species occurs in the
West Indies, the other extending from our west coast through all the eastern seas)
and in Callianisea the abdominal feet also bear gills, thus presenting a resemblance to
the Stomatopoda, to be described further on.

The GALATHEIDEA present us with a feature which we shall notice in connec-
tion with the Schizosomi, that the hinder pair of thoracic feet are carried bent up
under the carapax, and in both groups, as in the Paguridea, the last thoracic segment
is not immovably united to the rest, a feature which also occurs in the genus Astacits.
Grimothea is a pelagic form which occurs swimming at the surface in the Pacific
Ocean, sometimes appearing on the California!! shores. ^Eglea is a fresh-water genus
(the only one of the Anomura), and the single species occurs in the streams of Chili
and Peru.

The last division of the Macrura which we have to consider is the PAGURIDEA,
or hermit crabs. In these forms, with the exception of Birgus, the abdomen is
always soft, the usual salts of lime not being deposited, and hence the animal inserts
this defenceless portion of his body in the empty shell of some univalve mollusc.
With this external protection there is usually an obsolescence of some of the abdominal
feet, while the spiral character of the shell has caused the abdomen to become coiled
in a similar manner. The posterior pair of abdominal feet are modified so as to form
a hook, by means, of which the crab holds himself into his house.

Many amusing accounts have been given of the habits of the hermit crabs, and we

56

NATURAL HISTORY OF ARTHROPODS.

FIG. 66. Eupagurus bernhardus, hermit crab
iii a shell of Lunatia heros, natural size.

can do no better than to quote the account which Dr. Lockwood gives of the little
hermit crab, the Eupagurus longicarpus, so common on our eastern shores : -

"Though a recluse, for he lives in a vacated
shell all alone, yet of hermit gravity he has
none. In fact, he is constitutionally a funny
fellow. This crab has his two hands, or claws,
greatly larger than the other feet, and of these
the right one is much stouter than the left.
The next three pairs of claws are tipped with
simple hooks, which, having considerable lever-
age power, are really efficient grapnels with
which to pull himself along when he travels,
carrvino; his house on his back, while the claws

v C7

of the fifth or last pair are very diminutive.

" There is a queer monkey-like drollery in
the looks of our little hermit. We had one in
our aquarium of rather large size, and which
occupied a shell of the required capacity. Of
this specimen we were very proud; the shell
on its upper part was ashen white with a fine
colony of Hijdractinia, like tiny sea-daisies. We had also a little hermit in a small
llyanassa obsoleta shell. And what about this young scapegrace, whom we so soon
almost wished obsolete ? On he came and climbed right up into this pretty parterre,
and having secured himself with his grapnels on top of his neighbor's house, most de-
liberately, now with the right claw and now with the left, he pulled off my w r eesome
pets, stowing them into his ugly mug with a movement so regular that it seemed almost
rythmical, and yet so cruelly comical that it made me most laughably mad.

"But the hermit grows, while the shell which he occupies does not. Hence, like
many bipeds, he has his "first of May," so lie goes house-hunting. This must be
understood literally. He finds a shell. Will it do ? First, then, is it really to let ?
He will inquire within. This he does, if not most courteously, very feelingly.
Satisfied on this point, the next question is, will the house suit. He turns it over, then
turns it round. You see the weight of one's house is quite an item in the reckoning
to him who has to carry it on his back. One inspection more. How is it inside ? Is
it entirely empty and of the right size ? Up goes one of the slender limbs of the
second pair, and the interior is thoroughly explored. All right ! Just the house he is
after. His mind is made up to move. Look at him ! Quick ! or you '11 miss it ! Out
comes the body from the old house and pop it goes into the new one. The resolution
to move was taken, the surrender of the old house was made, and the occupancy of the
new was effected, and all within a fraction of a second of time.

" Sometimes this matter goes on less pleasantly. Two house-hunters may find the
same tenement. Should both desire it, then comes the tug of war. Live together they
neither can nor will. The affair is settled by a battle, in which the stronger proves
his claim right by the Carlyleian logic and morals, viz. might. Quite often from
these encounters a terrible mutilation results. To us it is a sad sight to see the little
hermit when his time has come, and he knows it ; that is, when Eupagurus must die.
However droll his career mav have been, the little hermit is o-yave then. And what a

* ^j

strange fact it is. Who can explain it ? The poor little fellow comes out of his house

PODOPHTHALMIA.

57

FIG. 67. Eupagurus with its asso-
ciated polyp.

to die. Yes, in order to die. To us humans home is the only right place to die in.
But for Eupagurus home has no attractions at this solemn time. Poor fellow, with a
sad look and melancholy movement, he of his own will quits the house for which he
fought so well. Those antennae, or feelers, that often stood out so provokingly, and
were so often poked into everybody's business, now lie prone and harmless. The eyes
have lost their pertness. There lies the houseless hermit on that mossy rock, stone
dead."

In the above account Dr. Lockwood incidentally mentions the fact that the shell
occupied by the hermit bears upon it a colony of Hydroids. Such associations are
very common, and sometimes specimens are found even
more interesting. In the deep waters off the New Eng-
land coast a polyp ( Gemmaria americana), allied to
the sea anemones, attaches itself to the shells occupied
by another species of Eupagurus, and by budding grad-
ually covers the entire shell ; and not only this, but it
possesses the power of dissolving the shell so that no
trace of it can be found. As this polyp increases in
size with the growth of the crab, there is no need of

a change of house on his part, his home grows as he does.
Even more remarkable is the case of a Chinese hermit, Diogenes
edwardsii, which always bears upon the outside of the large
claw a small anemone, which, when the hermit retreats into
his shell, closes the aperture. It occasionally occurs that the
hermits fail to find a shell suitable to their needs, and then
any object, such as an old bottle, is occupied. In looking over
some Floridan Crustacea the writer once found a specimen of
Coenobita diogenes which had thus occupied a " T. D." pipe.

The Paguridea are divided into two families, PAGURID^E
with fourteen genera, in which the antennulse are very short,
the species aquatic in habit ; and the CENOBITID^E with long antennulae and terres-
trial habits, and represented by only two genera. One of these, Birgus latro,
which is distributed throughout nearly the whole Indo-Pacific region, has received
the popular name of Palm Crab. This form, which is an exception to all of the
hermits in having the abdomen hardened, is said to feed on cocoanuts. Stripping
off the husk, it inserts the tips of the claws into the three holes found in the end,
and pounds the nut upon a stone until it is broken. Another method which they
are said to employ for this purpose is as follows : The husk is stripped off, leaving
but one or two fibres attached to the nut, then clasping these fibres the crab climbs
a tree and then drops the nut on a stone. The coarse, fibrous husk is used to line the
burrows which Birgus makes in the moist sand. When nuts are not to be had, the
crab is not greatly averse to eating its own kind. The natives adopt a curious method
of capturing these tree-climbing crabs. Watching until they see a Birgus ascend, they
tie a lot of grass around the trunk of the tree at a considerable distance from the
ground. By-and-by the crab descends, and feeling the grass thinks he has reached
terra firrna, and, therefore, looses his hold, and falling to the ground so maims him-
self as to become an easy prey to the savage. On a preceding page we have alluded
to the lungs of this crab, but as the subject possesses much interest we may return to
it again. The gill-chamber is divided into two parts, the gills being in the lower,

FIG. 68. Coenobita diog-
enes, natural size.

58

NATURAL HISTORY OF ARTHROPODS.

while the upper never contains anything but air. On the walls of the upper chamber
are found numbers of ramified tufts, containing in their interior an extraordinarily
developed network of vascular spaces, thus furnishing a large respiratory surface,
while the arrangement of the blood-vessels conclusively proves that blood poor in
oxygen enters it from the body, and the vessels leading from it open directly into the
auricule.

In their development the Paguridea hatch as zoese, but from this point they closely
resemble the Brachyura in the omission of a Mysis stage.

SUB-ORDER II. - - BRACHYURA.

This group, which contains the crabs, the highest of the Decapods, possesses nmch
more interest than any other division of the Crustacea, The body is generally broad
and flattened, the carapax very seldom exhibiting the cylindrical form so characteristic
of the Macrura. The abdomen is relatively small, and is almost always carried flexed
under the thorax, which is frequently excavated for its reception. The antennae are
small (except in a few forms), and the inner pair frequently can be folded in small
grooves or pits in the anterior part of the carapax. The external maxillipeds are oper-
cular in character (that is, they form a sort of lid, covering the other mouth-parts) and
rarely have but a distant resemblance to the ambulatory feet. The abdomen, as has
been said, is small ; the abdominal appendages are very rudimentary, and some of them

are frequently aborted. In many cases, especially in the males,
two or more of the abdominal segments become coalesced,
all traces of the sutures being occasionally obliterated. All
of the Brachyura, except a few of the land crabs, .leave the
egg as zoeas, the carapax being armed with three or, in the
higher groups, four long spines. Of these one springs from
the front of the carapax and points forwai-ds, one arises on
either side and is directed downwards and backwards, while
the fourth, when present, is dorsal in position, a portion of the
heart extending into it. The appendages at first present are
but seven in number, the series ending with the second maxil-
liped, while the thoracic members are absent or very rudi-
mentary. During the zoea stage the larva increases rapidly
in size, the growth being accompanied by frequent castings of
the shell, and the development of all of the series of append-
ages. Then by a single moult the megalops stage is acquired,
a schizopodal stage not intervening, a feature which, as we have seen, is shared by
the hermit crabs among the Macrura. The Brachyura may be divided into the
following groups : Schizosomi, Teleosomi, Maioidea, Corystoidea, Leucosoidea, Can-
croidea, and Grapsoidea.

The SCHIZOSOMI embraces the brachyuran forms which have the outlets of the
ovaries in the bases of the third pair of legs instead of in the adjacent parts of the
sternum, as in most Brachyura, and also the last thoracic segment free from the
others. In some the abdominal appendages are well developed, in others they are
rudimentary. So far as is known the zoeas do not develop a doi-sal spine, but the
other spines frequently are greatly elongated, and in the porcelain crabs these spines
reach a length of several times that of the body.

FIG. 69. Zoea of Carcinus,
a. Natural size.

Co
<3

ui

e+
(D

P

-s

d

5'

<!

o"

cr

en

rf-

a>

~t

PODOPHTHALMIA.

59

The LITHODID^E, which in their form of body closely resemble the Maioid crabs,
to be mentioned further on, are represented on our East coast by two species, the
family acquiring its greatest development on the West coast of both North and South
America. The abdomen is without caudal appendages, and at lirst sight it would
appear that the name Decapods was a misnomer, as only four pairs of thoracic feet are
externally visible, but a little investigation shows that the fifth pair are present, though
folded up under the carapax. Of the habits scarcely anything is known.

The POROELLANID^E are small, brightly-colored crabs,
with a shell always kept clean, and from its general re-
semblance to porcelain giving the name to the principal
genus. In these, as in the family just mentioned, the fifth
pair of legs are not used in locomotion, being carried
folded upon the back. The species, which are numerous
in the warmer seas of the world, live under rocks or amoncr

~

the coral reefs. These forms are worthy of notice from a
morphological standpoint, for it would seem that here the
appendages of the seventh abdominal segment were par-
tially developed, showing the validity of its recognition as

one of the body segments.

The HIPPID^E have an elongate body, and feet fitted
for swimming, while the way in which the abdomen is
bent also fits it for burrowing. The folloAving account
of the habits of the American Hippa emerita is con-
densed from that furnished by Professor Smith : " This
species prefers a narrow zone of sandy beaches, near
low-water mark, where it lives gregariously, burrowing
beneath the surface. They burrow with the greatest
rapidity, and always backward, pushing themselves in
by means of their thoracic feet. In an aquarium they
at once plunged entirely beneath the sand, and then
in an iipright position showed just the tips of the an-
tennulse and the eyes at the surface. Of the food but
little can be said. In all the specimens examined the
alimentary canal was filled with fine sand, nearly free
from organic matter, though under the microscope a
small amount of vegetable matter is seen, rendering it

FIG. 70. Petrolisthes annatus,
porcelain crab, natural size.

FIG. 71. Hippa emerita.

probable that the sand is swallowed for the
nutritive matter it may contain."

The TELEOSOMI differ from the group
just mentioned in having the last thoracic
segment anchylosed to the others, as in most
Decapoda, while the outlets of the female
genital organs occupy the same position as
in the group just mentioned. The first
form we will notice is Hypoconcha, the
"false hermit" of the older writers, of which
three species are known in tropical Ameri-
can waters. In these forms the dorsal surface of the carapax is soft, resembling in

FIG. 72. Dromia.

60

NATURAL HISTORY OF ARTHROPODS.

consistence the abdomen of the true hermit crabs, and, for protection, ffi/poconcha
takes a half of a bivalve shell, and inserting the angle of its abdomen in the depression
beneath the hinge, holds the shell in position by the fourth and fifth pairs of thoracic
feet. A similar habit has been noticed in the Chinese genus, Conchoecet.es. In some
of the sub-genera of Dromia the crab carries in a similar manner a sponge, polyp, or
compound ascidian.

FIG. 73. Dromia covered with a sponge.

The remaining groups of Brachyura all have the female genital openings on the
ventral surface of the body, between the bases of the feet, while in the zoeas a dorsal
spine is almost universally present.

The MAIOIDEA or Oxyrhyncha, which in the older works were regarded
as forming the highest of the Decapoda, and, indeed, of the whole Crustacea, are in
reality the next in order ; for although in some respects they have a high grade of
structure, they, nevertheless, retain many embryonic features even in the adult stage,
the young Cancer, for instance, at a certain portion of its development being strongly
maioidean in appearance. The antennulse are folded in longitudinal pits in the front of
the carapax. The external maxillipeds are broad, the fourth joint being borne on the
inner angle, or the summit of the third, while the carapax is usually elongate and tri-
angular, being narrowed in front. The Maioidea are divided into several families and
over a hundred genera, the distinctions, however, being of too technical a character to
suit a work like the present, the systematic student being referred to the paper by
Mr. E. J. Miers in the Journal of the Linnean Society for 1879.

PODOPHTHALMIA.

61

Among the Maioids, inter-
esting from their appearance,
arc the group of spider crabs,
whose long and slender legs
are greatly disproportionate
to the body they have to sup-
port. These forms frequent
the bottom, walking slowly
and deliberately as though
they had scarcely strength to
move their attenuated mem-
bers. Some of these forms
keep their shell perfectly
clean, seeming to rely upon
their general resemblance to
the Sertularians and other
Hydrozoa, among which they
dwell, for protection. Others,
however, permit all sorts of

foreign bodies, both animals and plants, to become attached to their bodies, so
that they are effectually concealed, and even when moving it seems as if a small
forest of sea-weed were being transplanted to another locality. To these spider
crabs the Macrocheira of Japan, the largest of all crustaceans, belongs. The

FIG. 74. Maia squinado, natural size.

FIG. 75. Leptopodia sagittaria, spider crab, half natural size.

relative proportions of legs to body in this species can be seen from the following meas-
urements of a specimen captured at Yokohama in 1878, in which the legs extended to
a distance of twelve feet, while the carapax was sixteen inches long by twelve in
breadth. The largest specimen in any collection is said to be that in the British
Museum, which measures between the tips of the first pair of legs eighteen feet, though
larger specimens are occasionally taken, an old and trustworthy sea-captain telling the
writer of one taken in 1871 which spread twenty-two feet.

62

NATURAL HISTORY OF ARTHROPODS.

The CORYSTOIDEA are entirely absent from the eastern coast of our continent,
though present in all other seas. They have the antennulae and maxillipeds much as
in the Maioids, but differ in the longer antennae and the very short epistome or region
in front of the mouth.

The LEUCOSOIDEA or Oxystomata are extremely narrowed in front, the ex-
ternal maxillipeds, when placed together, forming a triangle. The carapax is more or
less circular in outline, while the antenna are very small, and the epistome wanting.
In Dorippe we have a similar commensalism to those already noticed, one species of
this genus never being found without a sea-anemone ( Cancrisocia expansa) upon its
back, nor has this anemone ever been found except in this position. In Calappa the
sides of the body are expanded, while the two large claws, armed with strong spines
above, are carried closely applied to the front of the body.

The CANCROIDEA or Cyclometopa agree with the Maioids in their mouth-parts,
while the body is broader and the antennula? are transverse. They are well divided

into two families, according to their habits, -
the CANCRIDJE having the feet constituted for
walking, while in the PORTUNID^E the pos-
terior feet are flattened and thus converted
into efficient swimming organs.

The genus Cancer, which is represented on
our eastern coasts by two species and by four
on the California!! shore, may be taken as the
type of the group. Our eastern species range
from Labrador to the Bermudas, and by a
curious mistake in nomenclature, the form to
which the name borealis is applied extends
further to the south and not so far to the north
as does the more' common Cancer irroratus.
Cancer irroratus delights in secluded places
under rocks, where it is safe from enemies and
the pounding waves, while the stouter, heavier
borealis disdains such protection, and occurs
in places where it is exposed to the force of
the waves. By many European naturalists these
two forms are confounded, though in reality
they are very

FIG. 76. Megalops of common crab, Cancer
irroratus.

distinct, the teeth of the margin of the carapax being
smooth in C. irroratus and crenulated in the other species.
The European Cancer pagurus is used as an article of
food both in England and upon portions of the continent,
while none of our forms have much economic use. The
genera and species of the Cancridae are very numer-
ous, especially in the warmer seas of the world, many
being conspicuous by reason of their bright colors,
though in habits no particular interest attaches to
them. The mud-loving Panopeus of the warmer
waters of both coasts of America is the only other
species to which our space will allow us to refer.

tvr

FIG. 77. Panopeits depressus, mud crab,
natural size.

rc>
o

PODOPH T HALM I A .

63

FIG. 78. Platyonichus oce/latus, lady crab, natural size.

As examples of the swimming crabs we may mention the " Green Crab," ( '<trcinus
mcenas, which has a peculiar distribution, occurring on our coasts only from Cape Cod
to Maryland, and on the European from Finmark down through the Mediterranean
into the Black Sea. Besides these, its regular habitat, it has been reported from
Brazil, Panama, the Sandwich
Islands, and India. With
its restricted distribution on
our own coast, this wide dis-
tribution over the globe is of
peculiar interest. Another
of the swimming crabs, the
Neptunus hastatus, furnishes
the soft-shelled crab so well
known to epicures. This
crab, which extends along
our Atlantic coast from Mas-
sachusetts to Florida, buries
itself in the sand, exposing
only its eyes and antennae.
Like all of the Crustacea, it
sheds its shell, and just after
the moult it forms the delicacy
of the table, the integument
not then being hardened. At

^j

the time of moulting the flesh is hard, but in a few hours it becomes soft and watery,
and then is of inferior quality. Only a few days are required to bring the new skin
to its former consistency. Our figure of the lady crab, a beautifitl species covered
with rings of red and purple, will sufficiently illustrate the characters of the Portunidfe,
while the development is shown in figures 5, 6, 13, and 14, which represent the various
stages of young of the soft-shelled crab mentioned above.

The remaining divi-
sion of the Decapoda,
the OCYPODOIDEA
or Catometopa, are the
highest, both as shown
by structure and by em-
bryology. The anten-
nula? are transverse, the
fourth joint of the ex-
ternal maxillipeds artic-
ulates with the apex or
outer angle of the third ;
the body is broad, and,
in the higher groups,
quadrate in outline ; the
epistome is very short
and the male genital organs show a complication not found in other groups. In divid-
ing the group into families authors show a considerable diversity of opinion, as the

FIG. 79. Genjon tridens, from deep water, North Atlantic Ocean.

64 NATURAL HISTORY OF ARTHROPODS.

number varies in different works from six to sixteen. It is not necessary here to
discuss all of the families of the group, but merely to mention some of the more im-
portant forms. It is to the Ocypodoidea that the larger number of the terrestrial
Decapods belong. An account of their respiratory apparatus has been given on a
preceding page.

The PINXOTHERID^E are familiar to all in the little " Oyster Crab," Pinnotheres
ostreum, so common in the oysters of our coast. Many tales are told of the way in
which these forms act as guardians of the molluscs inside whose shell they dwell, and

which have been perpetuated in the generic name, but which
an iconoclastic science has shown to be false, these animals
seeking this home merely for protection and for convenience
of obtaining choice morsels of food in the currents of water
created by the cilia on the gills and mantle of the mollusc.
With our common oyster crab it is the female alone who thus
keeps house, the male living a life of freedom, being very
rarely seen. Other forms belonging to this or allied genera
have similar commensal habits, some living in the shells of mussels or other bivalves,
while one form from the Philippines is said by Dr. Semper to enter in the young state
the water-lungs of the Holothurians and there spend its life, the carapax growing for-
ward over the eyes, causing blindness or partial blindness, while the eyes themselves seem
to undergo a more or less extensive retrogressive metamorphosis. A somewhat similar
case is found in the Chilian Pinnaxodes chilensis, which enters the anal opening of a sea-
urchin, and sometimes occupies a third of the body-cavity of the host. It is one of the
peculiarities of geographical distribution that the common Pinnotheres pisum of the Eng-
lish shores also occurs in antipodal New Zealand, occupying in both places what appears
to be the same species of mussel. Pinnixa is an aberrant form, some species of which live
in the tubes of certain marine worms. In these the body is very short and broad, the
breadth being occasionally three times the length. The two genera, Jfarpalocarcinus
and Cryptochirus, belonging near the Pinnotheridae, agree in having a sort of pouch
for holding the eggs and young, formed by the lateral extension of the abdominal
plates, and in living in coral where they produce structures recalling the galls produced
upon plants by certain insects. Harpalocarcinus affects the branching forms, and,
settling down between two twigs, stays there until by the growth of the coral he is
rendered a prisoner for life, two small holes only remaining, through one of which he
draws the water necessary for his existence, the other serving as an exit for the water
which has served his purpose. The currents of water serve to keep the cavity open
as long as the crab lives. Cryptochirus prefers to make his home in the more solid
corals, where the young, settling down in the centre of a young polyp, kills it, while the
surrounding polyps continuing to grow soon build a tubular dwelling for the crab.

Passing by the Grapsidaa, witli its several hundred species, we come to a more in-
teresting family, the OCYPODID^E. Here belongs the genus Gelasimus. In the males
of this genus one of the claws is greatly larger than the other. When these crabs are
disturbed their claws are brandished in an amusing manner, strikingly suggestive of
the motions of a violinist, whence these forms have received the common name of
" Fiddler Crabs." These crabs live in burrows in the ground near high-water mark,
salt marshes being a favorite resort. One of these forms constructs an oven-like arch
over the top of its hole, and there spends a large portion of his time, ready to descend
to his underground home at the approach of an enemy. Ocypoda has a somewhat

PODOPHTHALMIA.

65

similar habit of burrowing-, but is much quicker in its motions. Our common Ocypoda
arenaria is fond of "beach fleas" (Amphipoda), which it catches by lying in wait
and springing upon them, very much as a cat catches mice.

FIG. 81. Gelaflmus puglllator, fiddler crab, natural size.

In the tropical regions of the globe are found the true Land Crabs, GECARCINID^E,
which spend almost their entire life away from the water, only going to the sea at the
breeding season. At all other times they frequent the mountains, running with great
rapidity at the approach of an enemy.

ORDER IV. STOMATOPODA.

The most important characters which separate this from the other orders of
Podophthalmia may be briefly stated as follows : The carapax is smaller than in the
Decapods, the first antennal and the last or last three or five of the thoracic rings
being perfect and uncovered by the carapax. The ambulatory and raptorial feet are
seven in number, the two external maxillipeds of the Decapoda here being enlarged
and losing their functions as mouth-parts, thus showing an approach to the Edrioph-
thalmia. The five anterior pairs of these feet are furnished with an imperfect pincer,
the last joint closing upon the preceding one. These three posterior feet are all
bifurcated or schizopodal in character. In the gills also we notice important features,
for these organs instead of being carried upon the bases of the thoracic feet, and pro-
jecting into a respiratory chamber, are borne upon the fh % st five pairs of abdominal
feet, and hang freely in the water. The heart, instead of being a small and compact
thoracic organ, as in the Decapods, here is a long, slender tube, extending the length of
the abdomen. The principal venous sinus, as would be inferred from the location of
the gills, is also abdominal. The nervous system is formed upon the usual arthropodal
type, and the abdominal ganglia are united by double commissures, which have not
been united as in the Decapods.

The early phases of the development of the Stomatopoda have not been studied.
The eggs are laid in burrows in the bottom of the sea, and from this to the Alima
stage nothing is known. Fritz Mtiller, Glaus, and Professor W. K. Brooks have
studied the development of this order from this point on, the results of which are here

66

NATURAL HISTORY OF ARTHROPODS.

greatly condensed. There are two
types of development, one passing
through the forms which were for-
merly considered as adult, and de-
scribed as Erichthus and tiquiller-
ichthus, the others through an
Alima stage, with the probabilities
that the former represents the larva
of Gonodactylus, the latter certainly
that of Squilla. In the youngest
known Erichthus type we have
both stalked eyes and a single
median ocellus, while the first ten
pairs of appendages are developed,
the sixth to tenth being biflagellate.

O ~

Behind these are three segments of
the body without appendages. A
large carapax covers the anterior
portion of the body, and is pro-
longed into a spine in front. After-
ward the last three maxillipeds be-
come aborted, and then grow out
again in their permanent form.
The abdominal feet develop in suc-
cession from before backward, and
all are fully formed before the ap-
pendages of the three posterior tho-
racic segments appear. In the Alima type of devel-
opment, which has been followed through by Profes-
sor Brooks, it seems probable that the young leaves
the egg in nearly the Alima form, and in the youngest
stage known the six appendages, eight to thirteen, are
absent, although three of the corresponding segments
of the body are developed, while the abdominal seg-
ments and their appendages are well developed. None
of the thoracic members are biramous. From this,
which- corresponds to the Erichthus after the atrophy
of the appendages, a regular development produces
the adult form.

There are two well-marked genera of Storaatopoda,
Squilla and Gonodactylus, the former being divided
into several sub-genera. Thirteen species of the
Squillidas are found in American waters, Squilla em-
pusa extending as far north as Newport, K.T., where
it burrows in the mud, forming large irregular holes.
The colors are very bright, green, red, yellow, and
black predominating. The large pincer in both genera

. , , , , . . P .1 ' < -i T ^ FIG. 83. Advanced larva of Squilla em-

is formed by the last joint or the leg folding upon the pu sa, enlarged.

FIG. 82. Squilla empusa, mantis shrimp, reduced.

PODOPHTHALMIA. 57

preceding joint, and in tiquitta this claw is armed with strong teeth or spines, which
are wanting in Gonodactylus, which is represented by a single species, G. chiragra,
in the warmer waters of the Southern States, as well as other parts of the world.

ORDER V. CUMACEA.

But little popular interest attaches itself to this order, which is represented by only
a few small species. Their exact position is a matter of doubt, though their embry-
ology shows them, as pointed out by Dohrn, to be intermediate between the Podoph-
thalmia and Edriophthalmia. The carapax covers only the first six cephalothoracic
rings, and is followed by twelve segments, mostly without appendages. The telson is
pointed, but does not extend as far as the appendages of the preceding segment. The
anterior cephalothoracic appen-
dages (excepting the mandi-
bles, which are without palps)
are two-branched, but in the
three posterior pairs the exop-
odites are wanting. The ab-

1< i. s4. Diastyhs quadrispinosa, enlarged.

dominal appendages are better

developed in the males than in the females, and in the early days of science this differ-
ence between the sexes led to the establishment of genera which had no real founda-
tion. The organ of vision consists of a single (or two closely approximated) sessile
eye in the median line on the front of the body. The respiratory organs consist of
branchial plates attached to the first thoracic appendage.

Besides the differences already alluded to, the sexes may be further distinguished
by the antennae ; these in the females are smaller than the antennulse, while in the males
they are very long. In the females plates arising from three of the thoracic segments
form a brood-pouch similar to that which has already been described in the opossum
shrimps. In this pouch the eggs undergo their development, hatching in nearly the
adult condition. In the flexure of the body, and in the possession of a "dorsal organ"
(a structure of unknown functions), the early embryos show a decided approach to the
Edriophthalmia, but later in life they more nearly resemble the Decapods.

Several species are common on the Eastern shores of the United States, frequent-
ing muddy bottoms. They creep about, using the end of the tail to push themselves
forward ; or, folding the tail over the back, they swim with great facility. Their colors
are usually dull, though they are occasionally ornamented with more marked tints.

J. S. KINGSLEY.

FIG. 85. Side view of Alima stage of Squilla empusa, enlarged.

68 NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS IY. EDRIOPHTHALMIA.

This group of Crustacea, which derives its name from its sessile eyes, in contradis-
tinction to the Podophthalmia, with the organs of vision seated upon movable stalks, is
also known as Tetradecapoda, or fourteen-footed Crustacea. These forms, which are
mostly small, possess but very slight popular interest, for but few of them are either
markedly injurious or beneficial, and their habits are not such as to attract much
attention. From a scientific standpoint they also possess but few attractions, for their
structure and their mode of development present but slight valuations except in
minute details.

The group is characterized by a body never consisting of more than twenty seg-
ments, though frequently, by abortion or coalescence, even Jess than this number are
seemingly present. The segments which enter into the composition of the head are
always united, but those which correspond to the thorax of the decapods are never
entirely covered by a carapax ; from four to seven segments of this region being always
free and uncovered. The abdominal segments are frequently reduced in number. The
normal appendages of the body are two pairs of antennae, a pair of mandibles, two
pairs of maxillae, and but one pair of maxillipeds. Next in order are the seven pairs
of walking feet, while the abdomen bears six pairs, which are frequently adapted for
swimming. We here notice a difference from the Podophthalmia in the number of
walking feet, which is occasioned, as is readily seen, by the transfer of the last two
pairs of maxillipeds from the mouth parts to the ambulatory series. The eyes are
usually sessile, though in forms like Munna they are seated on movable stalks, or, as in
some other forms, they may be entirely absent.

The respiration is usually effected by means of gills, but in some few degraded
forms these organs are entirely wanting. The gills, when present, are borne either
beneath the thorax (amphipods) or the abdomen (isopods). Among the former the
gills take the shape of membranous sacs, attached to the bases of some of the walking
feet, while in the latter the inner branch of the abdominal feet becomes modified for
respiratory purposes. Frequently, in the Isopods, five pairs of these gills are developed,
the anterior pair of abdominal feet forming a door, or operculum, which closes in the
others, the rest of the wall of the gill cavity being formed by the lower surface of the

body. In the terrestrial Isopoda, however, but three pairs of
gills are thus developed.

The heart is an elongated, many-chambered organ. The
alimentary canal is short and straight, and in some forms vessels
empty into the intestine near its termination. In the stomach
is found a triturating organ, and a straining apparatus similar
to that of the Podophthalmia. The liver is usually large, and
FIG. 86. Embryo of Gam- empties into the alimentary tract by several mouths.

marus. m. Micropyle. x .

.v. Yolk. b. Brain, i. The eggs, after impregnation, undergo their development in

brood-pouches beneath the thorax, similar to those which we

described while treating of the opossum shrimps. In the embryology we miss the
startling changes which we have seen in the other groups of the Crustacea, for the

EDR I OP II Til A L MIA .

69

Edriophthalmia have a direct development without metamorphoses, hatching from
the egg in the perfect form. There is usually a partial segmentation of the egg, fol-
lowed by the formation of an embryonic disc, and the subsequent out-buddino- of
the limbs. In connection with the embryonic state there is developed on the dorsal
portion of the body a peculiar structure, the so-called micropyle, or dorsal organ, the
functions or signification of which are entirely unknown.

The Edriophthalmia are divided into two well-marked orders : Isopoda and Am-
phipoda.

ORDER I. --ISOPODA.

The name of this order signifies equal feet, and was given from the apparent simi-
larity of the locomotive members. Strictly 'speaking, it does not fully apply to all of the
individuals of the group, for in several forms (for example, Astacilla, from our own
shores) the walking-feet are not so uniform as the name would indicate. The Isopoda
are usually flattened (depressed) forms, occurring either in the sea, in fresh water, or
on the land.

The antennulai lack the secondary flagellum so common among the Decapods ; the
mouth parts, four in number, are strong and well developed. The legs are, for the
most part, small, and more or less uniform in shape,
terminating in hook-shaped claws, a chelate condition
being comparatively rare. From this uniform struc-
ture of the ambulatory members variations may be
noticed in many directions, to which we shall recur
in treating of the various families. In the female
Isopoda the legs bear at the base a series of mem-
branous plates, each extending horizontally toward
the leg of the other side, thus forming, with the
under surface of the body, a brood-pouch, in which the eggs undergo their incuba-
tion.

The abdomen is well developed, but the segments of which it is composed are fre-
quently fused together to a greater or less extent, all being distinct, for instance, in
Lygia, while in Asellus the sutures have almost entirely disappeared. The first five
pairs of abdominal limbs play no part in locomotion, but are developed into broad
foliaceous membranous plates, specialized for respiratory purposes. The last pair
always differ from the others, and either form a cover to protect the respiratory plates
closing over them like folding-doors, or, as is rather more usual, retain more or less of
the functions and structure of the other locomotive limbs.

In internal anatomy we have nearly the typical structure of the Crustacea, the vari-
ations being comparatively few, and unimportant. The development is direct, the
young hatching in nearly the form of the adult, or occasionally
with a smaller number of segments and appendages.

The Isopoda are, to a large extent, carnivorous, living almost
wholly upon animal substances. Among them we find a number
of parasitic forms, which live on the skin, among the gills, or in
the mouth of fishes, while others affect other Crustacea. The
greatest number are found in the sea, where the service they do
in consuming decaying animal matter is inestimable. The fresh- FIG. ss.
water forms are less numerous, while the whole family Oniscidre, or farged" e

FIG. 87. Transverse section of Parcel iio,
showing brood-pouch, a. Plates en-
closing c, brood cavity. I. Legs.

70

NATURAL HISTORY OF ARTHROPODS.

FIG. 89. Leptochelia alyicola, enlarged twenty times.

" sow-bugs," live on the land. The Isopocla are usually divided into two groups,
named, respectively, Ambulatoria and Natatoria, according to their walking or swim-
ming habits, with which are correlated many anatomical features. We will here, how-
ever, omit these two larger divisions, and proceed at once to the discussion of the
families.

The first of these families, the TAJSTAID^E, is of doubtful position, but, according to
Fritz Miiller (whose opinions are seconded by other aiithorities) they probably repre-
sent an ancestral type of Isopoda.
They differ from all other Isopoda
in having the respiratory organs be-
neath the head and first thoracic se-

O

ment, the eyes, when present, upon
jointed stalks, while the abdominal
appendages have no respiratory func-
tion, and the first pair of ambulatory feet are chelate. In their embryology the

Tanaidae are said to present points of resemblance to Asellus, Lygia, and Cnma.

But two genera, Tanais and Leptochelia, are represented,

so far as is known, upon our shores.

In the GNATIIIID^E we find a type more allied to the

normal isopod. The thorax apparently consists of five

segments, and only five pairs of limbs possess the normal

form. In the typical genus Gnathia (Praniza and Anceus

of authors) there is a great difference between the males

and females, so great, in fact, that different sub- families

have been erected for the two sexes of the same species.

The larva? are more nearly like the normal isopod than are

the adult. A single species, G. cerina, is found on the

New England coast.

Passing the ANTHURID^E, a small group of slender

forms, the next families to be noticed are the CYMOTII-

ERID.E, ./EGID.E, and CIROLANID.E, which embrace most

of the parasitic forms of this order. Yet the parasitic

habits have not produced such a profound effect upon the struc-
ture as among the root-barnacles and the Siphonantia, already de-
scribed. From their habits the term "fish lice" is
eminently appropriate for them, as they live at-
tached to the integument or within the mouth of
fishes. Usually these three families are considered
as one, under the name .^EgidaB. They all agree in
having all of the segments behind the head dis-
tinct, and in the lack of an operculum closing in
the respiratory cavity.

Among the more interesting forms belonging
to this family may be mentioned jSSga, psora, the
" salve-bug " of the fishermen, which is frequently

found attached by its sharp claws to the cod and halibut, and Cymothoa

prcpgustator, which occurs attached to the roof of the mouth of the

menhaden. Mr. J. F. Bullar has shown that in certain genera (Cymo- psora, skive-bug

Fn;. 00. Gnathia, male.

FIG. 91. Gnatliia,
female.

EDRIOPHTHA LMIA .

71

FIG. 93. Limnoria Itg-
iiornm, gribble.

thoa, Nerocila, and Anilocra} a peculiar type of hermaphroditism occurs. The youn-,
at a certain stage of development, have well-developed male organs, and also ovaries
but the oviduct has no external opening. Later in life the male organs are lost, while
the oviduct communicates with the exterior and the brood pouch
is developed. It has further been shown that these forms are in-
capable of self-impregnation.

The little wood-boring Limnoria has a family (LIMNOEIDJE) all
to itself. Small as it is this little form docs a great amount of

^j

damage to wharves and shipping. Whenever wood is submerged

beneath the salt-water these Limnoria lignorwn are apt to be

found. The mandibles have sharp cutting-edges, and w v ith them

the Limnoria eats its way into the wood, their immense numbers

making them very destructive. Many plans have been proposed

for preventing the ravages of the gribble, as it is commonly called,

but none of them have proved very successful, and at the same

time cheap. Possibly the best is the impregnation of the wood

Avitli creasote, or "kyanizing." Limnoria occurs in the waters

of Europe and America, and on our Pacific coast is said to do a great deal of damage,

especially in San Francisco Bay.

The IDOTEIDJE is the largest of the isopodan families, as well as the best known.
The body is usually long and slender, while several of the abdominal segments are
united into a large caudal plate. In this family the operculum of the respiratory cavity
acquires its most perfect condition.

The genus Idotea is the most prominent in the family,
and our common I. irrorata has a very extended distribu-
tion in the northern hemisphere. It varies greatly in
color, closely resembling in this respect the rocks and
weeds among which it dwells. It is very abundant in
tidal pools along our northern Atlantic coast. Less com-
mon is Idotea phosphorea, which has the same habits, but
which is especially noticeable from its phosphorescent
powers. Our two species of Chiridotea (coeca and tuftsii)
are much broader than the typical forms of the family.
They live burrowing in the sand from near high-water
mark to about twenty-five fathoms. The name of the
first species is not very appropriate, for it is not blind.

Passing by the MUNNOPSID^E, a small family of blind
marine Isopoda, we come to the ASELLID^E, the mem-
bers of which are found in both salt and fresh water. The
abdominal segments are united, the legs are fitted for
walking, while the eyes may be present or absent. Asettus is the typical genus, and its
members are common in the fresh waters of Europe and America. A blind form,
described under the generic name Ccecidotea, occurs in the waters of the caverns of
Kentucky and Indiana.

The BOPYRIDJE embraces forms which are parasitic on other Crustacea. By
their parasitic habits the females have become greatly altered in shape, frequently
losing many of their appendages. They usually inhabit the branchial chamber of
decapod Crustacea, attaching themselves to the gills and sucking the juices of their

FIG. 94. Idotea irrorata, en-
larged.

72 NATURAL HISTORY OF ARTHROPODS.

host. The males are much smaller than the females, and have not been so ex-
tensively altered by parasitism. They usually are found attached to the modified
abdominal feet of the females. These forms have not been exhaustively studied,
and comparatively little is known of our American forms. The principal char-
acters separating the genera are the number and shape of the abdominal branchial
feet.

The last family of Isopoda which we have to notice is the ONISCID^E. The forms
belonging here are almost entirely terrestrial, for although some of them may be found
on the seashore they are not aquatic in their habits. The antennulae are minute, but
the antenna? have from six to nine joints, the differences in number affording im-
portant systematic characters. The legs are all fitted for walking, while
the abdomen is composed of six distinct segments. In common parlance
these forms are known as "sow-bugs," "pill-bugs," and "wood-lice."
They live in damp situations, in cellars, under decaying wood, etc.
In Armadillo and its allies the body can be rolled up in a compact ball,
recalling the similar capacities of the mammalian genera Tatusia, Dasy-
pus, and Tolypeutes. The more common forms, belonging to the genera
OnisciiS) Porcellio, etc., usually do not have this capacity. These forms
are largely if not entirely vegetable feeders, devouring much which
FIG. 95. Porcei/io, -\vould become offensive or injurious to man. In olden times, when the

sow-bug, enlarged. .

more disgusting a thing was the more erncacious it was considered as
a remedial agent, some of these " sow-bugs " played an important part in the Pharma-
copoeia, but doubtless they had very little therapeutic value.

ORDER II.-- AMPHIPODA.

As a rule the members of this order present a very strong contrast to those of the
Isopoda. These have the body flattened vertically, the legs, as the name indicates,
divided into two dissimilar series, while some frequently terminate in a more or less
perfectly formed pincer. They are not so largely modified by parasitic habits, while
their mouthparts are less variable than in the group which AVC have just left. The gills
are in the form of sacs attached to the bases of the thoracic limbs. The sessile eyes
are compound, but the investing integument is not faceted. The antennulae are
sometimes two-branched, and the mandible usually bears a palpus. The two anterior
pairs of walking feet are usually fitted for grasping, sometimes bearing a pincer as per- (
feet as those found in the Decapoda. Moulting is effected by a transverse fissure just,
behind the head, and a longitudinal one extending from this down the back. The
individuals have not that power of amputation of members which has been noticed in
connection with certain Decapoda.

SUB-ORDER I . - - L^MODIPOD A.

In the older works the forms included under the name Lsemodipoda were regarded
as belonging to the Isopoda, the next view placed them as an order intermediate
between the Isopoda and the Amphipoda, while more recently the weight of authority
is in favor of the position here accorded them. In these aberrant forms the most
striking characteristic is the rudimentary condition of the abdomen, which is repre-
sented by an inconspicuous tubercle without appendages. The number of thoracic

EDRIOPHTHALMIA .

73

feet varies from five to seven, and the branch ial sacs are attached to the first four
segments, or to only one or two of them.

The CAPKELLID^E are long and slender forms, with well-devel-

oped antennae and antennulae. They live in salt-water, walkino-

around on submarine plants in a very deliberate manner, and

progress by a doubling-up of the body in about the same way

that the measuring worm does, and the most common species

on the Atlantic coast, received its name ( Caprella geometrica)

from this habit.

The other family of this sub-order has re-

ceived the name CYAMID^E, from its leading

genus, Cyamus. These are the whale-lice

which live attached to the skin of whales.

Each species of these marine mammals prob-

ably has its own species of parasite. They

are small forms, a quarter or a half an inch

in length, with rudimentary antenna?, five

P f ***** ^ tW P* f branchial S&CS

metrica on a branch attached to the third and fourth segments

of the body. The size of these sacs exhibits much variation ; in
C. ceti they equal the longest of the limbs in length ; in other forms they are pro-
portionately much shorter.

FIG. w.-

g eo-

SUB-ORDER II. AMPHIPODA GENUINA.

This group contains the numerous forms in which the head is clearly distinct from
the first thoracic segment, and which have the abdomen well developed, and composed
of from five to seven segments, most of which bear appendages.

Our first family, OXYCEPHALID^E, embraces a few long and slender forms found on
the high seas. The head is greatly elongate, and the feet do not have the basal joint
expanded. The peculiar features acquire their greatest development in Rhabdosoma,

FIG. 98. Rhabdosoma batel, enlarged.

of which we figure a species from the middle of the Pacific ocean. None have been
recorded from either coast of the United States. These forms swim by doubling the
body, and then suddenly extending it.

In the family PHRONIMID^E the antennae are absent, at least in one sex ; while the
antennulae are well developed, the maxillae are more or less rudimentary. Phronima,
the typical genus, is a sort of hermit among the Amphipoda ; for it lives in the dead
tubes of Beroe, Pyrosoma, and other similar pelagic forms. A species occurs in our
waters. Near Phronima and Hyperia is to be placed the large Amphipod, JTtcm-
mops pellucida, which was taken by the "Challenger" expedition off Gibraltar, at a
depth of nearly twelve hundred fathoms. It is perfectly transparent, and receives its

74

NATURAL HISTORY OF ARTHROPODS.

generic name from its remarkable optical organs, the facets of which cover the whole
of the upper surface of the head. Cystosoma is a closely related form, which was

FIG. 99. Thaumops pellucida, a little reduced. . Upper surface of head, showing

the large eyes.

found off the Cape Verdes, at a depth of fifteen hundred fathoms. For these two
forms a family, CYSTOSOMID^E, has been erected.

The HYPERID^B are represented on our coast by two or more species, which possess

commensal habits. One of these inhabits the
genital folds of Awelia, Cyanea, and other
jelly-fishes, but it is not compelled to stay there,
for it is a good swimmer, and leaves its host
whenever it wishes. All of the forms belong-
ing to this family have a very thin integument,
which is free from hairs ; the antennulae are
present in both sexes ; the eyes are very large.
They are found in all parts of the world, and
many have the same habits as the species mentioned above, some affecting jelly-
fishes, others living with Salpce, etc. Some of the European species find a home in

FIG. 100. Hyperia, enlarged.

EDRIOPHTHA LMIA .

75

the dead tests of Doliolum (one of the ascidians), in which they dwell much after
the fashion of hermit crabs, while Beroe, one of the jelly-fislies, furnishes a habi-
tation for others.

The family CHELUKID^E contains but a single species, Chelura terebrans, which
has several of the abdominal segments united, while the last three abdominal feet are

FIG. 101. Cystosoma neptuni, slightly reduced.

greatly modified from the usual type. This species is, next to -Limnoria, the most
destructive of all Crustacea. The animal only reaches a length of about a third of an
inch, but its immense numbers make up for the diminutive size. Like Limnoria they
excavate burrows in the hulls of ships, the piles of wharves and bridges, and any other
submerged timber. It is in Europe that this species has caused the greatest damage ;
it is almost unknown in this country, as it
has only been seen in our waters in a few
isolated cases.

The COROPHID^E is a much larger fam-
ily, represented in our waters by many
species. The forms are largely dwellers in
tubes, which they either form for them-
selves or find in the deserted homes of

-r ,1 FIG. 102. Ceratms rubricornis, female; below the

marine worms, etc. Many of the species pincerof the male, enlarged.

76

NATURAL HISTORY OF ARTHROPODS.

FIG. 103. Unciola irrorata,
enlarged.

have peculiar glands in their legs, which secrete a substance which binds together the

sand and mud in which they dwell into a tube. The mem-
bers of the genus Amphithoe construct such tubes, which
they attach to the under surface of stones, while the species
of Cerapus carry their dwellings about with them much after
the fashion of caddis-fly larvae. Unciola does not build a
tube, but takes any that it may find vacant. All of these
forms have the power of leaving their tube ; but, for the
most part, they are content to stay at home, their heads
projecting from the opening, and all of their sense organs
on the alert for any passing morsel of food.

The GAMMARID^E is the largest in number of species
of any of the Amphipoda, Like the last its members are
aquatic, and when removed from the water they endeavor
to travel lying upon their sides, but the attempt is not very
successful. When placed beneath the water they are at
once in their element, and swim with ease, or buoyed up
by that medium they walk in an upright position. Their
swimming is mostly done upon the back or side, and is a
rapid but somewhat corkscrew-like motion. They have
the antennula? large, and frequently bearing a secondary
branch. The species are mostly marine, only a few being
found in fresh water.
The most prominent genus is Gammarus, numbers of which abound among the
Fucus or rock-weed on our shores, and in most of our inland lakes and rivers as
well. They do not venture out into the open water, but remain mostly among the
vegetation alonof the shores. Others dwell in or on the mud at the bottom. Of their

O O

habits scarcely anything of popular interest can be said; but though uninteresting they
are far from unimportant, for their vast numbers render them very prominent in
the food supply of fishes.

The members of the family
ORCHESTID^E are the most ter-
restrial of the Amphipoda, and,
although never found but a short
distance from the water, there are
several species which will die if
kept too long in that element.
These forms are familiar to those
who have spent much time at the
seashore, as the "beach-fleas" so
common on the sandy beaches.
The ordinary observer, however, has but a very slight idea of their real abundance.
If he will turn over some of the sea-wrack (the dried seaweed, etc.) which forms long
windrows along the sand above high-water mark, he will have some conception of the
incalculable number of individuals. When the weather becomes so warm that the
windrows no longer retain their moisture, the Orchestidae burrow into the sand. From
their habitat these forms are of slight importance as a fish food, but they play their
part in the economy of nature by devouring all decaying animal and vegetable matter

FIG. 104. Gammarus ornatus, enlarged.

EDRIOPHTHALMIA .

77

FIG. 105. Orchestia agilis, beach-flea, enlarged.

which comes in their way. While they furnish many a meal for the shore birds,
the tisrer beetles consume an immense amount of them.

O

In speaking of the amphipods,
Professor Verrill says : " These
small Crustacea are of great im-
portance in connection with our
fisheries, for we have found that
they, together with the shrimps,
constitute a very large part of the
food of our more valuable edible
fishes, both of fresh and salt waters.
The amphipods, though mostly of
small size, occur in such immense numbers in their favorite localities that they can
always be easily obtained by the fishes that eat them, and no doubt they furnish ex-
cellent and nutritious food, for even the smallest of them are by no means overlooked
even by large and powerful fishes, that could easily capture larger game. Even the
voracious blue-fish will feed upon these small Crustacea where they can be easily ob-
tained, even when menhaden and other fishes are plenty in the same localities. They
are also the favorite food of trout, lake whitefish, shad, flounders, scup," etc.

The Edriophthalmia make their appearance in the coal measures of Europe and
America. These early forms are amphipodal in their general appearance, but in many
details they resemble some of the true shrimps. The coal-measures of Illinois are
especially rich in these forms.

J. S. KlNGSLEY.

FIG. 106. Amphithoe maculata, enlarged twice.

78 NATURAL HISTORY OF ARTHROPODS.

AKTHKOPODA OF DOUBTFUL POSITION.

As was mentioned on a preceding page, there are several groups of jointed-footed
animals the position of which, in the branch of Arthropoda, is very uncertain. No
one has yet conclusively proved that any of these forms belong to either the crustaceans
or to the insects, and it may possibly be ascertained that some at least are to be con-
sidered as equivalents to the groups just mentioned. With this great uncertainty we
have considered it advisable to place these forms in an intermediate position between
the Insects and Crustacea, and in their treatment to omit the terms class, sub-class,
and order, except in one group where it seems that their use is warranted. With the
exception of Limulus, the living forms are generally small and not of frequent occur-
rence, facts which in part explain the uncertainty which exists regarding their
systematic position.

PYONOGONIDA.

The " Sea Spiders " form a problematical group which agrees with the true
Arachnida in the possession of eight pairs of legs, but they present so many points of

difference from them, and indeed from all Tra-
cheata, as to justify Dr. Hoek, their latest student,
in regarding them as a class. The body is always
small, and is divided into four segments, the an-
terior of which has received the name of cephalo-
thorax. To this is attached a proboscis, which
has recently been shown to be not the united
chelicerae and pedipalps, as was supposed by Pro-
fessor Huxley. Behind the proboscis are three
pairs of appendages, the mandibles, palpi, a-nd
ovigerous legs. Sometimes the first two pairs
are lacking in the adults, but the ovigerous legs

~ O

are always present, and only one exception is
FIG. 107. PhoxicMUdium maxiiiare, sea-spider, known to the rule that the male bears the effffs

twice natural size.

attached to these limbs. On the doi'sal surface

of the cephalothorax is a small prominence known as the oculiferous tubercle, which
bears the four simple eyes. These eyes, however, are occasionally rudimentary or
absent, especially in the deep-sea forms.

The thoracic portion of the cephalothorax, and the three thoracic segments, bear
four pairs of walking feet, each supported on an outgrowth from the body. The legs
are long, frequently many times the length of the body, and are eight-jointed. The last
thoracic segment also bears the rudimentary abdomen, which is occasionally articulated.

The nervous system consists of a brain and five (rarely four) infra-oesophageal
ganglia, connected by commissures. From the brain nerves go to the eyes, mandibles,
and upper portion of the proboscis ; from the first ganglion behind the oesophagus, the
lower portion of the proboscis, the palpi, and ovigerous legs are innervated. The other
ganglia supply the legs. The digestive system presents some interesting peculiarities.

ARTHROPODA OF DOUBTFUL POSITION.

79

A short oesophagus opens into a muscular enlargement, the walls of which are lined
with chitinous projections, the whole presenting a strong resemblance to the anterior
portion of the stomach of the lobster. From
this stomach a tube of varying length goes
to the anus. From this tube arise elongated
pockets or cosca, varying in number from four
to six pairs, which enter, to a greater or less
extent, the proboscis, mandibles, and legs.
The heart is a short tube, which has usually
three incurrent apertures, while the blood
by its action is forced forward through an
anterior excurrent orifice into the spaces be-
tween the muscles and the viscera, there
being no arteries or aorta present. Respira-
tion is effected through the general surface

O O

of the body, there being no specialized organs
for the purpose.

The sexes are always separate. The gen-
ital organs are lodged in the ambulatory legs,
and have their openings in the basal joints.
The eggs are impregnated after emission, and
are transferred to the ovigerous legs of the
male, where they are enveloped in small sacs,
and usually hatch with the proboscis, palpi, mandibles, and three pairs of legs devel-
oped, though some species have only one pair fully developed, and others have four

FIG. 108. Galls and young of Phoxichilidium,
enlarged.

The eggs undergo a total segmentation,

FIG. 109. Colossendeis colossea, one-half natural size. a. Palpi, d. Proboscis. I. Legs. o. Ovigerous legs.

at the time of leaving the egg. The young of the genus Phoxichilidium live a semi-
parasitic life within the digestive cavities of certain tubularian hydroids, where they
form what may be called galls.

Pycnogonids are not rare on our coasts, and may be sought for on Campamdarice

80

NATURAL HISTORY OF ARTHROPODS.

and other hydroids, as well as sponges. The dredge frequently brings up specimens.
About thirty species are known from American waters.

About a hundred and fifty species of pycnogonids have been described, divided
into about thirty genera and four families. In the first of these families, PHOXICHILID:E,
the mandibles and palpi are rudimentary or absent, and the ovigerous legs are usually
present only in the male. The PALLEXLDJE have the mandibles well developed, the
palpi rudimentary or absent, while the ovigerous legs are occasionally absent in the
female. The COLOSSENDEID^E reverse the features of the last family, as they have the
mandibles rudimentary or absent, while the palpi are present. This is the largest
family both in genera and species, and in the size of some of its species as well, the
form which we figure occasionally spreading twenty-one and one half inches, while
Willemoes-Suhm mentions one "measuring nearly two feet across the legs." The
remaining family, NYMPHONID.E, has the mandibles and palpi well developed.

On the systematic position of the Pycnogonida, anatomy and embryology throw
but little light. Dr. Hoek says, " The Pycnogonida form a distinct and very natural
group (class) of arthropodous animals. Their common progenitor (their typical
form) must be considered as a hyp&thetical pycnogonid with three-jointed mandibles,
multi-jointed palpi, and ovigerous legs with numerous rows of denticulate spines on
the last joints." Of their relationships to the Crustacea or the Arachnida we know
nothing.

TARDIGKADA.

The Water Bears derive their common name from a more or less fanciful resem-
blance to the true bears, most evident in side views,
while the scientific name of the group has reference to
their slow progression. The Tardigrada are microscopic
forms which are occasionally found in moist sand and
moss, and but rarely free in the water. The body is
elongated, and indistinctly shows signs of segmentation.
Like the sea-spiders which we have just passed, they
have four pairs of limbs, each terminated by two or
more claws. The mouth is at the anterior end of the
body, and is armed with organs which closely resemble
those of some of the true mites to be described farther
on. A little distance behind the mouth occurs the mus-
cular pharynx, and from this the alimentary tract, widen-
ing out in the middle to a considerable extent and then
contracting, pursues a straight course to the anus at the
posterior end of the body. No respiratory or circula-
tory apparatus exists. The nervous system is of the
usual arthropodal character, and consists of a supra-
oesophageal ganglion or brain, and a ventral chain of
four large paired ganglia corresponding to the limbs.
Occasionally a couple of simple eyes are connected
with the brain. The water-bears are hermaphroditic,

b. Gullet, c. salivary glands. . d. piiar- the same individual and opening together into a

ynx. e. Ovary, f. Vesicula semin-

alis. g. Testes. 1, 2, 3, 4. Legs. cloaca.

ARTHROPODS OF DOUBTFUL POSITION. 81

The little that is known about the embryology of the group does not throw any
light on their systematic position, but the facts that are known of their anatomy would
seem to indicate that the position of these forms may be near the lower mites
(Acarina). The eggs are very large, and when they are laid the parent casts its
integument, which covers them in a manner somewhat like that of the ephippia of the
Entomostraca described on a preceding page. The egg undergoes total segmentation,
and the young hatch with four, or occasionally three, pairs of appendages.

The water-bears are not very common, but should be looked for in Avater squeezed
from the damp moss of swamps. Like the rotifers which occur with them they are
said to withstand desiccation, the addition of water to their dried bodies reviving
them. There are several genera, Mdcrobiotus^ Milnesium, and Echiniscus being the
most prominent. No fossil forms are known.

SUB-CLASS. GIGANTOSTRACA.

Only one living genus remains to illustrate this group which once formed a very
prominent feature in the fauna of the world. Naturalists are now pretty well agreed in
the union of the trilobites, horseshoe crabs, etc., in a group to which Professors Haeckel
and Dohrn have applied the name Gigantostraca, and Dr. Packard the name Paleocarida.
To the latter student belongs the credit of first clearly showing the close relationships
existing between the Trilobita and Merostomata. Of the extinct forms of course but
little can be known. Geologists can learn but little of the anatomy or embryology of
the fossil forms, and hence we must depend largely upon analogies drawn from the
study of Limulus for our knowledge of the trilobites.

ORDER I. TRILOBITA.

There are but few groups of fossil animals which possess more popular interest than
those peculiar forms known as trilobites. This arises not only from the beauty of their
form, but from the questions which have arisen in regard to the position which they
should occupy in the systems of classification. Linna3us described the few which were
known to him as EntomolitJms paradoxus, thus clearly indicating his belief , that they
were fossil articulates. Latreille, struck by their superficial resemblance to the chitons,
thought to range them near those forms among the Mollusca. Usually, however, they
have been regarded as Crustacea, and have been assigned varying positions within that
group, some considering them as allied to the Phyllopoda, while others placed them
near the isopodan genus, Serolis. More recently they have been considered as near
relatives of the horseshoe-crab, and together with that problematical form they have
been shifted about, at one time being regarded as Crustacea, at another as Arachnida,
or as occupying a place between these two groups.

This uncertainty has arisen partly from the fact that we know almost nothing of
the structure of the trilobites, and until recently but little of the anatomy of Limulus,
and less of its development.

The name Trilobite, which means three-lobed, is applied to certain articulated
animals, in which the body is usually divided into three well-marked regions : first, a
head, rounded in front and usually bearing large compound eyes ; second, a thorax made

VOL. II. 6

82

NATURAL HISTORY OF ARTHROPODS.

FlG. 111. Triarthrus becki,
trilobite, natural size.

up of a varying number of nearly similar segments, and lastly an abdomen, or as it is
called in technical works, a pygidium, composed of a number of segments united to-
gether. Until very recently nothing has been known of the
nature of the imder-surface, or the character of the limbs

of the trilobites. The first specimen, showing the under-
surface of a trilobite, was described by Mr. Billings, but, as
the appendages were rather indistinct, the evidence Avas not
accepted by all. Mr. Walcott then investigated the subject
by means of sections of the fossils, arriving at many satis-
factory results, but leaving many other problems still un-
settled. Lastly, Professor Mickelborough described another
specimen, showing the limbs, but without throwing any new
light on the subject.

The head is rounded in front, and frequently its posterior
angles are produced into spines, which sometimes exceed the
body in length. The central portion of the head is raised
above the rest and constitutes the glabellum. On either side
of the glabellum are the eyes, w r hen these organs are present.
These eyes are either composed of isolated ocelli, or groups
of ocelli, or lastly, compound eyes similar to those of other arthropods, and which,
if we may accept the sections of Mr. Walcott, as interpreted by Professor Packard,
are essentially similar to those of Limulus as far as the hard parts are concerned.
On the under-surface of the head is a shield-shaped upper lip, behind which is the
mouth. Of the other organs of manducation nothing certain is known. The
thorax is divided into three longitudinal portions by two furrows. The medium
ridge is known as the axis, the lateral portions as the pleurae. The joints of
the thorax, in many forms, were freely movable on each other, and some of these
animals possessed the power of rolling themselves into a ball just as does the familiar
pill-bug of to-day, and fossils in this condition are frequently found. On the under-
surface of the thorax occur the several jointed limbs, one pair to each segment. Attached
to the basal joint of each leg is a peculiar organ, curled in a spiral, which Mr. Walcott
interprets as a gill.

The abdomen is divided in the same manner as the thorax, the axis being continued
to the end of the body. Beneath the abdomen, Professor Mickelborough thinks that
he has found lamellar appendages like the gills of Limulus ; but
Mr. Walcott, in his restoration, continues the ambulatory legs
into this region.

The development of the trilobites has been studied by Bar-
rande in Europe, and by Walcott in our own country. In the
earliest known stages the body is a small, oval disc, without any
distinct segmentation, but with growth, seg-
ments appear, their number increasing with
age. There is no metamorphosis, the devel-
opment being direct. The head of the adult can be resolved into
six segments ; the thorax contained from two to twenty-six, while
the abdomen was composed of, at the most, twenty-eight segments.
FIG. us. Larva of The trilobites made their appearance in the lowest Silurian, and

Sao hirsutus, natural

size and enlarged. died ou t at the close of the carboniferous. Both in number of

. FIG. 112. Larva of tri-
lobite, Trinwlcns ornatus,
natural size and enlarged.

ARTHROPODA OF DOUBTFUL POSITION.

83

individuals, and in variety of forms, the order attained its highest point in the upper
Silurian. About four hundred species distributed among fifty genera have been de-
scribed.

Of their habits nothing definite is known. Dr. Burmeister thought that they lived
in large schools in the shallow water along the shores, swimming back downwards like
so many Phyllopoda to-day. Dr. Packard, on the other hand, thinks that, like the
living horseshoe crab, they burrowed just beneath the surface of the mud and sand at
the bottom of shallow waters, a view which we are inclined to consider most
probable.

ORDER II. MEROSTOMATA.
The o-enus Limulus, which embraces the forms familiarly known as horseshoe

o /

crabs, king-crabs, and Molucca-crabs, is the only living representative of the group

Gigantostraca. The living species have

a peculiar distribution. On our own

coast Limulus polyphemus extends

from Maine to Florida and the West

Indies, while L. mohtccanns and ro-

tundicaudus and two other doubtful

species are found on the eastern shores

of Asia. No examples are found on

the western shores of either continent,

and none have been reported from

South America.

The horseshoe is composed of three
portions movably articulated to each
other. The anterior, the cephalothorax,
closely resembles in outline the foot of
a horse, and gives the common name
to these animals. Behind this comes a
wedge-shaped abdomen, and then a long,
bayonet-shaped caudal spine. On the
upper surface of the cephalothorax are
the eyes. Of these two are compound,
one on either side of the body, while
near the front margin in the median
line a couple of simple eyes occur. The
lower surface of the cephalothorax
closely follows the upper, so that in-
stead of the thick body which would be
expected from seeing the vaulted back,
the body is really very thin. Near the

ppntrp nf tliP Inwpr Qiirfinp ITMP iv FlG - 114 ' - Under-surface of horseshoe crab, Limulus . ..

OWei SUliace ailSe SIX plumus. a. Abdomen, c. Cephalothorax. jr. The first

mirs of IPOX nml hpfwpon tliP Qoonnrl gill-bearing abdominal appendage, m. Mouth, o. Oper-

legS, an culum. s. Metastoma. 1 to 6. Cephalothoracic limbs.

pair is the mouth. The first pair are

small, and differ considerably in the two sexes ; in the female they end in a regular
pincer, but in the male the finger is bent and folds over the thumb. The next four
pairs of feet may either terminate in a pincer, or one or more may end in a simple

84

NATURAL HISTORY OF ARTHROPODS.

claw, there being a difference in the different species and sexes. The sixth pair, how-
ever, terminates in two Hat spines, and just above these on either foot is a whorl of
similar plates. These are of great use to the animal in walking, as they give a firm
foothold in the soft mud and sand. Between the bases of the sixth pairs of feet is the
metastoma, a pair of single-jointed appendages.

The abdomen above shows indistinct traces of its original segments, while its
lateral margins are armed with movable spines. Beneath are found the gills. These
are composed of numbers of thin plates, arranged like the leaves of a book, and sup-
ported on five pairs of greatly modified limbs, the whole being covered by the anterior
pair of abdominal appendages which form the operculum.

FIG. 115. Longitudinal section of Limulus. a. Anus. b. Brain, c. Cone. cp. Cartilaginous plate. /(.Heart.
i. Intestine. I. Liver, m. Mouth. . Nervous cord. o. OEsophageal ring. p. Proventriculus. s. Stomach.

From the mouth the alimentary canal first goes forward, widening out into a crop
or proventriculus, the Avails of which are lined with chitinous folds. This crop bends
on itself and communicates by a small tube with the intestine, which pursues a straight
course to the end of the abdomen. The liver and genital organs occupy the greater
part of the body. The heart is an elongate organ, and the nervous system consists of
a ring around the oesophagus, from which arise the nerves supplying the cephalo-
thoracic members, and a long cord which gives off nerves to the gills, etc. One

remarkable peculiarity should be mentioned here: The oeso-
phageal ring and the nervous cord are ensheathed in the ven-
tral arteries so that they are bathed with the blood.

It is extremely probable that the same individuals deposit
their eggs more than once each year, the favorite time being
at the time of the full moon, when the tides run unusually high.
The eggs and milt are placed in hollows near high-water mark,
and are covered with sand by the retreating tide. The time
of spawning is in the months of May, June, July, August, and
probably in the Southern States, March and April. The eggs
are small, resembling in appearance seed-pearls, and are not
easily distinguished from the sand in which they are deposited.
Of the early stages of development nothing certain is yet known. By some process
the eggs become enveloped at an early day with a cellular membrane, and subsequently
the six pairs of cephalothoracic limbs appear simultaneously. Next, the body segments

FIG. 1 16. Early stage of
Limulus embryo.

ARTHROPODA OF DOUBTFUL POSITION.

85

FIG. 117. Limulus embryo, nearly
ready to hatch.

and the first two pair of abdominal limbs appear as flattened plates, resembling in
appearance the same appendages in the adult. Soon the cephalothorax and abdomen
become separated from each other, the limbs acquire
more of the adult character, and the abdomen becomes
segmented, while the jointing of the anterior part of
the body disappears. At about this time the egg ab-
sorbs a quantity of water, and by the pressure the egg-
shell is ruptured, but the embryo still remains within
the cellular membrane. It now shows the first move-
ments but in a very slight degree. The body is still
enclosed in the first larval skin, but within this the
spines of the sides of the abdomen and the hairs of the
gills are seen to develop gradually, pushing off the old
integument, although it does not really cast the skin
until it hatches or leaves the cellular membrane in
which it is enveloped. On leaving the egg the young
Limulus bears a very close resemblance to the young trilobite, as can be seen by a
comparison of figures 112 and 118. At this time the caudal spine has not been

developed, existing only as an inconspicuous lobe at the
extremity of the abdomen. The sutures of the abdomen
have nearly disappeared. The young horseshoe swims
freely, and with the first moult the caudal spine begins
to assume the adult form.

The question as to whether the horseshoe crab is a
crustacean or an arachnidan is too abstruse for consid-
eration here. The chief advocate of the latter view is
Professor E. Ray Lankester, and the arguments upon
which he places the most dependence are the nature
and homologies of the walking legs, and the origin of
the nerves which supply them ; the structure of the eye,
and a more or less perfect homology existing between
the gills of the horseshoe and the pulmonary lamellae of the scorpions, to which
we shall refer in a subsequent portion of this volume. Additional evidence for this
view is also found in the little which is known of the embryology. In the opinion
of the writer enough has been discovered to show that Limulus is not a crustacean,
but it has yet to be proved that it should be placed near the scorpions. The most
important objection to such a course are the gills, which are fitted for aquatic respira-
tion, and the absence of any trachea.

The horseshoe crab frequents sandy and muddy shores, and especially sheltered
bays and estuaries where it is not exposed to the full force of the waves. It burrows
just beneath the surface, a life for which its structure is eminently adapted. The sharp
anterior edge of the thorax is peculiarly fitted for being forced through the sand, while
the caudal spine, and especially the sixth pair of feet with their whorls of flat spines,
afford a firm foothold for forcing the body forward. The crab first arches its body by
bending it at the joint between the cephalothorax and abdomen, draws the sixth pair
of legs forward, and then extends the body, pushing with all its might with the legs
and tail. Occasionally it leaves its underground burrows and moves over the bottom,
where its progression is a true walk, in which the last five pairs of legs are employed.

FIG. 118. Limnlus, just hatched,
natural size and enlarged.

86

NATURAL HISTORY OF ARTHROPODS.

Limulus lives upon the many small animals which it finds in the mud, worms forming
the bulk of its diet. It grasps the food by one or more of its numerous pincers, and
places it between the spiny basal joints of the legs, which are kept in constant motion
rasping the food into minute particles and forcing them into the mouth.

The horseshoe crab, like other Arthropoda, allows for increase in size by moulting.
The hardened integument of the cephalothorax splits along the sharp margin, and
through the opening thus afforded the animal extracts himself, leaving even the lining
of the anterior and posterior portions of the digestive canal behind.

Like many other types of animals which have existed on the earth through many geo-
logical periods, the horseshoe crab has great vitality. Not only can it bear immersion in
fresh water for several days, or even a complete removal from any aqueous element for
the same length of time, but its eggs are laid in the sand, where they are twice a day left
uncovered by the retreating tide, and are exposed to the fresh water of the frequent
rains of spring.

SUB-ORDER I. - - POECILOPODA.

Limulus and its nearest fossil allies are united into a sub-order under the above
name. Of the living species of Limulus we have already spoken above. The genus
makes its appearance in the lithographic slates of Solenhofen, Bavaria, which are of
Jurassic age. Prestwichia and Euproops are found in the carboniferous rocks of Illi-
nois. In their general appearance they differ but little from the Limulus of to-day.

SUB-ORDER II. - - EURYPTERIDA.

The animals which are associated together under the sub-ordinal name Eurypterida

appear in the upper Silurian,
and become extinct in the
carboniferous. In general ap-
pearance they are intermedi-
ate between the king-crab
and the scorpions. To the
anterior portion of the body,
which we may call the cephal-
othorax, are attached at the
most but five pairs of limbs
which, like those of Limulus,
have spines on the basal joints.
One or more of the anterior
pairs may terminate in a pin-
cer, while the posterior pair
are usually expanded so as to
form a broad paddle. A met-
astoma is present, occupying
the same place as that of Lim-
ulus. On the upper surface
are the two eyes. The ab-
domen is large and long,

FIG. 119. Eurypterus remipes, reduced. A, dorsal, and B, ventral view. and is Composed of twelve

Meta8toma - ^ Cephalothorax. ,

ARTHROPODA OF DOUBTFUL POSITION.

87

terminated by a bayonet-shaped or spoon-shaped caudal spine. No abdominal limbs
are present. JEurypterus remipes, the typical species, is common to the Silurian rocks
of Europe and America. Eusarcus scorpionis occurs in the water-lhne group of
Buffalo, N. Y. Pterygotus is another prominent genus. It is supposed that the
Eurypterida swam near the surface, and were more predatory animals than the king-
crabs.

In the lower carboniferous rocks of Great Britain and the con-
tinent a number of small fossils have been found, the systematic posi-
tion of which is extremely doubtful. From their approximately
circular outline they have received the generic name Cyclus. In
length they average between a quarter and a third of an inch. Dr. de
Koninck would consider them as most nearly related to the trilobites,
while Dr. Woodward, the able paleontologist of the British Museum,
thinks that they may be " the larval stages of JPresttvichia, Belinurus,
etc., the ante-types in carboniferous times of the modern king-crab."

FIG. 120. Cyclus
jonesianus, en-
larged. .

FlG. 121. Linguatula diesinr/ii, enlarged four times.

PENTASTOMIDA.

In the Pentastomida, for which no common name exists, we have a type so modi-
fied by a parasitic life that it is difficult to trace at first sight even arthropodan char-
acters, much less features by which it
can be assigned to any of the well-
defined groups, although it seems
probable that, like the Tardigrada, it
belongs near the mites. The body is
long and worm-like, and is constricted
by numerous thickenings of the body-wall, so that it appears as if made up of many
short segments. The mouth occurs near the anterior end of the body, and on either
side of it are two very minute curved hooks, and in front of them a pair of rudi-
mentary palpiform organs. These hooks can be drawn into small openings, and as
these with the mouth are five in number, the applicability of the name (five mouths)
is evident. Each of these hooks is solid, and is moved by appropriate muscles inside
of the body. Another name, Linguatulina (little tongue), has been given to these
forms.

From the mouth the alimentary tract pursues a nearly straight course the whole
length of the body, being held in place by a membrane similar to the mesentery of the
vertebrates. The nervous system consists of a ring around the oesophagus, with a pos-
terior enlargement, from which nerves are given off to the different portions of the
body. The sexes are distinct, the males being usually much smaller than the females.
The eggs undergo their development in the ovary, and the larva? resemble, in general
appearance, both the young of the mites and of some of the parasitic Crustacea.

The habits of these forms are more interesting than is their structure, and in this
respect they show a great resemblance to the cestoid worms, of which an account is
given in the first volume of this series. In their sexless condition they are found in
the lungs and liver of various rodents and herbivorous mammals, and also of some
of the reptiles. Leuckart has traced out the life-history of some of the forms with
great care. When the flesh of the hare or rabbit containing these forms is consumed

88 NATURAL HISTORY OF ARTHROPODS.

by a dog, wolf, or other carnivore, these sexless forms pass to the nasal region, and
there gradually acquire the sexual condition, develop their young, which pass out with
the nasal mucus, and fall upon the grass, or other food of the rodents. These young
may then be eaten by the rabbit, and in his body they develop by a series of changes,
pass through the walls of the intestine to the lungs or liver, where they become
encysted, ready to go through the same cycle of changes as did their parents. Thus,
like the tape-worms, two distinct hosts are necessary to complete the circle of life.
Other forms occur in serpents, apes, etc., and even in man, but their life-history has
not been traced with the completeness of .that of Pentastomum tcenioides detailed

above.

J. S. KINGSLEY.

FIGS. 122 and 123. Agnostus nudus, trilobite, larva and adult.

INSECTS.

89

CLASS II. INSECTA.

THE term Insecta is used with varying significations by different authors, some
restricting it to the six-footed forms, while others enlarge it so as to include the spiders,
mites, and millepeds as well, reserving the term Hexapoda for the Insecta of the
former.

In the present work the term is used in its most comprehensive form, and includes
all arthropods in which the body is more or less clearly divided into three regions, -
head, thorax, and abdomen ; which respire by trachea instead of gills ; undergo a more
or less complete metamorphosis in passing from the embryonic to the adult condition ;
and which have, at no stage of development, the two-branched appendages which we
have found so common among the Crustacea.

<j

The variety of forms contained in the Insecta is so great that only the most general
statements can be made regarding the class as a whole, and the more special characters
are hence reserved for mention under the different divisions.

The body of insects, like that of all arthropods, is made up of a series of segments
ranged one after another, forming a body of varying length. The number of these
segments varies greatly, there
being, for instance, ten in some
Myriapoda, and tw T o hundred in
others of the same group. Each
of these segments (and the same
is also true of Crustacea) is re-
garded as made up of eight por-
tions, the relations of which may
be seen in the accompanying
diagram. Of these segmental
elements the two upper are
the terga (singular tergum), the
upper lateral ones are called
epimera, the lower lateral epi-
sterna, while those on the ventral
surface are known as the sterna. These elements are variously developed in the dif-
ferent forms. Between the sterna and the episterna arise the legs and their various
modifications, w T hich, as has just been said, are composed of but a single series of joints,
and never present a two-branched condition in either embryo, larva, or adult. Be-
tween the episterna and the epimera are the openings to the respiratory system, a
feature which is entirely confined to the group now Tinder discussion. In the six-
footed forms there are additional locomotive organs, the wings, never more than two
pairs, and these when present are inserted between the epimera and the terga.

The body of insects is usually divisible into regions or groups of segments. In the
typical six-footed forms we have three of these divisions known as head, thorax, and
abdomen. In the spiders the head and thorax are more or less completely united into
a cephalothorax, while the abdomen remains distinct. In the myriapods the head is
well distinguished, but the remaining segments are so similar that no differentiation

FIG. 124. Section through the thorax of an insect, a. Alimentary
b. Tergum. c. Episteriium. h. Heart. /. Leg. m. Epimerum.
n. Nervous cord. s. Spmacle. t. Trachea, v. Sternum, w. Wing.

90

NATURAL HISTORY OF ARTHROPODS.

into thorax and abdomen exists. Lastly, in the mites all of the regions are more or
less confused and merged into each other.

The number of segments which enter into the composition
of the head is variously stated, some authors admitting only
two, while others strive to recognize seven. It would, how-
ever, seem that there are in reality four cephalic segments, a
view which receives confirmation, according to Savigny's law,
in the number of appendages in this region, which are also four.
These appendages are a pair of antennas and three pairs (man-
dibles, maxillae, and labium) concerned in the preparation of
bn food for the mouth. In the simpler types of insects (as the
FIG. 125. Head of grass- grasshopper) these mouth-parts acquire their typical develop-
f /Eye! ment 5 in others ( as the % and butterfly) they become greatly
n. LabiTpaipus. ^oJem. modified, so that the study of their relations becomes a matter
^Maxillary palpus, x. Max- o f some difficulty. In the spiders, if we regard all four of the

walking feet as thoracic, there are but two pairs of appendages
which can be regarded as belonging to the head, the
chelicei'ae, or mandibles, and the palpi, or pedipalpi.

The head also bears the eyes. In the spiders and
most myriapods only simple eyes or ocelli are found ;
but in most hexapods we have a pair of compound
eyes, and usually, except in most beetles, two or three
ocelli in addition are present. The antennae may
with great probability be also regarded as sense
organs, authors interpreting the minute structures
found upon them as either olfactoiy, auditory, or
tactile organs.

The thorax, which exists as a distinct region only
in the Hexapoda, is there composed of three segments,
each of which bears a pair of limbs fitted for locomo-
tion (making six legs in all), and in addition each of
the two hinder segments usually supports a pair of
wings. These thoracic rings have their distinctive
names ; the first being the prothorax, the middle one the mesothorax, and the hinder
one the metathorax.

Each thoracic leg is made up of a series of joints, and as each of these has a tech-
nical name of frequent use in all descriptive works, and, from necessity, in the following

pages as well, we insert them here. The first joint, the
one which articulates with the body, is called the coxa ;
next conies another small joint, the trochanter; the thigh
or femur, a long and stout portion, is third ; the shank or
tibia, also long but more slender, conies next ; and, lastly,
we have the tarsus or foot, Avhich is made up of a number
of small joints arranged one after the other like the joints
of the human finger. The number of these tarsal joints
varies considerably, but the typical number in most hexapods is five.

In the adult insects the appendages of the abdomen are used in locomotion only in
the myriapods. In the other groups, when present, they are much altered in form, and

FIG. 126. Mouth-parts of grasshopper.
/. Labium. Ip. Labial palpus. tr. La-
bruiu. i. Mandible, mp. Maxillary pal-
pus, mx. Maxilla.

FIG. 127. Typical insect leg. c.
Coxa. /. Femur. o. Trochauter.
r. Tarsus, t. Tibia.

INSECTS.

91

adapted for varying purposes. Thus in the spiders, the spinnei-ets, and in the true
insects, the ovipositor or sting lias been shown to be in reality composed of modified
appendages homologous Avith those on the other segments of the body. These greatly-
modified abdominal legs do not occur on all the segments of the adult, but in the larval
stages most insects have these appendages developed to a greater or less extent, and
frequently of use in locomotion. Even here frequently some of the segments are with-
out well-marked limbs. The discussion of these changes produced by metamorphosis
will be resumed when treating of the sub-classes and orders.

cr>

The nervous system of insects is constructed upon the same plan which, in the
preceding pages, we have found to be common to all Arthropoda. There is an enlarge-
ment in front of the oesophagus, the so-called brain, which is connected with a longer
or shorter chain of ventral ganglia, or nervous centres, behind that tube. In Peripatus
this ventral chain consists of two widely-separated nervous cords connected by numer-
ous fine filaments, and as the main cords are without well-marked enlargements or
ganglia the ventral chain closely resembles a ladder. In the myriapods the nervous
system most closely approaches what is considered as the typical condition, there being

~ ss

FIG. 128. Anatomy of a butterfly, a. Anus. ao. Aorta, b. Brain, c. Colon, cp. Copulatory pouch, d. Ovi-
duct. /. Food reservoir, h. Heart, m. Malpighian vessels. . Nervous cord. o. Ovary, oe (Esophagus,
s. Stomach, sg. Salivary gland, ss. Sucking stomach.

a compound ganglion in each of the segments of the body. In the six-footed insects
the ventral chain is usually abbreviated to a certain extent by a fusion of some of the
ganglia ; and in the Arachnida this reduction is frequently carried out to the greatest
degree, there being in some forms but a single compound ganglion behind the oesoph-
agus, while in others the brain almost entirely disappears.

Besides the nervous system thus briefly described, there are two other portions well
developed. One of these supplies the alimentary tract, and is called the sympathetic
from its analogy with a system in the human body with a similar distribution and the
same name. The other is distributed to the respiratory organs, giving off branches to
the spiracles and trachea.

The digestive canal of insects, like that of all animals above the Ccelenterata, is
divided into three regions; the middle portion being formed fi'om the primitive
embryonic stomach, while the anterior and posterior portions are produced by the
subsequent pushing in or invagination of portions of the outer embryonic layer until
they meet and join the middle portion (see fig. 11). A distinction is however to be
noticed here between the insects and the crustaceans, as in the latter the primitive
stomach is produced by a true invagination, a regular gastrula being produced, while

92 NATURAL HISTORY OF ARTHROPODS.

in the insects there is no true gastrula, the primitive stomach always being formed in
the yolk. The anterior and posterior divisions are lined with a hardened chitinous
layer, Avhile the median portion has no such lining. The anterior portion, the function
of which is the preparation of the food and its introduction into the stomach, is usually
a simple tube or oesophagus, but frequently it is divided into several portions, with
other functions. In some forms, as the moths and butterflies, there is a " sucking
stomach " in the head which acts as a pump, drawing the fluids into the mouth and
forcing them back to the true stomach. Others, as the crickets, have an enlargement
farther back (the crop) lined with chitinous teeth, the object of which is to still further
comminute the solid food upon which these forms live. The proventriculus or gizzard
is another enlargement of the anterior portion found in most insects.

The stomach proper is either a simple tube or it may have pocket-like prolongations
which greatly increase its digestive surface. These pockets are especially noticeable
in some of the flies, the grasshoppers, and especially in the spiders. Digestion is
accomplished by the passage of the nutritive portions through the Avails of the stomach,
when they enter into the general circulation without the intervention of a system of
lacteals like those found in the human body. It is a peculiar feature that in the young
of some of the bees and wasps and flies the stomach ends blindly, there being no
connection between that organ and the intestine, though in later life the connection
is made.

The hinder portion of the alimentary canal, the intestine, is usually short. Into it
open numerous tubes, the so-called Malpighian vessels, the function of which is the same
as the kidneys of the higher forms. These urinary tubules are found only in insects.
A still further feature or accessory of the digestive canal are the salivary glands, which
pour their secretion into the mouth. These organs are present in almost every member
of the group, and, on the contrary, are entirely absent in the Crustacea. Usually there
is but a single pair of salivary glands, but this number may be increased, there being
not unfrequently two, and even three pairs of these organs.

The heart of insects may be said to resemble in a general way that of most
Crustacea. As in that group, it is a long, many-chambered organ lying above the
intestine. It forces the blood forward through an aorta of varying length, which runs
from the anterior end of the heart to the vicinity of the brain. In returning to the
heart the blood collects in two venous trunks, by which it is brought to the posterior
portion of the central organ. Finer subdivisions of the arterial and venous systems
are absent, and during a portion of its course the blood flows in open spaces between
the muscles and viscera.

In the phenomena of respiration, and the organs concerned therein, insects present
one of the greatest differences from the Crustacea. In the latter group, as we have
seen, organs of respiration, when present, take the form of gills, borne on some of the
feet, and the blood in passing through them is brought in contact with the oxygen
dissolved in the water. Insects, on the other hand, are fitted for breathing air by
means of tubes or trachea which penetrate to all parts of the body, and which give the
name, synonymous with Insecta as here used, of Tracheata to the group. In the
thoracic and abdominal regions of the body there occur small openings on the sides,
never more than one on a side in each segment, which are known as spiracles or
stigmata. It is through these, and not through the mouth, that an insect breathes.
In some larvae there are eleven pairs of these spiracles, while in the adults the number
is frequently much less. In most hexapods there are but nine pairs.

INSECTS.

93

Each spiracle consists of a horny ring placed, as we have seen, between the epimt 1:1
and episterna of a segment. The opening is provided with a pair of valves by which
it may be closed, and besides there is frequently a strainer of fine hairs and intei Incin-
meshes, the object of which is to prevent foreign particles from entering the air tubes.

The air tubes, or tracheae, are minute branching canals, arising from the inside of
the spiracles, by which the air necessary for respiration is conveyed to all parts of the
body. They are composed of three layers, the middle
of which only possesses any popular interest. This is
composed of a filament wound in a spiral between the
other two, giving the trachea the spiral character so
often seen in microscropic preparations. In many
cases branches of the tracheae unite to form a con-
tinuous air tube along each side of the body, and
oftentimes large cavities or air sacs are formed in
various portions of the body. These, when filled
with air, tend to reduce the specific gravity of the
insect, and hence may play an important part in
flight. In Peripatus the tracheal tubes are irregu-
larly distributed over the inner surface of the body
cavity, the anterior and posterior portions of the ali-
mentary canal and the oviduct ; in most other forms
the branches are regularly arranged, and have a more
extensive distribution.

In the aquatic larva? of many insects there are
no stigmata, and to replace these openings, gills are
introduced, usually on the abdomen. These gills,
the purpose of which is to extract oxygen from the
water, differ materially from those of crustaceans,
for they are penetrated by tracheae instead of blood-vessels, and these air tubes convey
the oxygen to other portions of the tracheal system. With the development these
gills are almost invariably lost, the stigmata appear, and a connection is established be-
tween them and the system of air tubes.

In the spiders an additional feature appears, the existence of so-called lungs.
These are formed by a trachea which arises from a spiracle in the ordinary manner.
It then breaks up into a number of small flattened branches or plates, which are
arranged like the leaves of a book. These are the organs to which Professor Lankester,
as mentioned on a preceding page, would compare the gills of a horseshoe crab.
There may be one, two, or four pairs of these lungs or pulmonary organs, which are
only found in the abdomen.

In some of the insects, as the lower mites, and the " spring tails " (Collembola) the
tracheal system has entirely disappeared, and respiration is carried on through the
general integument of the body.

The act of breathing can be easily witnessed in the larger insects, especially in
those which, like the grasshopper or hornet, have the abdomen naked and not covered
with the wings or hairs. Holding one of these insects with the fingers or with a pair of
forceps, the abdomen will be seen to elongate and contract with great regularity.
Each time it elongates air is drawn in through the spiracles, while the contraction, by
lessening the capacity of the body, forces out the air which has been used in aerating

FIG. 129. Trachea of an insect.

94 NATURAL HISTORY OF ARTHROPODS,

the blood. Here, as in the higher vertebrates, respiration raises the temperature of
the body, and for the same reason. We have the authority of both Huber and New-
port for the fact that humble-bees when incubating pupae raise the temperature by
increasing the number of respirations.

We can best discuss the question of the development of insects, and especially the
metamorphoses, in connection with the various groups, there being such differences
that a general account which attempted to take cognizance of all would be very con-
fusing. There are, however, several features which are common to all which may be
mentioned here, especially since they serve to make more evident the great differences
existing between the Crustacea and the Insecta.

The segmentation of the egg is iisually superficial, the central portion not dividing
at first. From this central yolk arises the primitive stomach of the embryo, a
marked difference from the way in which the same portion is formed in the crustaceans,
where, as we have seen, there is a true invagination. At an early stage the eggs of
most insects become enveloped in a cellular membrane, which, from being formed in
a strikingly similar method to that in which one of the foetal membranes of the higher
vertebrates arises, has been called the amnion. The appendages grow in much the
same way as in the group just passed, but it is to be noticed that in no stage of the
development of the insects do we find a two-branched appendage, a feature so common
among the crustaceans. The middle germinal layer (mesoblast) also arises in very
distinct ways in the two groups.

There is no group of animals upon which more has been written than upon the
insects. Ever since naturalists began the study of nature these forms have attracted
especial attention. From every point of view they possess interest. Their shapes and
colors make them attractive to lovers of the beautiful and the grotesque ; their habits
are interesting, and their metamorphoses are marvellous. There is a far more practical
side to their study. A large number are of economic importance. Some few are of
direct value to man : from the silk-worm we obtain one of the most valuable textile
materials, from the cochineal insect one of our most brilliant dyes. In another very
important manner insects play a part in matters which affect human interests. It is
now, thanks to the labors of Darwin and Hermann Muller, a well-known fact that a
large proportion of the flowering-plants are incapable of self-fertilization, and were not
pollen brought to the stigma from another flower of the same species no seeds would
be produced. This fertilization is effected to a certain extent by the winds and other
agencies of like character, but it is to the insects that we must turn for the most effec-

O 7

tive Avork in this line. These in their search for honey visit plant after plant, and
from one they carry the pollen which becomes entangled upon their legs or bodies,
and in such a position that in the next flower visited it will be brought in contact with
the stigma, and fertilization will thus be effected. It has been clearly shown that for
this purpose there exist many mutual adaptations, there being many insects which
can fertilize only one species of plant, and, conversely, many flowers which require
the presence of a peculiar insect to carry the pollen from the stamens to the pistil.
The subject is a large one, and we can but touch it in this brief manner; but those
who wish to study it further will find ample material in the writings of Darwin,
Muller, and Trelease, and better, in the relations of the animals and plants around
them.

Still other insects are of value to man from their carnivorous habits. Some of these
dispose of large amounts of refuse matter which would otherwise decay, producing

INSECTS. 95

disagreeable or unhealthy products. Others by feeding on insects reduce the number
of the forms which injure the crop.

In their injurious aspects the insects have possibly attracted the most attention,
and long statistical tables are frequently published showing the value, in dollars and
cents, of the human possessions destroyed by these apparently insignificant forms. In
the following pages especial attention will be paid to these noxious insects, and we
have here only to instance the grasshopper-plague of Kansas and Nebraska, the damage
produced by the Hessian-fly, the onion-fly, and the chinch-bug, and the ravages of
the clothes-moth and the carpet-beetle, to call to mind this important aspect of the
group.

In number of species, as well as of individuals, the group Insecta is by far the largest
of the divisions of the animal kingdom. It is estimated that from a quarter to half a
million distinct forms exist on the face of the globe. These are divided as follows :
Myriapoda, 1,000 ; Arachnida, 5,000 ; Neuroptera, 7,000 ; Orthoptera, 7,000 ; Hemip-
tera, 10,000; Coleoptera, 125,000; Diptera, 30,000; Lepidoptera, 25,000; Hymneoptera,
25,000. Of course these numbers are merely guesses ; but when we consider that nearly
100,000 species of beetles are catalogued as being in the various collections of the world,
we see that these estimates are probably within limits. The number of individuals is,
of course, beyond any possibility of estimation.

For our purposes we may divide the class of Insecta into four sub-classes:
Protracheata, embracing the single genus Perlpatus ; Arachnida, Myriapoda, and
Hexapoda, or insects proper.

J. S. KlNGSLEY.

FIG. 130. Larva showing abdominal legs.

96 NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS I. MALACOPODA.

To this division of insects (for which the name Protracheata has also been proposed)
belongs the single genus Peripatus. In the early part of the present century the Rev.
Lansdown Guilding described the first species, from the West Indies, under the name
Peripatus iuliformis, the specific name alluding to its general resemblance to the galley
worms. Other forms have since been described from South America, New Zealand,
and the Cape of Good Hope. Mr. Guilding was under the impression that this form
belonged to the molluscs ; but subsequent students assigned it a place among the
worms, through its affinities to the insects, and especially to the myriapods, were hinted
at. In 1874 Mr. Moseley, one of the naturalists of the " Challenger " expedition,
described the anatomy of the species occurring at the Cape of Good Hope, and set at
rest all questions regarding the systematic position of Peripatus.

Peripatus is strikingly like a myriapod in general appearance. It has a long body,
which is supported on numerous legs, varying in number from seventeen and nineteen
to thirty and thirty-three in the different species. The head bears a pair of ringed
antennae, and at their bases are a pair of simple eyes. On the lower surface of the head
is the mouth, armed with two pairs of laterally moving jaws, and at each side of the
mouth is a small papilla, at the summit of which a slime gland opens.

FIG. 131. Peripatus, enlarged three times.

The alimentary canal is nearly straight, and is composed of a narrow oesophagus
and intestine, and a broader stomach. A pair of salivary glands are also present.
The heart is a simple tube, and is but little specialized. The nervous system has
already been referred to.

The most interesting anatomical feature is the respiratory apparatus. Scattered
over the surface of the body are the spiracles, but in certain regions, as between the
bases of the legs, they are most numerous. Each spiracle opens into a short tube,
from which arises a bunch of fine tracheae. These tracheae but rarely branch, and have
the spiral filament very imperfectly developed. The sexes are separate, and the young
undergo a large part of their development within the mother. But little is as yet
known concerning the embryology of this form, although the subject has been studied
by such masters as Balfour, Moseley, and Sedgwick.

PERIPATUS.

97

Peripatus is especially interesting from the fact that its structure, and especially
that of its tracheae, and the little that is known of its development all point to it as
the living representative of the ancestor of all insects, and as a connecting link !><>-
tween that group and the worms.

But little is known of the species of this genus, although four have been describe! I.
The best known form is P. ccyiensis, and next comes P. nova-zelandice, the habitats of
each being indicated by the specific name. Peripatus capensis lives in damp situations,
under decaying wood, etc., and when at rest coils itself in a spiral, like a milljped, with
its head in the centre. When in motion it extends its body to about twice its length
when at rest. It has a gait like that of a caterpillar, its short, stout legs holding the
body free from the ground. When annoyed it ejects a quantity of slime from peculiar
glands within the body, the openings of which, as we have said, are on either side of
the mouth. This slime is a very sticky and tenacious fluid, adhering very strongly to
everything with which it comes in contact, and resembling bird-lime in its general char-
acters. It, however, dries very rapidly.

The little that is now known concerning these very interesting forms will doubtless
soon be greatly increased, for an English naturalist has just gone to the Cape to study
their development, while two others are now at work at a monograph of the species.

J. S. KINGSLEY.

FIG. 132. Embryo of Peripatus.

VOL. II. 7

NATURAL HISTORY OF ARTHROPODS.

SUB-CLASS II. AEACHNIDA.

In this division are included the mites, scorpions, harvest-men, and spiders. These
animals usually have the body divided into two regions, an anterior, cephalothorax, and
a posterior, abdomen. In the mites, however, these distinctions become obliterated, and
the boundaries between the regions are very indistinct. The cephalothorax bears four
pairs of legs adapted for locomotion, and in front of these are two pairs of mouth-
parts, the anterior pair being called chelicerte, or mandibles, the other the palpi, or
maxillae. These pairs are both post-oral, and hence we see that the antennae are lacking
in this group. The walking-legs are composed of a series of joints, usually seven in
number; but in some, as in the harvest-men, the last, or tarsal joint, is broken up into a
large series of articles, while in some mites the distinctions between the joints of the
limbs are greatly obscured, if not wholly obliterated.

The organs of vision, when present, are always simple eyes, placed upon the dorsal
surface or the sides of the cephalothorax, and varying in number from two to twelve ;
their number and arrangement affording characters which are largely used in separating
the different forms. Compound eyes, like those found among hexapods and many
Crustacea, are entirely lacking.

The abdomen is without appendages except in the spiders, where the spinnerets,
which are frequently jointed, are homologous with the other limbs.

The alimentary canal is nearly straight. Rarely it is a simple tube, but in most
forms there are a number of pockets arising from the stomach, thus increasing the
digestive surface. In some of the mites these pockets, or coeca, are so numerous and
so greatly developed as to remind one of the extensively ramified digestive tract of a
planarian worm. In the true spiders these appendages of the stomach are seen in their
simplest form, and will be referred to again in treating of the common garden-spider.
In Galeodes the pockets are very long, extending for some distance into the legs,
reminding one of a similar extension of the alimentary tract which is found in the
Pycnogonids. A sucking stomach is also frequently found. Salivary glands are almost
invariably present, w T hile in the higher forms a well-developed liver pours its secretions
into the intestine.

The circulatory organs in the higher groups consist of a chambered heart and sev-
eral arteries, distributed to the various portions of the body. In the scorpions we find
in addition a venous system, while in the lowest mites not only blood-vessels but even
a heart is wanting ; the blood, propelled by the movements of the body, flowing between
the various muscles and viscera in the same way that it does in many of the lower
Crustacea.

In many of the lower mites, most of which are extensively degraded by their para-
sitic habits, no traces of respiratory organs have yet been found, respiration being
effected by the whole surface of the body. In all other forms organs for the aeration
of the blood, in the shape of tracheae or modified trachea?, are always present. These
trachea? may be of the normal type or they may be modified so as to form the lungs
which have already been mentioned, or both lungs and tracheae may be present
together. The number of pulmonary sacs varies from two in most spiders and the
whip-scorpions, and four in the Mygalidas, to eight in the scorpions.

MITES.

99

The sexes are separate in the Arachnida, and may usually be distinguished by the
modifications of the palpi, pincers, or some of the legs. Some, as the scorpions, are
viviparous, but the majority do not hatch from the egg until after oviposition. The
eo-gs may either be deserted by the parent or carried around with her. We shall refer
to the development when treating of the different groups.

The Araclinidoe are usually divided into three orders: Acarina, Araneina, and
Arthrogastra.

ORDER I. --ACARINA.

This, the lowest order of the Arachnida, embraces the forms familiarly known as
mites and ticks. In these the hinder segments of the body are usually distinctly sepa-
rated from each other, but there is no constriction marking the division of the body
into cephalothorax and abdomen, such as is so evident in the true spiders. The mouth
parts (upper lip, cheliceraa, and palpi) are usually united to a greater or less extent,
forming a sucking tube, which in some forms acquires a considerable development.
Respiration is usually effected by tracheae, which commonly arise from twe stigmata,
but, as we have just said, sometimes all respiratory organs are entirely absent. With
the exception of the Oribatidre, which bring forth living young, all are viviparous, and
the young, when they leave the egg, almost invariably have three pairs of feet, resem-
bling, in this respect, the hexapod insects. The fourth pair are added with growth.

The different forms present many differences in habits ; many are parasites ; some
live in the water, both salt and fresh, some in the earth, while others pass the greater
portion of their life parasitic upon animals or plants. Directly they enter but slightly
into the affairs of man, but indirectly many of them play an important part in human
interests, some destroying injurious insects, while others, on the other hand, attack
many objects which are of use or value to mankind.

The Acarina are divided into seven families, but it must be borne in mind that at
least the minor divisions cannot all be regarded as firmly established ; for there exists
among many members of the order a marked polymorphism, the same species, at differ-
ent ages or under varying environment, assuming characters so different as to lead
naturalists to assign the different forms to distinct genera, or in some cases even to
different families, and the errors thus introduced have only been discovered after long
and careful study of the life-history of the form in question. So far as is known, the
mites first appear in the pliocene division of the tertiary age, specimens of Hydraclma
and Trombidmm being found in the amber of Pomerania.

The first family to be considered is the ACAKID^E. These have a soft skin, the body
oval or elongate, ocelli absent, and the feet frequently terminated with an adhesive
vesicle. The cheliceras are chelate or needle-shaped. Though minute, these forms are
by no means to be despised, as they all come under the head of noxious insects, and
besides injuring and destroying many human products they even produce disease in
mankind. Space will allow us to mention but a few prominent representatives of the
family.

In 1841 Henle described a peculiar parasite found in the hair-follicles of the human
body, and a little later Simon published a careful account of the same form. From
this time to the present this form has attracted considerable attention, and has been
described under five generic names, that of Demodex having priority. The number of
species is uncertain, it not being known whether the forms found in different animals

100

NATURAL HISTORY OF ARTHROPODS.

are really distinct. Demodex folliculorum, which sometimes occurs in the hair-follicles
and sebaceous glands of man, especially those around the nose, is a minute worm-like
form, Avith four pairs of legs near the anterior end of the body. In the
human subject it is comparatively harmless, but either this form or a
closely allied species is sometimes very injurious to hides. Dr. Faxon
records a case where numerous cowhides, from Illinois and Wisconsin,
were seriously damaged by this parasite ; in some of the samples as many
as eight or ten pits, some of which penetrated nearly through the skin,
were found within the area of one square inch. Each of these pits was
filled with a fatty substance containing multitudes of individuals.
Similar injury to the skins of hogs has also been reported. But little
is known concerning the development of these forms, some authors
thinking them oviparous, w r hile others think that the young are born
alive. The larvae, like those of most mites, have but three pairs of
limbs.

The members of the genus Sarcoptes are very minute. They have
a round or oval body, very short three-jointed legs, the two first pairs
FIG. 133. D e - terminating in a sucking disc, while in the male the posterior pairs

modex folliculo- . . .

rum, follicle-mite, terminate in the same manner, but in the female these end in a long-
bristle. Several species have been described inhabiting various animals
but the most prominent is the / scabei, the Itch-mite, which produces this disgusting
disease in unclean people. The connection between the mite and disease was first
pointed out by Avenzoar, an Arabian physician, in the twelfth
century. These forms burrow just beneath the skin, especially
in such protected parts as those between the fingers, the inside
of the wrist, etc. The female is much the larger, attaining a
length of about a sixtieth of an inch. The usual remedy is
sulphur ointment rubbed into the skin. 8. canis produces the
mange in dogs, while other species are found in horses, cattle,
sheep, etc. These latter are sometimes referred to a genus
Dermatodectes.

Among the more typical forms are the genera Tyroglyphus
and Typhlodromus. In these the feet are long, four-jointed,

and terminate with a sucking

disc, and the mandibles are scissor-like. The cheese
mite, Tyroglyphus siro, is a familiar example, and
scarcely less so is the flour mite, T. farince. Another
species, T. sacchari, is frequently abundant in soft
unrefined sugar, Imt it is rarely, if ever, found in re-
fined sugar, which is apparently too hard for its exist-
ence. This form is supposed to cause the grocers'
itch. One species is of benefit to man ; T. phylloxere,
as its name indicates, feeds on the Phylloxera, so in-
jurious to the grapevines. Under certain conditions
some of the species of Tyroglyphus assume a differ-
A hard, brown chitinous covering develops
within the skin, and then the latter cracks and the
new form (originally described as Hypopus) emerges.

_ Sarcoptes
6 ' greatly

FIG. 135. Ixodes albipictus, white-spotted ent form,
tick of moose, a. Mouth-parts, b. Six-
footed young. (I. Foot with sucking
disc. e. Adult, natural size, gorged
with blood.

MITES.

101

By this metamorphosis the forms are enabled to withstand desiccation, while a sli<>-ht
exposure to dryness kills the normal forms. The species of Typhlodromus usually
occur on plants, where they eat the epidermis of the leaves.

The Ixomrjji, or family of ticks, embraces the largest individuals of the Acarina.
The body is enclosed in a leathery skin, the palpi are four-jointed, enclosing the
denticulated beak, which is formed of
the chelicerae and labrum. Eyes are
sometimes lacking, and the legs are
slender, terminating with two claws.
Ixodes is the typical and largest genus,
embracing the forms commonly known
as ticks. These live in the woods, and
attach themselves to cattle, dogs, and
man whenever they have a chance.
Here they suck the blood until the body
swells up so that it resembles a pea.
Several American species have been
described, mostly by Dr. Packard, the
White-spotted Tick, Ixodes albipictus,
being possibly the best known. The
European Ixodes ricinus attaches its
eggs to its body by a clear fluid which
flows from the mouth, and this, to-
gether with the position of the open-
ing of the oviduct, which is very far
forward, gave rise to the idea that the FlG - * -** t
female laid its eggs through the mouth.

oo o

The genus Argas, which is blind, contains two well-known species, the A., reflexus
of Europe, which is parasitic on birds, especially on doves, and A. persicus, of Persia

and adjacent countries, which
lives in houses, and by its
punctures produces convul-
sions in man, and it is said
that even death has resulted
from its sting. Another less
known form, Arc/as nif/ua,
the Pique, produces distress-
ing, and sometimes even dan-
gerous, sores on men and
cattle.

But little is known of
the American species of the
next familv, the ORIBATID^E,

. Upper and under surface of Argas reflexus, dove-tick, enlarged. ' '

though the European species

have been more extensively studied. These forms have the body hard and horny,
the ocelli almost obsolete, the mandibles chelate, and the palpi four-jointed and
short. The legs are fitted for walking, and terminate in from one to three claws.
The sides of the cephalothorax are frequently expanded, and bear on their edges two

102

NATURAL HISTORY OF ARTHROPODS.

FIG. 138. Oribates ovi-
vorus, enlarged.

FIG. 139. Hoplophora arc-
tutu, enlarged, showing
two positions assumed.

or three pedicellate stigmata. The forms are all terrestrial, occurring under moss,
the bark of trees, and stones. The American Oribates concentrica and glabrata,

are blackish species, while 0. ovivorus is a reddish brown. The
latter species has been observed by Dr. Packard to eat the eggs
of the canker-worm. Hoplophora arctata
in its shape strongly reminds one of a
fresh-water mussel. The cephalothorax is
much smaller than the abdomen, and so
flexibly articulated that it folds over the
latter, as Dr. Riley expresses it, like "the
lid of a box, whenever the animal with-
draws its head and limbs, which it does
on the slightest disturbance." Some of
the species are said to be hatched with eight legs, but one is known to have only six
on emerging from the egg.

The members of the family GAMASID^E are parasitic upon other animals, attaching
themselves to the outside of the body. They have the mandibles chelate, the legs
equal and hairy, with two terminal claws and no ocelli. Frequently specimens of
carrion beetles (Silphidse) are found covered with minute bright-orange parasites.
These usually belong to the genus Gamasus, and are nearly allied to if not identical
with G. coleoptratorum of Europe. Species of Uropoda also have similar habits.
They attach themselves to the host by means of an anal filament of excrementitious
matter ; and Dr. Riley has described in addition, in Uropoda americana, a long and
flexible organ composed of the maxilla?, each of which terminates in a pincer, which
serves to attach the parasite to its host after the fracture of the somewhat brittle anal
cord, or after that means of connection is broken by moulting. Bats are frequently
infested with parasites of this family belonging to the genera Pteroptus and Dermanys-
sus. A species of the latter genus is also occasionally found on birds and poultry.
The HYDRACHXID^E, or water mites, have an unsegmented body, with two ocelli on

the anterior portion. The legs are haired, and terminate in
two claws, which in some genera are retractile into a socket
in the end of the last joint. The palpi are five-jointed,
and are either hooked or needle-shaped. These forms, as
both their common and scientific names denote, live in the
water, both salt and fresh, but most of the species are found
~ '"x^- ^^ in rivers and lakes. Many are parasitic on fresh-water beetles
FIG. 140. ciaw of Hydrachnid. and bugs, at least in their early stages. Some pass their

a. Retracted, b. Extended. i- , .\ --M f -i

lives as parasites on the gills ot tresh-water

mussels, and others may be found running over fresh-water plants.
The principal genera are Hydrachna, Limnochares, Atax, and Pont-
arachna, the latter being marine. Atax ypsilophorus, a black
species with a sulphur-yellow median line, forked in front, is com-
mon to Europe and America, living in the former country in the
gills of Anodonta cygnea, in the latter in those of A. flumatilis.
Atax humerosa is white, with dark-brown markings. It is found
in Unio cylindricus. The eggs of the Hydrachnidae are laid in the
spring, in the stems of water plants. Dr. Packard has described a marine form,
Tkalassarachna verrillii, from Eastport, Me.

FIG. 141. Atax Jiume-
rosa, enlarged.

SPIDERS.

103

In the BDELLID^ the palpi are five-jointed, the ocelli are sometimes absent, at
others they vary from two to six; the legs are long and stout. The mandibles are
chelate. Bdella, the principal genus, is represented in America by B. maritima a
species occurring under stones between tidemarks, and B. oblonga, which has been
found in Georgia under stones and the bark of trees, in rather moist situations. The
latter is a bright-red species.

One frequently finds in the earth of gardens and conservatories small, slender-legged,
stout-bodied red mites, their surface greatly wrinkled, and presenting the appearance
of the softest velvet. Others are found upon plants. These are members of the
family TROMBIDILD.E. Under the microscope it is seen that they have claw-shaped or
needle-formed mandibles and short palpi.

The genus Trombidium is represented in the United States by three known species,
scabrum, sericeum, and holosericum. All three of these forms are red, and live in the
ground, where they feed on the eggs of insects. Their labors in this line are so
important that T. sericeum is mentioned as a very efficient agent in checkino- the
ravages of the grasshopper. Another species, T. tinctoria, found in Guiana and
Surinam, furnishes a dye. The larval forms of some species of this
genus were formerly described under a distinct generic name, Astoma ;
these six-legged young are found living parasitically on other insects,
clinging around the base of the wings and sucking the blood of their
hosts. Larva? of other species have been described under the generic
name Leptus. Trombidium is easily recognized by its claw-shaped
mandibles, and by having the first pair of legs the longest. Tetrcu-
nychus has needle-shaped mandibles, the two anterior pairs of feet FlG - ^ j Astoma
widely separated from the posterior, and two ocelli. Tetranychus
telarius, a yellowish species with two red spots on the sides, is not uncommon on plants
in greenhouses and conservatories.

The last family, PCECILOPHYSID^E, is of rather doubtful character. It was estab-
lished by the Rev. O. P. Cambridge for a minute form, one-third of a line in length,
from Kerguelen Island. Poecilophysis Jcerguelenensis has filiform palpi, which termin-
ate in a single claw, while the other legs are didactylous. Its describer thinks that it
combines characters of spiders, Solpugidae, chelifers, and Acari, and has erected for its
reception a possible new order, but other students of the Arachnida are inclined to
place it among the mites.

ORDER II. ARANEINA.

This, the second division of the Arachnida, contains the true spiders, and in its
treatment we use, by permission, the excellent work "The Structure and Habits of
Spiders," by Mr. J. H. Emerton, with such alterations and condensations as are
necessary to render it conformable to the space at disposal and the plan of the present
work.

The common round-web spider, Epeira vulgaris, will serve to show the anatomy
of spiders in general. The body is divided into two parts, connected only by a narrow
joint just behind the last pair of legs. The front part of the body, called the cephalo-
thorax, contains the stomach, the central part of the nervous system, and the large
muscles which work the legs and jaws. The hinder half, the abdomen, contains the
intestine, the breathing-organs, the principal circulating-vessels, the organs of repro-

104

NATURAL HISTORY OF ARTHROPODS.

FIG. 143. Foot of Epelra vulgaris.

duction, and the spinning-organs. Connected with the thorax are six pairs of limbs -

four pairs of legs, a pair of palpi, and a pair of mandibles.

The legs are used chiefly for running, jumping, and climbing; but the front pair

serve often as feelers, being held up before the body while the spider walks on the

other six. One or both of the hinder legs are used
to guide the thread in spinning ; the spider at the
same time walking or climbing about with the other
six or seven. The legs are seven-jointed, and on
the terminal joint are three claws and various hairs
and spines. In many spiders a brush of hairs takes
the place of the middle claw, as in the jumping
spiders. Spiders with these brushes on their feet
can walk up a steep surface, or under a horizontal
one, better than those who have three claws.

In front of the legs are the palpi a smaller
pair of limbs, with six joints and only one claw or
none. They are used as feelers and for handling
food, and, in the males, carry the curious palpal
organs, which will be described farther on. The

basal joints of the palpi are flattened out and serve as chewing-organs, called maxilla?.
The first pair of limbs, the mandibles or cheliceraj, are two-jointed. The basal

joint is usually short and stout, and furnished on the inner side with teeth and hairs.

The terminal joint is a small and sharp claw, which

can be closed against the basal joint when not in

use.

On the under side of the abdomen, just behind

the last pair of legs, are two hard, smooth patches

which cover the front pair of breathing-organs, the

openings to which are two little slits, or stigmata.

Between these is the opening of the reproductive

organs, and, in female spiders, the epigynum, an

apparatus for holding the reproductive cells of the

male.

At the end of the body are the spinnerets. There

are three pairs of them ; but many spiders close them

together when not in use, so as to cover np the middle

pair. The third pair of spinnerets are often several-
jointed, and extend out behind the body like two tails.

In front of the spinnerets is a spiracle which leads to air-tubes which give off branches

to different parts of the abdomen.

Turning now to the dorsal surface, on the front of the head are eight eyes which

are differently arranged in different spiders. At the back part of the thorax is a

groove, beneath which is attached a muscle for moving the sucking-stomach. On the

abdomen are several pairs of dark, smooth spots, which mark the ends of muscles

extending downward through the abdomen.

d? tj

The mouth is just under and behind the mandibles, and between the maxillae. It
has an upper and an under lip, each lined with a horny plate, in the middle of which
runs a groove. When the lips are closed the two grooves form a tube which leads to

\

FIG. 144. Foot of Attus mystaceus.

SPIDERS.

105

the oesophagus, and so into the stomach. At the end of the oesophagus is the sucking-
stomach. This consists of a flattened tube, to the top of which is attached a muscle
connected with the back; and to the bottom, other muscles attached to a tough
diaphragm spreading across the cephalothorax, and fastened between the legs on each
side. When these muscles contract the top and bottom of the sucking-stomach are
drawn apart, and whatever is in the oesophagus is sucked in. By this pumping motion
the spider takes liquid food from the mouth and drives it backward into the abdomen.
Just behind the sucking-stomach the intestine gives off two branches, which extend
forward around the stomach muscle and meet over the mouth. Each of these branches
gives off on the outer side four smaller branches which extend downward, one in
front of each leg, uniting on the under side of the thorax. The intestine con-
tinues backward through the abdomen to the little knob behind the spinnerets. The
brown mass which surrounds the intestine, and fills the abdomen above it, is the liver,
which discharges into the intestine at several points.

FIG. 145. Section of Epeira vulc/aris, garden spider, a, b. Upper and lower lips. c. (Esophagus, d, f. Upper
and under muscles of the sucking-stomach, e. Stomach. J. Post-oral ganglion, k. Brain. /. Nerves to the legs
and palpi, in. Branches of the stomach, n. Poison-gland, o. Intestine, p. Heart. R. Pulmonary sac. S. Ovary.
t. Air-tube, u. Spinning-glands.

Over the intestine and parallel with it is the heart, a muscular tube with open-
ings along the sides to receive the blood, and branches through which it flows to
different parts of the body. The greater part of the blood enters near the front of the
heart, and passes backward into the abdomen or forward into the thorax. In the front
of the abdomen are the principal breathing-organs, or lungs, a pair of sacs contain-
ing a number of thin plates, through which the blood passes on its way to the heart.
Besides these there is a pair of trachea opening near the spinnerets.

The spinning-glands lie above the spinnerets, along the lower portion of the abdo-
men. They will be more fully described when we come to discuss the webs. The
reproductive organs lie along the under side of the abdomen, and open between the two
lungs.

Persons unfamiliar with spiders find it hard to tell young from old, and male from
female. This is caused by the great differences between different ages and sexes of the
same spider. The adult males and females are, however, easily distinguished from
each other, and from the young, by the complete development of organs peculiar to
each sex, which will be described further on. The males are usually smaller than the
females, and have, in proportion to their size, smaller abdomens and longer legs. They
are usually darker colored, especially on the head and front parts of the body ; and
markings which are distinct in the female run together and become darker in the male.

106

NATURAL HISTORY OF ARTHROPODS.

In most species these differences are not great ; but in some no one would ever suppose,

without other evidence, that the males and females had any relationship to each other.

The most extreme cases of this kind are Argiope and Nephila, where the male is about
a tenth as long as the female.

In the genus Erlgone, which includes the smallest known spiders,
the males often have curious humps and horns on their heads. The
most extreme example is shown in Fig. 146, where the eyes are car-
ried up on the end of the horn. The females of all these species have

FIG. 146. Head of plain round heads ; and what use the humps are to the males nobody

Erlgone. J

knows.

The peculiar organs by which the adult males and females can always be dis-
tinguished are, in the males, the palpal organs, on the ends of the palpi ; and, in the
females, the epigynum.

As the male spider gets nearly full grown the terminal joints of the palpi be-
come swollen, and, after the last moult, the palpal organs are
uncovered. The simplest form of palpal organ is found in
the large Mygalida?. It consists of a hard bulb, drawn out
to a point, in which is a small hole leading to a sac within.
In most spiders the terminal joint is flattened, and lias a hollow
on the under side, in which the palpal organ is partly concealed.
The bulb is flattened to fit this hollow, and the point of it is pro-
longed into a distinct tube of various shapes furnished with num-
erous spines and appendages. In Tlieridion the outer tube is so
long that it is coiled up over the basal part of the bulb, and the
end rests on a strong spine at one side of the palpus. The shape
of these organs is very constant in the same species of spider, and
thus they afford good characters in distinguishing species.

When the female spider is nearlv full grown there appears a FIG. 147. Palpal organ

. of Theridion.

hard, swollen place just in iront ot the opening ot the ovaries,

and after the last moult the epigynum is uncovered
at this place. The epigynum consists of two sacs
or spermathecae, which connect by two little tubes
with the oviduct near its mouth, and by two larger
tubes with the outside of the spider. The mouths
of these larger tubes are often surrounded by vari-
ous hard appendages. These parts, like the palpal
organs, furnish convenient marks for distinguishing
species. The spermathecae vary but little in shape

FIG. 148. -Epigynum of Theridion. E.Sper- in different spiders, but the tubes are often length-
S a Tubes ofen?ng b outward ng tO oviduct ' ened and twisted into shapes nearly as complicated

as those of the palpal organs. Thus in the epigy-
num of some species of Theridion the larger tubes are very much elongated and
twisted up, corresponding to the long discharge-tube of the palpal organ of the male
of the same spider.

When the reproductive organs of the male spider are mature he discharges the liquid
contained in them on a little web spun for the purpose ; dips his palpal organs into it,
and in a few moments takes up the whole into the little sacs inside the bulb ; then he
seeks the female, and inserts the palpal organs into her epigynum. The soft part at

SPIDERS.

107

FIG. 149. Drassus laying eggs. A. Web.
E. Eggs.

the base of the organ swells up, and presses in the discharge tube, forcing out the
contents of the bulb into the spermathecae, from which it escapes, in course of time, by
the small tubes into the oviduct, and fertilizes the
eggs about the time they are laid.

When the eggs are mature the female proceeds
to make a little web and lays the eggs on it.
Then she covers them over with silk, forming a
cocoon in which the young remain till some time
after they are hatched. The laying of the eggs
is seldom seen ; for the spider does it in the
night, or in retired places ; and often in confine-
ment refuses to lay at all.

Many spiders make their cocoons against a flat surface, where they remain attached
by one side. Attus mystaceus spins, before laying, a thick nest of white silk on the
under side of a stone. In this she thickens a circular patch on the upper side, next
the stone, and discharges her eggs upward against it. They adhere, and are then

covered with white silk. JEpeira
strix spins, before laying, a bunch
of loose silk. She touches her spin-
nerets, draws them away a short
distance, at the same time pressing
upward with the hind feet, then
moves the abdomen a little sidewise,
and attaches the band of threads so
as to form a loop. She keeps making
these loops, turning round at the same time so as to form a rounded bunch of them,
into the middle of which she afterwards lays the eggs. The eggs, which are like
drops of jelly, are held up by the loose threads till the spider has time to spin
under them a covering of stronger silk. Epeira vulgaris makes a similar cocoon
upward, downward, or sidewise, as may be most convenient. Drassus spins a little
web across her nest and drops the eggs on it. They are soft and mixed with liquid,
and are discharged in one or tw r o drops like jelly. They quickly soak up the liquid
and become dry on the surface, sometimes adhering slightly together. After the
eggs are laid this spider covers them with silk, drawing the threads over them from
one side to the other, and fastening them to the edges of the web below. When
the covering is complete she bites off the threads that hold the cocoon to the nest, and
finishes off the edges with her jaws.

The Lycosiclae make their cocoons in the same way, but rounder, and showing only
slightly the seam where the upper part was attached to the lower. The Lycosas carry
their cocoons about attached to the spinnerets,
bumping them over the stones without injury
to the young inside. The large species of
Argiope makes a big pear-shaped cocoon
hanging in grass or bushes. These are made
late in the summer, and the young stay in
them till the next season. Out of six hun-
dred cocoons collected by Wilder in the spring less than a quarter were entire, the
rest being pierced or torn in some way by birds or insects, so that the spiders were

FIG. 150. Attus mystaceus laying eggs.

FIG. 151. Lycosa, with cocoon attached to
spinnerets.

108

NATURAL HISTORY OF ARTHROPODS.

saved the trouble of gnawing their way out. The young of Micaria cut a smooth,
round hole in their paper-like cocoon just large enough for them to come out one
by one.

The fertilization of the eggs takes place when they have reached their full size and
are about to be laid. After the eggs are laid it is very easy to watch their develop-
ment. They grow just as well anywhere else as in the cocoon, and, in order to see
through the shell, it is only necessary to cover the egg to be examined with oil, alcohol,
or any liquid that will wet it. The rate of growth varies according to circumstances.

abed

FIG. 152. Segmentation of spider's eggs. a. Before segmentation, b, c, d. Three stages of division.

Some eggs laid in autumn develop slowly all winter, while others laid in summer are
ready to hatch in a fortnight. The segmentation is regulai', but from the relations of
the protoplasm and yolk we do not find the regular segmentation spheres so common
in most forms, but in their stead beautifully-irregular cleavage cells, which are shown
in the adjacent figures.

In about four or five days the young of the long-legged cellar spider becomes
lengthened out into a sort of barrel shape, and six whitish rings run half way round it,
on each of which appears soon after a pair of little knobs, one each side. These are
the six segments of the thorax, and the six pairs of limbs, and their gradual growth is
shown in Fig. 153, a to d. At first there is no sign of a head or abdomen ; but shortly

FIG. 153. Later stages of spider's eggs. a. Division into segments, b. Appearance of legs. c. Formation
of abdomen and abdominal legs. d. Nearly ready to hatch.

after there appears an opaque knob at one end, under which is a pair of little knobs,
such as appeared at first on the thoracic segments ; then appear two pairs, then three,
and so on, till there are six pairs, which mark the six segments of the abdomen. Up
to this time the embryo has been rolled up with the under-side outward, but now it
begins to turn, and in a day or two has its back outward. The constriction between
the thorax and abdomen begins about this time, and in a few days more the spider is
ready to hatch, Fig. 153, d.

The hatching occupies a day or two. The shell, or rather skin, cracks along the
lines between the legs and comes off in rags, and the spider slowly stretches itself and
creeps about. It is now pale and soft, and without any hairs or spines, and only small
claws on its feet ; but in a few days it gets rid of another skin, and now begins to look

SPIDERS.

1011

like a spider. The eyes become darker-colored, marks on the thorax become more
distinct, and a dark stripe appears across the edge of each segment of the abdomen.
The hairs are long and few in number, and arranged in rows across the abdomen and
along the middle of the thorax. Before the next moult they usually leave the cocoon
and for a time live together in a web spun in common. Where large broods of young
spiders live together they soon begin to eat one another, and if kept in confinement
one or two out of a cocoon-full may be raised without any other food. The young of
the running spiders, Lycosidae, when they come out of the cocoon, get on their mother's
back, and are carried round by her for some time.

As spiders grow larger they have to moult from time to time. The spider then
hangs itself by a thread from the spinnerets to the centre of the web. The skin cracks
around the thorax just over the first joints of the legs, and the top part falls forward,
being held only at the front edge. The skin of the abdomen breaks irregularly along
the sides and back, and shrinks together in a bunch. The spider now hangs by a
short thread from the spinnerets, and works to free her legs from the old skin.

That which more than anything else distinguishes spiders from other animals is the
habit of spinning webs. Some of the mites spin irregular threads on plants, or cocoons
for their eggs, and many insects spin cocoons in which to pass through the change from
larva to adult. In the spiders the spinning-organs are much more complicated, and
used for a greater variety of purposes, for making egg-cocoons, silk linings to their
nest, and nets for catching insects. The
spider's thread differs from that of insects
in being made up of a great number of
finer threads laid together while soft
enouo'h to unite into one.

O

The external spinning-organs are little
two-jointed tubes on the ends of the spin-
nerets. There is a large number of these
little tubes on each spinneret, and in cer-
tain places a few larger ones, each tube
being the outlet of a separate gland.
When the spider begins a thread it
presses the spinnerets against some ob-
ject, and forces out enough of the secre-
tion from each tube
to adhere to it. Then

it moves the spinnerets away, and the viscid liquid is draAvn out
and hardens at once into threads, one from each tube. If
the spinnerets are kept apart a band of threads is formed, but
if they are closed together the fine threads unite into one or more
larger ones. If a spider is allowed to attach its thread to glass
the end can be seen spread out over a surface as large as the
ends of the spinnerets, covered with very fine threads pointing
towards the middle, where they unite, Fig. 155.

The spinning is commonly helped by the hinder feet, which
guide the thread and keep it clear of surrounding objects, and
even pull it from the spinnerets. This is well seen when an insect has been caught in
a web, and a spider is trying to tie it up. She goes as near as she safely can, and

FlG. 154. Spinnerets of Epeira.

FIG. 155. End of
spider's thread.

110

NATURAL HISTORY OF ARTHROPODS.

draws out a band of fine threads, which she reaches out toward the insect with one of
her hind feet, so that it may strike the threads as it kicks, and become entangled with
them. As soon as the insect is tied tightly enough to be handled the spider holds and
turns it over and over with her third pair of feet, while with the fourth pair she draws
out, hand over hand, the band of fine threads which adhere to the insect as it turns,
and soon cover it entirely.

It is a common habit with spiders to draw out a thread behind as they walk along,
and in this way they make the great quantities of threads that sometimes cover a field
of grass or the sides of a house.

In confinement spiders begin at once to spin, and never seem comfortable till they
can go all over their box without stepping off their web.

The uses to which the silk is put are very various, the principal being in the forma-
tion of nest, webs, and egg-cocoons. Among the simplest nests are the very interesting
tubes of the Trap-door spiders, principally belonging to the Mygalidae. Cteniza cali-
fornica, common in New Mexico, Arizona, and California, digs its hole in a fine soil,
which, when dry, is nearly as hard as a brick. The holes are sometimes nearly an inch

FIG. 156. Nests of trap-door spiders. A. Nest of Atypus. B. Nest with thick door. C. Nest with thin door.
D. Branched iiest. E. Nest with two doors. F. Branched nest with two doors. G. Nest with two branches.

in diameter, and vary in depth from two or three inches to a foot. The mouth is a
little enlarged, and closed by a thick cover that fits tightly into it, like a cork into a
bottle. The cover is made of dirt fastened together with threads, and is lined, like
the tube, with silk, and fastened by a thick hinge of silk at one side. When the cover
is closed, it looks exactly like the ground around it. The spider holds on the inside
of the door with the mandibles and the first two pairs of feet ; while the third and
fourth pairs are pressed out against the walls of the tube, and hold the spider so firmly
that it is impossible to raise the cover without tearing it.

Among the trap-door spiders of Southern Europe are species which make different
kinds of nests. The cover, instead of being thick, and wedged into the top of the
tube like a stopper, is thin, resting on the top of the hole, and is covered with leaves,
moss, or whatever happens to be lying about ; so that it is not easily seen. Two or
three inches down the tube is another door, hano-ino- to one side of the tube when not

* O O

in use ; but, when one tries to dig the spider out from above, she pushes up the lower
door, so that it looks as if it were the bottom of an empty tube.

Another species digs a branch obliquely upward from the middle of the tube, closed
at the junction by a hanging-door, which, when pushed upward, can also be used to

SPIDERS.

111

close the main tube. In these nests the spiders live most of the time, comino- out at
night, and some species in the daytime, to catch insects, which they carry into the
tube, and eat.

Moggridge once took a Cteniza californica out of her nest and put her on a pot of
earth, and the next morning had the good luck to see her at work digging. She loos-
ened the earth with her mandibles, and took it in little lumps with the mandibles and
maxilla?, and carried it away piece by pie<;e. It took her an hour to dig a hollow us
large as half a walnut. He saw the making of the door twice by other species. Once
he dug a hole for a spider in some earth, and the next day found her in it and the top
covered by a little web, on which were scattered bits of earth and leaves, which had
evidently been put there by the spider. The second night enough dirt and silk were
added to make the door of the usual thickness, but the spider never finished it so that
it would open properly on its hinge. Another time Moggridge saw at the mouth of a
very small hole a spider at work making a door. She spun a few threads across the
hole, then gathered up with her front-legs and palpi an armful of dirt, and laid it on
top of the threads. She then got under the pile, into the tube ; but the motions of the
dirt showed that she was still at work on it, and next morning the under-side had been
thickly covered with web, and the whole separated from the mouth of the tube except
at one side, where the usual hinge was left. The new door was at first soft, but in two
or three days hardened, and appeared exactly like an old door.

These spiders are accustomed to put on the door moss like that which grows around
it, and so conceal the door from sight; but when Mr. Moggridge took away the moss,
and dug up the ground around a hole,
and then destroyed the cover, the
spider made a new one, and brought
moss from a distance to put on it,
thereby making it the most conspicu-
ous thing in the neighborhood.

There is one spider, Argyroneta
aquatica, that makes a bag of silk on
water-plants, and lives in it under
water, as in a diving-bell, the opening
being below, so that the air cannot

O *

escape. Mr. Bell describes the filling
of these nests with air by the spider.
After the nest had been made as
large as half an acorn, she went to
the surface and returned fourteen
times successively, and each time
brought down a bubble of air, which
she let escape into the nest. The
bubble was held by the spinnerets
and two hind-feet, which were crossed
over them ; and the method of catch-
ing it was the following : The spider
climbed up on threads or plants nearly to the surface, and put the end of the abdomen
out of water for an instant, and then jerked it under, at the same time crossing the
hind-legs quickly over it. She then walked down the plants to her nest, opened her

FIG. 157. Aryyoneta aquatica, water-spider, natural size.

112

NATURAL HISTORY OF ARTHROPODS.

hind-feet, and let the bubble go. The water-spiders run about on water-plants, and
catch the insects which live among them.

The simple nests and tubes that have been described are made by spiders, most of
which spin no other webs. The larger and better known cobwebs for catching insects
are made by comparatively few species. On damp mornings in summer the grass-fields

\

FIG. 158. Web of Agalena.

are seen to be half covered with flat webs, from an inch or two to a foot in diameter,
which are considered by the weatherwise as signs of a fair day. These webs remain
on the grass all the time, but only become visible from a distance when the dew settles
on them. Fig. 158 is a diagram of one of these nests, supposed, for convenience, to be

spun between pegs instead of grass. The
Hat part consists of strong threads from
peg to peg, crossed by finer ones, which
the spider spins with the long hind-spin-
nerets, swinging them from side to side,
and laying down a band of threads at
each stroke. At one side of the web is
a tube leading down among the grass-
stems. At the top the spider usually
stands, just out of sight, and waits for
something to light on the web, when
she runs out and snatches it, and carries
it into the tube to eat. If anything too
large walks through the web, she turns
around, and retreats out of the lower
end of the tube. In favorable places
these webs remain through the whole
season, and are enlarged, as the spider
grows, by additions to the outer edges.
Similar webs are made by several house-
spiders, and are enlarged, if let alone,

FIG. 159. Web of Linyphia marmorata. . . . ,

till they are a toot or two feet wide, and
remain till they collect dirt enough to tear them down by its weight.

Nearly all spiders that make cobwebs live under them, back downward ; a.nd many

SPIDERS.

113

are so formed that they can hardly walk right side up. Linyphia marmorata makes a
dome-shaped web, supported by threads that extend up into the bushes two or three
feet. The spider stands under the middle of the dome, where it draws in a small cir-
cle of web with its feet. The upper threads of the web interfere with the wings of
small insects flying between them, and they fall down to the dome below, where they
are seized, and pulled through the nearest hole. Linyphia communis makes a double
web. The spider stands under the upper sheet, which curves a little downward. What
the use of the lower web is is not 'easily seen.

The webs of Theridion usually have at some part a tent, or at least a thicker portion,
under which the spider stands ; and from this run irregularly simple threads, crossing
each other in all directions, and held in place by threads above and below. Such irreg-
ular webs are often made in houses by Theridion mdgare, in cojners of rooms, under
furniture, and in cellar-stairways. The same spider spins occasionally out of doors on
fences, but never on plants. When it has caught an insect, and tied it up, it fastens
to it threads from above, which, as they dry, contract, and pull it up a little. It brings
down more and more threads, until the insect is at last hoisted to the top of the web,
where the spider can suck it with-
out exposure. Pholcus^ the long-
legged cellar-spider, makes an
irregular web of this kind, and has
a curious habit when alarmed. It
hangs down by its long legs and
swings its body around in a circle,
so fast that it can hardly be seen.

Round cobwebs are made by
the family Epeirida?, and the pro-
cess of making them by the com-
mon spider, from which our figures
are drawn, can be easily observed
in any garden. They generally
choose for their web a window-
frame or fence, or some such open
wooden structure, where there is a
hole or crack in which they can
hide in the daytime. The spider
begins by spinning a line across
where the web is to be, and attaches
another to it near the middle. She
carries the last line along, holding
it with one of the hind-feet, and
makes it fast an inch or two from one end of the first ; then she goes back to
the centre, attaches another line, which she carries off in another direction and
fastens; and so on until all the rays of the web (Fig. 160) are finished. She stops
occasionally at the centre, turns around, and pulls at the threads one after another,
and spins here and there short cross-lines to hold them more firmly. She seems,
by thus feeling the rays, to decide where to put in the next one, and does it
always in such a way as to keep tight what has been done before. When the rays are
finished to her satisfaction, the spider begins at the centre to spin a spiral line across

VOL. II. 8

FIG. 160. Web of Epeira vulgaris. a. Spiral thread, b. Radial
threads, c. Threads to nest. The spider is seen spinning the
adhesive threads.

114

NATURAL HISTORY OF ARTHROPODS.

them, the turns of the spiral being as far apart as the spider can conveniently reach.
She climbs across from one ray to the next, holding her thread carefully with one of
the hind-feet, till she gets to the right point, and then turns up her abdomen, and touches
the ray with her spinnerets, thus fastening the cross-thread to it. The figure shows her
in this position. When this spiral has been carried to the outside of the web, the
spider begins there another and closer one, of thread of a different kind. While the

first thread was smooth, the latter
is covered with a sticky liquid,
which soon collects on it in drops,
and makes it adhere to anything
that touches it. After going
round a few times, this spiral
would cross the one that was
spun first if the spider would
allow it to ; but, as she comes
to the old spiral, she bites it
a way. By beginning thus at the
outside, the spider is able to cover
the whole web with adhesive
threads, and, without stepping
on them, take her usual place in
the centre. She usually is care-
ful enough to spin beforehand a
thread from the centre to her nest,
and sometimes stays there, with
on foot on the thread, so as to feel if anything is caught in the w r eb. When she feels a
shake, she runs down to the centre, feels the rays to see where the insect is, and runs
out and seizes it. We have described the web as consisting of one regular spiral ; but
this is seldom the case. It is usually wider on one side than the other, or below than
above, where outside the spirals are several loops going partly round the web. The
web of Zilla consists entirely of such loops going three-quarters round the web, and
returning, leaving a segment without any cross-threads, in which is the line from the
centre to the spider's nest. The web of Nepldla plumipes also consists of loops run-
ning round about quarter of a circle ; and in this web the smooth cross-lines which are
first spun are not removed, but remain after it is finished.

The round-web spiders repair their webs by tearing out a dirty, tangled piece, and
putting a new one in its place. Wilder says that Nephila plumipes tears off and
replaces half the web at one time. Epeira vulgaris often takes away an old web, and
puts a new one in the same place, tearing down the old in pieces, and putting in the
rays of the new as it goes along. The spider walks on the nearest sound thread, and
gathers in witli her front-feet as much old w r eb as she can tear off, and rolls it up with
her palpi and mandibles into a ball. As she walks along, gathering up the old web in
front, she at the same time spins a new thread behind, and, when she gets to a suitable
place, makes it fast as one of the rays of the new web. The common story has it, that
the spider eats the old web. She certainly gathers it up in her mouth, and some-
times throws it away at once, but at other times sits and chews it a long time, with
apparent pleasure.

Various attempts have been made to use the silk of spiders, and chiefly that of the

FIG. 161. Web of Zilla.

SPIDERS.

115

large round-web spiders, for practical purposes, either by carding the cocoons or by
drawing the thread directly from the spider. The latest experiments and plans for
this purpose are those of Professor Wilder. He shows how Nephila plumipes might
be raised in large numbers, each spider kept by herself in a wire ring surrounded by
water, fed with flies bred for the purpose from old meat, and milked every day of their
thread. Every day or two each spider should be
taken down, put into a pair of stocks, and the thread
} Hilled out till it stops coming. In this way he thinks
an ounce of thread could be got from each spider
during the summer. The thread is from a seven-
thousandth to a four-thousandth of an inch thick,
and much smoother and more brightly colored, as
well as finer, than that of the silk-worm. Several
threads would have to be twisted together to get

o o

one of manageable size. The principal difficulties
are the space needed for keeping each spider by
herself, and the amount of labor needed to pro-
vide them with living insects for food and to draw
out the silk, which would make it too expensive
to use.

The Ciniflonidae, in addition to the usual plain thread, make a peculiar kind of
their own. They have in front of the spinnerets an additional spinning-organ, called

the cribellum. It is covered with fine
tubes, much finer than those of the spin-
nerets, set close together. They also
have on the last joint but one of the
hind-legs a comb of stiff hairs, the cala-
mistrum.

When they spin their peculiar web

they turn one of the hind-legs across under the spinnerets, so that the calamistrum is
just under the cribellum, and the foot rests on the opposite leg (Fig. 164). The hind-
legs are then moved rapidly back
and forth, so that the calamistrum
combs out from the spinning-tubes,
and at the same time tangles a

FIG. 16H. Spinnerets of Amaurubius,
a. Cribellum.

-;

FIG. 163. Calamistrum of Amaurobiua

FIG. 164. Dictyna, spinning curled web. a, b. Smooth thread.
c. Curled thread.

band of fine threads. This band

is laid along, and attached here

and there to a plain thread, so as

to make it adhere more readily to

an insect that happens to touch

it. As one leg gets tired, they

change and work with the other. In the webs of these spiders this adhesive band

can be seen with the naked eye.

Among those spiders that use the calamistrum is one which makes a web unlike any
other. It has been described by Professor Wilder under the name of the triangle
spider. It lives usually among the dead branches around the lower part of pine and
spruce trees, and is colored so like the bark that when it stands, as it usually does, on
the end of a branch it is easily mistaken for a part of it. The web seems to be made

116

NATURAL HISTORY OF ARTHROPODS.

in the night. A single thread five or six inches long runs from the spider's roost, and
from its extremity radiate four branches attached to various twigs in the neighborhood.
Between the rays the spider spins the peculiar curled web, and then going back toward
its usual resting-place gathers up the slack of the single thread. The net is now set
for use, and she stands holding it till something touches it ; then she lets go with her
hind legs, and the net springs forward, bringing more threads into contact with the
insect. If she thinks it worth while she draws up another loop and snaps the web
again. When she is satisfied that the insect is caught she gathers up part of the web
till she comes to him, covers him with silk, and carries him up to her roost.

Often in summer the bushes are covered with threads attached by one end, blowing
out in the wind, and bits of cobweb are blowing about with occasionally a spider
attached. To account for such threads curious theories have been thought of, among

others that spiders are able to force the thread from their
spinnerets, like water from a syringe, in any direction they
choose. If a spider be put on a stick surrounded by water
si ie manages, in course of time, to get a thread to some
object beyond, and to escape by it. To find out how this
is done Mr. Blackwall tried some experiments. He put
spiders on sticks in vessels of water, and they ran up and
down unable to escape as long as the air in the room was
still. But if a draught of air passed the spider she turned
her head toward it, and opened her spinnerets in the op-
posite direction. If the draught continued a thread was
drawn out by it, which at length caught upon something,
when the spider drew it tight, and escaped on it.

There is a still more curious use of this method of spin-
ning threads, that is in flying. Small spiders, especially
on fine days in the autumn, get up on the tops of bushes
and fences, each apparently
anxious to get as high as pos-
sible, and there raise themselves up on tiptoe, and turn
their bodies up with their heads toward the wind and spin-
nerets open. A thread soon blows out from the spinnerets,
and if the current of air continues spins out to a length of
two or three yards, and then offers enough resistance to the
wind to carry the spider away with it up into the air. As
soon as she is clear the spider turns round and grasps the
thread with her feet, and seems to be very comfortable and
contented. Sometimes they rise rapidly and are soon out
of sight, at other times blow along just above the ground.

This habit is not confined to any particular kind of
spiders, but is practised by many small spiders of the genus
Erigone, and by the young of many spiders of all families
that when adult would be too large for it. The best places
to watch them are garden fences, where they often swarm,
and can be more distinctly seen than on bushes.

It is still unexplained how the thread starts from the spinnerets. It has been often
asserted that the spider fastens the thread by the end and allows a loop to blow out

FIG. 165. Young Lycosa, about
to fly.

SPIDERS.

117

FIG. 167. Head

and mandibles of
Epeira.

in the wind, but in most cases this is certainly not done, only one thread being visible.
Sometimes while a thread is blown from the hinder spinnerets, another from the front
spinnerets is kept fast to the ground, so that when the spider blows away it draws out
a thread behind it entirely independent of the one from which it hangs. Some-
times instead of a single thread several are blown out at once, like a long brush.

When undisturbed spiders never bite anything except insects useful for food ; but
when attacked and cornered all species open their jaws and bite if they can, their
ability to do so depending on their size and the strength of their jaws. Notwith-
standing the number of stings and pimples that are laid to spiders, undoubted cases
of their biting the human skin are very rare ; and the stories of death,
insanity, and lameness from spider-bites are probably all untrue. The
biting apparatus is shown in Fig. 167, which represents the head and
mandibles of Epeira vidgaris, seen from in front. When not in use
the claw is closed up against the mandible between the rows of teeth ;
but when the jaws are opened to bite the claws are turned outward,
so that their points can be stuck into anything between the jaws.
Fig. 168 is the claw still more enlarged, showing a little hole near
the point at a, out of which is discharged the secretion of the poison
gland. The ordinary use of the mandibles is for killing and crush-
ing insects so that the soft parts can be eaten by the spider, and in this they
are aided by the maxilla?. They will sometimes chew an insect for hours, until it

becomes a round lump of skin with all the blood sucked
out of it ; this is then thrown away, the spider swallowing
only such bits as may happen to be sucked in with the
liquid portion.

Many experiments have been tried to test the effect of
the bites of spiders on animals. Doleschall shut up small
birds with My gale javanica and My gale sumatrensis, both
large and strong spiders, and the birds died in a few
seconds after being bitten. The same author was bitten
in the finger by a jumping spider. The pain was severe
for a few minutes, and was followed by lameness of the
finger, and gradually of the hand and arm, which soon
went away entirely.

Bertkau allowed spiders to bite his hand. On the ends
of the fingers the skin was too thick, but between the fingers they easily pricked it.
The bite swelled and smarted for a quarter of an hour, and then itched for some
time, and for a day after itched whenever rubbed, as mosquito bites will. Mr.
Blackwall made several large ones bite his hand and arm, and at the same time
pricked himself with a needle. Although the spiders bit deep enough to draw blood
the effect of their bite was exactly like that of the prick of the needle. No inflam-
mation or pain followed, and both healed immediately.

In the classification of the spiders the relative position of the eyes and the length
of the legs are very important, affording both family and generic characters. The
shape of the web is also distinctive.

Fie. ir,S. Ti
greatly enlarged
poi son-gland.

of mandible,
a. Outlet of

118

NATURAL HISTORY OF ARTHROPODS.

FIG. 169. Attus,
jumping spicier.

SUB-ORDER I. - - DIPNEUMONIA.

These forms have but two pulmonary sacs, and two or four stigmata. When the
latter number are present, two of them open into a regular tracheal system. The man-
dibles work laterally. There are six pairs of spinnerets, and usually
eight ocelli. This sub-order contains the great majority of the
spiders, and we need here to mention but a few of the most im-
portant families, and some of the prominent forms.

The jumping spiders form the family ATTID^E. These have the
body short and the cephalothorax large and square. The eyes are
usually arranged in three transverse rows. They spin no web,
but capture their prey by leaping upon it. Some of the species
are very common. Before leaping some of the forms always fix
a thread on the point from which they jump. By this they are
suspended in the air if they miss their aim, and are thus secured
from falling far from their hunting-grounds.

Closely allied to the Attidre is the family LYCOSID^E. Like the
last they make no webs, but capture their prey by running. Their long legs (the hind
pair the longest) enable them to run very rapidly. The arrangement of the ocelli is
shown in the cut. The cephalothorax is narrowed in front. Possibly the best-known,
certainly the most celebrated
species, is the Tarantula, Taran-
tula, apidice, which lives in Italy
and Spain. It is fabled that the
bite of this spider produces epi-
lepsy, or dancing madness, in its
victims, which could only be re-
lieved by a particular kind of
music. The species of Lycosa
and Dolomedes, another genus
of the family, are very numerous.
They live on the ground, under
stones, etc.

The TIIOMISID^E have re-
ceived their common name,
Crab-spiders, from the fact that
some species like the crabs walk
better sidewise that in the nor-
mal direction. They have the
abdomen broad, the ocelli of nearly equal size, and arranged in two parallel urcuate
rows. They make no regular webs, but spin single threads by which they fasten
leaves together to make their homes.

The family EPEIRID^E contains some of the most showy examples of the Arachnida.
The two first pairs of legs are longer than the others, and the eyes are widely separated.
They make circular webs, consisting of radiating threads crossed by a spiral. Epeira,
with its numerous species, is the typical genus, and one species has served for our ana-
tomical account of the Araneina. In this genus the abdomen is nearly globular. In

FIG. 170. Tarantula apulice, tarantula, natural size.

.

s

as

a

SPIDERS.

119

o

O o

o O

Acrosoma, a tropical genus rich in species, the abdomen is prolonged into a long

horn on either side. Nepliila has a long cylindrical abdomen. N. plumipes is found

in the Southern States. The sexes differ greatly in size.

Van Hasselt has made some interesting comparisons of

the relative proportions of the two sexes, and says that

the same dimensions applied to the human species would

result in a man six feet in height and weighing 150

pounds, married to a woman from seventy-five to ninety

feet in height, and weighing 200,000 pounds !

Most of the Epeiridae are brightly colored, and make
no attempt at concealment when in the web. Others
have odd shapes and colors, and hang in the web in such
positions that they look like anything but animals. Some
species draw up their legs against their triangular abdo-
mens, and look like bits of bark fallen into the web.

-I-. -11 -,! FIG. 171. Epeira diadema. cross-

Some are long and slender, and when at rest, either in spider; above; the arrangement of

the web or out, lay their legs close together before and

behind their bodies, so as to look like straws. Others have oddly shaped abdomens,

under which the rest of the body is partly concealed.

The THERIDIIDJS is the largest family of Spiders. Its members have the first pair
of legs the longest. The webs are more or less irregular in shape, and the species
always live upside down, hanging by their feet from the under side of the webs. They

FIG. 172. Acrosoma arcuata.

are almost invariably found in shady places. Theridion vulgare, a species which varies
greatly in color, from a cream white to a livid brown or plumbeous, is very common in
houses, and with Tegenaria clomestica shares the common name, house-spider. In Phol-
cus the legs are very long and slender. Erigone embraces some of the smallest
spiders known. To this family belongs also the blind genus Anthrobia, a species of
which is not uncommon in Mammoth Cave.

120

NATURAL HISTORY OF ARTHROPODS.

The DBASSID^E is a large family, which has the eight eyes arranged in two rows.
There is considerable variation in the relative length of the limbs, but the two middle
pairs are shorter than the first and last. The species are mostly dull-colored, and live
under stones, or in silk tubes on plants, but all do not spin a web for the capture of
their prey. We have already referred to the habits of the water spider of Europe,
Argyroneta aquatica.

In the species of Drassus the feet terminate with two claws and a bundle of flat-
tened hairs. Tegenaria domestica is the common house-spider, which has followed
man from the old to the new world. The species of Clubione are nocturnal in their
habits. A favorite place for their silken tubes is under the loose bark of trees or
between the boulders of a stone wall. Many species are known. The family CINI-
FLONID^E has been separated from the last on account of its peculiar spinnerets.

The family DYSDERTDJS is an exception to the rule, as its members have but six eyes,
and a closely allied Cuban form (Nops guancibacoce) has but two. The first pair of legs
are the longest. The species are few in number, and the American forms are far from
common. They are usually found under stones, but can move very quickly when so in-
clined.

SUB-ORDER II. - - TETRAPN.EUMONIA.

This group, which, as its name indicates, possesses four pulmonary sacs, embraces
the largest spiders known. It is composed of a single family, MYGALID^S. The man-
dibles are very large, and work up
and down instead of laterally.
The eyes are always eight in
number, and are placed close
together. Mygale is the best
known genus. It is a native of
tropical and semi-tropical Amer-
ica. The large Bird spider of
Surinam reaches a length of two
inches. The body is a pitchy
black, and is covered with long
reddish-brown hairs. It is said
that it catches small birds, kills
them with its poisonous bite, and
then sucks their blood. Mygale
hentzii is a not uncommon species
in the Southwestern States. The
genus Cteniza contains the Trap-
door spiders, of whose wonderful
architecture an account has been
given in the preceding pages.
The two best known species are
Cteniza ccementaria, of Southern
Europe, and C. californica, of
California. Atypus is another
genus of the family which lives further north. According to Mr. J. Wood-Mason
some of the large Indian Mygalidse are possessed of organs for producing a noise.

FIG. 173. Mygale hentzii.

Myc/ale aricnlaria, bird spider.

HARVESTMEN.

121

These consist of a comb and rasp, on the outside of the chelicerae and the inner sur-
face of the maxillae, which by being rubbed together produce a loud noise.

The spiders of North America have been studied by Hentz, Emerton, Keyserling,
and Thorell. It is estimated that there are about eight hundred species in the United

States.

ORDER III. - - ARTHROGASTRA.

This order is characterized by an unsegmented cephalothorax (except in the Solif ugse)
and a usually elongate abdomen in which the segments are more distinct, and which
is joined directly to the cephalothorax without the intervention of a slender petiole as
in the spiders. The chelicerae and palpi are frequently chelate. Respiration is effected
by means of pulmonary sacs in the scorpions and whip-scorpions, and by tracheae in the
other forms.

SUB-ORDER I. --- OPILIONEA.

Here come those slow-walking, long-legged forms familiarly known as harvestmen
and daddy-long-legs. They have two ocelli, small chelate chelicerae, and moderate
palpi. The legs are very long, and
the last or tarsal joint is broken up
into a long series of articulations,
sometimes as many as fifty in num-
ber. Not only in this many-jointed
structure but in function as well,
these elongate limbs seem to re-
semble antennae, for they are ap-
parently used as organs of sense,
and especially of touch, by those
animals. The daddy-long-legs are
perfectly harmless to man. They
live on small insects, and strive to
avoid the full glare of the sun
though they are not nocturnal in
habits.

Members of this sub-order are
foiind in all parts of the world, and
in tropical countries, especially in
South America, they assume the
most bizarre forms. Three fami-
lies are described.
The GONYLEPTI-
DJE have the body
broad and de-
pressed, and the palpi and hinder femora spined. The species are
largely South American, Gonyleptes curvipes occurring in Chile.
Phryxus longipes is found in Mammoth Cave, Ky. The family
PIIALANGID^E embraces our more common forms. Fifteen species
of Phalangium are known from North America ; in the northern

FIG. 174. Phalangium dorsatum, daddy-long-legs.
b. Male. Natural size.

a. Female.

FIG. 175. Cosmetus
ornatus, male, nat-
ural size.

122

NATURAL HISTORY OF ARTHROPODS.

FIG. 176. Gonyleptcs curvipes.

states Phalangium dorsatum, a grayish species with a darker dorsal band, is very
common. Cosmetus ornatus occurs in the southern states, while Acanthocheir

armatum is a blind form found in Mammoth Cave.
These forms have an inflated, oval body, and the
hinder femora unarmed. The family TROGULID^E,
with a flat, elongate abdomen and the cephalothorax
produced forwards, covering the mouth-parts like a
roof, has not been reported from America.

SUB-ORDER II. - - PEDIPALPI.

These forms, which are commonly known as
whip-scorpions, are all inhabitants of tropical and
semitropical countries. They have eight ocelli, two
in the median line and three on either side. The
chelicerse are short and two-jointed, while the palpi
are long and large, terminating in a more or less
perfectly formed pincer. The first pair of legs is the longest, and the tarsal joint is
broken up into a long series of articles, well shown in our figure of Phrynus. The
abdomen is slightly constricted at the base, and is composed of eleven or twelve joints.
There are two pairs of stigmata.

Two well-marked types exist, forming the genera Phrynus and Thelyphonus, each
of which may be regarded as forming a family to which the names PHRYJSTID.E and
THELYPHONID^E are re-
spectively applicable.

In Phrynus the palpi
are very long, the carpal
joint strongly spined.
The first pair of legs
are long, and both the
tibial and tarsal joints
are broken up into a
series of rings. The
abdomen is oval. The
young are born alive.
The species are all trop-
ical, none occui'ring
within the limits of the
United States, though
Phrynus asperatipes
occurs in Lower California ; a second species is found in the West Indies, and two
more are known from Southern Mexico and Central America. Other forms are found
in the tropics of both hemispheres.

ThelypJiomis is much more scorpion-like in appearance, and to the species of this
genus the name whip-scorpion is most applicable. The palpi are short and stout, and
the joints are covered with stout, sharp spines ; the first pair of legs is very long, but
only the tarsus is broken up into small joints. The abdomen is long and somewhat
slender and twelve-jointed, the last three joints being much smaller than the rest.

FIG. 177. Acanthocheir armata, enlarged.

I

o

s

WHIP-SCORPIONS.

123

From the last joint arises a long, jointed, caudal appendage, much like a whip-lash
in appearance. The species are found
in both hemispheres, but in the eastern
hemisphere it is said by Stoliczka that
none are found west of India and Cey-
lon, not even in East Africa. But one
form, T. giganteus, has been found in
the United States.

The species of both of these genera
are very difficult to identify, and much
difference of opinion exists concerning
them. Like many of the arachnids
they are furnished with a poison ap-
paratus which here, as in the true
spiders, is placed in the cheliceras.
Of the development of the Pedipalpi
nothing is known.

FIG. 178. Phnjnus lunatus.

SUB-OKDER III. - - S

These forms are readily separated from all other arachnids by the segmented
cephalothorax. The body is long; the chelicerae are chelate, and the palpi resembles

FIG. 179. Thelyphonus caudatus, whip-scorpion.

the true legs. Specimens are far from common in the United States, but thanks to
the late J. Duncan Putnam our native forms are very well known.

There are fifteen genera, two of which (Datames and Cleobis) are represented in
the United States by nine species. These forms, which are found in the warmer parts

124

NATURAL HISTORY OF ARTHROPODS.

of the world, are nocturnal in their habits, hiding during the day under stones, etc.
They are very active and pugnacious, and are reputed to be very venomous, but the
effects of their bite are probably considerably exaggerated. Solpuga araneoides, a
very hairy species, is found in the region of the Volga.

SUB-ORDER, IV. - - PSEUDOSCORPII.

As their name indicates, these small forms closely resemble the true scorpions in
appearance, but one important distinction is at once noticeable ; the long and slender
termination of the abdomen with its poisonous sting is absent. The chelicerae are
rudimentary and fitted for sucking, while the palpi are large and stout, each terminating

/ ' ^^m

"VJ ff^^~.

FIG. 180. Solpuya araneoides.

in a pincer as in the true scorpions. Two or four or no ocelli are present, and the
abdomen is eleven jointed. They breathe by means of tracheae.

Nine genera, represented by forty living and eleven fossil species, are known, but
in the United States only the genera Chelifer, Chernes, Chthonius, and Obisium, with
nine species, have been found. The fossil forms occur in amber and copal, and one
species has been found in the coal formations. These forms are all small, none exceed-
ing a few lines in length. They occur under moss and bark of trees, and one species
at least (Chelifer cancroides} is not uncommon in houses and books. They are fre-
quently found attached to insects, especially to flies, but whether this is from a parasitic
habit or from a desire for a more rapid locomotion is uncertain. The probabilities are
in favor of the latter. The food is supposed to be the juices of other insects, for which
their sucking mouth-parts especially adapt them.

SCORPIONS.

125

FIG. 181. Under surface
of scorpion, c. Combs,
s. Spiracle.

After laying, the eggs are carried by the female attached to the first segment of the
abdomen, and, according to Metchnikoff, the development is much different from that
of the scorpions.

SUB-ORDER V. - - SCORPIODEA.

With the exception of the spiders the scorpions are possibly the most familiar, at
least by reputation, of any of the Arachnids. They have an elongate body, the last
six segments of the abdomen being of nearly equal size, forming a
flexible tail armed on the tip with the well-known and much-
dreaded sting. The cheliceraa are short and end in a pincer,
while the palpi are long and also terminate in a forceps. The
ocelli vary from six to twelve, and their numbers were formerly
employed to distinguish the different families. On the under
surface is a peculiar pair of comb-like appendages, just behind
the last pair of feet. The respiration is effected by two pairs of
pulmonary sacks, which communicate with the exterior through
four stigmata.

The young are developed within the mother. After birth the
mother apparently shows great regard for the young, which she

carries for some time about with her, attached by their
pincers to all portions of her body.

Mr. J. Wood-Mason, the able naturalist of Calcutta,
says that in Scorpio afer, and some other forms, there
are well-developed organs for producing sounds. These
stridulating organs are composed of a scraper on the out-
side of the terminal
joints of the palpi, and
a rasp occupying a cor-
responding position on
the first pair of legs.
When these are rubbed
against each other a
noise is produced.

Scorpions are espe-
cially noted as venom-
ous insects. The sting
is the sharp point of
the last segment of the

abdomen. In this segment are the two poison glands
which empty through two minute orifices near the
point of the sting. When irritated the scorpions,
apparently fully aware of their power, show great
fierceness, waving their abdomen about in a most

* O

threatening manner, and when the opportunity occurs
a sudden straightening of the hinder portion of the
body forces the sting into the offending object. The
sting of the scorpion rarely if ever proves fatal to
man, but the larger species, especially in the warmer

FIG.

carolinus, scor-
pion, natural size.

FIG. 183. Centrums phaiodacty'us,
scorpion, natural size.

126

NATURAL HISTORY OF ARTPIROPODS.

climates, produce very severe wounds which are attended with serious constitutional
derangement. Jousset, who has studied this subject, concludes that the poison o'f
the scorpion acts directly on the red corpuscles of the blood and on them alone. The
poison causes them to unite together in masses too large for entrance to the capillary
system, and thus the circulation is obstructed. The best remedy is ammonia applied
externally, and also administered in small doses internally.

In the older schemes of classification the number of ocelli was used to divide the
group into families, but in the system now in vogue the shape of the sternum is em-
ployed, together with other characters. The family ANDROCTONID.E has this region
sub-triangular, in the TELEGONIDJE it is very short, while in the VEJOVID^E and PAK-
DINID^E it is sub-pentangular. These four families contain thirty-one genera, repre-
sented by numerous species in the warmer parts of the globe. Nearly twenty species
are known from North America. While most of the species are comparatively small
the Scorpio afer of the East Indies reaches a length of nearly six inches. The species
figured are all American.

The scorpions are among the most ancient of the arthropods, forms closely allied to
those living at the present time being found in the rocks of the carboniferous age of
both Europe and America.

J. S. KINGSLEY.

FIG. 184. Nest of spider (Dolomedes).

MYRIAPODS.

127

SUB-CLASS III. MYRIAPODA.

The group of centipedes, niillipetls, and thousand-legged worms, receives both its
scientific and popular names from the large number of locomotive organs possessed by
the various individuals. In scientific terms myriapods may
be defined as terrestrial arthropods, with distinct head and
numerous similar post-cephalic segments; there is a single
pair of antennas, and two pairs of jaws ; the legs are num-
erous, and the respiration is by trachea.

In external form, as well as internal structure, the myria-
pods present many similarities to the larva? of the hexapods.
The nervous system is composed of a long series of similar
ganglia, one to each segment. The digestive canal, with rare
exceptions, pursues a straight course through the body. The
long heart extends through all the body segments and forces
the blood forward. In some forms the mouth-parts are adapted
for sucking. Ocelli are visually present. The young hatch

J J FIG. 185. Young myriapod

from the egg with a varying number of appendages, many (Stnmgyiosoma), just

having but three pairs, thus showing a marked resemblance

to the larvae of many of the hexapods. Three well-marked groups are found.

ORDER L CHILOGNATHA OR DIPLOPODA.

These are the millipeds proper. The body is round or flattened, the feet are
inserted close together, and all the segments behind the third bear two pairs of limbs.
They frequent dark places, and feed largely on decaying vegetation. Many have the
power of curling themselves in a spiral when disturbed.

The POLYZONID.E have a very small head; the mouth-parts are united so as to
form a sucking tube, and the eyes are few or wanting. The IULID^S have a large head,
free mouth-parts, and a cylindrical body. The various species of lulus are known as
galley worms, and are not uncommon in decaying timber and similar locations. When
disturbed they coil themselves into a spiral like a watch-spring, and also emit a strong
odor. This is produced by glands inside the body Avhich open on the sides of the seg-
ments, the small openings superficially resembling spiracles. The odor is evidently a

provision for defence. In 1. canadensis, a
chestnut-colored species with a black dorsal
band, these openings are ringed with black,
thus making them more prominent. The
LYSIOPETALID^E are closely related to the
luHdaB. They have numerous ocelli, except
in the blind forms, and seven-jointed an-
tennae, and the body is constricted behind the head. The forms are mostly small.
We figure Scoterpes copei, a blind form found in Mammoth Cave.

The POLYDESMID^; have the sides of the segments expanded in broad plates, and
the segments themselves are comparatively few. The POLYXEOSTID^; embraces forms

128

NATURAL HISTORY OF ARTHROPODS.

FIG. 187. Polydesnms, enlarged.

with even fewer segments (nine to eleven), and but thirteen pairs of feet. The species
are all minute. The remaining family, GLOMEKID^E, which has twelve or thirteen

segments, and from sev-
enteen to twenty-one
pairs of legs, is not rep-
resented in the United
States.

Mr. Scudder has pro-
posed the name AECHI-
POLYPODA for a group of
fossil myriapods, which,
while closely related to
the Chilognatha, show
several important points
of difference. The dor-
sal part of each segment

(tergum) is much smaller than in that group, and is armed with huge spines. The
sterna are proportionately very large and bear between the bases of the feet peculiar
crater-like cups, supposed by Mr. Scudder to be the possible supports for gills, but
more probably they are comparable to the similar openings on the ventral surface of
Scolopendretta. While Mr. Scudder considers the group as a sub-order, Dr. Packard
thinks that the characters are of not more than family rank. Almost all the known
forms come from the carboniferous, of Mazon Creek, 111., a few having been found in
Great Britain.

ORDER II.--PAUROPIDA.

This group, which was first recognized by Sir John Lubbock, the banker-naturalist
of London, forms, to a certain extent, a connecting link between the chilognaths and
chilopods, while in many respects it is distinct from both. There are but six segments
in the body behind the head, while the antenna? are greatly different from anything
found in the whole class of insects, the basal joints bearing three flagella. Two well-
marked types, represented by four species, are found in America, -fauropus, with a
rounded body, and Eurypauropus, in which the lateral edges of the body are so
expanded as to completely hide the feet. These forms, which live in damp places, are
very minute, about one twentieth of an inch in length. The young are hatched with
three pairs of feet.

ORDER III. CHILOPODA.

This order contains those flattened forms to which the name Centipedes is most
applicable. They have long, many-jointed antennae, and but a single pair of limbs to
each segment of the body. They are predacious in their habits, moving rapidly, and
living largely upon animal food. Many of the forms are poisonous. They have
poison glands in the base of the first pair of legs, which are so modified as to lead
to their being formerly regarded as mouth-parts, these poison glands emptying by
ducts which terminate in the same way as the similar organs in the spiders.

In the GEOPHILID^E the segments are similar and very numerous, varying from
thirty to two hundred ; the eyes are lacking ; the antennae are fourteen-jointed, and
the legs are short, terminating in single-jointed tarsi. As indicated by the name,

MYRIAPODS.

129

these forms are terrestrial in their habits, living under stones and decaying wood, and

preying upon the smaller insects which are found there. The genera are largely

founded upon the shape of the anterior segment of the head, and upon

the structure and form of the mouth-parts. Geophllus, the typical genus,

has the anterior segment of the head square. The European G. electri-

cus (which belongs to the section Arthronomalus) is phosphorescent,

shining in the dark like a glow-worm. Strigamia elliptica, of Oregon,

which reaches a length of five and a half inches, is the largest member

of the family known.

The SCOLOPENDEID.E are characterized by usually possessing four
ocelli on either side, seventeen to twenty-jointed antenna?, and usually
unequal body-segments. To some of these characters an exception
occurs in Cryptops, which is blind, and which has equal segments;
further characters of this genus are seventeen-jointed antennae, and
twenty-one body-segments and pairs of limbs, each of which terminates
in a single-jointed tarsus. Scolopendra, the typical genus, has eighteen
or twenty joints in the antennae, twenty-one segments and appendages
and two-jointed tarsi. The species of Scolopendra are inhabitants of
the warmer climates, and are the famous centipedes of fact and fiction.
The largest known species is S. gigantea of the East Indies which reaches

nine inches or even a foot in length. Scol-
opendra morsitans, of South America, is
nearly equal in size.

The larger forms of centipedes are cele-
brated for their poisonous bite, which is FIG. iss. <?eop/
fatal to insects and other small animals,
and very painful and even dangerous to
man. To us the centipedes are far from pleasant objects,
especially when regarded as articles of food ; but Plum-
boldt says that the children of some of the South Amer-
ican Indians extract large specimens from their holes,
and having torn off the head with its poisonous fangs,
eat the remainder with evident gusto.

Several species have been found within the limits of
the United States. Our largest form is /S. castaniceps,
which reaches a length of five and a half inches. It is
found throughout the Southern States. Our other forms
are smaller, and their bite is far less venomous than that
of the large tropical species.

The LITHOBIID.E have a body with unequal segments,
there being nine large and six smaller dorsal scutes.
There are numerous ocelli on either side of the head,
and the antennas are many-jointed. There are fifteen
pairs of feet. Lithobius, with forty jointed antennae,
flattened head, and two-jointed tarsi, is represented by
TJ. americanus, a widely distributed American form.
The species of this genus prey largely upon earth-worms and insects, to which their
bite is poisonous.

VOT,. II. 9

FIG. 189. Ccrmatia forceps,
natural size.

130

NATURAL HISTORY OF ARTHROPODS.

The CEKMATIID.E have the antennae bristle-like and longer than the body ; the legs
are also very long, and facetted eyes instead of ocelli, are present an exceptional
feature among the myriapods. Our only species, Cermatia forceps, which is rarely
found in New England, but which is more common in Philadelphia and the South, is
a beautiful form ; its general color is a greenish brown, sometimes inclining towards
purple, the body and legs being striped and banded with green. It is commonly
reputed to be poisonous, but authentic cases of its bite are at least rare.

As a rule the Myriapoda are beneficial to the agriculturist. The carnivorous forms
destroy immense numbers of injurious insects, while most of the vegetable feeders
live on decaying wood and plants, thus converting them into the very best form of
plant food. All, however, are not so innocuous, for some forms, especially the galley
Avorms, are known to eat the roots of plants or even to attack the fruit of the straw-
berry, cucumber, etc. These forms are often erroneously included under the term
wire-worms by gardeners and farmers.

J. S. KlNGSLEY.

FIG. 190. Lithobius americanus.

HEX A PODS. 131

SUB-CLASS I Y . HEXAPODA.

The Hexapoda, or insects proper, derive their systematic name, which means six-
footed, from the fact that the adults (with a few inconspicuous exceptions) have three
pairs of feet fitted for locomotion. Besides this there are many other correlated and
distinctive characters, and the group is as well defined and as closely circumscribed as
any in the animal kingdom. The body of all hexapods is divided into three well-
marked regions, head, thorax, and abdomen, each composed of a number of
segments. In the larval stages these distinctions are frequently not so easily traced
as in the adult, but still they can be readily recognized. In our discussion of the
morphology of the hexapods we will first give the characters of the adult and after-
wards those of the larval and pupal stages.

The head, which, as has been stated on a preceding page, consists of four segments,
bears a pair of compound eyes and usually two or three simple eyes in addition. There
is but one pair of feelers or antenna?, and three pairs of mouth-parts. The most
anterior of the appendages connected with the mouth are the mandibles, which are
always without the palpi so common in the Crustacea ; next come the maxilla?, and
then the labium, both of which bear articulated prolongations known respectively as
maxillary and labial palpi. Besides these, there are other parts concerned in eating,
which, though not appendages, deserve mention here. These are the labrum or upper
lip, and the metastonia, lingula or tongue. These mouth-parts are variously modified in
different insects, thus affording most impoi'tant systematic characters. In the Lepi-
doptera they form a long sucking-tube which, when not in use, may be coiled in a spiral,
while in the Hemiptera and many Diptera, in addition to being adapted for suction,
they form a piercing organ. In all the other orders the mouth-parts retain more
nearly their primitive character, and are fitted for biting.

The second region of the body, the thorax, is composed of three segments, each of
which bears a pair of legs, and in addition the two last usually bear a pair of wings.
To each of these rings of the thorax a distinctive name is applied, and since these
portions are very important and often referred to the names may here be given. The
first is the prothorax, the second mesothorax, and the third and last metathorax.
Sometimes all of these rings are distinct and equal, but more frequently one is en-
larged at the expense of the other two. Thus in the Hemiptera, Coleoptera, and
many Orthoptera, the prothorax is very large, while in the others it is relatively
much smaller.

Of the legs we need here say nothing, referring the reader to page 90 of this
volume. The wings, however, deserve a passing notice. According to the older
views of morphology these organs were regarded as modified limbs, homologous with
the legs, but the present view regards them as but extensively-developed folds of the
skin, comparable to the respiratory organs. The wings never exceed two pairs in
number, and in the Diptera only one pair is well developed, the posterior being
represented by little stalked balls, the halteres. Usually the wings are strengthened
by veins, each of which has its proper name. Though the patterns of venation in
many forms seem very complex, they arc readily referable to a common plan, the
outlines of which may be obtained in any handbook of entomology.

132 NATURAL HISTORY OF ARTHROPODS.

The abdomen, which encloses most of the vegetative and all of the reproductive
organs, is composed of ten segments which are but rarely provided with appendages
in the adult condition. An exception to this may be noted in the fact that the stints
and ovipositors of many forms are in reality composed of the modified appendages of
the last three segments of the abdomen.

Among the most striking features of the Hexapoda are the wonderful meta-
morphoses undergone by many members of the group in passing from the larval
to the adult condition. A few forms are ovoviviparous, that is bring forth living
young, but the great majority lay eggs which in the course of time hatch out the
young. The eggs of many forms are very interesting from the peculiar and beautiful
ways in which their surface is ornamented. The eggs undergo a partial segmenta-
tion, the central portion not dividing, and soon from the cells thus produced an
envelope arises which from being formed in the same way as one of the foetal envelopes
in the mammalian embryo has received the name amnion. This finally envelops the
whole of the egg ; soon a portion of the egg proper becomes differentiated, forming an
embryonic disc which soon becomes divided into the future segments of the body.
On each of these primitive segments there frequently appears a pair of small swellings,
the rudiments of the future limbs. Frequently, however, some of the segments show
at no time any trace of appendages. With the progress of growth the embryo acquires
what is known as a larval condition, and then the egg hatches and the young begins a
free life.

The term larva is applied to very varying stages of development as far as organs
and perfection of parts are concerned, but the word may be defined in general terms
as applying to the young insect just after hatching. In the grasshoppers, for instance,
the larva closely resembles the adult, the most prominent difference being that the
wings are extremely rudimentary. In the Diptera, on the other hand, the body is
long and slender and without limbs, and, in some forms, even a distinct head is lack-
ing. Between these two extremes almost all gradations can be found. The larvae of
Diptera (flies) are known as maggots, of the Lepidoptera (butterflies and moths) as
caterpillars, and those of the Coleoptera (beetles) as grubs. The early stages of the
other orders have received no popular names.

Between the larval and adult conditions the features of growth are as different as
the characters of the larvae, but the phenomena exhibited may be roughly divided into
three groups. In the first (ametabolic) the insects undergo no metamorphosis, and
the adult, which never has wings, differs from the larva in little else except size. The
second (hemimetabolic) type passes through what is known as an incomplete metamor-
phosis. The larva increases in size by numerous moults and passes into a pupal con-
dition, in which the wings are rudimentary and the general adult form is apparent.
This pupa, however, is markedly different from that of the next group, in that they are
active instead of quiescent. This type of development is exemplified in the grass-
hoppers, dragon-flies, bugs, etc.

The last, the holometabolic or complete metamorphosis, occurs among the ^bees,
butterflies, flies, beetles, etc. We may take for an example of this type one of our
American silk-worms. The larva upon hatching eats voraciously, the consequent
growth being permitted by numerous moults, until at last the young insect is ready to
enter the pupal stage. The larva has mouth-parts adapted for biting, threeji* pairs of
thoracic legs, while five of the abdominal segments bear locomotive appendages known
as pro-legs. During the later stages the wings of the perfect insect begin *''cir devel-

m

vaff

Carrion beetles and flies.

HE XA PODS.

133

FIG. 191. Larva of Polyphemus moth ( Telea polyphemus).

opment as scale-like pads within the larval skin, no trace of them being visible from
the exterior. In the larvae of other insects which undergo a complete metamorphosis,
the abdominal append-
ages may be reduced in
number, and may be en-
tirely wanting, and even
the thoracic legs may
disappear.

When about to pass
into the pupal stage, the
silk-worm spins a fine ^

thread, which it coils into
an oval case known as the
cocoon. Frequently in
spinning this cocoon
leaves are included, so
that the envelope is a compound of silk and leaves. Other forms do not spin a cocoon,
but, with this exception, the process of metamorphosis is essentially the same. Now

by a moult the pupal condition is attained. The
body is enveloped in a chitinous integument,
and on the anterior and ventral portions may
be seen the sheaths which cover the wings,
legs, antenna?, and mouth-parts. In the form
under discussion these sheaths are all closely
united to the body, but in others (e. g. beetles)
these parts are all distinct and separate. The
length of pupal life varies from a few days or
weeks to several months, and in the case of some beetles evidence is not lacking to
support the opinion that the pupal stage may last for many years.

At last the insect is ready to enter its perfect state. It moults for the last time
and emerges from its pupal envelopes. In the case of the Lepidoptera, the wings are
moist flabby sacs, biit soon they are distended by fluids which are forced into them,
and then, drying rapidly, they acquire the firmness necessary for their use as organs of
flight. By taking a moth when it has just emerged from the cocoon, one can easily
produce deformed wings by pinching or puncturing these members, thus preventing
their distension.

In the moth which we have taken as the type of complete metamorphosis, the
mouth-parts have lost their capacity for biting, and some
of them have been converted into a long tube adapted
for sucking the nectar of flowers, the antenna? are trans-
formed from short and inconspicuous organs into long
feathery feelers, the compound eyes appear, the thoracic
legs become longer and more slender, and the full com-
plement of joints is produced, while the pro-legs of the
abdomen have entirely disappeared.

Correlated with these external changes so superficially reviewed are as great and
important modifications of the internal organs. The reproductive organs acquire
their adult functions, the digestive organs become adapted to the changed food, the

FlG. 192. Cocoon of Telea.

FIG. 193. Pupa of Telea.

134

NATURAL HISTORY OF ARTHROPODS.

tracheal system has a different distribution, and equally important changes occur in
the circulatory system. Our space is not sufficient to detail these changes, but their
extent can be seen by a comparison of the adjacent figures, which represent the
nervous system in the larva of a bee, and also in the adult insect. These changes
are not sudden, but are accomplished by constant modifications of the organs con-
cerned.

Besides the common sexual reproduction, some insects can produce young without
the intervention of males. In some of these cases of agamogenesis or parthenogenesis

FIG. 194. Nervous system of a larval bee.

FIG. 195. Nervous system of adult bee.

the eggs are laid and undergo the regular development of fertilized eggs, but in
others the eggs are developed inside of the parent, and the young are born in an active
condition.

The systems of classification of the Hexapoda are very numerous and very differ-
ent, though now it is pretty universally conceded, both in this country and in Europe,
that the Thysanura are the lowest and the Hymenoptera the highest orders. But
within these extremes the sequence of orders varies greatly. We shall here follow
Dr. Packard's latest scheme, without, however, adopting all the features of his arrange-
ment. Dr. Packard groups the hexapods under five super-orders and ten orders, but
for our purposes the former may be omitted.

THYSANURA.

135

ORDER I. - THYSANURA.

Tliis order comprises the lowest, simplest six-footed insects. They are called Thy-
snnura (from the Greek thusaneros, hairy or bristly, and oura, tail), in allusion to the
hairy or bristly abdominal appendages of some of the typical forms. They are all
wingless, and undergo no metamorphosis. There is a great variation in their form
and structure, especially in the parts of the mouth, and it is difficult to put into few
words a general account of them. They are divided into three groups of sub-ordinal

rank.

SUB-ORDER I. COLLEMBOLA.

b. sucker.

These forms, for which the common name spring-tails may be adopted, are small,
often of microscopic size ; their mouth-parts are partially abortive, while they are
enabled to leap by means of a curious spring be-
neath the abdomen. A distinctive feature of the
Collembola, and one which gives the name to the
group, is the remarkable organ situated on the lower
surface of the basal segment of the abdomen. It
is a small tubercle, consisting of two valves, from
between which is thrust a fleshy sucker, or in
Smynthurus a pair of long tubes, which are capable
of being darted out on each side of the body, en- FlG< 196 . _ P op iriug .
abling the insect to attach itself to small objects,
and even to stand upside down. There are two families. These forms are often col-
lectively known as podurans, and furnish the " podura scales " used by microscopists
as test objects.

The curious little creatures, forming the family PODURIDS, occur everywhere
except in dry places. Besides a tracheal respiration they undoubtedly breathe directly
through the skin, and therefore inhabit moist places. They take up their abode under
stones in damp, grassy, shaded spots, live in damp cellars, or hide under mushrooms
and logs ; we have seen them in greatest abundance in hot-beds, leaping in the air,
and appearing like a shower of sand. One species (Anurida maritima) is often found
under stones at tide-marks. A species of Achoreutes is sometimes found floating in
large masses on the surface of roadside puddles, or under the bark of old trees ; and
one species sometimes abounds on the surface of the snow. On
the glaciers of the Alps there is a species peculiar to that unusual
habitat.

The podurids, as well as the sminthurids, leap by means of a
curious two-forked 'spring,' which bends under the body, and when
at rest is retained in place by a sort of catch ; when the muscles of
this catch are relaxed it lets the spring fly back, and this sends the
little creature into the air, out of harm's way. The facility with
which they leap is a constant source of vexation to the zealous col-
lector, but this trait may be turned to advantage by cautiously
placing over them a vial, into which they may be made to leap. The
podurids are thick-bodied ; the segments, though in the Thysanura
generally of equal size, are in this family inclined to become unequal,

FIG. 197. Lepido-
cyrtus gibbulus.

136

NATURAL HISTORY OF ARTHROPODS.

that next to the head, especially, is often small and collar-like. In the lowest forms,

however, such as Anura, the segments are of nearly equal size. The mouth-parts

are very rudimentary, they are situated mostly within the head,
the jaws not being strong and adapted for biting, as in other
insects ; hence they only nibble decayed vegetable matter.
Our commonest poduran is Tomocerus plumbeus, a leaden gray
insect with long feelers. The species of Orchesella are gaily
ornamented ; those of Lepidocyrtus are white. The scales on
different parts of the body are of different shapes, sometimes
becoming hair-like.

In the SMYNTHURIDJE the body is globular or oval, while
the legs are long and slender, and most of them are very
prettily colored ; they often occur on flowers. One species is
often found in the spring on the flowers of the dandelion. The

family name is derived from Smynthurus, which embraces our commonest species.

The species of Papirius are even more minute.

FIG. 198. Smynthums au-
rens, enlarged.

SUB-OEDER II. - - S YMPHYLA.

This most remarkable group contains but a single family, SCOLOPENDRELLID/E, and
a single genus, Scolopendrella; and because the species have a
series of abdominal legs they are frequently regarded as myria-
pods. By Mr. Ryder, who first called attention to its remarkable
peculiarities, it is considered as the type of an order connecting
the winged insects and the myriapods. These singular forms in-
habit the same situations as other Thysanurans, and might be mis-
taken for the young of our common northern centipede (Lithobius).
The Scolopendrella immaculata is found in Europe and the eastern
and central United States. The head and mouth parts, as well as
the antennas, are like those of Campodea, but there is a series of
nine pairs of five-jointed abdominal legs, which give it a rnyriapod-
like appearance. We thus see that in Scolopendrella we are deal-
ing with a remarkably composite or synthetic animal, which with
fundamental thysanurus characters combines features which ally
them with the myriapods. As we have already stated, the pos-
session of functional abdominal legs by Scolopendrella does not
imply that it is necessarily a myriapod ; the feet differ in important
respects from those of centipedes, and the presence or absence of
abdominal feet is not an ordinal or very important character. We
shall see further on that the Cinura (Campodea, Lepisma, etc.)
have a series of one- or two-jointed abdominal appendages, which
are homologous with the legs of Scolopendrella. At the end of
the body is a pair of short, pointed stylets, which are spinnerets.
This genus may be regarded as an ancestral type, i. e., it is possible
that the winged insects have descended from a Scolopendrella-\ike
form. This view is strengthened by the fact that the embryos of
many-winged insects have at first a series of abdominal feet, which
disappear later on in embryonic life.

c \

FIG. 199. Scolopen-

THYSANURA.

137

FIG. 200. Abdominal
legs of Campodea.

SUB-OilDER III. - - ClNURA.

Like those of the last, the forms in this group are frequently much larger than the
podurids. The mouth-parts in many respects resemble those of the Orthoptera, and
the abdomen is provided with imperfect or abortive legs. From
the long abdominal appendages these forms receive their scientific
name, which may well be translated into a more popular form,
bristle-tails.

The family CAMPODE^E comprises two genera, which are quite
dissimilar in form. The group is distinguished by the long, slender
body, and by the mouth-parts, jaws, etc., being still withdrawn
mostly within the head. The common form is Campodea, and C.
fragilis is found everywhere under stones in shaded, damp places.
It is yellowish-white, its antennae long and slender, and its body
ends in two long caudal jointed threads, about a sixth of an inch
long. It looks at first sight like a young centipede (Lithobius), and
is very agile in its movements. A much larger species ( C. Cookei),
and also differing in having longer antennas, inhabits Mammoth
Cave.

lapyx is the other genus of this family. It is rather more highly
developed than Campodea, and differs in the body ending in a pair

of stout forceps. While Campodea has a series of
little one-jointed movable appendages along the under
side of the body lapyx has none. Our North Ameri-
can species is lapyx subterraneus, which is found
under stones at the mouth of a small grotto near Mam-
moth Cave. Another species occurs in Mexico.

We now come to the bristle-tails proper (LEPIS-
WATID^E). These agile creatures are seen gliding
swiftly over the floor or walls of damp rooms or over
outhouses, or running away rapidly from under up-
lifted stones. The body is long and slender, either
flattened or cylindrical, and covered with metallic
scales. Their antenna are long and thread-like ; their
jaws and feelers (palpi) are well-developed, and in
general like those of cockroaches. The caudal stylets
or filaments are very long, and usually finely bristled.
These insects run with great swiftness, and in their
structure, especially of their body-segments and leu-,
as well as their motions, they remind us of immature
cockroaches.

In the genus Lepisma there are seven caudal
bristles, of which three are longer than the others.
The peculiar motions of these animals are due to
the nature of the legs, the tarsal joints being much as in cockroaches, broad, flat, and
almost triangular. A common species in damp, shut-up apartments is Lepisma sac-
charina. It has somewhat the habits of the cockroach, eating clothing, tapestry, the

FIG. 201. Campodea.

NATURAL HISTORY OF ARTHROPODS.

silken trimmings of furniture ; and at times will injure books by devouring the paste
of the binding, as well as by eating holes in the leaves and the binding. I have

seen old envelopes which had been riddled
with holes gnawed by these insects.

Another species locally very common is
Lepisma domestica, which I discovered liv-
ing in great abundance in a house, especi-
ally the kitchen, about the range. This is
a heat-loving species, and it may prove iden-
tical with Lepisma tliermophila of houses
in Brest, France. Our most common out-
of-door species is Lepisma quadriseriata,
which may be seen running over the walls
of outhouses.

The genus Machilis stands at the head
of the Thysanura ; its advanced standing
is seen in the rather large, full compound
eyes, and its well-developed mouth-parts.
The body ends in three bristles, but the
chief characteristics are the two-jointed
stylets, arranged in nine pairs along each
side of the abdomen, and which remind us
of the abdominal legs of myriapods. They
affect damp, though not Avet places, living

FIG. 202. lapyx solifiimis, enlarged. . . n i -i /->

in partial darkness under stones. Our com-
mon eastern species is -Machilis variabilis, but other species occur in the western
states.

A. S. PACKARD, JR.

\

FIG. 203. Lepisma saccharina, enlarged.

DERMATOPTERA.

OEDEE II. - -DERMATOPTERA.

This order comprises the earwigs, as they are called in Europe, and is a small group,
usually placed among the Orthoptera. There are, however, certain characters which
forbid our placing it with that order. The fore wings are small, short, like the
elytra of certain beetles, notably the rove beetles (StaphylinicUe) ; while the large
broad hind wings are very peculiar, and quite unlike those of the Orthoptera;
they are folded under the fore wings, or elytra, much in the manner of beetles, and
the process of folding the wings is aided by the singular forceps at the end of the
body, which is also another peculiarity of these insects. The body ils usually long,
narrow, and much flattened. It will thus be seen that these insects are composite
forms, and anticipate in a degree the beetles. On the other hand the larva resembles
lupyX) with its anal forceps, and upon the whole the Dermatoptera stand below the
Orthoptera, and indeed all the other winged insects.

But a single family (FORFICULARID^E) represents this order, and there are two
principal genera, Forficula, and a short-bodied genus called Labia. In Forjlcula the
antennae are compound, of fifteen joints, while those of Lcibia have less than twelve.

The earwigs are nocturnal in their habits, hiding in the daytime among leaves and
in flowers, and flying about at dusk. In Europe, where they are common and annoying
garden pests, they feed on the corollas of flowers and on fruit, and will eat bread and
meat. With us the earwigs are among the rarest of insects, but are more common in
the Gulf States than northward.

A. S. PACKARD, JE.

&

FIG. 204. Forjicula croceipennis.

140

NATURAL HISTORY OF ARTHROPODS.

ORDER III. - - PSEUDONEUROPTERA.

It is difficult to satisfactorily characterize by a sharp-cut definition this very elastic
order. The definition in Dr. Hagen's " Neuroptera " is as follows : " Mandibulate
insects with an incomplete metamorphosis (active pupa) ; lower lip mostly cleft ; four
membranaceous, reticulate wings (rarely with rudimentary wings or apterous) ;
antennae either subulate, and then the tarsi three- to five-articulate, or setiform, or
filiform, in which case the tarsi are two- to four-articulate." This is not very satis-
factory, as the characters given are for the most part of a superficial nature. It is
easier to separate the present order from the Neuroptera than from the Orthoptera,

FIG. 205. Diplax Berenice, female.

FiG. 20C. Diplax Berenice, male.

or grasshoppers, etc. For example, the cleft labium is to be found in Orthoptera, and
though, as a rule, the Orthoptera have five-jointed tarsi, the family of Mantidse have
four tarsal joints. The Pseudoneuroptera are closely connected with the Orthoptera>
especially the cockroaches (Blattame), by the white ants (Termitidas) which in some
important respects very closely resemble the former. Except in the characters above
given we have been unable to discover in the trunk or body itself any fundamental
characters peculiar to the Pseudoneuroptera, and which will apply to all taken together.
The parts of the head, the thorax, and the abdomen, show a great lack of uniformity
in the different groups, as does also the structure of the wings.

SUB-ORDER I. - - PLATYPTERA.

These forms may readily be separated from those of the next group of equivalent
rank by the flattened body and by the usually broad and quadrate prothorax. The

sub-order contains four families, all of which are repre-
sented in our American fauna.

The species of the family PERLID^E are called stone-
flies from the fact, we suppose, that they are so abundant,
in the pupa state, under stones in streams, while the
winged insects themselves, especially ferla, are to be
found by anglers in such situations. In England Perla
bicaiidata is called the stone-fly; a small, greenish species,
belonging to the genus Chloroperla, is called the yel-

FIG. 207. Perla paiiida. low-sally ; while a species of Nemoura is called the

willow-fly ; all these per lids are considered in England
excellent bait for trout ; in this country they are not used for bait, and have received

PSEUDONEUROPTERA.

no common names. They all have flattened bodies, and the abdomen ends in two lon-
appendages. The larvae are aquatic.

These insects frequent damp, wooded, shaded places, especially along the banks of
brooks and rivers, where they are found throughout the summer, usually resting upon
the leaves ; the smaller kinds occur the farthest from the water, being less sluo-o-ish
in their motions than the larger species, i. e., those of Perla and Pteronarcys. The
species of the latter genus are remarkable for uniformly being provided with persistent
gills, which are little tufts of short, slender filaments, a pair being situated on the
under side of each thoracic, and the first and second abdominal segments. Similar
external gills have recently been found to occur in a few other species of the family.
The males of Perla differ a good deal from the females, having very short wings. The
Perlidae in general have narrow flat bodies, with a large, square prothorax ; the antennae
are long and thread-like, and from the end of the body arise a pair of similar-jointed
appendages. A peculiarity of many of the species of this family are the soft, mem-
branous, toothless mandibles, the flies apparently taking no solid food. The wings are
peculiar, the front pair being long and narrow, while the hinder pair are twice or
three times as broad. Both pairs are net-veined, there being a good many small trans-
verse veins ; when folded they lie flat on the back, extending beyond the end of the
body. The tarsal joints are three in number.

In their transformations the changes of form from larva to imasro are rather slight.

j ^j ^3

The larvas are of much the same shape as the imagoes but with strong horny jaws.
They do not live in cases, but free under stones and sticks ; the pupae simply differ
in having wing-pads or rudimentary wings ; and they are active, like the larvas. The
larvae and pupae breathe by tufts of gills on the under side of the thorax. The females
are said to carry their little, black, shining eggs in a sac or bag attached to the end of
the body.

There is no common English name for the species of the family PSOCID^E collec-
tively, but the most familiar member of it is the little book-louse, " death-tick " or
death-watch, which is often seen running over books. The winged forms bear a strik-
ing resemblance to plant-lice or aphides, as they are of the same size, of much the
same shape, their heads, antennae
and legs being of nearly the same
proportions, while the wings also
strikingly resemble those of the
aphides in being small, folded roof-
like over the body, the hinder pair
being smaller than the fore pair
with very few veins, and even these
disposed somewhat as in those of

. FIG. 208. Psocus lineatus, enlarged.

the plant-lice. These insects are

common on shaded fences, and the leaves of trees. One species (Psocus novce-scotice)
is as large as any we have met, and abounds in New England among the leaves and
twigs of evergreen trees, especially the spruce and fir. The nature of their food is
not with certainty known, but they probably feed on lichens and dry vegetable matter
rather than small living insects. Their movements are active, and when disturbed
they will run out of sight around the tree or leaf upon which they are situated. They
appear in the winged state late in summer. The species of Coecilia are small and pale

142 NATURAL HISTORY OF ARTHROPODS.

yellowish-green. They occur everywhere in gardens, and a common species has been
observed by us to lay its eggs, from late in August until the last of October, on the
leaves of the lilac, pear, and horse-chestnut. The eggs are oblong-oval, not numerous,
and are covered by a flat, round web, like the ' cocoon ' of a spider, but only about

a line in diameter. The development of the embryo requires but
jp ^. a few days, and the process of development appears to be substan-
tially like that of other Pseudoneuroptera (Diplax and Termes).
The larvae resemble the pupae, and the latter only differ from the
adults in having wing-pads, i. e., undeveloped wings. In certain
genera the wings are almost undeveloped, as in Clothilla and
Atropos. The little book-louse or " death-watch," the name it is
known by in England, is a little dirty-white insect which is to be
FIG. 209. Clothilla seen rapidly running over dusty books, and in boxes or drawers

pulsatoria. . -i -i i i

ot insects, where it does considerable injury to specimens or books,
feeding upon the paper. In England it is said to make the ticking sound, like that
made by the death-tick beetle (Anobiuni), heard in walls of rooms, and certain popular
superstitions are connected with this insect.

The family EMBID^E embraces but a few species of insects, and those very rare,,
inhabiting tropical countries, none of them occurring in the United States. They are
small insects, forming a connecting link between the white ants and fsocus ; they
are characterized by the linear, depressed body, with the head free from the thorax,
the wings equal in size, with few veins, and with three-jointed tarsi. The larvas are found
under stones, and are protected by a cocoon which they renew at each moulting of the
skin. One of the best known species is Embia savignyi of Westwood, which inhabits
Egypt. A species of embid (Olyntha, referred to Embia by McLachlan), is stated by
Dr. Hagen to occur in Cuba. Mr. J. Wood-Mason, who has recently studied these
forms in India, is of the opinion that they are true Orthoptera.

The family TERMITID^E is perhaps the most interesting group of the order, whether
we take into account the structure, or the wonderful difference in the form and
habits of the various sets of individuals forming a colony. They are called white ants
from the general resemblance of the wingless forms to ants, and from their color, as well
as owing to the fact that they exist like ants in large numbers in mounds or " hills."
These insects had established themselves in the world long before the true ants
appeared, as their remains are found in the coal measures of Europe, while the true
ants did not appear in geological history until the tertiary period. Hence the white
ant is an old-fashioned form which has persistently held its own from the early geo-
logical ages until the present time, and this fact alone invests their history with a
peculiar interest. As it is, at the present day, white ants, though mainly tropical, are
wide-spread throughout the temperate regions of North and Soiith America, and
are sometimes extremely annoying from their great numbers and destructive habit
of eating out the interior of articles of furniture, such as chairs and tables, or the sills
of houses. For example, our common white ant (Termes flampes), while usually
running hidden galleries or mines in stumps or trunks of trees, often in a similar way
mines the roots of grape-vines, or enters the interior of timbers forming the sills of
houses, leaving but a shell. In the same way these insects in India enter houses by
subterranean passages, effect an entrance into the legs of tables and chairs, mine the

PSEUDONEUROPTERA. 143

interior completely, until but an empty shell is left, although the exterior appears
unhurt, until some unusual shock or service causes them to fall to pieces. The annoy-
ance from these insects in warm countries is increasing, and it is almost impossible to
prevent their attacks.

Regarding the mischief done in houses by an African species ( Termes arborum)
Smeathman has given full particulars. This species builds in trees, and often estab-
lishes its nests in the roofs and other parts of houses. The entry of these white ants
is difficult to guard against, since they make their approaches chiefly underground,
descending below the foundations of houses and stores at several feet below the surface,
and extending their mines into the floors, or entering at the bottoms of the posts of
Avhich the sides of the buildings are built, following the course of the fibres to the
top. " While some are employed in gutting the posts, others ascend from them, enter-
ing a rafter or some other part of the roof." Again writes Smeathman : " They
sometimes, in carrying on this business, find, I will not pretend to say how, that the
post has some weight to support, and then if it is a convenient track to the roof, oi-
ls itself a kind of wood agreeable to them, they bring their -mortar and fill all or most
of the cavities, leaving the necessary roads through it, and as fast as they take away
the wood replace the vacancy with that material ; which being worked together by
them closer and more compactly than human strength or art could ram it, when the
house is pulled to pieces, in order to examine if any of the posts are fit to be used
again, those of the softer kinds are often found reduced almost to a shell, and all, or
a greater part, transformed from wood to clay, as solid and as hard as many kinds of
freestone used for building in England. It is much the same when the Termites betti-
cosi get into a chest or trunk containing cloaths and other things ; if the weight above
is great, or they are afraid of ants or other enemies, and have time, they carry their
pipes through, and replace a great part with clay, running their galleries in various
directions. . . . These insects are not less expeditious in destroying the shelves, wain-
scoting, and other fixtures of a house, than the house itself. They are forever
piercing and boring, in all directions, and sometimes go out of the broad side of one
post into that of another joining to it ; but they prefer, and always destroy the softer
substances the first, and are particularly fond of pine and fir boards, which they exca-
vate and carry away with wonderful dispatch and astonishing cunning : for, except a
shelf has something standing upon it, as a book, or anything else which may tempt
them, they will not perforate the surface, but artfully preserve it quite whole, and eat
away all the inside, except a few fibres which barely keep the two sides connected
together, so that a piece of an inch-board which appears solid to the eye will not
weigh much more than two sheets of pasteboard of equal dimensions, after these
animals have been a little while in possession."

In St. Helena they have been known to seriously injure a collection of books. It
has also been stated that a Spanish man-of-war, recently returned from the Philippines,
was completely destroyed by a species of Termes, in the port of Ferrol.

The body of the wingless individuals are not only ant-like, but there is a general
resemblance in the winged males and females to ants, though the body is much larger
and flatter. They differ decidedly, however, from ants in the shape and structure of
the wings ; these are very large and long, straight and rather narrow, and finely veined,
while the hinder wings are not, as in ants, much smaller than the front ones, but both
pairs are of the same size, with the veins and veinlets arranged in the same manner in
both. The head is of moderate size except in the workers, where it is often of enor-

144 NATURAL HISTORY OF ARTHROPODS.

mous size, and is extended horizontally, not held vertically as in ants. The eyes are
rather small, rounded, and between them are two simple eyes or ocelli, a third nearly
obsolete one being situated in front. The antennas are slender, not very long, and
with about twenty joints, and they are not elbowed as in ants. The jaws (mandibles)
are not so long and sharp as in ants, but are shorter and stouter, more adapted for
gnawing, with fine teeth on the cutting or inner edge.

The most striking features of the white ants, and in which they differ from any
other of their order, is the fact that there are besides males and females certain wing-
less forms, called workers and soldiers. For example, if one will open a stump, or
turn over a log under which our common white ant has established a colony, he will
find besides the winged males and females that by far the larger number of wingless
individuals are not the active larvae but fully grown individuals, with heads of mod-
erate size and small jaws. These are called workers, because like the wingless worker
ants they perform all the various duties of the colony. Besides these a few wingless
individuals will be seen which have very large square heads and large, long jaws.
These are called soldiers, as they guard the nest from attack, and are bolder and more
pugnacious in disposition than the smaller workers.

All the wingless individuals are sexless, the organs of reproduction being undevel-
oped. They may be compared, therefore, to the wingless workers among ants, or to
the winged workers of bees, and should lie regarded as individuals specialized or set
apart for the performance of certain, duties, involving the preservation of the entire
colony. Indeed the winged males and females have little to do beyond providing for
the continuance of the species and the preservation of the colony, the population of
which is exceedingly large, the females being very prolific. The soldiers, as Smeath-
man long ago observed, act as " sentinels and soldiers, making their appearance when
the nest is invaded, attacking the intruders and inciting the laborers to work. The
more peaceful and laborious workers are estimated to be one hundred times more
numerous than the soldiers." They collect food, work as miners in tunnelling then-
covered ways, guard the males and females, and take care of the eggs and young.

After impregnation the females, as in the case of the ants, lose their wings. They
are then conducted into the interior of the nest by the workers. Here, in the African
species (the gravid females of our North American species have never been discovered),
the body of the female becomes enormously distended with eggs, being over two
inches in length, and it is known to lay eighty thousand eggs in the course of a day.

As has been stated, there are several kinds of individuals among the white ants, and
in this respect they resemble the true ants, wasps, and bees. In our common Termes
flavipes, besides males and females there are Avorkers and soldiers ; so also with the
west African species studied by Smeathman, who divides the colony or community
into a king, a queen, with many laborers and a number of soldiers. Smeathman
describes five species of white ants which he studied, and whose habits he records in
his famous tract, published in 1781 in the "Transactions of the Royal Society of
London," entitled " Some Account of the Termites which are found in Africa and
other hot countries." In our author's own words : " Of every species there are three
orders ; first, the working insects, which for brevity I shall generally call laborers, next
the fighting ones, or soldiers, which do no kind of labor ; and last of all, the winged
ones, or perfect insects, which are male and female, and capable of propagation. These
might very appositely be called the nobility or gentry, for they neither labor, nor toil,
nor fight, being quite incapable of either, and almost of self-defence. These only are

PSEUDONEUROPTEllA. 145

capable of being elected kings or queens; and nature has so ordered it, that they emi-
grate within a few weeks after they are elevated to this state, and either establish new
kingdoms or perish within a day or two."

Latreille also enumerates four sorts of individuals in Termes lucifugics, a tropical
form which has been introduced into France ; i. e., besides males and females, soldiers
and workers. In the South American white ants, however, this number is much
exceeded, and the differentiation of the individual is carried on, perhaps, to a much
greater extent than in any other known insects. We are indebted to Fritz Miiller,
who had more than a dozen living species at his disposition, for some curious details,
which he first published in a letter to Darwin. Miiller found that the species he
observed differed much more in their habits and in their anatomy than is generally
assumed. "In most species there are two sets of neuters, viz., laborers and soldiers;
but in some species ( Oalotermes) the laborers, and in others {Anoplotermes) the sol-
diers, are wanting. With respect to these neuters I have come to the same conclusion
as that arrived at by Mr. Bates, viz., that, differently from what we see in social
Hymenoptera, they are not modified imagoes (sterile females) but modified larvae, which
undergo no further metamorphosis. This accounts for the fact first observed by Les-
pes, that both the sexes are represented among the sterile (or so-called neuter) Termi-
tes. In some species of Calotermes the male soldiers may even externally be distin-
guished from the female ones. I have been able to confirm, in almost all our species,
the fact already observed by Mr. Smeathman a century ago, but doubted by most
subsequent writers, that in the company of the queen there lives always a king.

" The most interesting fact in the natural history of these curious insects is the
existence of two forms of sexual individuals, in some (if not in all) of the species.
Besides the winged males and females, which are produced in vast numbers, and which,
leaving the termitary in large swarms, may intercross with those produced in other
communities, there are wingless males and females which never leave the termitary
where they are born, and which replace the winged males or females whenever a
community does not find in due time a true king or queen. Once I found a king (of
a species of Eutermes) living in company with as many as thirty-one such comple-
mental females, as they may be called, instead of with a single legitimate queen."
Fritz Miiller then goes on to make the following reflection : " Termites would, no
doubt, save an extraordinary amount of labor if instead of raising annually myriads
of winged males and females, almost all of which (helpless creatures as they are) per-
ish in the time of swarming, without being able to find a new home, they raised solely
a few wingless males and females, which, free from danger, might remain in their native
termitary ; and he who does not admit the paramount importance of intercrossing
must, of course, \vonder why this latter manner of reproduction (by wingless individ-
uals) has not long since taken the place, through natural selection, of the production
of winged males and females. But the wingless individuals would of course have to
pair always with their near relatives, whilst by the swarming of the winged Termites
a chance is given to them for the intercrossing of individuals not nearly related."

We will now turn to the matter of the internal economy of the termite commu-
nity. And here it may be said, that we actually know more of the habits of African
and Brazilian species than of our own, though the latter is so common in the United
States. So far as our own observation goes, the males and females of Termes flavipes
acquire their wings and ' swarm ' in Kentucky during the first week in May, occurring
in great numbers under the bark of stumps. They swarm about three or four weeks

VOL. II. 10

146

NATURAL HISTORY OF ARTHROPODS.

later in Massachusetts. I have never seen the flight of such a swarm in the open
air, but Dr. Hagen notes an immense swarm of this species at Cambridge, Mass., on
the morning of May 19, 1878, forming a dark cloud. He adds that they were accom-
panied by fifteen different species of birds, some of which so gorged themselves with
these insects that they could not close their beaks. This swarm appeared early, as
Hagen observes that the white ant usually takes its flight in the middle of June. At
the same time or shortly before they begin to fly, many pupae may be found with the
wings in different stages of development.

The most remarkable structures formed by white ants are the famous nests or
termitaries of Termes bellicosus of the Avest coast of Africa. These, from their

FIG. 210. White ants.

, worker; /. (/, soldier, h, T. bellicosus,

e ants, a, b, Termes dims, male; c, bead; <J, e, worker; /. ;/, soldier,
worker; i, pupa, k, T. regina, female, the abdomen distended with eggs.

number and great size, appear like the villages of the natives. These white-ant hills
are said by Smeathman to be in the form of sugar-loaves, about ten or twelve feet high,
and are so solid that an ox can stand upon them. The exterior is one large, dome-like
shell, which is much stronger than the inside or habitable part ; the latter is divided
into a great number of apartments surrounding the royal chamber for the king and
queen ; these apartments serve as abodes for the young, as well as magazines, which
Smeathman " always found well filled with stores and provisions."

In the accompanying figure, a and b represent the male, c the head, d and e the
worker, f and g the soldier of Termes dirus ; h the worker, i the pupa of T. bellicosus;
and k the female of T. regina with her abdomen distended with eggs. Winged
females of T. bellicosus are found flying about at the beginning of the rainy season.
After being on the wing for a few hours they descend to the ground, certain of them

PSEUDONEUROPTERA. 147

being elected by the workers kings and queens of new colonies ; those not thus selected
soon perish. The workers immediately enclose the king and queen in a small chamber
of clay suitable to their size, into which at first they leave but one small entrance,
large enough for themselves and the soldiers to go in and out, but too small for the
exit of the royal pair.

It is not until this time that the marriage of the royal pair takes place. The queen
then lays her eggs, at the rate of sixty a minute, which would amount to eighty
thousand in a day. The eggs are taken up by the workers as soon as they are laid
and placed by them in a small nursery which they in the meantime have constructed
at places four or five feet in a straight line from the royal chamber. Here the young
are carefully attended and fed until they are able to shift for themselves, and take their
turn in working for the interests of the community.

Of the faithful services rendered by the workers to the queen, Smeathman bears
witness, saying, "These faithful subjects never abandon their charge even in the last
distress ; for whenever I took out the royal chamber, and, as I often did, preserved it
for some time in a large glass bowl, all the attendants continued running in one direc-
tion around the king and queen with the utmost solicitude, some of them stopping in
every circuit at the head of the latter as if to give her something. When they came
to the extremity of the abdomen they took the eggs from her and carried them away,
and piled them carefully together in some part of the chamber, or in the bowl under
or behind any pieces of broken clay which lay most convenient for the purpose."

It appears, from the observations of Mr. H. J. Hubbard on the white ants of
Jamaica, that the young are fed upon prepared food which is stored up in the form
of very hard and tough rounded masses, evidently composed of comminuted wood,
some nests containing many pounds weight of them. Besides these lumps, adds Dr.
Hagen, there is prepared for the young white ants another kind of food, probably
partaken of by the youngest larvae. Among the eggs occurred a large number of very
small, hard, round bodies, which were recognized by Professor Farlow as the sclerotium
of a fungus.

SUB-OKDER II. ODONATA.

The sub-order Odonata and the family LIBELLULID^B are co-extensive. The group
comprises the dragon-flies, of which the larger kinds are called devil's darning needles,
and sometimes mosquito hawks.
Looking at the dragon-flies in the
winged or imago state we observe
some notable differences which we
have not met with in our ascent
from the Perlidae. In the first
place the large, spherical thorax has
some remarkable features. The pro-
thorax is very small and collar-like,
while the pieces which in the Platyp-
tera form broad, flat areas, are in the
dragon-flies minute, and the upper

part of the thorax is in reality formed FlG 2n> _ LibMula maculata> dragon . fly .

of the side pieces which are enor-
mously developed. The dragon-flies literally live on the wing ; they never walk, and

148

NATURAL HISTORY OF ARTHROPODS.

thus the muscles of flight, which are attached to the side-pieces, have a great develop-
ment ; so much so as to give a unique appearance to these creatures.

Moreover the head of dragon-flies is remarkable for the enormous size of the eyes,
which in many of them not only completely encircle, but form a large proportion
of the head, so that the head appears " all eyes." The mouth-parts, jaws, etc., are
constructed much like those of grasshoppers, but the under lip differs in its strangely
modified palpi or feelers, which are broad and saucer-like so as to cover the lower part
of the face. Add to these characteristics the long slender abdomen, which balances
the body during its rapid, headlong flight, and we have an insect with a decided outre
appearance. None of its contours can be said to be lines of beauty, and the dragon-fly
is upon the whole one of the most repulsive of insects, though gaily colored, and
decorated with the brightest of trappings and spots. In the popular estimation dragon-

in lie

a vn vi v
213.

I c

212.

vi vir

II IV VI
III V VII

e I n HI iv n a
214.

215.

FIGS. 212-215. Development of a dragon-fly; I, antennae. II, mandibles. Ill, maxillae. IV, labium.
V-VII, legs, a, abdomen, c, clypeus. e, eye. i, intestine, n, nerve, t, trachea.

flies hold an unenviable position ; but worse qualities are ascribed to them than they
really possess. They do a, great deal of good in devouring mosquitoes, and other
noxious flies and insects, as they are continually hawking about after gnats, etc.

The transformations of the dragon-flies have always attracted interest. They are
' incomplete,' i. e., the larva and pupae are active, creeping about over the bottom of
pools among aquatic plants, and feeding upon other aquatic larvae.

We will now consider the singular mode of egg-laying practised by these insects,
and we will tirst quote Mr. Uhler's account. In laying her eggs the Libellula "alights
upon water-plants and, pushing the end of her ovipositor below the surface of the
water, glues a bunch of eggs to the submerged stem or leaf. Libellula auripennis
I have often seen laying eggs, and I think I was not deceived in my observation that
she dropped a bunch of eggs into the open ditch while balancing herself just a little
way above the surface of the water. I have also seen her settled upon the reeds in

PSE UDONE UR OP TEH A .

149

'too 1 -

brackish water, with her abdomen submerged in part, and there attaching a cluster of
eggs. I feel pretty sure that L. auripennis does not always deposit the whole of her
eggs at one time, as I have seen her attach a cluster of not more than a dozen small
yellow eggs. There must be more than one hundred eggs in one of the large bunches.
I have observed females of Perithemis domitia on a sunny day late in July hoverin<>-
over the surface of a pond, dipping the abdomen (the body being in a perpendicular
attitude with the wings in rapid motion) lightly into the water, which just covered a
piece of floating cow-dung, and then fly off to return again and repeat the operation.
Several dragon-flies were coursing over the small pond, and we are inclined to think
that two or more dragon-flies pushed their eggs into this same mass of ordure. The
dipping motion was the work of an instant ; whether one alone or a packet of eggs
were deposited at a single dip of the hind-body I could not say, but from the arrange-
ment of the eggs they were probably deposited singly." The eggs of a smaller and
more common dragon-fly (Diplax) were found
by Professor Hyatt early in July (the 2d) at-
tached to the leaves of a submerged sedge.
They were dispersed through a long ropy gela-
tinous mass, about a quarter of an inch thick,
which twined about the leaves of the grass.
These eggs must have been laid for a week
or more, as on the 16th of July large numbers
had already hatched. They continued to hatch
while in glass jars till the first week of Septem-
ber, those eggs situated in the middle of the
gelatinous mass seeming to hatch last ; in this
way a succession of young dragon-flies were
disclosed through the summer. The eggs are
oval-cylindrical. The egg-laying habits of the
small Agrions and their allies are most singular.
These creatures of the air and sunlight, when
impelled to deposit their eggs, deliberately
enter the water, walk down some submerged
stem, and with their ovipositor cut gashes in
the stalk into which they push their eggs.

The larva? of most dragon-flies are rather
stout-bodied, sometimes broad and flat, espe-
cially the hind-body, and are very active in
their habits, constantly foraging after food,
creeping about over the bottom, or making
their way through thickets of submerged
aquatic plants. They can also propel themselves forwards for
inches by a curious method. The end of the intestine
wards of the water, which fills up the dilated rectum ; the walls of the rectum are
provided with many small air-tubes, by which the air is extracted from the water
and distributed throughout the body. After all the air is extracted from the water
the walls of the passage violently contract and force the water out in a powerful
stream as if from a syringe, and thus the insect is sent headlong through the water.
In the larva; of the smaller genera of the family, such as Agrion, etc., respiration

FIG. 216. Larva of dragon-fly, just hatched.
d, heart, n, nervous cord, t, trachea.

a distance of several
opens for the passage in-

150

NATURAL HISTORY OF ARTHROPODS.

is external, the larvae breathing by three leaf-like gills containing finely-branching air-
tubes.

The most striking peculiarity of the larval dragon-fly is the nature of the labium or
under lip. This is greatly enlarged and bent, so that at rest it forms a broad, smooth
mask covering the jaws. When any small insect approaches, the array of jaws and
accessory jaws is unmasked, the under lip being darted out after the prey. The under

FIG. 217. Metamorphoses of dragon-flies. 1, larva, and 2, larval skill of JSischna; 3, larva, 4, moulting, and

5, adult of Libellula depressa.

lip thus serves as a mask, and also as a grappling-iron to seize the victim, as it is armed
at the extremity with a pair of hooks, by whicli the struggling insect is firmly held
and irresistibly drawn to the mouth, where it is torn to fragments by the sharp
jaws. This structure is well shown in the adjacent figure.

The pupal dragon-fly differs from the larva only in possessing the rudiments of

wings, which are like long, slender pads on the back. " When
the insect is about to assume the pupa state, the body, having
outgrown the larva skin, by a strong muscular effort opens a
rent along the back of the thorax, and the insect, having fas-
tened its claws into some object at the bottom of the pool, the
pupa gradually works its way out of the larva skin. It is now
considerably larger than before. Immediately after this tedious
operation its body is soft, but the crust soon hardens. This
change, with most species, probably occurs early in summer."

"When about to change into the adult fly. the pupa climbs
up some plant near the suiiace of the water. Again its back
yawns wide open, and from the rent our dragon-fly slowly
emerges. For one hour or more it remains torpid and list-
less, with its flabby, soft wings remaining motionless. The
fluids leave the surface, the crust hardens and dries, rich and
varied tints appear, and the dragon-fly rises into its new world
of light and sunshine." (Guide to the Study of Insects.)

The Odonata are divided into three groups ; the lowest, called Agrionina, and
represented by the genus Agrion, comprises small, slender-bodied, delicate forms,

FIG. 218. Pupa of
sEschna.

PSE UD ONE UR OP TERA .

151

beautifully marked with metallic green, or blue, while their larvae have external, leaf-
like gills. In ^sEschna and its allies the two pairs of wings are unequal, the abdomen
is cylindrical, and the species of large size, ^hile in the Lilelhdina the abdomen is
often flattened ; most of the dragon-flies belong to this latter group.

220.

219. 221.

FIG. 219. Libellula quadrimaculata. FIG. 220. Nannophysa bella. FIG. 221. Agrion saucium, dragon-flies.

The sexes often, as in Agrion and Libellula^ differ greatly in color, the males being
bright-colored, while the females are dusky and of one color. Moreover dimorphic
forms occur among dragon-flies, there being two sets of females, differing in the vena-
tion of the wings, one set resembling the males.

SuB-OiiDER III. EPHEMERINA.

The May-flies, forming the family EPHEMERID.E, differ so much from other Pseudo-
neuroptera that they may properly be referred to a distinct sub-order (Ephemerina).
These insects are called may-flies because many of them appear upon the wing in the
month of May, or early in summer. The name Ephemera is given in allusion to their
shortness of life, many of them living in the adult stage only a few hours, or no more
than a day, hence they are sometimes called
day-flies. They are among the most deli-
cate and fragile of insects, and their motions
during flight are exceedingly graceful.
West wood speaks of their elegant flight in
swarms (composed, as in the gnats, almost
entirely of male insects), in fine afternoons,
over or near water, alternately rising and
falling, and he states that in this opera-
tion the upward flight is produced by the
repeated action of the wings ; but that in
descending, the wings are widely extended,

as well as the tails, or caudal filaments. FIG. 222. - Lachlania abnormis, enlarged.

The head is small and rounded, the thorax

is spherical, the pro thorax being small and collar-like, while the abdomen is long and

slender, ending in two or three long, slender filaments. The wings are densely net-

152 NATURAL HISTORY OF ARTHROPODS.

veined, and the hinder pair are much smaller than the fore ; and in certain forms, as
the species of Cloeon and Ccenis, the hinder pair are entirely wanting. Returning to
the structure of the head : while the eyes are very large in the males, meeting, as in
the dragon-flies, on top of the head, the antennae are also minute, slender, and awl-
shaped. The singular condition of development of the mouth-parts indicates that
these insects take no food during their ephemeral existence out of the water. The
mouth-parts are in an unusually rudimentary condition. We have been unable, in
a common Ephemera, to find any traces of mandibles, while the maxillae are very rudi-
mentary, the palpi being entirely wanting.

The Ephemera, weak as it is individually, maintains itself in the world by means
of its prolificacy. Brooks and ponds are richly populated with their young, and through
the summer, when they come to maturity and take their flight, these delicate beings
appear in immense numbers. They rise from the waters of our great inland lakes,
fall a rapid prey to the waves, and are washed ashore, in enormous quantities, their
dead bodies forming windrows, comparable in extent with the sea-wrack of oceanic
shores. They settle down in dusky dun-colored clouds in the streets of the lake cities,
obscuring the street-lamps, and astonishing the passer-by. We may feel some aston-
ishment at the hosts of these winged Ephemeras when we bear in mind their useful-
ness in the larva state as food for other insects, Crustacea, and fish. Westwood states
that the swarms of one species, with white wings, has been compared to a fall of snow,
" whilst in some parts of Europe, where they abound, it is the custom to collect their
dead bodies into heaps, and use them for manure. The fishes, at such time, eagerly
wait for them ; and so great are the numbei'S which fall into the water, that the fisher-
men call them manna." They are well known to the angler as excellent bait for trout,
and they are a favorite food of the smaller dragon-flies.

The may-flies pair while flying over the surface of the water, and the female drops
in the water her minute eggs, which are deposited in two long, cylindrical, yellow
masses. The species of Baetis creep down into the water and deposit their eggs in
rounded patches on the underside of stones. ' The larvae may be known by their long,
flat, slender bodies, provided with gills, arranged in pairs along the
sides, or upon the back, of the body. These so-called gills are some-
times leaf-like, either simple or with the edges often fringed with fila-
ments, or they are long, narrow pads or lobes, also fringed. In some
remarkable cases, as in the singular genus Jtcetisca, the gills are
covered by broad plate-like expansions of the thorax. In its larval
and pupal condition the entire thorax above forms one piece, like
the carapace of a shrimp, instead of being divided into three seg-
ments. This shield-like plate extends over one half of the abdomen,
in the form of a large shield, giving the insect, as Walsh says, "a
very crustacean appearance." While in most Ephemera larvae the
FlG> 2 Jo><Isra Upa f am ple gills are used in swimming, as well as for breathing, in JBcetisca
they are covered over by the shield, and are of no use in locomotion.
A similar larva is that of Prosopistoma, which has long been known, but whose life-
history has only recently been discovered. Here, as in Jlcetisca, the entire thorax and
the basal half of the abdomen is covered with a large shield, which conceals the broad
gill-sheets.

The Ephemeras, both in their larval and pupal states, are sometimes cai'nivorous,
preying upon other insects, and their jaws are well developed, sometimes remarkably

A swarm of Ephemerce, May-flies.

PSEUDONEUROPTERA. 153

so, as in Ephemera, Palinyenia, and Leptophlebia, one of the teeth extending in a
long, sharp point beyond the head ; most of them, however, feed on mud or minute
aquatic plants. The habits of the larval Ephemera? vary somewhat. Some prefer
running streams, others inhabit quiet basins or sluggish streams; in these situ-
ations they reside in burrows in the mud, under stones, or among grass and weeds,
where they may be taken with the water-net in great abundance, and are beautiful
objects for the aquarium. It is generally agreed by authors, that in their preparatory
state they live for two or three years, though we doubt if most species live longer than
nine or ten months, hatching in summer and acquiring their wings the following
spring, before acquiring wings, so that the whole life of some Ephemeras may be
much longer than that of most insects.

The number of moults, or changes of skin, is unusually great in these insects. The
larva of Heptagenia has been found by Vayssiere to shed its skin eight times before
leaving the water, i. e. there are nine stages of immaturity. The extreme in the num-
ber of stages is seen in Cloeon, which has been found by Lubbock to moult its skin
twenty-one times before assuming the imago state, or twenty times before it leaves the
water.

Shortly after the winged insect casts its pupa-skin, it throws off a thin skin, or pel-
licle ; the insect, in this stage, is called the sub-imago, or pseudimago. The best
description of the process has been given by Westwood. When in the pupal stage
they crawl to the surface, where they cast off their pupa skin, appearing, at first sight,
to be fully developed, with the wings extended to their full size. " They then make
their way, flying with difficulty, to the shore, where they affix themselves to the trunks
of trees, stems of rushes, walls, or even persons standing upon the bank, when they
again cast off a very delicate pellicle, in which they had been entirely encased, and
which remains, unchanged in form, attached to the objects on which they had stationed
themselves. The skin, however, in which the wings had been enclosed, shrivels and
curls up into a mass, hanging down at the sides of the thorax. After this process, the
wings, disengaged from the outer covering, assume a brighter appearance, and the tails
grow to twice their previous length."

Westwood invariably found that the casting off of this pellicle takes place during
the night. In some European species the operation of shedding the thin skin takes
place immediately after flight, and is so quickly performed that the whole operation is
over in three minutes, and the insect takes wing immediately after. Westwood adds,
that he has observed, in one instance at least, that the insect remained in the sub-imago
state upwards of twenty-four hours.

We will now glance at the principal generic forms of these
interesting insects. In Ephemera there are three long caudal
filaments, of equal length. One of our commonest species, in
the northeastern States, is Ephemera (Leptophlebia^) cupida.
The largest species of the family belong to the genus Palin-
yenia, in which the middle caudal filament is shorter than the
others, or sometimes absent. It is common in our northern
lakes and streams late in the summer.

The genus Eaetis has but two caudal threads: near this FIG. 224. - Potamanthus

margmaius.

comes the curious jBaetisca, already referred to ; then comes

Potamanthus, which again has three caudal filaments. Fig. 224 represents P. mar-

ginatus, which we have often captured in Labrador in July. It is also found in

154 NATURAL HISTORY OF ARTHROPODS.

northern Europe, especially Lapland. In Cloe there are sometimes but two wings,
the hinder pair wanting ; while the species of Coenis never have any hind wings.
The most abnormal ephemerid is Oligoneuria, in which the wing-veins are very few,
and far apart, and the legs are imperfectly developed, and there are three caudal
threads. Allied to this is a Cuban form, Lachlania abnormis, in which there are
but two caudal threads.

A. S. PACKARD, JR.

FIG. 225. Psocus.

NEUROPTERA.

155

ORDER IV.--NEUROPTERA.

The genuine Neuroptera are those net-veined insects which have a complete meta-
morphosis. The larvae are entirely unlike the adults, as they are long and slender,
with more or less cylindrical bodies, some, as the caddis worms and larval forceps flies
(Panorpci), being much like caterpillars. The pupae are never active, and are in many
cases protected by a cocoon. A neuropterous pupa is a good deal like the chrysalis
of a moth, differing, however, besides other characteristics, in the wings and limbs
being free and movable, not soldered to the body.

The adult Neuroptera are only net-veined in the Sialids and gauze-winged flies
(Hemerobidae), and the cross veins are much less numerous than in the false Neuroptera.
There is one feature in which the Neuroptera almost invariably differ from the Pseudo-
neuroptera, and this is in the nature of the extremity of the under lip (ligula), which

FIG. 226. Cofydalus cornutus, horned corydalus, female.

is not cleft at the tip, but is broad and flat. Moreover, the prothorax is often small
and collar-like, though large and square in the two lower families. In the higher
groups of caddis flies and forceps flies the thorax is more or less rounded, spherical,
like that of moths, and the fore wings are in the caddis flies rather smaller than the

* o

hinder pair.

The family SIALID^E (the members of which are thick and stout, with a large, square
prothorax and net-veined wings, and usually aquatic larva?) is represented by one of
the largest and most singular insects in this country ; nothing of the sort existing in
the Old World. It is the Corydalus cornutus of Linnaeus. Though exceedingly for-
midable and alarming in appearance, it is in reality entirely harmless. Moreover, it
flies mostly by night, though we have known one case of its flying in the day-time and
alighting on a person's clothes. It is fully two inches in length, while the wings expand
a little over six inches, the two pairs being of nearly the same size. An interesting
peculiarity of this insect is the remarkable size of the jaws in the male ; in the female
the jaws are very large, flat, and toothed at the extremity, but in the male they are
remarkably long and slender, cylindrical, not toothed, the sharp tips crossing each
other. Their only use is evidently for seizing the soft, somewhat yielding body of the

156 NATURAL HISTORY OF ARTHROPODS.

female during the act of pairing; hence, during its short life, the male, at least, proba-
bly takes no food.

After pairing, which occurs in the middle of summer, the female deposits her eggs,
to the number of about three thousand, in flat, rounded masses, on trees overhanging
water, etc. On breaking forth from the egg the young larva readily finds its Avay into
the water, and descends to the bottom. It undergoes six moults before pupal life.

The fully grown larva is as large an insect as is to be found in our streams, and it
is a very singular creature. It crawls actively about, seeking smaller aquatic worms
and larval insects, which it snaps up and tears to pieces with its large toothed jaws.
It can breathe both out of and in the water, since besides a series of spiracles on each
side of the body it possesses eight pairs of bushy breathing appendages, or gills, with
a long supplementary filament, which it ordinarily uses while in the water. The spi-
racles come in play late in larval life, as it lives several weeks out of water before
seeking its cell, within which to transform into a pupa.

The following account of its metamorphosis is copied from the " American Ento-
mologist."

After it first leaves the water, the larva crawls rapidly about, in the night-time, to
find a suitable place for its pupal transformation, usually selecting for this purpose the
under surface of a flat board or log, or burrowing under some large

O 7 O O

stone. In pursuit of this object they sometimes wander almost a
hundred feet from the water's edge, and we have known them to
crawl up the walls, and on to the roof of a low, one-story frame
building, and then tumble accidentally down the chimney, to the
great dismay of the good w r oman of the house. At this period of
their existence they are much sought after as fish-bait, having a
very tough integument, so that one larva suffices to catch several
fish ; and they are called by fishermen " crawlers," " dobsons," and
sometimes, we hope rarely, " hellgrammites." They can pinch pretty
sharply with their strong jaws, though not sufficiently hard to draw
blood ; and they also use the processes at their tails as prehensile
organs to aid them in climbing.

"After it has selected a suitable hiding place, the larva forms
FlG ' 2 l 7 siaiid arva f a ru( ^ e ce ^ m tne earth, within which it transforms into an inactive
pupa, with no mouth to receive food, and no anus to discharge fasces.
It usually leaves the water about the beginning of June, and by the end of that month,
or the fore part of July, the winged fly bursts from the shell of the pupa."

A smaller form, though still a large insect and an interesting one, is the Chauliocles ;
it chiefly differs from the foregoing genus in its beautifully pectinated, or feathei-ed
feelers, and its more delicate wings. Such is Chauliodis pectinicornis, our commonest
species. The larva of another species ( C. nastricornis) is like the hellgrammite, but
considerably smaller, and with no caudal filaments; while the last pair of spiracles
is on the tips of a pair of contractile filaments.

The genus Sialis, which gives its name to the family, comprises a few small spe-
cies, which inhabit the Old and New Worlds, while the singular genus Raphldia, so
far from being aquatic, lives under the bark of trees, where it pursues small insects ;
the species in this country are confined to the Pacific States.

The lace-winged flies, which form the family HEMEEOBID^:, are characterized by a
slender body, a small, square prothorax, and net-veined wings, while the lame, which

NEUROPTERA. 157

are terrestrial, feed on plant lice. Very useful and entertaining in their habits are the
lace-winged Hies, whose larvae are called " aphis-lions," and " ant-lions." The common-
est example is the delicate green, golden-eyed, lace-winged fly, so common everywhere,
and so offensive in its odor when handled. These delicate, graceful, gauzy-winged
gems have as their sole protection an abominable odor, which they leave upon the fin-
gers when rudely handled, and it is doubtless their bad taste which prevents their being
snapped up by birds ; for one may notice how extremely exposed to the attacks of
birds are these insects. The lace-winged flies, when young, do the greatest service to
gardeners, from their exemplary habit of devouring plant-lice, or Aphides. The larvae
of different species of Hemerobius, which are common among evergreen and other
trees, after piercing with their long, sickle-like jaws the bodies of the Aphides, make
a thick, loose mantle of the dried skins of their victims.

It is well known that the Aphides congregate in great numbers on the stems or
leaves of plants ; among them the common golden-eyed, lace-winged fly ( Chrysopa
ocidata) lays its eggs. We have observed that the female Chrysopa lays between
forty and fifty eggs, which are placed upon long,
slender stalks, so as to be out of the reach of wander-
ing, predaceous mites, and other egg-eating insects.
One Chrysopa. which was observed in confinement,

,.,,.. A . tfiG. 228. - Chri/sopa and eggs.

laid forty-six eggs; another, whose reproductive

powers were evidently impaired, laid eighteen stalks, upon only nine of which were
well-developed eggs, the remaining nine being barren stalks, some only half the usual
height, while others were provided with the knob, formed of cement, at the end, on
which the egg is ordinarily fastened. It is evident that the fly, in depositing an egg,
first attaches the stalk to the surface of the leaf, and afterwards forces the egg from
her oviduct and attaches it by the mass of cement to the end of the stalk, as in one
case an egg was glued to the end of the stalk very much out of centre, the insect's
ovipositor not having aimed straight, so to speak, at the mass of cement. The eggs
are at first of a pale, delicate green, turning grayish just before the embryo hatches.

The eggs are laid throughout the summer, so that there is a constant supply of
aphis-lions, and the time of embryonic growth is limited, as the young appear in six
or seven days from the time the eggs are laid. When the larva is ready to turn to a
chrysalis it spins a round cocoon of silk, and two weeks later the winged fly appears.

The species of Hemerobius have essentially the same habits as those of Chrysopa,
but they are smaller, obscurely colored, and less frequently met with, occurring in
forests.

Another notable form is Mantispa, so-called from its mimicry of the praying
insect, or Mantis. The neck or prothorax is remarkably long, but most remarkable are
its fore-legs, which are very large, and bent, like those of Mantis, in the attitude of
prayer ; but in reality they are admirably adapted for seizing, and retaining in their
grasp, other insects.

The metamorphosis of Mantispa is of unusual interest, inasmuch as the larva passes
through two stages, with quite different habits in each, before spinning its cocoon and
assuming the pupa state. Thus far we are acquainted only with the life-history of an
European species, Mantispa styriaca, which has been worked out by Brauer, an
Austrian entomologist of distinction. The rose-red eggs are laid in great numbers, in
July, and, like those of Chrysopa, are laid on long, slender stalks. The larva hatches
in twenty-one days, and spends the winter without taking food. In the succeeding

158

NATURAL HISTORY OF ARTHROPODS.

FIG. 229. Mantispa interrupta ;
the wings not shown iu the
lower, side view.

April the minute larva of the first stage finds its way into the egg-sacs of spiders be-
longing to the genera Lycosa and Dolomedes, biting a curved slit, through which it
enters into the sack. By the middle of May the larva is still in the first stage, but

surrounded by dead spiders, showing that it is carnivorous,
and diets on young spiders. Before the first moult it some-
what resembles a Campodea, but after casting its skin it
is maggot-like in appearance, with rudimentary limbs, its
motions being like those of a larval bee ; the short, stumpy
legs not capable of use. The head is remarkably small, and
retracted iinder a fold of the thick second segment, and is
transversely oval with an eye-speck on each side, each com-
posed of six simple eyes. The jaws (mandibles and maxilla?
united) extend straight out, ending in a fine point. On the
side are the pointed antennae, which extend beyond the
jaws ; the legs are short, thick, obscurely 3-jointed, and situated far apart on the sides.
As in the first stage, the larva lies coiled up among the egg-shells and carcasses of the
spiders, winding and turning helplessly along. It reaches a length of 7-10 mm.
The insect pupates as in Chrysopa and Myrmeleon, the larva first spinning a
roundish or oval cocoon within the egg-sack of the spider, where it remains about
fourteen days before moulting, the pupa maturing under the larval skin. Pupation
occurs in the middle of June, and four weeks after the w T inged insect appears.

In the metamorphosis of Mantispa there is thus a hypermetamorphosis, i. e., two
larval stages. The first stage is Campodectr-formed, and the second is caterpillar-shaped.
The transformations of Mantispa appear to give us the key to the mode in which a
metamorphosis in the insects was brought about. The larva, born a Campodea-likc
form, active, with large, long, four-jointed feet, living a sedentary life in the egg-sac
of a spider, before the first moult loses the use of
its feet, while the antennae are partly aborted. The
fully grown larva is round-bodied, with small, cater-
pillar-like feet, and a small, round head. Its external
appendages retrograding and retarded, acceleration
of growth goes on within, and thus the pupal form
is perfected while the larva is full-fed and quiescent ;
hence, as a result the pupal stage became a quiescent
one, and by inheritance it gradually became a per-
manent habit characteristic of Neuroptera, all of
which have a complete metamorphosis. This com-
plete metamorphosis has probably been inherited by all the orders of metabolic insects,
which possibly originated from Neuroptera-like forms, and the imago represents a
highly accelerated stage.

The Ant-lion has always attracted much general interest, from its singular form and
peculiar habits. It is the larva of Myrmeleon, and our best known species is Myr-
meleon immaculatus. Its habits have been described, as follows, by Mr. Emerton.

The larva digs a pit-fall, about two inches in diameter and one in depth. In digging
its lair the creature begins by making a complete circle, and afterwards throws out the
sand from the centre. "In digging it uses its flat head and jaws, which are pushed
under several grains of sand and then jerked upwards, throwing their load sometimes
as far as six inches, and always far enough to avoid leaving a ridge around the pitfall.

FlG. 230. Second larva of Mantispa.

NEUROPTEliA.

159

When the pit is finished, it lies entirely concealed except the jaws, which are spread
apart horizontally at the bottom. The sloping surface of the pit being as steep as the
sand can be piled up, is very easily disturbed, and when an insect ventures over the

FIG. 233. Section of pit of ant-lion.

FIGS. 231 and 232. Myrmeleon immaculatus, and M. obsoletus, adult of ant-lions.

edge the ant-lion is apprized of it by the falling sand. It immediately begins to throw
up sand from the bottom, deepening the pit, and so causing the sand to slip down from
the sides, and the insect with it. The ant-lion then seizes it with its long jaws, and
holds it above its head until the blood is all sucked out, when the bloodless carcass of
its victim is cast out of its hole. It then repairs the break in the wall of its pit."
Regarding its habits in confinement, Mr. Emer-

^j tj *

ton gives us the following account :

" After eating he became more timid, and some-
times would not take a second insect. If, however,
several were put into the pit at once, he would bite
one after the other until all were killed, before de-
ciding on which to begin. I fed him two or three
times a week, usually with house-flies, cutting their
wings off and letting him take them in his own
way. In October, having occasion to travel some

distance, I put him in an ounce bottle half filled with sand, corked him up, and carried
him with me in my bag. In about a week I gave him a large house-fly, which he did not
catch, not having room enough to make a pitfall. I gave him no more food till the next
March. . . . About the first of March, when flies began to be plenty, I commenced to feed
him again. He found it rather awkward to catch insects in the bottle, as there was

O '

not room enough to make a pitfall, and his inability to move forward made it hard for
him to seize an insect, unless he met it directly between his jaws. He soon, however,
made pitfalls half an inch in diameter, which answered the purpose. Sometimes he
lay on the surface of the sand, with a few grains scattered over his back to conceal
him from notice, and his jaws extended on the surface. If a fly was put into the bot-
tle it would circle around it, close to the glass, and usually run over the ant-lion's back.
He would jerk up his head, and attempt to seize it, which he seldom succeeded in
doing the first time. If he caught a leg or wing he was unable to move nearer, and
shorten his hold, and the fly escaped. He would often throw up the sand and try to
undermine the fly. He would sometimes work an hour in these ways before the fly
would get into a favorable position. I fed him every day or tw r o until May 15th, when
he spun a spherical cocoon around him, and remained enclosed until June 25th, a very
hot day, when he came partly out, and leaving his pupa skin half in the cocoon
appeared as a perfect fly, but did not spread his wings completely."

160

NATURAL HISTORY OF ARTHROPODS.

While the ant-lion's pit found by Mr. Emerton was a solitai-y one, no others being
found, Mr. Birge records his discovery of a large colony of ant-lions in a sheltered,
sandy place, under a cliff, in Albany County, New York. In August, 1871, the colony
numbered rather more than six hundred individuals, but on July 6, 1872, there were
scarcely half that number. Another colony, at a different locality, but in the same
county, observed in 1871, consisted of some three hundred members. Mr. Birge
remarked that the ant-lion did not, so far as his observation went, " throw up sand to
bring down its prey, but throws it up in every direction in order to keep its jaws free

:_ -

FIG. 234. Nemoptent coa ami Ascalaphus Jongicarnis.

to seize the insect when it reaches the bottom of the den." Further on he says, in the
most crowded portions of the colony " the chief employment of the insects was to throw
out the dirt which their active neighbors were depositing on their own premises."

In JVemoptera coa, a species from the Mediterranean region of Europe, the fore-
wings are very broad, while the hinder ones are greatly elongate, so that they suggest
a pair of oars.

The last type of this family is Ascalaphus, which superficially bears a resemblance
to a butterfly, since the long, slender antenna? end in a conspicuous knob. The head
is large and hairy, with large, round eyes, the large wings are often highly tinted with
yellow and black spots and bands, while the abdomen is short and thick, like that of

NEUROPTERA.

butterflies. In repose the wings are held down on each side, while the abdomen is
erect, or nearly so.

Nothing is known of the habits of our American species, which are of very rare
occurrence, and of rather dull tints, compared with those of southern Europe, about
the shores of the Mediterranean. Even in Europe little is known of the habits, but
from what is recorded it appears probable that its transformations are like those of the
ant-lion, to which it bears a strong resemblance, though the hind body, or abdomen, is
flattened, and much wider, and it is a much larger insect. WestAvood tells us that the
eggs, when laid, are hedged around by little pales, like a fence, and are so placed that
nothing can approach the brood; nor can the young ramble abroad till they have
acquired strength to resist the ants and other insect enemies. On the other hand,
Roller observed the eggs of Ascalaphus macaronius deposited on a stem of grass.

Our third family of true Neuroptera is the PANORPID^E. These forms have a
slender body, the head with a long beak, the prothorax small, and like a collar ; the
wings are but slightly net-veined, and the abdomen of the male ends in a forceps.
The larvaa are terrestrial, and resemble caterpillars in general appearance. The type
of this family is a four-winged fly, not uncommonly seen in damp places in summer,
which has a slender body, while the head is remarkably prolonged into a beak, at the
end of which are the mouth-parts. The antennas are filiform, and shorter than the
wings, the latter being weak, long, and narrow, with a few cross veins, and more or
less spotted. The prothorax is collar-like, and the thorax is rather deep, and somewhat
rounded. The species of Panorpa are called scorpion-flies, from the large forceps-like
apparatus at the end of the abdomen of the males, which resembles the tail, or sting
of a scorpion.

These weak, defenceless flies are probably saved from extinction by birds, and
other enemies, by emitting a disagreeable odor. For example ; when disturbed, the
European species (Panorpa germanica^ or P. communis)
dart out a long, slender tube towards the disturbing object.
Through this tube a little drop of malodorous, whitish fluid
is forced, which is undoubtedly repugnant to its enemies.
Our common species are Panorpa rufescens and P. debilis.

Nothing is known of the habits of our species, and we
are obliged to recur to the admirable account of Dr. Brauer,

FIG. 235. Panorpa rufescens.

of Vienna, concerning the European Panorpa communis.

Four days after pairing the female lays a few eggs in a mass, situated in a shallow
hole, which she bores with her long abdomen in damp earth. In a few days afterwards
both males and females die.

The male is polygamous. The eggs are rather large for so small an insect, and are
about half a line in length ; at first white, and afterwards dark brown. The larva
hatches in eight days from the time the eggs are deposited. They are at first one and
a half lines long, and grow very rapidly, becoming fully grown in thirty days, then
being seven lines in length. The body is thick, fleshy, cylindrical, much like a cater-
pillar ; the segments are full and convex, and beset with brown, horny warts, bearing
short bristles. On the last three segments are cylindrical tubercles, bearing long bris-
tles. But the point of most interest, and that which causes them to resemble cater-
pillars, is that besides the three pairs of jointed, horny feet there are eight pairs of
fleshy, ventral, or abdominal feet, which correspond to the abdominal, or prop-legs of
lepidopterous larvas, though no caterpillar is known to possess more than five pairs of

VOL. II. 11

162 NATURAL HISTORY OF ARTHROPODS.

such legs. It should be observed, however, that the abdominal legs in the larval
Panorpa are quite small and rudimentary.

Moreover, as in caterpillars, there is a large pair of spiracles on the prothoracic
segment, but none on the second or third segments ; while the fourth to eleventh, be-
hind the head, each have a pair of spiracles. This arrangement of the spiracles, or
breathing pores, is identical with that of caterpillars. The head is rounded, and not
very large. On the whole, as Brauer observes, " the form of the larva is caterpillar-
like." In confinement the larva digs a horseshoe-shaped passage, an inch deep, in damp
earth, and lives on putrid meat and bread. Brauer also found one larva in a deep
mouse's nest, situated between decaying roots ; another under a stone, in a damp,
though nearly dry, forest brook ; and a third time, one was found under a moss-grown,
mouldering stump, with ants, not feeding on them, but rather sharing with them their
food, dead animals. In order to pupate, the larva makes an oval cavity in a lump
of earth, and buries itself deep in the ground. As a rule the larva? are sluggish, but
can, if pursued, creep rapidly. The larva? remain in their holes from ten days to three
weeks before casting the larval skin, and after remaining in the pupa state fourteen
days transform into the final, or imago state.

The life-history of Bittacus possesses similar interest. This insect is like Panorpa,
but the male has no forceps, and in form, with its slender body and long legs, strik-
ingly resembles a Tipula, or daddy-long-legs fly, except that it has four instead of two
wings. The imagines, or adult flies, live in a sort of chamber, covered in by leaves,
grasses, nettles, etc., forming an airy abode, or vivarium. Here they feed on such flies
as enter their habitation. The flies die after laying their eggs in the soil and the earth
at the bottom of the chamber dries up, but in the following April, when the soil is
again wet by the spring rains, the larva? hatch out. And now a remarkable fact has
been noticed by Brauer. He has observed that if the marshy or wet ground, where
the female Bittaci customarily lay their eggs, does not dry up, no females appear until
the second year following ; so that the eggs lie over unhatched two years. The first
condition of their hatching is a complete drying of the earth in which the eggs lie;
the second condition is a succeeding thorough wetting of the ground in spring. If the
ground remains dry from want of snow in the winter, or of rain in the spring, and there
follows in the next summer a very thorough wetting of the soil, then the time of appear-
ance of the adult will be retarded three or four months. This is quite analogous to
the case of the eggs of Phyllopod Crustacea, which will remain unhatched for several
years if deposited in mud which becomes dry.

The larva of Bittacus, unlike those of Panorpa. and Boreas, does not bore into the
earth, but lives on top of the ground under leaves, or remains secreted under a clod ;
in confinement it will live for several weeks if fed with raw meat.

The larva? have, like those of Panorpa, a remarkable resemblance to caterpillars,
especially certain silk-worms, or caterpillars of butterflies, as well as to saw-fly larva?,
such as certain species of Selandria. Unlike the young of Panorpa, the larva of
Bittacus is protected by two rows of dorsal spiny tubercles which end in long stiff
filaments, and which extend from behind the head to the tail. They also have, besides
the six thoracic legs, a pair of small two-jointed prop-legs on each abdominal segment,
or eight pairs in all, and are thus like the larva? of certain saw-flies (Lophyrus). From
their reddish-gray color, and the resemblance of the hairs on their back to particles of
earth and bits of plants, they are hard to detect, and are thus easily overlooked by
birds and other enemies, Moreover, at the least disturbance they assume an erect

NEUROPTERA.

position, throwing the body into the shape of an S, or they roll up spirally like
a saw-fly larva, and fall into the cracks in the ground. In this position they are
like a ball bristling with spines, and are on all sides inaccessible to the attacks of
smaller enemies, while reminding one of a hedgehog or porcupine among the higher
animals.

On approaching the time of entering the chrysalis state they bury themselves in the
earth one or two inches, and, hollowing it out by the spiral motions of the body, form
an oval hole. In this little cell the larva changes, its body becoming shorter, thicker,
paler, indeed almost white, while the spine-like appendages become flabby, and lie on
the side of the body instead of standing erect ; meanwhile the larva, like most cater-
pillars, keeps turning on its longitudinal axis. After a period of ten days it casts
the larva skin and appears as a slender white pupa, and fourteen days later the imago
appears.

A still more remarkable insect is the Snow Insect or Boreus. It is a smaller insect
than the foregoing. In the males the wings are very rudimentary, being about half as
long as the abdomen, and narrow and stiff
like a style, being entirely useless for flight.
The female is entirely wingless, and is pro-
vided with a large sabre-like ovipositor.
The skin is dark, with bronze tints, and
altogether it is a remarkable insect. More-
over its habits are singular. It occurs in

FIG. 236. Pupa of Boreus, snow insect, enlarged.

moss, and though a rare insect in general

is found in considerable abundance when it does occur, leaping about on the snow. We
have in the northern States two species, both described from New York by Dr. Fitch.
Boreus nivoriundus is about one-seventh of an inch long, and is reddish, with a bronze
tinge, while B. brumalis is entirely brassy black, and is smaller than the other species.
Boreus californicus was found near Fort Bidwell in northern California about the
middle of December, when they were observed walking on the snow in the morning,
disappearing when the sun shone brightly at noon.

In the PHRYGAJSTEID.E or caddis flies the body is slender, the thorax rounded.
There are no jaws in the adults, which closely resemble some of the moths. The
larvas are aquatic, and live in cases or tubes formed from the surrounding materials.
The members of this family are quite unlike any other Neuroptera, and form a sub-
order (Trichoptera) by themselves, though the Panorpidce approach them in some
important respects, and serve as connecting links between the present and the other
families of Neuroptera. The larvae of the Phryganeida? are called Case Worms or
Caddis Worms, and the imagines are called Caddis Flies.

The bodies of the caddis flies are cylindrical and have much the same shape as that
of a moth, the head being small and rounded, the thorax spherical (owing chiefly to
the small collar-like prothorax). Moreover the jaws are either rudimentary or wanting,
not being used in adult life, while the wings are shaped like those of a small moth,
being folded roof-like on their back, and the venation or veins of the wings resemble
those of the Lepidoptera, the short transverse veins being few in number. A number
of species of the smaller caddis flies would be easily mistaken for moths, and owing to
the close resemblance in nearly all the parts of the body to the Lepidoptera it has been
suggested that Lepidoptera have either descended from the caddis flies or that the two
groups have had a common origin.

164

NATURAL HISTORY OF ARTHROPODS.

The caddis flies are very common, flying about damp places and brooks, sometimes
in swarms ; they are usually dull-colored, but a few species are beautifully colored ;
the species of Setodes, for example, are usually snow-white.

FIG. 237. Limnophilus rhombicus, caddis fly; , case; 6, larva; c, pupa; d and e, adult.

The transformations of the caddis flies are interesting. The eggs are deposited in
a double gelatinous green mass, which is attached to the surface of some aquatic plant.
Westwood says that the female of Phryganea grandis has been observed to creep down
the stems of aquatic plants under the water, very nearly a foot deep, for the purpose
of laying its eggs. On the other hand, according to McLachlan, the egg-masses, prob-
ably of Halesus, are sometimes deposited on leaves of trees far from water.

With one known exception, which lives in moss on land, the larvae
of all the caddis flies live at the bottom of ponds and streams. They
are all protected by some sort of a case ; hence their name, case-
worms. There is no end to the variety of form in these cases, and
the material of which they are constructed. The accompanying illus-
trations will serve to represent a few characteristic forms.

Certain caddis worms roll up leaves, cutting them properly so as to
roll up with ease, or they sew them together by spinning silken threads
from their mouth, attaching to their case large irregular bits of leaves ;
others attach deserted or " dead " snail shells, or bits of gravel, coarse
or very fine, or sand ; and others, living in mill streams, cover their
cases with coarse sawdust. The cases are usually
straight, sometimes curved like a horn, while that of
Helicopsyche is wound in a spiral like a snail shell.
More is actually known about the case-worms of southern Brazil than
those of North America, owing to the observations of Fritz Mtiller, who
resides in that country, but as there are undoubtedly many similar species
in North America we will refer at some lenerth to the different Brazilian

O

forms. Of a genus (Tetracentron) allied to Z/eptocerus, and whose
imago is remarkable for having gills, one species uses hollow sticks for
its case. Of certain forms allied to Rhyacopldlus one lives, almost
without any case, between the tangled stems of water-plants ; the an-
terior legs of the larva are armed with curious, powerful forceps ; the cocoon of the
pupa is not protected by a regular case. Smaller species of an allied genus build

Fm. 238. Larva and
case of Limnophi-
lus subpunctulatus.

FlOf. 239. Larva
of Leptocerus.

NEUROPTERA.

165

portable cases, agreeing with those of most of the " Hydroptilidse " in not showing any
difference between the two extremities ; in one of them the water gains access by
a small, upright, cylindrical chimney in the middle of the case, in another by small
openings along the dorsal side. The group of Hydroptilidae are divided roughly into
six genera, with cases of the following form : -

1. Cases resembling those of the European (and probably North American) species,
either naked or covered with fine sand, diatoms, etc, more or less compressed, and
with a slit at each end. 2. Very minute, nearly cylindrical, coriaceous, brown tubes
covered with fine sand, fixed by either end to the underside of stones, and generally
showing two adhesive disks at the anterior, and one on the posterior end. 3. Diaulus.
Strongly compressed oval cases, elegantly covered by diatoms, with a narrow slit at
each end, and with two (or sometimes three) cylindrical chimneys for access of water.

FIG. 240. Different forms of caddis worm cases.

4. In Lagenopsyche the cases resemble a bottle with the bottom cut away and the
lower part compressed until only a slit is visible, the neck representing the mouth-end
by which it is held in an upright position. Before transformation to a pupa the case
is fastened by disks of silk, and the larva then turns itself in the case so as to keep the
head of the pupa iippermost. 5. Cases of younger larva? of Mhyacopsyche are brown,
coriaceous, nearly cylindrical, widening in the middle. From one end proceeds a
silken thread, sometimes more than twice the length of the case, by which it is fastened
to stones so as to prevent its being swept away by the rivulets in which it lives.
Before transformation to the pupa the thread is much shortened, so as to sustain the
case in an upright position.

The case of Helicopsyche merits attention from its resemblance to certain fresh
water shells, such as Valvata, for which it has been mistaken even by conchologists of
experience. The larvae of Helicopsyche glabra may be found in lakes in the north-

16G

NATURAL HISTORY OF ARTHROPODS.

FIG. 241. Case
of HMcopsyche
ylabra.

eastern States. The case is like a Helix or Valvata shell, usually very regular in form,
though the umbilicus varies in size. It is composed of fine grains of sand so arranged
that the outer surface is smooth. It is closed during the pupal stage by a dense, silken,
concave, suborbicular operculum, with concentric lines, rounded on one
side, and but slightly convex on the other, with a slightly curved slit
for the passage of water situated on the less convex side, each side
of the slit being provided with slender straight teeth which nearly
touch each other, thus forming an imperfect grate. The larva does not
spin a cocoon, but after spinning its operculum lies in its case with its
head just behind it. Though the body of the larva is curved it is not spirally so, as
would be inferred from the shape of its case. It is a quarter of an inch long. The
adult or imago of the species of this genus is not very dissimilar to other small caddis
Hies.

The larvas of the Phryganeidaj are, in general, cylindrical, and bear a general
resemblance to caterpillars, except that they possess only six pairs of feet the
thoracic ones. Living constantly in the water and never leaving it, they breathe by
so-called gills, by which they are enabled to extract the
air from the water. The gills are long, slender filaments
containing an aii'-tube or trachea, which branches off
from the main tube. The larvae are mostly carnivorous,
living on Entomostraca, so far as we have observed,
though they may at times eat decaying vegetable matter.
When about to pupate they close up the mouth of the
case with a grating, or, as in the cases of Helicopsyche,
by a dense, silken lid with a single slit, and in some instances spin a slight, thin, silken
cocoon, within which the pupa state is passed. Our large Neuronia semifasciata
transforms to a pupa in the spring, the larva passing the winter in its case. Most of
the smaller caddis flies appear in July.

A. S. PACKARD, JR.

FIG. 242. Neuronia semifasciata.

ORTHOPTERA.

167

ORDER V. - - ORTHOPTERA.

The insects comprising this order were first recognized as different from all the
other Hexapoda by De Geer in 1773, who gave to the group the name Dermaptera,
from their semi-membraneous anterior wings or elytra. Linne placed them with the
Hemiptera, and Geoffroy united them with the Coleoptera. Olivier, however, was the
first to propose for them the name Orthopteres in 1789, but the Latin form did not
appear until 1806, when Latreille used the term in Sonnini's Buff on. The name
Orthoptera (orthos, straight ; pteron, wing) was given to the order from the char-
acter of the front wings, which are straight, usually narrow, pergameneous or parch-
ment-like, thickly veined, and overlapping at the tips when closed. The hind-wings
are membraneous, with the veins quite straight. They fold up like a fan.

As an order the Orthoptera have never been as satisfactorily restricted as have
been some of the other groups. From time to time it has been made the provisional
resting-place for various small but comprehensive families that appeared to belong to
none of the other orders.

One of the latest systems of classification is that by Dr. A. S. Packard, Jr., who, in
an article on the arrangement of hexapodous insects into orders and sub-orders, proposes
for a certain group the name of Phyloptera, under which he places as of equal rank
the Dermaptera, Orthoptera, Pseudoneuroptera, and Neuroptera as sub-orders. In
this article he shows the

necessity for such a
change, and bases his
views upon the most
recent researches in the
embryology and devel-
opment of insects.

The order Orthop-
tera, as restricted and
generally accepted by
entomologists, and as we
shall treat of it here,
contains but the follow-
ing families, all of which
are terrestrial, with, perhaps, a single exception among the Phasmidee : the Blattidas,
or cockroaches ; the Mantidre, or rear-horses ; the Phasmidas, or walking-sticks ; the
Gryllidoe, or crickets ; the Locustidae, or grasshoppers and katydids, and the Acrididas,
or locusts.

The transformations of orthopterous insects are incomplete, i. e., the young when
first hatched differ but very little from the mature insect except in size and in the
absence of wings or rudiments of these appendages. There is no state of quiescence
as among those insects which undergo complete metamorphosis, the nymph or pupa
being quite as active as the imago, and differing from it chiefly in possessing the wings
and genitalia in a rudimentary state. The genitalia are, however, sufficiently developed
in some instances to permit of coition. The number of moults varies in different groups
as well as in the individuals of a species, some undergoing as many as six, while others
pass through only three or four. It is generally the case that those species in which

FIG. 1M3. Mole crickets.

1(58

NATURAL HISTORY OF ARTHROPODS.

the wings are entirely wanting or in which they are only in a rudimentary condition
pass through fewer moults than those possessing full wings. Among many of those
forms that have the wings rudimentary it is sometimes quite difficult to distinguish the
pupa from the imago. In such cases a safe criterion will be found in the presence or
absence of articulation in these appendages. Another and unerring criterion by which
the pupa and imago of such species may be distinguished will be found in the position
of the wings. The elytra of the pupa are thrown back and twisted around so that the
surfaces and margins are precisely reversed when closed as compared with the imago
or perfect state. That which is to be the inner surface in the imago is the outer
surface in the pupa ; the costal margin which is inferior in the imago is the upper or
anterior margin in the pupa ; the apical veins which curve upward in the former curve
downward in the latter. This peculiar arrangement, in connection with the others
mentioned, will enable anyone to determine whether a short-winged specimen is a pupa
or a mature insect.

The chief characters used in the classification of orthopterous insects are the
genitalia, the mouth-parts and the antennre ; though other characters are largely
used, as position and form of the eyes, form and comparative length of wings and
legs, shape of the head, thorax, and general contour of the whole insect. The cerci

FIGS. 244 and 245. End of abdomen of male and female locust (Acrydlum}; d, cerci; y h, ovipositor;

*, egg guide.

and ovipositor have, however, become recognized within the past few years as the
most reliable characters by which species and even genera can be recognized. Especi-
ally is this true among the Acrididoe or locusts, where neither size, color, nor the
presence or absence of well-developed wings signify specific differences. The sexual
organs are most characteristic in the male in some of the families ; those of the female
most so in others ; Avhile in still others these organs in both sexes are of equal import-
ance for classificatory purposes.

The mouth-parts of the Orthoptera, although varying somewhat among the
different families, are essentially the same. All the representatives of the order have
these parts admirably fitted for biting and gnawing the substances upon which they
feed. There are three pairs of these appendages. The true jaws or mandibles are
single-jointed, broad, short, and solid, with a toothed cutting and grinding edge. Be-
hind the mandibles are the maxilla?, which are accessory jaws, and serve to hold and
arrange the food to be ground by the true jaws. The floor of the mouth is formed by
the labium which in reality is composed of a second pair of maxillae, soldered together
in the middle. Both the maxillae and the labium are furnished with a pair of jointed
feelers which also aid in the process of feeding. In front of all these hangs the labrum
or lip, a loose flap that covers the jaws like a curtain when they are closed.

ORTHOPTERA. 169

The bead in this order, with but a single exception, is perpendicular; it is quite
large and full between and above the eyes, and is generally partly sunken into the
prothorax. The antennae are generally quite long and thread-like, and are composed
of an indefinite number of joints. There are, however, some exceptions to this rule.
The legs are well developed in all, and by their form the order has been separated into
five sections ; viz. : Ambulatoria or walkers, Cursoria or runners, Raptatoria or
graspers, Saltatoria or jumpers, and Fossoria or burrowers. In each of these sections
the legs are modified to the uses indicated by the names, and furnish a character by
which any individual can be assigned to its proper place at a glance. The legs also
vary very much in their comparative length and robustness, and thereby greatly aid
in the definition of the smaller divisions. The species of Orthoptera are spread over
the entire surface of the earth, but are most numerous in the countries lying within
and adjoining the tropics. Here the herbivorous species are found during both day
and night amongst the trees and other vegetation ; while the carnivorous species find
abundant lurking-places in which they await the coining of their prey. The Orthop-
tera comprise some of the largest of the class of insects, and in the tropics assume
remarkable forms. The Saltatorial Orthoptera are among insects what the Passeres
are among birds. They are the chief insect choristers, and during late summer and
autumn cause wood and meadow to ring with their merry and chirping stridulations.

The Orthoptera are among the first forms of insect life that appeared upon our
globe. In upper Devonian times a few low and synthetic forms lived amid the vegeta-
tion charactei'istic of that period. In the carboniferous era, when large tracts upon
the earth's surface were clothed with dense jungles of tropical vegetation, the repre-
sentatives of this order became common. In the tertiary period when insect life had
become exceedingly abundant, the remains of Orthoptera are found in the greatest
numbers. In Europe, where considerable attention has been paid to the study of fossil
insects, the number of Orthoptera found is comparatively large. In this country,
however, where beds of fossil insects are equally common, comparatively few species
have yet been described. The fossil insects found in the tertiary beds of the Rocky
Mountain region indicate a tropical relationship to a remarkable degree ; and there can
be little doubt that the faunal elements of tropical America of to-day entered into the
insect life of the central United States in tertiary times. Of these ancient Orthoptera
various species of cockroaches and earwigs figure most conspicuously, and represent by
far the greatest number of species. Mr. S. H. Scudder, to whom we are indebted for
his studies of fossil insects in North America, describes a cricket very similar to our
common striped field cricket (Nemobius vittatus) under the name JSTemobius terti-
arius, from the Green River shales. He also refers to several species belonging to
the Locustidre that were taken from the tertiary shale at different localities in the
Rocky Mountain region. Some of the leading localities for fossil insects in this
country are as follows : Morris, 111. ; the coal measures of New Brunswick and Nova
Scotia; Florisant and White River in Colorado; Green River in Wyoming; Hodge's
Pass and Bear Lake in Idaho, and the Tertiary beds of the Nicola and Similkameen
rivers in British Columbia. Those of Europe are distributed pretty evenly over the
continent, though the most perfect remains have thus far been found in Prussia.

Some of the species comprised in the family of the Cockroaches (BLATTID^E) are
among the commonest and at the same time the most disgusting of the insect tribe.
They are unpleasant to look upon, and offensive to our sense of smell on account of
their fetid odor, while they excite our antipathy because of the waste and destruction

170 NATURAL HISTORY OF ARTHROPODS.

they cause. The Blattidas have received all sorts of popular names, but they are best
known as " black-beetles " and cockroaches. Their colors, as a rule, are various shades
of dull brown and black, which agree well with their nocturnal habits and the dark
haunts they frequent. The body of most species is comparatively large, broad, and
flat, and is covered by a very flexible, leathery integument. In some genera the head
is almost, while in others it is entirely, concealed beneath the prothorax. The antennae
are very long and thread-like ; the feet and limbs are strong and spined, and admirably
adapted for running as well as for crawling into narrow cracks and crevices a habit
belonging in a greater or less degree to all the species of the family. During the day-
time we see very little of these insects, and become surprised by their sudden appear-
ance at nightfall. This, however, is owing to their nocturnal habits and their trait of
hiding themselves away, in which they are materially aided by their compressible
skins and the flatness of their bodies, which allow them to squeeze into very nar-
row places.

The species of Blattida?, on account of their mode of life, are the most widely
distributed of all Orthoptera, and are exceedingly common in some localities. This is
especially the case in seaport towns, and on board of ocean steamers, where, favored
by the warmth from the engines and the prevailing dampness, they thrive and multiply
amazingly. It is therefore an absolute necessity that all goods to be transported from
one country to another be well packed in order to be secure against injury from these
insects. They have become generally distributed over the entire face of the globe
wherever navigation has extended, and have, in fact, very generally followed man.
We may rejoice that these cosmopolitan species are so few when we reflect upon the
great amount of injury caused by each. Besides these wide-spread and generally-known
species, there are numerous other representatives of the family that we find in the
woods under bark of trees, in old and rotten logs, and under stones and all sorts of
debris. This family is most numerous within the tropics, where many of the species
are of great size, but do not differ greatly in habit from those living in our woods.

FIG. 246. Egg cases of a cockroach, Periplaneta oriental is : natural size above.

The principal characters used in the classification of the Blattidas are the form of
the prothorax, the limbs, the terminal plate of the abdomen, and the cerci. The rela-
tive position of the head also aids materially, while the presence or abbreviation of
the wings is likewise significant. The eggs of cockroaches are all laid at once, and
encased in a purse-like pod, the form of which varies among the different genera.
The operation of egg-laying with these insects, it is claimed, requires many days. The
ootheca, as these egg-cases are called, contains a double row of eggs that are placed
upon either side of a slit or opening which extends the entire length of the pod. The
color of this ootheca when first protruded from the body is almost white, but with
time it generally assumes the color of the species to which it belongs. The female

ORTHOPTERA.

171

cockroach carries the egg-case about with her until the young are ready to emerge,
when it is dropped. Some writers claim that the mother assists the young to escape.
These egg-pods are composed of the same elastic material that forms the outside cover-
ing of the insects themselves, and when the young escape they close again, leaving the
empty shells lying about on the ground. When first born the young cockroaches are
perfectly white, and are brooded over by their mother in a similar manner to the brood-
ing of the earwig already alluded to. The accompanying figure represents the ootheca
of Periplaneta oriental-is, natural size, and magnified. The number of moults suffered
during growth varies from four to six ; and immediately after each moult the insect is
quite white, to which fact the numerous reports of albino cockroaches must for the
most part be attributed.

The Blattidae as a rule are omnivorous, and consume everything which can possibly
be eaten that comes in their way. Nothing comes amiss to them, and they inflict
great losses upon merchants as well as upon householders. Imagine the disgust of a
cook on board a vessel when, upon opening a box that should contain victuals, he finds

KIG. 247. Ectubia, yermanica, and E. lapponica, cockroaches.

in their stead a living mass of these creatures ! On long voyages such is very apt to
be the case.

The smallest of these cosmopolitan species is the German Cockroach, Ectobui
germanica, which is here figured in conjunction with Ectobia lapponica, a small
species from Lapland. This little roach is of a rather light color, and has two longi-
tudinal dark stripes upon its prothorax. It is chiefly found in houses, and especially
about the kitchen, where it lurks in some dark corner till the coming of night when it
sallies forth seeking what it may devour. This species is very common in houses in
and about all the large cities of New England, where it is called the " Croton bug."
Although an almost universal feeder it prefers wheat-bread to all other articles of diet.
It is therefore a very common and troublesome pest about bake-shops, where it lurks
about the ovens and the dough-trough, and, notwithstanding the utmost care on the
part of the baker, sometimes becomes incorporated with the dough and baked in the
loaf. It also causes serious damage to libraries, having a special fondness for cloth-
bound books, the covers of which it gnaws and renders unsightly. Leather-bound
books it does not touch. The use of good pyrethrum powder on the book-shelves is
the best remedy for this difficulty.

172 NATURAL HISTORY OF ARTHROPODS.

A second and much larger species is the Oriental Cockroach or "black beetle,"
Periplaneta orientalis, which sometimes appears about meal bags, after dark, in badly

infested houses. This insect is very dark brown, or almost black,
and has the wings shorter than the body in the male, and only
rudimental in the female. It frequents chimney-corners and sinks,
and only comes forth after nightfall. The species is said to moult
six times before maturing.

The remedies recommended for the preceding species are applic-
able to this one ; for while the pyrethrum does not invariably kill,
it renders them stupid and helpless, so that they may be swept up
and destroyed. Powdered borax well sprinkled about their haunts
will drive them away, and is said to kill them if mixed with pow-
dered white sugar. A simple and effective roach trap, commonly
used in England, is a dish or soup plate half filled with stale beer.
This is set upon the floor with thin sticks of kindling wood placed
round it like scaling ladders, up which the roaches climb into the

I' IG. 248. Feriplaneta

black allurin 2; beverage.

beetle."

The two roaches just mentioned seldom swarm simultaneously

in the same house, and this fact is generally believed to be due to their feeding on one
another. Indeed, the omnivorous habits of the Periplaneta orientalis are some com-
pensation for its annoyances. It is not only a great scavenger, keeping pantry and
kitchen corners clean and wholesome, but it has the very commendable habit of feed-
ing on that far more obnoxious household pest, the bed-bug, so that the encouragement
of the " black beetles " may sometimes be desirable.

Our American Cockroach, Periplaneta americana, is somewhat larger than the
oriental species, is lighter brown, and has the wings well developed in both sexes. It
also frequents houses as do those already described, but prefers to linger about water-
pipes and sewers, and is the species most frequently seen among the cargoes of vessels.
It is also very numerous in greenhouses where it breeds in great numbers, and does
considerable injury to the various plants upon which it feeds. We have observed that
it is unusually fond of the foliage of the cinchona plant.

Platamodes penmylvanicus is a common species in the woods, where it is found
under stones and old logs. It also frequently enters houses after dark in midsummer.
In California a species of cockroach (apparently an undescribed species of the genus
Heterogamia) is sometimes found in which the female is wingless, and burrows in the
sand, while the male is furnished with long wings and flies about after nightfall, when
it is sometimes attracted by lights and enters houses. Similar species are found in
southern Europe and northern Africa. Among the large species inhabiting tropical
countries there are many wingless forms which bear a strong resemblance to some of
the crustaceans, and which also frequent similar localities.

There are numerous other forms of Blattidae that we might mention as being
of interest, but as they are all local in their distribution, and are chiefly confined
to countries lying within the tropics, we will pass them over. Mr. Scudder has
described several species of these insects from the coal-measures of North America,
and one from the tertiary beds of Colorado, while there are quite a number of species
described from the coal-measures of Europe. It is difficult to give an accurate
estimate of the number of species belonging to this family on account of the extremely
local distribution of many of the forms, and also on account of the Blattidae having

ORTHOPTERA.

173

Urn sorely neglected by entomologists. The latest synopsis, published by the British
museum, enumerates about nine hundred species.

The MANTHXE is the only family of the Orthoptera in which all the members are car-
nivorous. It is also separated from all the other families by the peculiar structure of
the front pair of legs, which are constructed for grasping. The species, as a rule,
are large, and, like the Phasmidae, often bear a striking resemblance to various
leaves and twigs upon which they sit while waiting for their prey. The Mantidae
have become popularly known under a variety of names, such as Rear-horses, Race-
horses, Praying-insects and Soothsayers, all of which have originated from the
peculiar positions assumed by them at different times, especially when waiting for
their prey.

The movements of the Mantidae are sluggish ; their colors are variable ; they
have long and linear bodies ; and in some species the wings are broad and leaf-like.
The head is triangular in form, perpendicular, and furnished with
sharp but small jaws. The eyes are very large and prominent, and
between them are situated the rather short and bristle-like antennae
and three ocelli. The front legs, which are the chief characteristic
of the family, are large, strong, and furnished with numerous sharp
spines ; they are mostly carried in a folded position, and but little
used in walking, their true use being that of seizing and holding the
insects upon which they feed. The males are more slender and more
active than the females, their narrower and longer wings permitting
more ready flight. In watching and seizing their prey their motions
are wary and stealthy until the final stroke of capture, and there are
few more amusing sights than that of one of these creatures silently
swaying from side to side, or stealthily moving one limb after another,
the head with its prominent eyes turning and watching every motion
of the coveted animal meanwhile. The eggs are laid in clusters upon
twigs and encased in a flattened ovate case or ootheca. This ootheca

^j

is composed of hardened silk, in which characteristic it differs from
that of the female cockroach. This peculiar habit of encasing the
eggs within a single receptacle would seem to indicate a common
origin and the close relationship of the two families.

The young mantis is long and linear, and has the habit of curving
up the end of the body and throwing back the head and neck. It
comes into the world encased in a thin and delicate pellicle (amnion)
which is soon cast off and eaten. The young mantes at once dis-
play their voracity by attacking one another. They are the counter-
part of the fully matured insect in respect to their mode of life, and what is true of
one species is also true of all the others.

The Mantidae are nocturnal to a certain degree, especially in their movements and
flights, which are mostly performed after sunset. The female, although possessing
pretty well developed wings, does not fly. The wings are used, however, in easing
herself from a higher to a lower elevation, also w r hen in battle with one of her own
kind, or when pouncing upon her prey, at which time she hoists them very much as
does a swan when irritated. These insects in some localities have gained the popular
reputation of being very meek and reverential, and on this account have received the
name of Praying Mantes.

FIG. 249. Egg cap-
sules of Phasmo-
mantis Carolina.

174

NATURAL HISTORY OF ARTHROPODS.

They are bloodthirsty creatures, and are forever quarrelling and at enmity among
themselves, as well as with all other insects. Many a fierce battle is fought by the
males in which neither eye nor limb is spared, and in which the winner ends by making
a repast off the body of the vanquished. They are so void of feeling that the male (the
female being the strongest and most voracious) risks his life in courting, and usually
succeeds only by slyly and suddenly surprising his mate, who, after accepting his
embrace, often coolly seizes and devours him. So tenaciously do these insects fight
that they will continue without cessation or inconvenience for some minutes after the
loss of their heads. We have seen a female, decapitated and with her body partly
eaten, slip away from another that was devouring her, and for over an hour after-
wards fight as tenaciously and with as much nonchalance as though nothing had
happened.

The most common representative of the family in the United States is Phasmo-
mantis Carolina. The eggs of this species are laid in a packet about an inch in length,

FIG. 250. PJtasmomantis Carolina, praying mantis.

and attached to twigs and leaf-stalks. The species is quite common through various
portions of the South and Southwest. Its food consists mainly of flies, though it is a most
voracious cannibal and will devour its own kind as well as any other insect that comes
within its grasp. It has been known to attack butterflies, grasshoppers, and caterpil-
lars of various kinds, and in one instance a single female devoured eleven Colorado
potato-beetles during one night, leaving only the wing cases and parts of the legs. It
disdains all dead food, and never makes chase for the living, but warily, patiently, and
motionless it watches till its victim is within reach of its fore-arms, and then clutches
it with a sudden and rapid motion. The newly-hatched larva is light yellowish-brown,
but after the second moult, many of them become green. This last color is retained by
most of the females, while the males, at maturity, are more often gray.

"We know with what fear the hawk is regarded by the great majority of small birds,
but that at the same time the common bee-martin defies, and even tantalizes and drives
it off. In like manner the mantis, which must be the dread of most flies, is defied by
certain parasitic species belonging to the genera Tachina and SarcopTiagra, and we
have found no less than nine maggots in the body of a female mantis, which must have

ORTHOPTERA.

175

hatched from eggs that had been deposited on her body by one of these flies. The
eggs of the mantis are at times infested and destroyed by the singular-looking hymen-
opterons parasite, Priomerus pachymerus, with large and serrate hind femora. A second
species found in the United States, is Mantis missouriensis, a slender species in which
the wings are gray and as long or longer than the body. It is found in the Missouri
valley, where it lives among grasses and low vegetation. This insect bears a slight

FIG. 251. Empusa pauper ata, rear-horses.

resemblance to Empusa pauperata, a slender species found in the maritime Alps of
Europe, and having somewhat similar habits. This latter insect, however, is very
handsomely colored. Its body is decorated with' a mixture of most delicate gray,
green, white, and violet tints, and the wings of the adult are of a clear sea-green
color, the borders and nervures being lilac.

The JSmpusce have a long leaf-like projection on their heads, short antenna, a very
thin thorax, and their legs are ornamented with curious leaf-like expansions. There is
also a third and undescribed species of mantis found on the sandy plains along the

176 NATURAL HISTORY OF ARTHROPODS.

eastern slopes of the Rocky Mountains. This is a still smaller insect than the preced-
ing, is wingless and rather stout-bodied. It lives entirely on the ground, which it
resembles very closely in color, and is very active, running with as great rapidity as do
the various species of tiger-beetles that are to be met with in similar localities.

The commonest species in Europe is the Mantis religiosa. In Buenos Ayres
Mantis argentina is said to seize and eat small birds.

The PHASMIDJE, popularly known as spectres, walking-leaves and walking-sticks, are
the most bizarre of the Orthoptera. They are sluggish in their movements, and are
found upon the twigs and leaves of plants, to which they bear a striking resemblance.
In fact, the species of this family are all imitative in a greater or less degree, and fur-
nish the strongest examples of that mimicry which is so frequent among insects, and
which brings them into harmony with their surroundings and enhances their protec-
tion. The body in most of the Phasmidae is remarkably long and slender, and the

wings are either aborted, very
small, or strikingly leaf-like.
The head is long and horizontal,
while in most of the species the
antennae are rather short. The
legs are of the ordinary type,
being made neither for jumping
nor seizing, and, as a rule, quite
long and stick-like. When the
insect is at rest the front pair are
stretched out in front so as to
increase the resemblance to a

no. 252. -Leaf insect. twi g' The characters by which

the insects of this family are

classified are similar to those used in other families in the Orthoptera. The antennae,
however, acquire more or less importance in different genera. Although there are a
few representatives of this family in the United States, they find their most congenial
home in the tropics, where some of the species attain to over a foot in length, ex-
clusive of the legs.

The walking-sticks are strictly herbivorous, and in color closely imitate the plants
upon which they feed. Their eggs are oval or elliptical, and have a lid on the front
end which is pushed open by the young larva when it is ready to escape. They are
dropped singly on the ground. The larvae differ but little from the imago except in
size and in their greenish color. Their mode of life varies somewhat from that of their
parents. During the first few weeks they generally live upon grass and low bushes,
where they readily drop to the ground when disturbed, thereby escaping notice. The
transformations of but few of the Phasmida3 have been studied. We cannot, there-
fore, be positive as to the number of moults suffered by the representatives of the
various genera. The history of Diapheromera femorata has been carefully studied
by Riley. The eggs are oval, slightly compressed at the sides, polished black in
color, with a ventral whitish stripe, and look something like small leguminous seeds.
They are tough and are simply dropped upon the ground: from whatever height the
female happens to be, so that during the latter part of autumn where the insects are
common they produce upon the dry leaves a constant pattering not unlike that of rain.
The number of eggs laid by a single female is near a hundred. They remain upon the

ORTHOPTERA.

177

ground nil through the winter and hatch for the most part during the month of May.
Some of them, however, continue hatching much later, so that all through the summer
and even into the fall, young individuals may be found. The embryo, just about to
hatch, lies within the egg with the head pressed against the oval lid and the body
curled round so that the end of the
abdomen, which is thickened and
contracted, reaches near the mouth.
The long antennae project in front of
the head and follow the curve of the
body, while the long legs are folded
up in the central space. When
hatched, the yoiing of this species
measures 4.5 mm., and with their
feelers and legs outstretched, nearly
double that length. The insect
changes very little in appearance
from birth to maturity except so far
as color is concerned. Growth is
rapid, averaging, under favorable cir-
cumstances, about six weeks from
birth to maturity. With age the
green color gives way to various
shades of gray and brown, though
exceptional individuals remain
green. In other words, these in-
sects put on their autumn tints just
as does most of the deciduous vege-

\U

tation. In this way we find great
correspondence with its surround-
ings. While the vegetation is green
the Diapheromera is green ; when
the foliage turns in autumn it changes
color accordingly. The species has
become very numerous in parts of
the Middle States, where it does
great injury to various trees, espe-
cially to the oaks. The eggs of
this species often lie on the ground
through two winters before hatch-
ing.

The species of the genus Phyl-
lium, found only in the East Indies,
bears a most remarkable resemblance to various leaves. The wings are often very
large and broad, and, as if to aid in carrying out the analogy, the legs have broad,
leaf-like expansions. One species has its front wings so veined and colored as to
resemble a dried and withered leaf, while Phyllium siccifoUum, which we figure, is
green. Prisopus fldbellicornis, a Brazilian species, according to A. Murray, spends
the whole of the day under water, adhering to stones in cool mountain streams till

VOL. II. 12

FIG. 253. Diapheromera, femorata, walking stick; a b, eggs.

178

NATURAL HISTORY OF ARTHROPODS.

toward dusk, when it flies about. This is the only true aquatic orthopterous insect
known.

In contemplating these singular creatures and their wonderful resemblances to the
vegetation upon which they occur, one cannot help noticing still further resemblances.
They are born with the bursting of the buds in the spring ; they drop their eggs as the
trees drop their seeds, and they commence to fall and perish with the leaves, the later
ones persisting, like the last leaves, till frost cuts them off. We have not more than a
half dozen representatives of the Phasmida? within the limits of the United States.

We now come to that extensive division of the Orthoptera known as the Saltatorial
Orthoptera. This division contains by far the greatest number of species, each of
which possesses rather exceptional powers of jumping or leaping, and hence has the

FIG. 254, Phy Ilium siccifolium, walking-leaf.

hind femora greatly developed for this purpose. While this character is common to
all the Saltatoria the division is readily separable into three very distinct families.
These families are the Gryllida?, or crickets, the Locustidae, or grasshoppers and katy-
dids, and the Acrididae, or locusts. While the families comprising the crickets and
katydids differ from each other in many respects, they are nevertheless very closely
connected in some of their wingless genera. They possess common characters, and
have similar habits ; many of the species in both families being wingless, and having
somewhat similar shapes. The antennae are long and threadlike in both. The Acri-
dida3, on the contrary, are widely separated from the rest of the Orthoptera in most
of their characters, and are the most highly organized representatives of the order.

We will mention these families one by one, and characterize each, in its turn, by
describing a few of the commoner species as well as those that are odd, and deviate
somewhat from the typical form.

ORTHOPTERA.

179

The GRYLLID.E, or Crickets, are characterized by having a somewhat cylindrical
body, and a large, vertical head, with elliptical eyes ; the antennae are long and thread-
like, and arise between and in front of the eyes ; the wings, when present, are of mod-
erate size and net-veined, and lie flat on the back ; the anterior pair are ovate, and
have the costal edge bent abruptly down at the sides of the body, while the hind pair
are triangular, net-veined, and folded like a fan. The genital armature is largely devel-
oped, forming long and slender exarticulate stylets, which are often nearly as long as
the body. The ovipositor is of variable length, cylindrical, more or less curved
upwards, with the end slightly enlarged and wedge-shaped. The prothorax is generally
small, and shield-like ; the legs are rather short, but well suited to the habits of these
insects. The legs are also often armed with long, sharp spines, especially among the
ground-dwelling species, and in their various modifications form an excellent character
for classification. The characters most used in classification are primarily the form,
but also the antenna?, ovipositor, posterior tibia?, and the labial palpi.

The colors of the field crickets, as a rule, are various shades of dull black, or
brownish-gray, agreeing well with their nocturnal and ground-dwelling habits. They
are hermit-like, and very retiring, especially during the daytime, almost always living
singly, in little burrows, which they dig for themselves, and from which they seldom
stray far. They are timid, and generally peaceful among themselves, as well as towards
other insects with which they come in contact.

In treating of the foregoing families of the Orthoptera we mentioned a great variety
of features belonging to each and all, some of which were interesting as well as unique ;
but in none did we find the power of song. The saltatorial Orthoptera, or at least all
such of them as possess wings, are capable of producing sounds by stridulation, which,
among the Gryllidse and Locustidas are not unpleasant to the ear, and may be likened
to the songs of birds. It is from this feature that they have become more popularly
known than are most of the other Orthoptera.

While the preceding families are chiefly confined to the tropics, and to the warmer
parts of the temperate countries, the Gryllida? are more equally distributed over the
earth's surface where the climate is sufficiently warm to permit
of their maturing. They are herbivorous, but not strictly so,
since they are known to devour dead animal matter, and to
prey upon other soft insects.

The lowest type of this family, as it is at present limited, is
composed of what may be called the Fossorial Orthoptera.
These are among the "rarities" of insect life, on account of
their secluded habits. They are odd looking creatures, and
bear a striking resemblance to the mole, with its greatly devel-
oped front legs modified for burrowing. These Mole-crickets,
as they are called, are of rather large size, and have their mem-
bers admirably adapted to burrowing. They live underground,
and very seldom leave their burrows to come to the surface,
and then always after dark. Their bodies are almost cylindrical,
quite long, and densely covered with very short, fine hairs ; their
feet are short and thick ; their front, or burrowing legs, are short, and greatly enlarged,
and, as it were, fingered, so as to greatly resemble in appearance those of the common
mole. They do not jump, like the rest of the Gryllidae, nor is there any necessity for
this accomplishment in the subterranean life they lead. They are the true moles of the

FIG. 255. Grt/l/o/alpa aus-
tralis, mole-cricket.

180 NATURAL HISTORY OF ARTHROPODS.

insect world, and make tortuous galleries, destroying everything that comes in their
way, cutting through roots and eating the tine underground twigs, as well as the worms
and grubs, which they meet with during their burrowings. Some authors have claimed
that these crickets are truly carnivorous, but this is a mistake. They do eat such
worms and insects as come in their way, but their nourishment consists principally of
vegetable food. Their excavations consist of vertical shafts, of various depths, and
of horizontal galleries, which lead from them in different directions. These are to
be found in the soft, moist earth on the margins of streams and about ponds, where
they can be readily detected by the small upraised ridges, like those made by the
mole.

The female Gryllotalpa lays her eggs, to the number of three hundred to four
hundred, in the remotest part of the gallery. They are laid in the spring of the year,
and are contained in tough sacs.

The males sing during the warm, still nights of spring and early summer. The
song is a low, continued, rather pleasant trill, quite similar to that of the common toad,
but more shrill. It is produced by rubbing together the anterior wings, which are
furnished with heavy veins, roughened on their contiguous surfaces, and so arranged
as to magnify the sounds.

The species are all of a dirty, brownish-gray color, and resemble one another very
closely. They are quite generally distributed over the inhabited world, though they
become more numerous towards and within the tropics. Gryllotalpa borealis is found
throughout the northern part of the United States and portions of British America,
while further south it is replaced by Gryllotalpa longipennis. In Europe Gryllotalpa
vulgaris i