THE LIBRARY

OF

THE UNIVERSITY
OF CALIFORNIA

PRESENTED BY

PROF. CHARLES A. KOFOID AND
MRS. PRUDENCE W. KOFOID

ZOOLOGY.

ZOOLOGY:

gt Sbp&tematic Account of

THE GENERAL STRUCTURE, HABITS, INSTINCTS, AND USES

OF THE

PRINCIPAL FAMILIES OF THE ANIMAL KINGDOM.

WILLIAM B. CARPENTER, M.D., F.R.S., F.G.S.,

AUTHOR OF "PRINCIPLES OF GENERAL AN'D COMPARATIVE PH YSIOLOGY," AND
OF "PRINCIPLES OF HUMAN PHYSIOLOGY."

IN TWO VOLUMES.
VOL. II.

LONDON:
WM. S. ORR AND Co., PATERNOSTER ROW.

MDCCCXLVIII.

i* "V

CONTENTS.

bsroArW

CHAPTER VI.

PAO8

OF THE CLASS OF FISHES ........ 1

ORDER I. — ACANTHOPTERYGII 28

ORDER II. — MALACOPTERYGII ABDOMINALKS . . 41

ORDER III. — MALACOPTERYGII SUB-BRACHIATI ... 48

ORDER IV. — MALACOPTERYGII APODA 51

ORDER V. — LOPHOBRANCHII ...... 53

ORDER VI. — PLECTOGNATHI 54

ORDER VII. — CHONDROPTERYGII BRANCHIIS LIBERIS . . 57

ORDER VIII. — CHONDROPTERYGII BRANCHIIS FIXIS . . . 58

ORDER IX. — CYCLOSTOMATA 63

CHAPTER VII.

GENERAL CHARACTERS OF ARTICULATED ANIMALS . . . . 74

CHAPTER VIII.

OF THE CLASS OF INSECTS ........ 84

SUB-CLASS A. — WINGED INSECTS . . . . . . 115

ORDER I. — COLEOPTERA, OR BEETLES . . . .117

ORDER II. — ORTHOPTEHA . . . . . . . 137

ORDKR III. — NEUROPTERA . . . . . .147

ORDER IV. — HYMENOPTERA 156

ORDER V. — LEPIDOPTERA . . . . . .172

ORDER VI. — HOMOPTERA .... . . 186

ORDER VII.— HETEROPTERA 192

ORDER VIII.- DJPTERA 195

SUB-CLASS B. — APTEROUS INSECTS ...... 205

ORDER IX. — APHANIPTERA ...... ib.

ORDFR X. — ANOPLURA 206

ORDER XI.— THYSANOURA 207

CONTENTS.

CHAPTER VIII.— Continued.

PAGE

ORDER VI. — HOMOPTKRA

ORDER VII.— HETEROPTERA

ORDER VIIL— DIPTERA • 195

SUB-CLASS B. — APTEROUS INSECTS 205

ORDER IX. — APHANIPTERA

ORDER X — ANOPLURA 206

ORDER XL— THYSANOURA . 207

CHAPTER IX.

OF THE CLASS OF ARACHNIDA ....... 209

ORDER I. — PULMONARIA 216

ORDER II. — TRACHEARIA ... . 226

CHAPTER X.

CLASS OF CRUSTACEA .... .... 231

SUB-CLASS MAXILLOSA .... ... 244

ORDER I.— DECAPODA . 246

ORDER II. — STOMAPODA ...... 254

ORDER III.— AMPHIPODA 258

ORDER IV. — L^MODIPODA ...... 260

ORDER V.— ISOPODA 261

ORDER VI.— PHYLLOPODA 264

ORDER VII.— CLADOCERA 267

ORDER VIIL— OSTRAPODA 269

ORDER IX. — COPEPODA 272

SUB-CLASS EDENTATA • . . . . 274

ORDER X. — SIPHONOSTOMA 275

ORDER XL— LSRN^IDA 277

ORDER XII. — ARANEIFORMES 27S

JUB-CLASS XYPHOSURA ....... . 279

ORDER XIII. — XYPHOSURA 279

GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA . 281

CHAPTER XL

PACK

OF THE CLASS OF MYRIAPODA 285

ORDER I. — CHILOPODA .....•• 287
ORDER II. — CHILOGNATHA .4 289

CHAPTER XiT.

OF THE CLASS OF CIRRHOPODA . . . . . 291

ORDER I. — PEDUNCULATA 293

ORDER II. — SF.SSILIA 29l>

CHAPTER XIII.

OF THE VERMIFORM CLASSES . . 296

CLASS OF ANNELIDA ......... 298

ORDER I. — DORSIBRANCHJATA 303

ORDER II. — TUBICOL*: 303

ORDER III. — TERRICOL*; 308

ORDER IV. — SUCTORIA 311

Crf^SS OF ENTOZOA 313

CLASS OF ROTIFERA . 317

CHAPTER XIV.

OF THE MLLUSCA OIN GENERAL . 326

CHAPTER XV.

OF THE CLASS OF CEPHALOPODA . . . . ... 338

ORDER I. — DIBRANCHIATA ...... 345

ORDER II. — TETRABRANCHIATA 352

CHAPTER XVI.

OF THE CLASS OF PTEROPODA 357

OF THE CLASS OF HETEROPOr/A ..... . 359

CONTENTS.

CHAPTER XVII.

PAOB

01 THE CLASS OF GASTEROPODA 361

ORDER I. — PULMONEA . .... 370

ORDER II. — NUDIBRANCHIATA . ... 373

ORDER III. — INFEROBRANCHIATA , 375

ORDER IV. — TECTIBRANCHIATA . • • . . . ib.

ORDER V. — PECTINIBRANCHIATA ..... 377

ORDER VI. — TUBULIBRANCHIATA . . . . . . 386

ORDER VII. — SCUTIBRANCHIATA . . . . . . ib.

ORDER VIII. — CYCLOBRANCHIATA 387

CHAPTER XVIII.

OF THE LAMELLIBRANCHIATE CONCHIFERA 390

ORDER I. — OSTRACEJE 397

ORDER II. — PECTINIDJE 401

ORDER III.— MARGARITACEJE 402

ORDER IV. — MYTILACE.E 405

ORDER V. — UNIONID* 407

ORDER VI. — ARCACEJE 408

ORDER VII.— CHAMACFJE 409

ORDER VIII — CARDIACE* 411

ORDER IX.— SOLENID.K . . . . . .413

ORDER X. — INCLUSA 414

CHAPTER XIX.

OF THE CLASS OF PALLIOBRANCHIATA . 420

CHAPTER XX.

OF THK CLASS OF TUNICATA , . . 423

CHAPTER XXI.

GENERAL CHARACTERS OF RADIATA ...... 435

CONTENTS. Vii

i

CHAPTER XXII.

PADS

OF THE CLASS OF ECHINODERMATA . . . ... 445

ORDER I — ECHINIDA. 446

ORDER II. — STELLERIDA . . . . ... 454

ORDER III. — FISTULIDA 461

CHAPTER XXin,

OF THE CLASS OF ACALEPH^ 468

CHAPTER XXIV.

OF THE CLASS OF POLYPIFERA 480

ORDER L — HVDKOIDA 482

ORDER ll. — HELIANTHOIDA 492

ORDER III. — A^TEROJDA . .... 516

ORDER IV. — OILIOBRACHIATA . 526

CHAPTER XXV.

OF THE CLASS OF POLYGASTRICA 540

CHAPTER XXVI.

OF THE CLASS OF PORIFERA 558

APPENDIX.

ON THE INSTINCTS CF SOCIAL INSECTS 567

CHAPTER VI.

OF THE CLASS OF FISHES.

515. THE fourth and last class of the Vertebrated sub-king-
dom, comprises the animals known as FISHES. These are destined
to live altogether in the water ; and this circumstance has im-
pressed a peculiar character on their entire organization : but
the most important differences which they present, when we
compare them with the other Yertebrata, consist in the confor-
mation of their apparatus for respiration and circulation. They
have no lungs at any period of their lives ; and they breathe by
gills only. Their heart contains but two cavities ; and receives
only venous blood. This liquid, after having been brought into
contact with oxygen, passes into a dorsal vessel, where no new
force accelerates its course through the different parts of the
body. Their circulation cannot, therefore, be as active as among
the higher animals ; and their blood is cold like that of Reptiles.
Their skin is covered only with scales, which, in some instances,
are scarcely discoverable, so that the skin appears quite bare ;
they have no mammary glands like the Mammalia, and they
are reproduced by means of eggs ; lastly, their members have
the form of fins.

516. The external form of Fishes varies; but their body is
generally but little divided. Their head, which is as broad as
the trunk, is not separated from it by any narrowing like the
neck of the higher Yertebrata ; and their tail, by its size at its
origin, is not distinguished from the rest of the body. Some of
these animals are quite destitute of fins ; but in general we find
a considerable number of these organs, placed, — some on the
central line of the back or the abdomen, and consequently single,
— others on the sides, and arranged in pairs (Fig. 245). These
last represent the four limbs of the other Yertebrated animals.

FIG. 245. — BEARDED MULLET, showing position of
fins ; p, pectoral fin ; v, ventral fin ; d\ first dorsal ;
dz, second dorsal ; c, caudal ; a, anal ; o, opening of
gill-covers.

2 EXTERNAL ORGANS OF FISHES.

The anterior members, which correspond with the arms of Man
and the wings of Birds, are fixed on each side of the trunk,
immediately behind the
head, and are called pec-
toral fins. The abdo-
minal members are less
separated from each
other, and are generally
found on the lower side
of the body ; they may
be situated more or less
forwards or backwards,
from the under part of
the throat to the com-
mencement of the tail ; these are called 'central fins. The single
fins occupy, as we have already said, the central line of the
body ; and are divided into dorsal fins, anal fins, and caudal fins,
according as they are placed along the back, under the tail, or
at its extremity. They have all very nearly the same structure,
and consist almost always of a fold of skin, supported by bony
or cartilaginous rays ; very nearly in the same manner as the
wings of bats and dragons are sustained by the fingers or by the
ribs, of the animals.

517. On the external surface of the body, large openings are
seen on each side ; which are placed immediately behind the
head, and which serve as an outlet for the water that has passed
through the gills. In general there is only one on each side ;
and its anterior edge is moveable, and resembles a flap or
valve. There exists on each side, along the whole length of the
body, a series of pores, which is termed the lateral line ; these
are the openings of glands imbedded in the skin, by which the
thick mucus is secreted, that covers the skin of Fishes, and gives
to it its peculiar slipperiness.

518. The skin is sometimes almost entirely bare, but it is
generally covered with scales. Occasionally these scales have
the appearance of coarse grains, at other times they exist as large
tubercles or plates of a considerable thickness ; but in general

SKELETON OF FISHES. 3

they present the aspect of very thin laminae or plates, arranged in
the manner of tiles upon a roof, and held together in the folds
of the skin. "We may compare them to our nails ; but they
contain a much larger quantity of calcareous salts. The colours
with which these animals are adorned, astonish us by their
variety and splendour. Sometimes they can only be compared
to the most brilliant gold and silver ; sometimes these present
tints of the richest green, blue, red, or the deepest black. The
silvery matter, which frequently gives to them so beautiful a
metallic splendour, is secreted by the skin, and is composed of a
number of small polished laminae.

519. The Skeleton of Fishes is usually bony; but amongst
several of these animals, such as the Ray and the Shark, it re-
mains permanently in a fibre-cartilaginous or cartilaginous state;
and there are even some in which this frame- work possesses still
less solidity, and remains perfectly membranous : certain Lam-
preys are in this condition ; and in this manner they form a

transition between the Vertebrated and Invertebrated animals.

The bones never have any medullary canal ; and the cartilage
which constitutes their foundation is not the same as that of the
Mammalia and Birds ; for, when boiled in water, it does not
give out any gelatine.

520. The skeleton is composed of the head, to which is

FIG. 246 — SKELETON OF THE PERTH.

joined a highly-developed apparatus which is subservient to

• 2

4 BONES OF THE HEAD OF FISHES.

respiration ; of the trunk ; and of the members. — The structure
of the head is very complicated. At first is seen a central or
median portion, composed of a great number of bones united
together by sutures, and forming a kind of immoveable keel,
with which are connected the bones of the jaw, the cheeks, &c.
This median portion, of which the general form is very nearly
that of a pyramid with three sides, having its summit directed
forwards, has at its back part the cavity of the cranium ; in
which is placed the apparatus for hearing, as well as the brain.
Its middle side is hollowed out to form the orbital cavities, or ;
and in front are seen the apertures belonging to the olfactory
apparatus, n ; and a kind of large knob, formed by the vomer,
and serving to support the upper jaw (Fig. 247.) We may dis-
tinguish the bones corresponding with the occipital, the temporal,
the sphenoid, the parietal, the frontal, the ethmoid, and the
vomer ; but most of these are composed of several pieces, which
never acquire the union that takes place at an early period
among the Mammalia and Birds. — At the anterior extremity of

-- op

FIG. 247.— Bones of the head of Pike; c, cranium; or, orbit; n, nasal cavities ; im,
intermaxillary bone ; »», superior maxillary bone ; t, lateral partition, separating gills
from mouth ; p, io, op, bones of operculum, or gill-cover.

this cranial portion of the head is placed the upper-jaw, which is
sometimes fixed there in an immoveable manner, but in general
preserves great freedom of motion ; there may be distinguished
in it on each side an intermaxillary bone, placed near the medial
line, and a maxillary bone, which extends sideways, and which
is moveable upon the first.

521. A chain of small bony pieces extends on each side, from

BONES OF THE HEAD OF FISHES. 5

the anterior angle of the orbital cavity to its posterior angle, and
thus .completes the circle of the orbit. Further inwards is
seen also on each side a kind of vertical partition, (Fig. 247 O
which is suspended to the skull, and which separates the orbits
and the cheeks from the mouth. It is formed by bones cor-
responding with the palatine, pteregoid, and tympanic bones of

Co ca ab h r

FIG. 248.— Bones of the head of the Perch, after the removal of the jaws, lateral par-
tition, and operculum, on one side, to show the interior of the mouth, and the hyoid
apparatus ; c, cranium ; or, orbit ; v, vomer (armed with teeth) ; im, superior maxil-
lary ; dp, teeth implanted on the palatine arch ; mi, lower jaw ; I, lingual bone ; b,
lateral branches of the hyoid apparatus ; s, process for the attachment of these to the
lateral partition ; r, r, branchio-stegal rays ; a, branchial arches ; ph, superior pharyn-
geal bones ; ar, articular surface by which the lateral partition is attached ; o to h, bony
framework supporting the pectoral &n,p ; o and o', scapula divided into two pieces ; h,
humerus ; ab, bone of the fore-arm ; ca, bone of the carpus ; co, coracoid bone.

the higher Vertebrata. At its under part it gives attachment to
the lower jaw; and behind it is prolonged in such a manner, as
to form a kind of moveable flap, which protects the respiratory
apparatus, and is termed the operculum or gill-cover. The
lower-jaw is formed of three pieces on each side. "Within the
lateral partitions just described, and lying at the bottom of the
mouth, is found a framework of very complicated structure,

6 BONES OP THE HEAD OF FISHES.

which serves for the support and protection of the gills, and
which appears to resemble the hyoid bone of higher animals
enormously developed (Fig. 248.) The bone of the tongue, I, is
continued backwards by a series of pieces on the central line ;
and is articulated on each side with a lateral branch of great
length and thickness, which, by its opposite extremity, is sus-
pended (as it were) to the internal face of the before-mentioned
partition. These lateral branches, formed of several bones, carry
at their lower border a series of flattened rays, r, r, curved
backwards, which unite with the opercular bones 'to complete
the walls of the branchial cavities, and which are known under
the name of branchio-stegal rays. Behind these branches we
meet with four pairs of bony arches, «, passing off from the
central portion of the hyoid apparatus. These are first directed
backwards ; then they curve upwards and inwards ; and at last
they are fixed to the base of the cranium by a series of small
connecting bones, ph, termed the superior pharyngeal. These
arches support the gills, and are thence called branchial arches.
Lastly, behind the last pair of these, at the entrance of the
oesophagus, are seen two inferior pharyngeal bones ; which are
usually so placed, as to apply themselves against the superior
pharyngeals just mentioned.

522: Such is generally the complicated structure of the bony
head of Fishes. Some anomalies, however, are occasionally
observed ; thus amongst the Sword-fishes and some other allied

species of Tunny, the upper jaw
is prolonged, so as to constitute
a kind of beak, like a spit or the
blade of a sword ; which serves
FIG. 249.— SWORD-FISH. these fish as a powerful weapon

to attack the largest marine ani-
mals. We shall not dwell here on the comparison of the different
pieces of which the head of Fishes is composed, with the bones
of the head of the Mammalia ; as there still exists much uncer-
tainty on this point:

523. The vertebral column, which immediately follows the
head, only presents two distinct portions, the one dorsal, the

BONES OF THE TRUNK OP FISHES. 7

other caudal (Fig. 246) ; for here there is neither neck nor
sacrum. The body of the vertebras has a peculiar form, being
hollowed before and behind into a conical cavity ; these two
cavities sometimes unite in such a manner, as to form a con-
tinuous passage ; and the double conical cavity, which is formed
when two vertebrae are placed together, is filled with a soft sub-
stance. The ring destined for the passage of the spinal marrow
is surmounted by a spinous process ; and on each side there is
generally seen a transverse process more or less distinct, which,
beneath the abdominal cavity, extends outwards, and is usually
united with the corresponding rib; but which, in the caudal
portion of the column, is directed downwards, and often forms
with that of the opposite side a ring, from the lower part of
which arises a long and spinous process, similar to that which is
situated on the dorsal side of the vertebras. — The ribs are some-
times entirely absent ; at other times they surround the abdo-
men, and amongst a small number of Fishes they are joined to a
series of single bones, which ought to be considered a sternum.
They often bear one or two pointed projections, which are
directed outwards, and penetrate into the muscles. There are
also, sometimes, similar processes, which spring from the bodies
of the vertebrae ; and it is thus that, in some tribes, such as
amongst the Herrings, the small bones of Fishes become very
numerous. Lastly, we find on the central line of the body a
number of bones, termed interspinous (Fig. 250), which are
usually applied against the extremities of the spinous processes

of the vertebras, and which
articulate at their opposite
ends with the rays of
the median fins. These
rays are sometimes pointed
bones, which are then term-
ed spines: but they are
sometimes ossified only at

FIG. 250.-DORSAL FIN, supported' on spiny rays, ^L- b ,1 rpmai-n^p1.

r, r, and these resting on interspinous bones,?, i. inG DaS6S> t]

being formed of a series
of little cartilaginous pieces, jointed together ; and often branch-

8 BONES OF THE EXTREMITIES OF FISHES.

ing at their summit ; these are termed articulated or soft rays ;
the caudal fin is entirely formed of them (Fig. 246) ; and some-
times there are no others.

524. The lateral fins, which represent the members, are ter-
minated by rays similar to those of the vertical fins, and analo-
gous to the fingers. In the pectoral fin are seen, at the base of
these appendages, a transverse series of four or five small bones
(c 0, Fig. 248), which are analogous to those of the carpus ; and
these, in their turns, are fixed to two flat bones, a b, which seem
to be the radius and ulna widened. This apparatus is supported
by a kind of bony girdle situated immediately behind the ears,
on which the operculum or gill- cover is fixed ; and it consists of
three bones, extending from the cranium to the hyoid apparatus,
and prolonged backwards into a pointed process. The principal
piece which enters into its composition, is that which bears the
fore-arm, and which may consequently be regarded as the hume-
rus, h ; it is united below with that of the opposite side and
with the central prolongation of the hyoid apparatus ; and it is
connected with the cranium by two bones (o, 0), which are
regarded by Cuvier as analogous to the scapula ; and lastly, the
pointed process which is prolonged over the sides of the body,
is ordinarily formed of two pieces, and may be compared to the
coracoid bone, co. — The posterior member is less complicated;
the rays of the ventral fin are only supported on a single bone,
usually of triangular form, which is frequently attached to the
central portion of the osseous girdle of the anterior member, and
which, in other instances, is merely suspended by the muscles,
having no bony connexion with the skeleton of the trunk.

525. In Cartilaginous fishes, such as the Rays and the Sharks
(of which the Dog-fish is a common species), the arrangement
of the skeleton differs from that which we have already described,
and exhibits a great resemblance fo that of the still cartilaginous
skeleton of the Tadpole. The skull is not divided by sutures,
and is only composed of a single piece ; this, however, is formed
in other respects very nearly like the skull of ordinary Fishes.
The upper jaw is formed by pieces analogous to the palatine
bones and the vomer ; the maxillary and the intermaxillary do

LOCOMOTION OF FISHES. 9

not exist, and are only found in a rudimentary state, hidden
under the skin. The lower jaw has in like manner only one
piece on each side, and the opercular apparatus is generally
altogether, wanting. The vertebral column is sometimes chiefly
formed of a single tube, pierced on each side for the passage of
the nerves, but not divided into distinct vertebra. The bodies
of the vertebrae are also frequently pierced through, so that the
gelatinous substance which fills up the intervals of these bones
forms a continued line through the whole column. The arrange-
ment of the bones of the shoulder, of the pelvis, and of the fins,
varies. Lastly, the hyoidean apparatus which supports the gills
is usually formed very nearly in the same manner as amongst
ordinary fish ; but in the lowest groups of this class (amongst the
Lampreys for example) the branchial arches are absent.

526. The greater number of Fishes swim with great agility ;
we are told that the Salmon, for example, advances sometimes
•with a rapidity of twenty-six feet in a second, and travels in
one hour the space of from twenty to twenty-five miles. In
general, it is through lateral strokes on the water, by the alter-
nate bendings of the tail and the body, that they can move in
this manner ; and the muscles which are destined to bend the
vertebral column laterally, are so developed, that they usually
constitute the greatest part of the mass of the body. The fins
on the central line, that is to say, the caudal, the dorsal, and
the anal, serve to increase the extent of this kind of oar : but
the lateral fins — the pectoral and the ventral — act but little in
progression, or forward movement ; and their principal use is
generally to influence the direction of the course, and especially
to support the animal in equilibrium.

527. A peculiarity in the organisation of Fishes, which is
a great assistance to them in swimming, is the existence of a
kind of bag filled with air, and constructed in such a manner as
to be capable of being compressed at will. This swimming
bladder is situated in the abdomen, and under the dorsal spine ;
and it usually communicates with the oesophagus, or with the
stomach, by a canal, through which the air contained in its interior
can escape ; but this fluid does not appear to penetrate into it by

10 LOCOMOTION OF FISHES.

this passage, for it rather seems to be the product of a secretion,
having its seat in a glandular portion of the walls of the reservoir
itself; and sometimes this is completely closed. By the move-
ments of the ribs, this elastic vessel is more or less compressed ;
and, according to the space that it occupies, it gives to the body
of the fish a specific gravity, equal, superior, or inferior, to that
of the water ; and thus enables it to remain in equilibrium, to
descend, or to rise, in this liquid. It has been remarked that it
is often absent, and that it is generally very small, in the species
destined to swim at the bottom of the water, or even to bury them-
selves in the mud, such as the Rays, Soles, Turbots, and Eels.

528. Amongst a small number of Fishes, the pectoral fins
have an extreme

development, and
thus permit the
animal to support
itself for some
minutes in the
air after it has
leaped out of the

FIG. 251.— DACTYLOPTERUS, ONE OF THE FLYING FISH.

water. The Dac-

tylopterus affords an example of this construction. There are
some, which, by crawling, or by repeated leaps, can advance
upon the ground. Some have been mentioned which can climb
trees ; but these examples are very rare.

529. In treating of the organs for movement amongst Fishes,
we must not omit to mention a very singular apparatus, which
is seen in some of these animals, and which enables them to

adhere with great firmness to foreign bodies.
This is a flattened disc, which covers the upper
part of the head, and which is composed of a
certain number of cartilaginous and moveable
plates, directed obliquely backwards (Fig. 252).
The Fish of the genus Echineis are the only
FIG. 252.— SUCKING- species which present this mode of organisation ;
»FTHEREMORA.aild one of fl^ which liveg in the Mediter-
ranean and in the Atlantic, and which has been for a long time

NERVOUS SYSTEM OP FISHES.

11

FIG. 253— REMORA.

celebrated under the name oiRemora^or Sucking-Fish, (Fig. 253)
has been the subject of many amusing and absurd fables.

It has been pretended that
this small fish supports
itself by a kind of suction
through the disc just de-
scribed ; and the power of
stopping a large vessel in
rapid progress has been attributed to it. A species allied to
the preceding is very common in the waters of the Isle of
France ; and it appears that, upon the coasts of Cafiraria, it is
employed in fishing, by allowing it to pursue fish, and then
drawing it back, by means of a line attached to its tail, as soon
as it has fastened itself upon its prey.

530. The life of a Fish is passed almost entirely in seeking
its subsistence, and in flying from its enemies. Its external
senses only appear to give it a few obtuse impressions ; and its
faculties are more or less limited. It shows no industry, nor
any remarkable instinct ; its brain is very slightly developed,
and its organs of sense are very
imperfect. The cavity of the
skull is small compared to the
size of the body ; and the brain
does not nearly occupy it. Be-
tween its sides and the brain is
found a spongy and fatty mass
of a considerable size, particu-
larly in adult individuals. The
lobes which compose the brain
are placed in a row, one behind
the other ; in front we see the
olfactive ganglia, o/, often sepa-
rated from the rest by a pedun-
cle or foot-stalk ; next the cerebral hemispheres, ch ; then the
optic lobes, op, which are often larger than the preceding ; then
the cerebellum, ce ; and, behind all these parts, the lobes belong-
ing to the medulla oblongata, sp.

F;o. 254.— BRAINS OF FISHES.
. A, Cod ; B, Shark.

12 ORGANS OF SENSE OF FISHES.

531. The nature of the integuments of Fish necessarily
renders their sense of feeling very imperfect ; and deprived as
they are of prolonged members, and particularly of flexible
fingers adapted to take hold of objects, it is only by means of
their lips that they can exercise the sense of touch. The fila-
ments which are often seen around the mouth, appear to inform
them of the contact of bodies. The sense of taste must also be
very nearly absent ; for their tongue is scarcely moveable, and
is not fleshy ; it receives very few nerves, and the food never
remains long in the mouth. The apparatus for smelling is of a
much more complicated structure ; but is not arranged so as to
allow either air, or the water serving for respiration, to pass
through it. The nasal fossa only consists of two cavities, closed
at the back ; each generally opens outwards by two nostrils,
and is furnished by a pituitary membrane folded in a very
remarkable manner. The ear is nearly always placed completely
within the cavity of the skull, upon the sides of the brain ; and
simply consists of a vestibule surmounted by three semicircular
canals, at which the sonorous undulations can only arrive after
having put into vibration the common integuments and the bones
of the cranium. In general we see nothing that can be compared
to the external ear, to the membrana tympani, or to the drum.
Lastly, the eyes are very large and nearly immoveable ; they
have no true eyelids, nor lachrymal apparatus. The skin is
continued over the eye, and is thin enough to be traversed by
the light. The cornea is almost flat ; the pupil very large, and

but little or not at all contractile ;
and the crystalline lens is sphe-
rical. These organs generally
do not usually present any pe-
culiarity as to their position ;
but amongst some fish there is
a remarkable anomaly. Thus,
amongst the Soles, Plaices,
Turbots, and other flat-fish,

they are not placed as usual on both sides of the head, but
are both situated on the same side ; and this kind of mon-

TEETH OP FISHES.

13

FIG. 256. — HEAD OF SHARK.

strosity coincides with a defect of symmetry in other parts of
the body.

532. Fishes are very voracious ; there are only a few which
live principally on vegetable matter ; and generally they swallow
without any selection all the small animals which come within

their reach. Some
species are destitute
of teeth, but amongst
the greatest part,
they exist in several
rows, as in the mouth
of the Shark, for
example ; and they
are more commonly
found, not only in
the two jaws, but also on the palate, implanted on the vomer
and palatine bones, — on the tongue, — upon the interior edge of
the branchial arches, — and even in the back of the mouth upon
the pharyngeal bones, which surround the entrance of the oeso-
phagus. They have never any roots, but are fixed to the bones
which support them ; they fall off nevertheless — probably by a
mechanism analogous to that of the fall of the horns of the stag
— and are replaced by new teeth, which arise sometimes beneath,
sometimes by the side of the old ones. The teeth with which
the jaws are armed, only serve, in general, to hold or to crush
the prey ; those situated at the bottom of the mouth are rarely
(in existing fishes at least) disposed in such a manner as to
reduce it. Their form varies very much ; sometimes they are so
fine and closely set, that they present the appearance of velvet ;
whilst in other instances they constitute strong hooks, plates
with cutting edges, or rounded tubercles.

533. There are some Fish which are not supported on solid
matter, and which live only by sucking the liquids which they
draw from the bodies of other animals ; the Lampreys are an
example of this. Their mouth, instead of having the usual
arrangement, presents a very singular structure, but one which
is in complete accordance with its functions. The cartilages,

14 ORGANS OF NUTRITION OF FISHES.

which amongst the Rays, &c. form the jaws, are here united into
rings, and support a fleshy disc, the surface
of which is furnished with teeth, whilst
its centre is occupied by the mouth. The
tongue also is supplied with teeth, and
moves forwards and backwards like a
W m? I Piston» so tnat tne animal can make use
of this apparatus, either to fix itself upon
FIG. 257.-MOUTH OF THE ailother body, or to pump up the fluids on

LAMPREY. ' '

which it is supported.

534. The mouth is not surrounded by any salivary gland.
The oesophagus is short ; the stomach and the intestines vary in
size and form. The liver is generally large, and of a soft tissue ;
the pancreas is nearly always replaced by peculiar ccecal appen-
dages placed around the pylorus ; the position of the anus varies
much ; sometimes it is found under the throat, at other times
under the tail. The kidneys are extremely large, and extend
themselves on both sides of the vertebral column, through the
whole length of the abdomen. Their excretory passages end in
a kind of bladder, whose external opening is placed immediately
behind the anus and the orifice of the reproductive organs. The

-digestive process appears to be performed very rapidly ; and the
chyle is absorbed by numerous lymphatic vessels, which empty
themselves by several trunks into the venous system near the
heart.

535. The blood of Fishes, as already mentioned, is red ; and
the globules have an elliptical form, and are of considerable
dimensions. The heart is placed under the throat, in a cavity
divided from the abdomen by a kind of diaphragm, and protected
by the pharyngeal bones above, by the branchial arches on the
sides, and in general by the humeral girdle behind. It is com-
posed of one auricle, which receives the venous blood collected
into a large sinus situated in its neighbourhood ; and of a ven-
tricle placed beneath it, and giving rise at its anterior extremity
to a pulmonary artery, which is swollen out at its origin into a
contractile bulb. This vessel soon divides into lateral branches,
which are distributed to the gills ; and the blood, after having

CIRCULATION OF FISHES.

15

traversed these organs, passes towards the head by another
vessel, which in like manner runs along the edges of the branchial

Branchial Artery

"\
Arterial Bull ^

Ventricle-.^
Auricle •••-,...
Venous Sinus*

Vena Porta, Liver, &C.-;— _-

Intestine

Vena Cavp..-

Vessels of the Gills

-Dorsal Artery

—-Kidneys

Dorsal Artery or Aorta-

FIG. 258.— CIRCULATING APPARATUS OF FISH.

arches. These canals then send out some branches to the
neighbouring parts, and are united together again to form a large
dorsal artery, which passes backwards, beneath the vertebral
column, and spreads its ramifications to all parts of the body.

16 RESPIRATORY APPARATUS OF FISHES.

Finally, the venous blood is not all directly returned into the
sinus, which we have before mentioned ; for that of the intes-
tines and of some other parts, before being sent back into the
heart, is distributed by the portal vein through the liver. We
see, then, that the blood, in passing through the circle of the
circulation, entirely traverses the respiratory apparatus, as
amongst the Mammalia and Birds ; but in this course it only
passes once into the heart, which consequently renders its pro-
gress much slower. The heart itself corresponds in its functions
to the right half of the same organ amongst the higher Yertebrata.

536. The Respiration of Fishes is effected by means of the
air dissolved in the water ; and takes place at the surface of a
multitude of projecting and very vascular membranous plates,
fixed on the external edge of the branchial arches, the position of
which has been already pointed out. In general there are on either
side four gills, each composed of two rows of lengthened plates.
In several of the Cartilaginous fishes, there are five, and in the
Lamprey we find seven. Amongst nearly all the Osseous fishes

these plates are simple, and
fixed at the bottom only; in
a small number, such as the
Hippocampus^ commonly call-
ed Sea Horse, they are, on

FIG. 259.— HIPPOCAMPUS. .- , ,

the contrary, rammed, and

somewhat resemble bunches of feathers. Lastly, amongst the
greater part of the Cartilaginous fishes, such as the Rays and
Sharks, they are fixed to the skin by their external edges, as
well as to the branchial arches by their internal.

537. The water necessary for respiration enters into the
mouth, and by a movement of deglutition is forced through the
openings which exist between the branchial arches, and thus
arrives at the gills ; after bathing the surface of these, it escapes
outwards by the opening of the gills. "We see, in fact, the
animal alternately opening the mouth, and raising its operculum.
Amongst those fish whose gills are free at their external edge, it
is sufficient to have one of these openings on each side ; but when
the gills are fixed, it is necessary for the exit of the water to

RESPIRATION OP FISHES. 17

have an opening for every one of the spaces between the gills.
Thus, in the Shark we find five, and in the Lamprey (Fig. 285)
seven pairs. We can therefore know the arrangement of the
respiratory apparatus, by the single inspection of its external
openings. It is also observed that amongst some fishes, the
water does not pass directly from the mouth into the respiratory
cavity by the openings situated between the branchial arches,
but arrives there by a canal situated beneath the oesophagus,
something like the trachea of the higher animals ; the Lampreys
show this kind of structure.

538. Fish consume but a small quantity of oxygen ; some,
however, are not satisfied with that which is dissolved in the
water, and come to the surface from time to time to breathe
air. There are even some which make use of it by swallowing it,
and converting its oxygen into carbonic acid as it passes along
the intestine ; the Loach of our ponds shows us an example
of this singular phenomenon. When fish remain out of the
water, they die in general very quickly from asphyxia; not
because they want oxygen ; but because the branchial plates,
being no longer supported by the water, fall together, and thus
cannot so easily be traversed by the blood ; and because these
organs, when dried up, become unfitted to perform their func-
tions. Thus, the fish that perish the most rapidly by exposure

to the air have their gill-
openings very wide, which
facilitate the evaporation
at the surface of the gills ;
whilst those which resist it
the best, have very small
apertures, or else possess
some receptacle, where
they can preserve sufficient
water to moisten these
organs. The different fish

FIG. 260. — RESPIRATORY APPARATUS OF ANABAS. o

which compose the family

of the Labyrinthiform Pharyngeans, are very remarkable in
this respect, and owe their name to the cellular reservoirs of

18 RESPIRATION AND HEAT OF FISHES.

water placed above their gills. These reservoirs, situated under
the operculum, and formed by the plates of the pharyngeal
bones, effectually serve to retain a certain quantity of water,
which keeps the gills moist when the animal is in the air, and
enables it to live there for some time : hence these fish are
accustomed to leave the rivers and ponds, which are their usual
abode, and convey themselves to considerable distances by
crawling in the grass or on the ground. Those which present
this labyrinthiform apparatus in its highest degree of complica-
tion, and which have received the name of Anabas, not only

FIG. 261.— ANABAS.

remain very long out of the water, but can even, we are told,
climb up trees. The greater part of the fishes of this family
inhabit India, China, and the Moluccas. One species, the
Gourami, which originally belonged to China, and which is
much esteemed for its savoury flesh, has been naturalised in the
ponds of the Isle of France and of Cayenne.

539. As already stated, Fishes produce scarcely any heat ;
that is, their temperature is usually but little above that of the
medium they inhabit. The Tunny, Sword-fish, and their
allies, however, constitute an exception to this rule ; for they
are able to sustain a fixed temperature of about 90° ; and they
are distinguished from other Fishes by the greater redness of
their blood, which results from the larger proportion of red
corpuscles. Several of this class have the singular power of
developing Electricity, and of giving very strong shocks to the
animals which touch them. The Torpedo, the Silurus or
Malapterurus, and a species of Gymnotus, are thus constituted;
and it is a remarkable thing that the electrical organ presents a
very different conformation in each of them.

ELECTRICAL PISHES; — GYMNOTUS. 19

540. It is the Gymnotus, or Electric Eel, which possesses
this curious power in the highest
degree. It inhabits Southern
America ; and very much resem-
bles ordinary Eels, except that
it has no fins at the end of its
tail, and that its skin is without
any visible scales. This fish at-
tains about six feet in length ; its
body is long, and of uniform size,
and its skin is covered with a
viscid matter. It is very com-

., ,, , FIG. 262. — GYMNOTUS.

mon m the small streams and

pools, which are met with here and there in the immense plains
situated between the Cordilleras, the Orinoco, and the Banda-
Orientalis of South America ; and we find it also in the rivers
Meta, Apure, and Orinoco. — The electric shocks which it gives
at pleasure, and in any direction that it chooses, are sufficient
to overcome men and horses ; and the Gymnotus has recourse to
this means to defend itself against its enemies, and to kill at a
distance the fish that it wishes to eat ; for water, as well as
metals, transmits the benumbing shock of this singular animal, —
in the same manner as lightning-conductors convey the elec-
tricity of the clouds from the atmosphere to the ground. Its
first discharges are in general weak ; but when it is irritated
and agitated, they become stronger and stronger, and are then
terrible. When it has thus struck repeated blows, it becomes
exhausted, and requires rest, for a longer or shorter time, before
it recovers its power of giving fresh shocks. We are told that it
employs this time in reloading its electrical organs, and that
the Americans profit by this circumstance to take it without
danger. In order to do this, they drive wild horses into the
ponds inhabited by these fish ; which, receiving their first shocks,
are soon stunned and overcome, or even killed ; they then seize
the exhausted Gymnoti with nets, or with harpoons.

541. The apparatus by which the Gymnotus produces these
disturbances lies along the back of the tail, and consists of

c 2

20

ELECTRICAL APPARATUS OF TORPEDO.

four longitudinal bundles, composed of a great number of parallel
membranous plates very closely approaching each other ; these
are nearly horizontal, and are united by an infinite number of
other smaller plates placed vertically throughout. The small
prismatic and transverse cells formed by the union of these plates,
are filled with a gelatinous matter ; and the whole apparatus
receives very large nerves.

542. The Torpedo is a flat cartilaginous fish, very much re-
sembling the common Rays. Its body is smooth, and represents

FIG. 263. —COMMON
TORPEDO.

FIG. 264.— ELECTRICAL APPARATUS OF THE TORPEDO :— c, brain ; me, spinal cord ;
o, eye and optic nerve ; e, electric organs ; np, pneumo -gastric nerves, proceeding to
the electric organ ; nl, branch from the preceding, covering the lateral nerve; n, spinal
nerves ; b, gills.

very nearly a circular disc, whose anterior border is formed by
two prolongations of the snout, which go on each side to join

ELECTRICITY OP TORPEDO AND MALAPTERURUS. 21

the pectoral fins ; leaving between these organs, and the head
and gills, an oval space, in which is placed the electrical
apparatus of these fish. This apparatus is composed of a
multitude of membranous vertical tubes, pressed one against
the other, like the cells of bees, and subdivided by horizontal par-
titions into small cells filled with mucous matter ; it is supplied by
several very large branches of the pneumo-gastric nerves. It is in
these singular organs that the electricity is produced, by which the
Torpedo can give violent shocks to those who touch them, and
produce the same phenomena which in physical experiments
result from an ordinary electric current ; such as sparks, che-
mical decompositions, &c. These fish are less powerful than the
Gymnotus ; but can nevertheless strike with sufficient force to
benumb the arms of those who touch them ; and it is pro-
bably by this means, that they seize their prey. It has been
ascertained that this property is dependent on the posterior lobe
of the Encephalon; and that by destroying this lobe, or by cutting
the nerves which spring from it, the power of producing these
shocks is destroyed. Several species exist in the seas which
wash the shores of Europe.

543. The electrical Silums or Malapterurus inhabits the Nile

FIG. 265.— ELECTRIC MALAPTJSRURUS.

and the Senegal ; its length is from about ten to fourteen inches ;
and it appears to derive the power of giving electrical shocks
from a particular tissue situated between the skin of the sides
and the muscles, and having the appearance of a laminated
cellular tissue. The Arabs give to this fish the name of Raasch,
which signifies thunder.

544. Fishes multiply by means of eggs ; and the number of
these is sometimes immense, several hundred-thousands being
often produced at a time. In general they have only a mucila-

22 MIGRATIONS OF FISH.

ginous envelope, and are fertilized after they are laid. Some of
these animals are, on the contrary, ovo- viviparous ; but whatever
may be the manner in which the young fish are brought into
life, they are from the moment of their birth completely aban-
doned to themselves, and many of them perish during the early
period of their existence. There are a few species, however,
such as the Gobies, which make regular nests for their young,
composed of sea-weed ; and tend them with great care.

545. It is to the simultaneous development of an incalculable
number of eggs deposited in the same place, and to the instinct
which induces different fish to follow each other, that we are to
attribute the union of certain species in immense and closely-
packed legions, called by fishermen shoals offish. We can hardly
term these unions, societies ; the individuals of which they are
composed do not assist one another ; the same wants to be satis-
fied keep them in the same locality, or remove them from it ;
and if we see them occasionally following an individual as a
guide, it is probably the consequence of a tendency to imitation,
which always accompanies the first dawnings of intelligence.

546. However it may be, these animals, thus united in
troops, often make long journeys, sometimes to gain the sea,
sometimes to ascend rivers or to change their climate. Certain
fish lead an almost sedentary life, and remain always in the
locality where they were produced ; others are always wander-
ing, and a great number of these animals periodically make
journeys of greater or less length. At the time for spawning,
they generally approach the coasts or enter the rivers ; and in
this manner they sometimes effect an extremely long passage.
Every year, towards the same period, large numbers of migrat-
ing fish arrive in the same places ; and it is generally believed
that several of these species regularly migrate from the north
towards the south, and from the south towards the north, fol-
lowing a determined route ; but perhaps it would be more true
to believe, that when they disappear from the shores, they only
retire into the greater depths of the sea. The Herring is one
of the most remarkable fishes in this respect, as well as the most
celebrated on account of the importance of the fisheries of which

MIGRATION OP HERRINGS. 23

it is the object. It inhabits the northern seas, and arrives every
year in innumerable legions upon different parts of the coasts of
Europe, Asia, and America, but never descends below the 45th
degree of north latitude. Some naturalists think that all these
shoals of herrings periodically retire beneath the ice of the polar
seas, and set out from this common retreat in an immense
column, which, by subdividing itself, is spread out over nearly
all the coasts situated above the parallel which we have men-
tioned. They have even gone so far as to trace upon the chart
the journeyings of these shoals ; but this long migration, and
this common rendezvous in the arctic regions, are far from being
demonstrated ; and there is reason to believe that these events
do not take place in this manner. It is very near our coasts
that the herrings deposit their eggs, and it is probable that the
young very soon retire into the depth of the sea, and there
direct themselves towards the north, where they meet in great
abundance with the small Crustacea and Animalculae, which are
fitted to serve them as food. In the spring, other wants bring
them towards the shore, and cause them to seek shallower and
warmer water. They collect themselves into immense shoals, and
descend towards the south ; but after having arrived in the Baltic,
upon the coasts of Holland, and even as far as Brittany, we do not
see them retake the route to the north, to pass the winter
under the ice of the pole, and to recommence in the following
spring their pretended periodical journey.

547. However this may be, in the months of April and
May, Herrings begin to show themselves in the waters of the
Isles of Shetland ; and, towards the end of June and July, they
arrive there in an incalculable number, forming large shoals,
which sometimes cover the surface of the sea to an extent of
several leagues, and which are several hundred feet in thickness.
Soon afterwards, these fish are spread along the coasts of Scotland
and England. During the months of September and October,
they give place to larger fish ; and from the middle of October
until the end of the year, they abound on the north coast of
France, principally from the Straits of Calais to the mouth of
the Seine. In July and August, they generally remain in the

24 MIGRATIONS OP HERRINGS AND SALMON.

open sea ; but they then come into shallower water, and seek a
convenient place for laying their eggs, where they remain until
towards the month of February. The older Herrings deposit
their spawn the first, and the younger ones afterwards; but
temperature and other circumstances also appear to have some
influence on this phenomenon ; for in particular localities, we
find eggs during nearly the whole year. After this period they
are thin and but little esteemed; fishermen then call them
" shotten herrings." Their multiplication is prodigious ; there
have been found more than sixty thousand eggs in the abdomen
of one single female of moderate size. We are told that their
spawn sometimes covers the surface of the sea for a great extent,
and at a distance appears very much as if saw-dust had been
spread tbere. Very little is known of these fish at an early
period.

548. The Pilchard, the Mackerel, the Tunny, and the
Anchovy, are also Fish of passage, which periodically visit the
coasts, and give rise there to important fisheries. The Salmon
is equally remarkable for its voyages : it inhabits all the arctic
seas, and every spring it enters the rivers in large numbers, and
ascends nearly to their source. In these migrations the Salmon
follow a regular order ; forming into two long files united in
front, and conducted by the largest female, who commences the
march, whilst the smaller males form the rear-guard. These
troops generally swim with a great noise in the middle of the
stream, and near the surface of the water, if the temperature is
mild, but nearer the bottom if the heat is great. In general
the Salmon advance slowly and by leaping ; but if some danger
appears to threaten them, the rapidity of their swimming is so
great, that the eye can hardly follow them. If a dyke or a
cascade opposes their progress, they make the greatest efforts to
overcome it. By supporting themselves against a rock, and
violently bending their body in a bow, they throw themselves
out of the water, and jump sometimes to a height of from 10 to
16 feet into the air, so as to fall again clear of the obstacle
which impeded them. The Salmon thus ascend rivers nearly to
their source ; and then seek in the small streams and quiet places a

MIGRATIONS OF SALMON. FISHERIES. 25

bottom of sand and gravel, fit to deposit their eggs. Afterwards,
when thinned and weakened by so much fatigue, they descend
in autumn to the mouth of the river, in order to pass their winter
in the sea. The eggs are deposited in a hole, which the female
digs in the sand. The male then comes to fertilise them. The
young Salmon grow very quickly ; and when they have attained
to about the length of a foot, they leave the rivers to proceed to
the sea, which they quit in turn to enter the streams, when they
have attained the length of 16 or 18 inches, which is towards
the middle of the summer that follows their birth. We have
already seen that the Swallows, which at the approach of the
cold season migrate towards the south, every year return into
the same places. It appears that the Salmon has the same
instinct. To ascertain this, a naturalist, named Deslandes, placed
a ring of copper on the tail of twelve of these fish, and set them
at liberty in the river Auzou, in Brittany. Soon afterwards
they all disappeared ; but the following year, five of these
Salmon were caught in the same place ; the second year, three ;
and the year after, three more.

549. The habits of Fish show but few curious peculiarities ;
but the history of these animals ought nevertheless to interest
us, if only on account of the fisheries to which they give origin.
At a period which is not very far removed from our own, this
branch of industry occupied a fifth of the population of Holland ;
and for the herring-fishery alone, that country covered all the
northern seas with its vessels. In England it has supported a con-
siderable number of good and hardy sailors ; and even in France,

where it has less
importance, there
are computed to be
thirty or forty thou-
sand fishermen, of
which nearly a third

FIG. 266— COD.

venture every year

as far as Iceland and Newfoundland to seek for the Cod, a large
and excellent fish, which abounds in those parts of the sea, and
which is found also, in a comparatively small number, in our
own seas.

26 CLASSIFICATION OP FISHES.

550. The classification of Fishes most generally received is
that of Cuvier, who made this group his peculiar study. It is
founded upon the condition of the skeleton, and upon the struc-
ture and arrangement of the fins. The first division of the class
is into the Osseous and Cartilaginous Fishes ; and this division
has reference, not merely to the quantity of earthy matter in the
skeleton, but to the number of pieces of which the jaws are
composed. Although the Osseous Fishes are in many respects
the most elevated in the scale, and have the most elaborately-
constructed mouth, yet many of the Cartilaginous Fishes surpass
them in the development of the cerebral hemispheres, which is
probably to be regarded as a measure of their comparative intel-
ligence (ANIM. PHYSIOL. § 452) ; and we find in many of the
latter group, also, a curious modification of the reproductive
apparatus, which enables the young animal to derive continued
assistance from its parent. Yet it is in this group, also,
that we find the very lowest members of the class, in which
the vertebrated structure is almost completely lost sight of
(§ 519). Thus we may regard the Osseous and Cartilaginous
Fishes as forming two parallel series, neither of which can be
regarded as above or below the other. Both are connected with
the class of Reptiles by some very curious links.

55 1 . The sub-class of Osseous Fishes is divided in the first
instance into the groups ACANTHOPTERYGII, or spiny-finned, and
MALACOPTEBYGII, or soft-finned^ Fishes. In the former, the
first portion of the dorsal, or the first dorsal fin (when there are
two) always have spinous rays (§ 523) ; of which there are also
some in the anal, and at least one in each ventral. In the latter,
all the rays, with the occasional exception of the first dorsal or
the pectorals, are soft or jointed. The Acanthopterygii cannot
be easily again subdivided, except into families ; but the Mala-
copterygii may be divided into three orders, according to the
position of the ventral fins. If these are situated under the
abdomen, the fishes are Abdominal ; if attached to the shoulder,
they are Sub-brachial ; and if wanting, they are Apodal. Each
of these orders, especially the first, contains numerous families.

552. The sub-class of Cartilaginous Fishes is primarily

CLASSIFICATION AND DISTRIBUTION OF FISHES. 27

divided into those having the extremities of the gill-filaments
unattached (as in Osseous Fishes); and those having them
fixed. The former group constitutes but a single order; but
the latter is again subdivided into those which have the jaws
moveable and adapted for mastication ; and those which have
them soldered into a ring for suction. The latter are termed
Cyclostomi, or circular-mouthed Fishes.

553. The following Table will perhaps enable this arrange-
ment to be more easily understood. "We shall presently find,
however, that there are one or two small groups not included in
it, which are separated from the rest by characters so remark-
able, as perhaps to entitle them to be ranked as distinct orders.

CAcanthopterygii, spiny-rayed ........... Acanthopterygli.

/'ventral fins beneath "
abdomen . . . .

Malacoplerygii, soft-rayed ™J^J« beneath Sub-brachiati.

^without ventral fins Apoda.

("gills free ........... Sturiones.

CARTILAGINOUS ...... < .,, fi A /jaws moveable . Plagiostomi.

Lgl1 d I jaws soldered . . Cyclostomi.

554. The class of Fishes is probably the most numerous of
the whole Vertebrated series, both in regard to the number of
families, genera, and species which it contains, and in regard to
the number of individuals of the same species. The structure of
a very large proportion of it has been but very imperfectly
investigated; and of the habits of these animals still less is
known. Instead, therefore, of giving a technical description of
every family, such as will be found in Systematic Treatises on
Zoology, we shall confine ourselves to a notice of those groups
which are of most general interest, either on account of pecu-
liarities in their structure, or their importance to Man. It has
been calculated that, exclusive of lakes and rivers, the seas
occupy full seven-tenths of the earth's surface. These seas yield
food even to the depth of several hundred feet ; and, as there is
no obstacle in the water to bar the movements of Fish, we see
that their pasture-grounds are almost unlimited in extent.
Different tribes are formed to inhabit different situations ; thus
we have some Fish adapted to live in fresh-water only, — others

28 DISTRIBUTION OF FISHES. — FAMILY PERCID^K.

which can only live in salt-water, — and others, again, which can
pass from the one to the other without inconvenience. Of fresh-
water fishes, some are the inhabitants of rivers, others of lakes,
whilst others prefer small streams. Of the marine fishes, some
keep near the shore, whilst others pass most of their lives in the
open sea ; some, again, float near the surface ; whilst others
never rise much above the bottom. It is probable that we might
regard the deeper parts of the ocean as divided (so to speak)
into strata^ each tenanted by certain species of fish ; for it is
quite certain, that there is a particular range of depth, in which
each species is usually found, and beyond which it seldom strays,
either towards the surface or the bottom of the ocean. It is
among the Fishes of shallow waters, and those which habitually
tenant the higher stratum of the deep seas, that we find the
most beautiful display of colours ; those of deep waters are for
the most part comparatively dull in tint. This difference is
probably due to the absence of light, which seems necessary to
the development of the most brilliant colours ; for the dimi-
nution in the intensity of the sun's rays, as they traverse water,
is very rapid. What may be the absolute depth of water, at
which all light ceases, and death and darkness reign, we have
no direct means of ascertaining. It varies, of course, with the
latitude ; since, the more obliquely the sun's rays fall upon the
water, the less will be the depth to which they will penetrate.

ORDER I.— ACANTHOPTERYGII.

555. Of this Order, one of the principal families is that of
PERCIDJE, or Perches; of whicli the common Perch of this
country may be taken as an example. In this group, the body
is oblong, and covered with hard or rough scales ; and the oper-
cular bone is edged with spines or small teeth, which do not,
however, extend over the cheek. The Perch is one of our most
common fresh- water fishes, abounding in rivers, lakes, and
ponds, especially such as are clear, and lurking under the banks,
or swimming near the surface. It is spread throughout the

PERCIDJE, OR PERCH TRIBE. 29

whole of temperate Europe, and is even found in Lapland ; other
species are found in America, and in the tropical parts of the
Old World. The food of the Perch consists of insects, worms,
and small fishes, which it devours with great voracity ; and it
may be rendered sufficiently tame, to take these from the hand.
Like the Carp, it is very tenacious of life ; and will live for
many hours if packed in wet moss, and occasionally refreshed
with water. The Basse is a marine fish, nearly allied to the
Perch in its general structure ; it is found on the whole line of
our southern coast ; and associates in shoals, which at the spawn-
ing time frequent the mouths of rivers, and even advance up the
stream to a considerable distance. It will not only live but
thrive in fresh- water, if well supplied with food ; which, in its
natural haunts, consists of small fishes and crustaceans. In
these, and other species, the ventral fins are placed immediately
beneath the pectoral (Fig. 246) ; and Fish in which this arrange-
ment exists, are characterised as thoracic. — Other Percidas, how-
ever, have the ventrals situated upon the throat, further forward
than the pectorals ; such are said to be jugular. In this group
we find the Trachinus or Weaver, which has the first ray of the
dorsal fin extended into a very long spine, and has also a strong
spine on each operculum. This fish lies in the mud, and inflicts
severe wounds with its dorsal spine, which the fishermen believe
to have a poisonous power ; the bad character of the wound,
however, merely results from the rugged nature of the instru-
ment which inflicts it. Something of the same kind is the case
with the Perch ; the sharp spines in its dorsal fin having been
known to lacerate the fingers of those who handle them incau-
tiously.— Another curious genus of this second group is the
Uranoscopus, or Star-gazer ; so called because the eyes are situ-
ated on the upper surface of the nearly cubical head, and directed
towards the heavens. "Within the mouth, behind the tongue, is
a long narrow slip, which the fish can protrude ; and which
serves as a bait to attract the small fishes on which it preys,
whilst it is itself concealed in the mud. One species inhabits
the Mediterranean ; but none of the others are eaten. — A third
division of the Percidse comprises those which are abdominal,

30 PERCIDyE, OR PERCH TRIBE. GURNARDS.

having the ventral fins behind the pectorals. This group in-
cludes the genus Polynemus, which is characterised by the very
curious extension of the rays of the pectoral fins into long fila-
ments, which hang loosely on each side of the body, being some-
times prolonged to twice its length, and giving it a very beautiful
appearance. The fishes of this genus are found in the seas and
rivers of tropical countries ; they are usually very brilliant in
their colours ; and they are regarded as most delicious articles of
food. The Mango-fish of the Ganges is a species of this genus ;
as is also the Suleah-fish of Bengal, to which attention has
recently been directed, as affording in its air-bladder a large
supply of excellent isinglass. — Besides the foregoing, there is a
group of Percidse, in which the ventral fins are placed still fur-
ther backwards ; these are for the most part marine fishes, some
of them inhabiting our own coasts, and others of larger size being
natives of tropical seas. Among the former is the Mullus or
Surmullet; which has been in great repute among epicures from
the time of the Romans, who used to feast their eyes upon the
changes of colour which the Red Mullet undergoes in dying,
before they devoured its flesh. This genus is quite distinct
from that of the Mullets properly so called. Of the tropical
species one of the most remarkable is the Barracuda, a large
and voracious fish, which is nearly as much dreaded in some
places as the Shark ; it is, however, a very palatable article of
food.

556. The next group includes a large number of Fishes
nearly allied to the Perches, but having the head defended by
spines and hard scaly plates. First among these we may men-
tion the Triglce or Gurnards ; of which we have several species
on our own coasts ; they are known by the squared form of their
heads, which are covered with bony plates. The pectoral fins
are usually large ; and in an allied genus, the Dactylopterus, or
Flying Gurnard, they are of sufficient size to support the
animal for a time out of the water (Fig. 250). The Gurnards
emit a curious grunting or croaking noise at intervals, when
taken out of the sea ; and this they continue for some time.
They are very tenacious of life; and mostly swim near the

HARD-CHEEKED ACANTHOPTERYGII. SQUAMIPENNES. 31

bottom of the water. The swimming-bladder is usually large,
and furnished with powerful muscles for its compression. To
this group also belongs the genus Cottus, or Bull-head, which
has a large and horizontally-flattened head, eyes looking upwards,
and its skin almost destitute of scales, and of a dusky hue : it
lurks among stones in the beds of rivulets ; and its food consists
of aquatic insects or small worms. The Scorpcena, or Hog-fish,
has the head flattened sideways, and armed with spines ; it is
a marine fish, associating in shoals, and haunting the rocky
shores. Allied to this is the Sebastes, or Norway Haddock, which
inhabits the northern seas, and is an important article of food ;
the Greenlanders use its long spines as needles. Also belonging
to this group is the Gasterosteus, or Stickleback, of which there
are several species, some inhabiting salt water, and others fresh.
The body has no proper scales, but is more or less plated at the
sides ; and the abdomen is covered by a sort of cuirass, formed
by a union of the pelvic and humeral bones. The common name
of these fish is derived from the circumstance, that instead of
possessing two dorsal fins, it has only one, the anterior being
replaced by a set of sharp spines varying in number ; whilst the
ventral fin is in the form of a sharp spine without any rays.
These fishes are active and rapacious, attacking other fishes with
great ferocity, and devouring almost any small animal that
comes within their reach. The Fifteen-spined Stickleback has
been seen to undergo remarkable changes in its hue, under the
influence of terror.

557. We may pass over the SCI^NID^:, or Maigres, and the
SPARID^E, or Sea-Breams, to notice the SQUAMIPENNES, or Scaly-
finned fishes ; which are thus designated, from the soft, and even
the spiny, portion of the dorsal fins being so covered with scales,
as not to be easily distinguished from the rest of their bodies.
The body, too, is usually itself much compressed, or flattened
laterally. The Chcetodons, which constitute the types of this
family, are beautifully-coloured fishes of singular figure, abound-
ing in the seas of the hotter climates. Their most common tints
are black and yellow ; but metallic blues and greens are not
unfrequent. Sometimes the colours are disposed in spots ; but

32 CJLETODON. SCOMBERIDE.E, OR MACKEREL TRIBE.

mostly in stripes or bands. They generally haunt rocky shores;
and their flesh is considered excellent food. One species of this
genus, the Chcstodon rostratus, is remarkable for the manner in
which it obtains its insect prey, by shooting drops of water from
its long snout, so as to bring them down within its reach.
Another fish of the same family, called the Archer, will in this
manner shoot drops of water to the distance of three or four feet,
rarely missing its aim. These fish inhabit the seas around
Java; and other species are found in different parts of the
Indian seas.

558. The next family, SCOMBERIDE^E, or the Mackerel
tribe, is one of the greatest importance to Man, from the large
supply of wholesome and palatable food which it affords
him. It consists of a number of species varying consider-
ably in size ; but distinguished by possessing a smooth
skin, covered with a multitude of small scales; and by
having a large and vigorous tail and caudal fin. They are
divided into several groups, according to the form of the fins,
tail, &c. In the first of these are associated the common
Mackerel^ the Tunny, and others, which are distinguished by
having the hinder rays of the dorsal and anal fins separated
into small fins. The Mackerel is remarkable for the beauty
of its colours, in which it is almost pre-eminent among British
fishes ; and for the rapidity with which it dies and becomes
tainted, when removed from the water. The periodical
appearance of large shoals of this fish upon our coasts, was
formerly imputed to its migration from north to south. But
many facts are opposed to this idea; and there can be little
doubt that it is an inhabitant of the deeper parts of the seas
around our island through the whole year, and that its appear-
ance on our coasts is solely due to its seeking the shore, for the
purpose of depositing its spawn. It is during the months of
May and June that this takes place ; and these months, there-
fore, constitute the most active season for Mackerel fishing.
This fish is most abundant on the southern coasts of England ;
but instances have been mentioned, in which large shoals have
been met with even off the coast of Greenland. — The Tunny is

FAMILY SCOMBERlDE^E j — TUNNY, SWORD-FISH. 33

a rare fish on the shores of Britain ; but it is very plentiful in

the Mediterranean, and has been
known and celebrated from the
remotest period of antiquity, at
which we have any mention of
Fish by particular names. It is a

FIG. 267.— TUNNY. „ , ' , . „ . ,.

far larger and stouter fish than

the Mackarel, though bearing a general resemblance to it in
form ; a specimen which was caught when chasing Herrings
into Loch Fyne, measured 7 ft- 10 in. in length, and weighed
460 Ibs. The Tunnies, like the Mackarel, are dispersed through
the ocean during most of the year ; but in the summer they resort
to the shores in vast shoals ; and a fishery of great importance
is then carried on along the north coast of the Mediterranean,
and in the island of Sicily. The flesh of the Tunny, both fresh
and salted, forms a considerable part of the food of the common
people of those shores ; and the fishery constitutes a large source
of profit to those who reside on the coasts. The Bonito or Striped
Tunny, also a native of the Mediterranean, and a rare visitant
on our shores, is a very handsome fish, though smaller than the
common Tunny ; it is further distinguished by its great activity
and voracity, being one of the chief enemies of the Flying-fish ;
and, in common with the Tunny, it can sustain a higher temper-
ature than most other members of its class.

558*. Another remarkable group of this family consists of the
Sword-fish and its allies, which have the muzzle elongated into a
spike, which terminates in a sharp point, and constitutes a very

formidable wea-
pon. These fishes,
of which there are
several species,are
usually furnished
with a high dor-
sal fin, by the

FIG. 268.-6woRD.FiSH. agency of which

they are enabled to propel themselves through the water with
great energy. They sometimes attain the length of 12 or even

34 FAMILY SCOMBERIDE^E ; — SWORD-FISH, PILOT-FISH.

15 feet ; and they do not hesitate in attacking very large fishes
(the Tunny, for example), transfixing them with their powerful
spear. Instances are on record, in which even Men have been
thus destroyed ; and it has not unfrequently happened that a
Sword-fish has struck a ship, and has driven its sharp weapon
through the planking. In the Mediterranean, where one species
of Sword-fish is not uncommon, it is regularly pursued by the
fishermen ; and its flesh is much esteemed in some places as an
article of food. It is seldom seen, however, in large numbers
together. — A third group of the Scomberidese is characterised by
having the rays of the first dorsal fin not connected, but existing
as separate spines. Of this group we shall only stop to notice
the Pilot-fish ; which has been, from very ancient times, the

subject of many
fictitious state-
ments. By the
ancients it was re-
garded as a sacred
fish, from its being
supposed to indi-

FIO. 269.-PILOT-FISH. cate their true di-

rection to doubtful

voyagers ; whilst, by sailors of the present day, it is commonly
regarded as a guide to the Shark in its pursuit of prey, and is
said to tempt it to take the bait which has been thrown out for
its capture. Certain it is, however, that the Pilot-fish will often
follow in the wake of ships for many hundred miles ; thus an
instance has been known, in which a vessel was accompanied by
two of this species, during its whole voyage from Alexandria to
Plymouth, which occupied 87 days. The common Pilot-fish of
the Mediterranean and Atlantic does not much exceed a foot in
length ; but there is a species on the South American coast, which
occasionally attains eight or nine times those dimensions.

559. The family ZEHXE strongly resembles the preceding;
but differs from it in the high and compressed form of the body.
Many of the species composing it are remarkable for the fila-
mentous prolongations of their fins. This is the case with one

FAMILY ZEIDJE; DORY.

35

of the types of the family, the Zeus or Dory, the peculiar form
and aspect of which will be better understood from the accom-
panying figure, than from any technical distinction. This fish has

been in great repute
amongst epicures,
even from the time
of the Romans; it
is not very com-
mon upon our own
coasts, being nearly
restricted to Devon
and Cornwall ; but
it is more abun-
dant in warmer lati-
tudes. The name
John Dory, by which

. 270 — THE DORY. it is commonly

known in this coun-
try, is evidently a corruption of the French jaune dore, or gold

FIG. 271.— BLEPHARIS.

and yellow ; which applies to the colour of its lighter parts when

D2

36 CORYPH^ENA, — LANCET-FISH, ANABASID^.

the fish is alive. — Another fish of this family, no less remark-
able for its form, is the Blepharis ; of which one species, in-
habiting the West Indian seas, is known under the appellation
of the Cobbler-fish, probably on account of the long thread-like
appendages for which it is so conspicuous. The use of these curious
appendages is altogether unknown. — With this family may also
be ranked the Coryphcena, or Dolphin of the ancients ; which is a
large and splendidly-coloured fish; celebrated for the velocity of its
movements, and for the variety of tint which its surface exhibits
under a play of light. The changes of hue which it undergoes
when dying, were a source of great enjoyment to the luxurious
Romans ; by whose poets this Fish was much celebrated. The
Dolphin of the moderns is not a Fish at all, but a Cetaceous
Mammal (§211).

560. The two succeeding families, — T^ENID^E, or Ribbon-
shaped Fish, — and THEUTID^E, or Lancet-fish^ — must be passed
over with but slight notice. The peculiar characters of the
former are indicated by their name ; the species of which it con-
sists (some of them bearing a very close resemblance to the
ScomberidesB), being distinguished by their lengthened bodies,
much flattened at the sides, and having very small scales. — The
Lancet-fish combine the small scales of the Scomberoid family
with the form and small mouth of the Chsetodon ; but their fins
are not scaly, like those of the latter. They are among the few
Fishes, which live on sea-weeds and other marine vegetables.
Several of the genera have sharp spines on the sides of the tail,
which they can draw back into a groove ; with these they can
inflict severe wounds upon the hands of those who touch them
incautiously ; but they are peaceful in their habits, never volun-
tarily making an attack, but contenting themselves with repel-
ling the assaults of their enemies.

561. The peculiar structure of the succeeding family, ANA-
BASiDuE, has been already mentioned (§ 538) ; and it adapts them
to a mode of life which the circumstances of this climate do not
render necessary. In cold or temperate regions, the ponds and
streams, which are capable of supporting fish at all, are not dried
up, except in seasons of extreme drought : but in tropical coun-

AN ABAS. MUGILIDJE OR MULLETS. BLENNIES. 37

tries there are many situations, in which there is an ample
supply both of food and water for Fish during the rainy season ;
but a complete deficiency of both, when this is succeeded by the
periodical drought. Such receptacles can only be tenanted
by Fish, which, like the Anabas, are furnished with the
peculiar pharyngeal apparatus (Fig. 260) for keeping the gills
moist ; since, when one pond or stream is dried up, they can
migrate in search of another. In the course of these journeys,
they climb up steep banks, and even trees ; and by a remark-
able instinct, they seem always to travel towards the nearest
water. This family contains a considerable number of genera,
all of which are inhabitants of fresh-water ; none have been
hitherto found except in the south-east of Asia and the adjacent
islands, and in Southern Africa.

562. This family is succeeded by that of MUGILLIXE, or the
true Mullets ; which are distinguished by several remarkable
peculiarities of structure. Their body is nearly cylindrical, and
is covered with large scales ; the head is broad and flat, and is
covered with large angular scaly plates ; and the stomach is fur-
nished with fleshy walls, giving it a resemblance to the gizzard
of a Bird. The Mullets associate in large shoals, and chiefly
inhabit the mouths of rivers, where they are often seen making
high leaps. They feed upon small Crabs and other Crustacea, which
they swallow entire ; and the almost total want of teeth is com-
pensated by the powerful gizzard, which serves to grind down
their food. The Grey Mullet is one of those fishes, which, —
habitually living at the mouths of rivers, where the salt and
fresh waters mix, — will thrive well in the latter alone.

563. "We may next mention the BLENNIDJE, or Blennies,
which are elongated Fishes, having a single dorsal fin, almost
entirely supported upon simple flexible rays. The ventral fins are
placed in front of the pectorals, and have only two or three rays in
each. They live in small troops near the coast ; and they can ex-
ist for some time without water (their gill openings beiog small),
especially if kept in moist grass. Many of this family retain
their eggs until they are hatched within the oviduct ; so that the
young are produced alive, fully formed, and capable of subsisting

38

; — ANARRHICAS. — GOBID.E, OR GOBIES.

for themselves. The Anarrhicas, or Sea- Wolf, must be referred
to this family, although differing from it in possessing no ventral

fins, and in hav-
ing the jaws
and palate armed
with large tuber-
cular teeth. —
This fish may be
almost regarded
as replacing the
Sharks in the
Arctic seas ; for

FIG. 272.-BLKN.Y. U attainS the

length of six or

seven feet, and is extremely voracious and bold. Its body, though
massive, is adapted for active and energetic motion; and its power-

FIG. 273.— ANARRHICAS LUPUS.

ful bite makes it a very formidable enemy. It often enters the
fishermen's nets, for the purpose of plundering them of the
entangled fish ; and when the fishermen attack it, and it cannot
dart through the net, it fights like a Lion. On the east coast of
Scotland it is not an unfrequent visitor; and its appearance and
habits cause it to be regarded with great dislike ; nevertheless
its flesh is wholesome and palatable. It is understood to prey
indiscriminately upon Fishes, Crustacea, and shelled Mollusca; its
jaws and teeth being capable of breaking the hardest shell. In
the family GOBID^E, or Gobies, we find the same simple flexible
rays in the dorsal fin, as in the preceding group ; but the ventral
fins are united beneath the chest, forming a sort of conical
sucker, which the Fish seem to use for the purpose of occasionally
attaching themselves to solid bodies. They live, like the Blen-

GOBIES. LOPHIADJ3, OR ANGLERS. 39

nies, near the shore, and prefer a clayey bottom, in which they
excavate canals, wherein they pass the winter. In spring, they
prepare a sort of nest, with sea- weed ; in which the young (often
produced alive, as in the Blennies) are protected; and the
parents exert themselves considerably to bring them food and to
defend them from their enemies. Several species of Goby exist
in the European seas ; but none of them are of much size, or of
any direct value to Man. In other seas numerous genera exist,
more or less allied to the Gobies of our own coasts.

564. There are certain spiny-finned Fishes, in which the
carpal bones are so elongated, as to form a sort of arm or wrist,
to the extremity of which the pectoral fin is articulated. This
conformation (an approach to which is seen among some of the
Gobies) gives to the Fishes which possess it a very strange
appearance ; and enables them, in some instances, to leap up
suddenly in the water, and seize the prey which they observe
above them ; in other cases to leap over the mud, somewhat
after the manner of Frogs. From the very peculiar genus
Lophius, or Fishing Frog, in which this character is combined
with some others of a very extraordinary nature, the family
may be designated as that of LOPHIAD^J, or Anglers. The com-
mon Angler of our own coasts has an enormous flattened head,
which constitutes the chief bulk of the Fish ; and a tail so com-
pressed on each side, that the creature seems composed of little
else than head and tail. On the former, in front of the eyes,
are two long rays or filaments of a horny substance ; and there
are also four others of a similar nature, but shorter, on the head.
The mouth also is furnished with numerous worm-like appen-
dages ; which seem to represent the tentacula or prolonged lips
of many Invertebrated animals. This animal is described as
concealing itself amongst marine plants, or behind hillocks of
sand, rocks and stones; when it opens its great mouth and
attracts small fishes as they swim past, by giving a wriggling
motion to the appendages just mentioned, which causes them to
mistake these for worms ; so that, in attempting to seize them,
they fall an easy prey to their subtle and voracious enemy,
being speedily engulfed between its enormous jaws. The

40 LOPHIUS OR FISHING-FROG; — CHIRONECTES.

hideous appearance of its monstrous and constantly- open mouth,
well armed with teeth, has gained for the Angler the vulgar
name of Sea Devil. There are few parts of the British shores
where it is not to be occasionally met with ; and when captured
in nets along with other fishes, it speedily begins to swallow its
companions. On some coasts it is sought for, on account of the
live fish in its stomach. In the Museum of the College of Sur-
geons in Dublin, there is a skeleton of an Angler, about two feet
and a half in length, in the stomach of which is the skeleton of
a Cod, two feet long, — in whose stomach again are contained
the skeletons of two Whitings of the ordinary size, — and in the
stomach of each Whiting there lay, when it was first examined,
numerous half-digested little fishes, which were, however, too
small and broken-down to admit of preservation. The Frog-
fish, with all these contents, had been taken by the fishermen,
and offered for sale in the market as an article of food, without
any reference at all to the size of its stomach, which was not at
all unusual. The contained fishes must have been all swallowed
on the morning on which the Angler was taken ; as they were
all, with the exception of the smallest, equally fresh and undi-
gested.— The Chironectes, or Hand-fish, bears a strong resem-
blance to the common Angler in its structure and habits ; but
its fins are still more capable of motion, enabling it to walk
along the ground almost in the manner of quadrupeds, — the
ventral fins, however, in consequence of their advanced position,
serving as the fore-legs, and the pectoral fins performing the
office of hind-legs. In some of the muddy estuaries of the north
coast of Australia, from which the tide ebbs far back in the dry
season, these Frog-fishes are abundant, and capable of taking
such vigorous leaps, that those who have visited these places
have, at first sight, mistaken them for birds. Their gill open-
ings are very small ; and they can live out of the water for two
or three days. They have the faculty of inflating their large
stomachs with air, so as to give themselves the form of a bal-
loon,— in this respect corresponding with the Diodon.

565. The L ABRIDGE, Wrasse or Rock-fish family, are chiefly
remarkable for their thick fleshy lips ; their jaws are armed with

FAMILY LABRID^E; — WRASSE, ROCK-FISH. 41

large teeth, and their colours are for the most part very brilliant.
Several species are found upon our own coasts, but they are not
in much repute, and are known among the fishermen by the
name of " Old Wives of the Sea." They chiefly frequent rocky
shores, as their name implies. — This family also includes the
remarkable genus Scarus or Parrot-fish ; which is furnished with
large convex rounded jaws, and these are covered with hard,
scale-like teeth, which succeed each other from the rear to the
front in such a manner, that the bases of the newest form a
cutting edge. Numerous species of these fish inhabit tropical
seas ; many of them are remarkable for the brilliancy of their
colours, whence, perhaps, their ordinary name has been derived.
These Fishes appear destined to restrain the extension of the
stony Corals, on the newest layers of which they are enabled,
by the immense strength of their jaws and teeth, to browse
without difficulty, — digesting the animal matter it contains,
and setting free the carbonate of lime in a chalky state.

566. The last family of Acanthopterygii is that of FISTU-
LARID.E, or pipe-mouthed Fishes; so named from the curious
conformation of the head, which is furnished with a long tube
projecting forwards, and having the mouth with its jaws at the
extremity of this. There is no other point, however, in regard
to which they demand peculiar notice.

ORDER II.— MALACOPTERYGII ABDOMINALES.

567. The CYPRINIDJS, or Carp tribe, constitute the first
family of this order; they are characterised by their small
mouth, and by their feeble and generally toothless jaws ; but they
have the pharynx strongly toothed, which compensates in some
degree for the feeble armature of the jaws. They are for the
most part fresh-water fishes, and live on aquatic plants. These
are masticated in the pharynx, which is a powerful instrument
of reduction, being furnished with strong muscles, that bruise
the food between its teeth and a stony disc fixed at the base
of the skull. The common Carp was not originally a native of

42 FAMILY CYPRINID^; CARP. BARBEL, LOACH, ETC.

this country, but was introduced from the South of Europe ; it
thrives very well, however, in the most slow-running parts of
rivers, and still better in ponds, sometimes attaining the length
of four feet. The beautiful little Gold and Silver Fish, belong
to a small species of Carp, which is very much disposed to pass
into varieties. Nearly allied to these are the Barbel, which
sometimes at-
tains the length
of ten feet; it
inhabits ponds
and sluggish 'iB
streams; and is ^
said to plough i=i
up the mud
with its long

SnOUt, SO as tO FlG'

set adrift in the water the minute animals imbedded in it, and
thus to attract the small fishes on which it is itself supported.
The Gudgeon, Tench, Bream, Roach, 'Bleak, Minnow, and many
other well-known pond and river-fishes, belong to this family ;
as do also the Loach, which habitually buries itself in mud when
the weather is cold ; and the Anableps, which is remarkable for
being apparently possessed of four eyes. This is not, however,
really the case ; for although the cornea and iris are divided by
transverse bands, so that there are two pupils on each side
(ANiM. PHYSIOL. § 533), yet the other parts of the eye are
single. The female of this species brings forth her young alive,
in a state of considerable advancement.

568. The family ESOCID^, or Pike tribe, is nearly allied to
the preceding ; but differs in having the jaws and palate usually

beset with teeth, and in the
voracity of the fishes which
it includes. Many of these
are inhabitants of fresh

FIG. 275.— PIKE.

waters ; others occasionally

ascend rivers ; whilst others again are confined to the sea. The
common Pike is well known as being one of the most voracious

FAMILY ESOCIDJE; — PIKE, FLYING-FISH. 43

and destructive of all the smaller fishes. Mr. Jesse mentions,
that eight Pike, of about 5 Ib's. weight each, consumed nearly
eight hundred Gudgeons in three weeks ; and that one of these
devoured five Roach, each about four inches in length, within a
quarter of an hour. The Pike not only makes havoc among
other fish, but will devour frogs, water-rats, field-mice, and the
smaller aquatic birds ; and instances are on record, in which
it has even attacked Man. It grows rapidly, and sometimes
attains the weight of more than 30 Ibs. It is a very long-lived
fish, — having been known to attain the age of 90 years, —
and having in one instance (there is reason to believe) lived to
the patriarchal age of 267 years, and attained the length of nine-
teen feet. — The Gar-fish^ or Sea-Pike, has a much more elon-
gated mouth, which is not so well furnished with teeth. It is
quick and active in the water ; swimming with considerable
rapidity near the surface, and leaping and gambolling as if in the
exuberance of vivacity. This fish comes in shoals to the south-
ern coast of Britain, in the months of April and May ; and from
its appearing a short time before the Mackarel, it is termed by
the fishermen the Mackarel-guide. It is not in much esteem as
an article of food. — To this group also belongs the Exocetus,
best known as the Fly ing -fish ; which is remarkable for the
enormous development of its pectoral fins, and for its power of
sustaining itself upon them out of water. It is necessary to
bear in mind that the term Flying-fish has been applied to this
genus, in common with the Flying Gurnard (§ 555) ; and that,
although really so different, they have been continually con-
founded together in the accounts of voyagers. The term Flying-
fish ought to be restricted to the Exocetus ; which is the one
that best deserves it. Various species exist in different parts of
the seas of warm latitudes ; and our own coast has been occa-
sionally visited by them. As elsewhere stated (ANIM. PHYSIOL.
§ 667), their flight through the air seems entirely to depend
upon the impulse they receive from the stroke of their fins upon
the water, at the moment of quitting it. They are to a certain
degree supported by their wing-like fins, while sailing through
the air ; but they do not seem able to raise or to propel them-

44 FLYING-FISH. FAMILY SILURID^E.

selves by striking them against it. The most usual height of
their flight is from two to three feet ; but they have occasionally
been known to spring to a height of fifteen or even twenty feet.
The utmost length of their flight seems to be between two and
three hundred feet ; and its extreme duration about thirty seconds.
Few spectacles are more beautiful, than the sudden rise of a shoal
of Flying-fish from the gently-undulating surface of the tropical
ocean, — their scaly surface and extended fins glistening in the
bright sunshine with all the varied hues of the rainbow, — and the
graceful curves in which they move at last terminated by a return
to their native element, from which they presently again spring
up with renewed vigour. These airy excursions are commonly
regarded as occasioned by the pursuit of Dorados, Bonitos, and
other fishes of prey ; but this is prpbably by no means the case,
for the Flying-fish seem frequently to rise from the water for the
mere sake of exercising, with pleasure to themselves, those powers
of movement with which they are endowed, — just as we see
other fishes gambolling about in their usual medium. Whilst in
the air, they are often seized upon by the long-winged sea-birds.

569. The next family, SILURIDJE, or Silure tribe, is distin-
tinguished by the want of scales, having only a naked skin, in
which large bony plates are frequently imbedded. Many of
them have the adipose or fatty second dorsal fin, which is a pro-
minent character of the next family. The species included in
this group are mostly river-fish, of considerable size, inhabiting
warm climates. Many of them have the first ray of the pectoral
fin very strong and bony ; and the fish can, at pleasure, lay it
flat on the body, or keep it fixed in a perpendicular direction, in
which case it becomes a formidable weapon, capable of inflicting
very troublesome wounds. There is no sufficient reason, how-
ever, to believe that these wounds are venomous. — The Malap-
terurus, remarkable for its electrical powers, has been already
noticed (§ 543).

570. The two remaining groups of this order are of great
importance to Man, from the large supply of wholesome and
palatable food which they yield. The first of these is the family
SALMON ID^E, or Salmon and Trout tribe; which is characterised

FAMILY SALMONIDJ3, OR SALMON TRIBE. 45

by having all the rays of the first dorsal fin soft or jointed;
and the second dorsal entirely adipose, being merely a fold of skin
inclosing fat. The species of this family are at once distin-
guished from the Siluridse, by having the body covered with
scales ; they are generally very muscular, and possessed of great
strength ; and they are voracious in their habits, feeding rather
upon Insects, small Crustacea, &c., than upon other Fishes.
The different subdivisions of the group vary considerably in
regard to the position of the fins, and the degree in which the
mouth is armed with teeth. Most of them frequent the estuaries
of rivers, and ascend the stream at regular periods to deposit
their spawn in its higher parts ; and it has been ascertained that
the same fish and their descendants resort in successive years to
one particular locality. Nearly all the members of the family
are clouded with transverse dusky patches when very young, and
undergo considerable changes in their livery before they arrive at
their full growth. Hence there is much difficulty in determining
their species; which is increased by the circumstance, that the
male, in many instances, appears to be capable of propagation long
before arriving at its full growth. The Salmon of our own
rivers is one of the largest of the whole family ; but in conse-
quence of the eagerness with which it is pursued by fishermen,
it does not often attain its full size in this country. Enor-
mous specimens, however, are now and then captured ; a weight
of 40 Ibs. does not seem very uncommon ; and in 1821, a speci-
men was exhibited in London, weighing 83 Ibs. The usual time
at which the Salmon leaves the sea, is the autumn ; it remains
in the rivers during the winter ; and returns to the sea, after
having deposited the spawn, in the spring. The young fry,
termed Smalts, are carried down to the sea in the months of
April and May. In some rivers, however, they do not make
their ascent until the winter ; and in others they even delay it
until the spring. These variations appear to depend upon
differences of temperature in the rivers themselves ; since, when
these are very cold, the fish avoid passing the winter in them.
Before depositing its spawn, the Salmon makes a furrow with
its nose in the gravelly bed of the river ; and its eggs, when

46 TROUT, ETC. — FAMILY CLUPEID^E, OB HERRING TRIBE.

deposited in this, are carefully covered up. The common Trout is
entirely a fresh- water fish, delighting in rivers which have a
rapid current, and abounding also in many stream-fed lakes ; it
lurks during the day in the deep pools, under the shadow of large
stones, or under precipitous banks ; and becomes active towards
evening, when it begins eagerly to pursue its prey, which seems
to consist especially of Insects and aquatic Larvae, and of small
Crustacea, — but also of small fishes, and the ova of the larger
ones. — The Char is considered as having the most delicate
flavour of any of the fishes of this family ; it is a lake fish, and
is not very common in this country. — The Smelt resembles the
Salmon in its habits, but is much smaller ; it has been found,
however, to thrive very well when confined to fresh water. —
Several other genera exist in various parts of the world ; some of
them approach other families in their general structure, and are
exclusively marine in their habits.

571. The only remaining family of this order is that of CLUPEI-
D-E, or Herrings, and their allies. These have a scaly body like the
Salmon's, but no adipose dorsal fin ; and there is also a differ-
ence in the arrangement of the bones of the jaws. They are for
the most part marine fishes ; only a few species, as the Shad
and White Bait, ascending rivers periodically like the Salmon.
The habits of the common Herring, in regard to its reputed
migrations, have been already noticed (§ 546) ; notwithstanding
the very circumstantial account given by Pennant, and copied
by later authors, it seems now to be well established that the
only migration of the Herring is from the deep seas to the shores
at the spawning season, and from the shores to the deep seas
when this is over. It is a curious and perplexing circumstance,
that the shoals of Herrings do not continue to resort to the same
localities ; but that they will leave some parts of the coast which
they had been accustomed to visit with regularity, and will make
their appearance on others which they had not previously fre-
quented. Their food consists of small Crustacea and Fishes ;
and it appears that they do not spare the young of their own
race, five small herrings having been found in the stomach of a
large female. They usually swim near the surface of the water ;

FAMILY CLUPEID.E; — HERRING FISHERY. 47

and, like other fishes whose habit is the same, their gill-openings
are large, their respiration considerable in amount, their muscular
energy great, and their demand for oxygen so constant, that,
when taken out of the water, they speedily die. The Pilchard,
Sprat, Shad, White-Bait, Sardine, and Anchovy, are all more or
less closely allied to the Herring, — the last departing from it
most widely. The range of the Pilchard, which abounds on
the Cornish coast, is more southern than that of the Herring ;
and the Anchovy and Sardine replace the Herring in the Medi-
terranean, where
it is unknown.
The importance of
the Herring and
Pilchard Fisher-

FIG. 276. — ANCHOVY.

ies is very great.

Some notion of it may be formed from the fact, that nearly
500,000 barrels of herrings only have been cured in one year ; of
which more than half were exported. The number of persons to
whom this Fishery gives employment in various ways, must, there-
fore, be very considerable, though it cannot be exactly estimated ;
and the value of the product as an article of export trade is very
important. The total number of persons directly employed in
the Cod and Herring fisheries of Britain, as Fishermen, Coopers,
Curers, &c., was nearly 87,000 in the year 1836. Of the extent
of the Pilchard fishery some idea may be formed from the fact,
that about 12,000,000 of these fish have been sold for home
consumption alone in a single year ; and it is said that more
than this number have been brought into one port in a single
day. The principal centre of the Herring fishery is at Yarmouth
in Norfolk ; that of the Pilchard fishery is the neighbourhood of
the Land's End.

572. With the preceding order is arranged by Cuvier the
Lepidosteus or Bony Pike, which has many of the characters of
the Pike, with the structure of the head of the Herring. It
differs from both these, however, in having the body covered
with a case composed of dense bony square scales ; which are so
fitted together as to form a most complete armour. An in-

48 LEPIDOSTEUS. GADID^E, OR COD TRIBE.

creased knowledge of its internal structure, however, and of the
fossil species most nearly allied to it (which are very numerous
in the older rocks), has led to a very different position being
assigned to it. Its skeleton differs in many particulars from
that of ordinary Fishes, and presents several points of resemblance
to Reptiles ; and this approximation is equally remarkable in
the structure of the respiratory apparatus, — the air-bladder being
double, and communicating with the oesophagus by a regular
trachea or wind-pipe, furnished with a glottis at its upper ex-
tremity, so as to be nearly as complete as the lungs of the
Siren. In regard to the order of Sauroid fishes, of which this is
nearly the only genus at present remaining, but which was
once the predominant group of Fishes, more will be said
hereafter (§ 582). The Lepidosteus is an inhabitant of the
rivers and lakes of America, most of the species being restricted
to its warmer parts.

ORDER III.— MALACOPTERYGII SUB-BRACHIATI.

573. The Fishes of this order, from the position of their fins,
have greater facility of ascending and descending, than the ab-
dominal fishes ; and the range of depth inhabited by the same
animal is consequently greater, — except where, as in the Flat-
fish, there is a peculiar adaptation to a residence at the bottom
of the sea. The first family is that of the GADID^E, or the Cod
tribe ; which have a long body, rather slender, and covered with
soft scales, — the head, however, being naked. They live for the
most part in the seas of cold or temperate climates ; and from
their size and their tendency to congregate in particular localities,
as well as from the wholesomeness and good flavour of their flesh,
they are probably more important to Man than any other family
of Fish. The Cod fishery on the banks of Newfoundland sends
a vast supply to almost every part of the world ; and the amount
caught on the British shores also is very considerable. The
appearance and quality of the fish vary considerably according
to the nature of the ground on which it is taken. Its repro-

PLEURONECTID^, OR FLAT-PISH. 49

ductive powers are enormous ; the roe of a single female
having been estimated to contain nine millions of eggs. Nearly
allied to the Cod, are the Haddock., Whiting, Hake, Ling} Rock-
ling, Coal-fish, and others. The first of these is considered as
the most delicate of the whole family, when fresh ; but it does
not take salt well ; and for preservation, the Cod and Ling excel
the rest.

574. The second family of this order consists of the PLEURO-
NECTID^E, or Flat-fish. These present several remarkable pecu-
liarities of structure ; by which they are distinguished, not only
from all other Fishes, but even from all other Vertebrated animals.
Their body is extremely compressed, or flattened at the sides ;
the animal, however, does not habitually swim with these sides
erect in the water, but usually lies flat on the bottom, one side
being in contact with it, and the other being directed upwards.
The lower side is generally white, whilst the upper is brown ;
and the former is commonly (but erroneously) regarded as the
belly of the fish, and the latter as its back. The dark colour of
the upper surface harmonises with that of the bed on which the
fish lie ; so as to enable them to conceal themselves from their
foes, or to watch for their prey, without being themselves ob-
served. Individuals are occasionally met with, in which both
sides are coloured alike ; these are said to be " Doubles." It is
usually the coloured side which is doubled ; though it is occa-
sionally the white one. By a change in the position of the
head, both the eyes are brought round to the light side, so as to
look upwards, when the fish is lying on the bottom ; this change
may be designated as a sort of twisting-round ; but it also in-
volves an unequal development of the bones on the two sides of
the head, which shows itself in the mouth. Of the pectoral fins,
too, one is usually larger than the other. The dorsal fin is con-
tinued along the whole of the ridge of the back, from the head
to the tail ; and the anal fin usually forms a like continuous ex-
pansion below, sometimes uniting with the ventral fins. These
fishes have no air-bladder, and they seem to have little power of
rising from the bottom. When disturbed, they will raise them-
selves into a vertical position, so as to show their white sides ; and

50 FLAT-FISH ; — TURBOT, ETC.

they then dart along with great rapidity ; but they soon return
to their usual posture, and glide along with a sort of undulating
motion, at a little distance from the bottom. The Flat-fishes
are very tenacious of life ; and the flesh of all of them is very
palatable. That of the Turbot is considered as the most delicate
afforded by any marine fish. Although most of the species
are exclusively marine, yet the Flounder and some others
occasionally ascend rivers, and thrive in brackish, or even in

quite fresh water. The Plaice,
Flounder, Turbot, Dab, Fluke,
Brill, Sole, and other well
known fish of this family, are
closely allied to each other,
both in structure and habits ;
and they are all inhabitants

of British seas. The Halibut,

% '

FJG. 277.— PLAICE. also an inhabitant of the

Northern seas, is larger than

any one of these, attaining a length of six or seven feet, and a
weight of 300 or 400 Ibs. Its flesh is rather coarse and dry, but
it admits of being salted. In some of the Mediterranean species,
the eyes look towards the left side, instead of towards the right ;
the latter, though the ordinary rule of the family, is sometimes
departed from in other species ; the individuals that exhibit the
unusual formation, being said to be " reversed." As an in-
stance of the extent and importance of the Fisheries, of which
this family is the object, it may be mentioned that the Dutch
draw about 80,000/. per annum, for the supply of Turbot alone
to the London market ; and it is estimated that, of the whole
quantity brought to Billingsgate, the Dutch is not more than
one-fourth.

575. The third and last family of the second division of Soft-
rayed fishes, is but a small one ; and consists of a group which
is characterised by the union of the ventral fins into a sort of
sucker, or disc, that enables them to form a strong adhesion to
rocks and other hard substances. In this manner they can
remain and find their food, in situations where every other

DISCOBOLI ; SUCKING-FISH. MUILENIDjE. 51

species of fish would be swept away by the current. From this
curious conformation, they have received the name of DISCOBOLI.
Their skin is slimy and naked, or with hard grains imbedded
in it. Their pectoral fins are large ; and they swim with great
vivacity in shallow water, and near coasts. Several species of
this family, most of them small, are found on the south and west
coasts of England. One of the largest is known as the Lump-
Jish ; this is found as far northwards as the margin of the Polar
ice, and is a palatable article of food ; its name is derived from
the clumsiness of its form, its height being about half its length,
and its thickness about half its height. The Remora, or Suck-
ing-fish, (§ 529), is placed by Cuvier in this family, although
its disc, or sucker, is so entirely different in its position; but
he remarks, that it might be placed by itself, as the type of a
distinct family.

ORDER IV.— MALACOPTERYGII APODA.

576. The fishes in which the ventral fins are always wanting,
form but a single natural family ; MUR^ENID^E, or the Eel tribe.
These are at once known by their long, slender, snake-like
bodies, covered with a soft skin, and having the scales very
minute, and often almost invisible. The gill-orifices are very
small, and are prolonged far back, so that a sort of long passage
is formed from the branchial chamber to the surface of the body.
In this manner the gills are so much sheltered, that the fish can
remain out of the water for a considerable time, without those
organs being rendered unfit (by becoming dry), to carry on the
respiration. Of course, the access of water to the gills cannot
at any time be so free, as it is in fishes with large gill-openings ;
and their respiration may be habitually less. It is in animals
with a feeble respiration, as has been already remarked in the
case of Reptiles, that we find the greatest tenacity of life ; and
every one knows the difficulty with which the Eel is killed — the
most cruel injuries being sustained by it without the loss of its
vitality. The ordinary Eels, of which there are several species,

E 2

52 MUR^NID^E, OR EEL-TRIBE.

inhabit ponds, rivers, and the brackish water at the mouths of
rivers. In the autumn they make their way to the sea in vast
numbers ; for the purpose, it is believed, of depositing their
spawn. Myriads of minute Eels, three or four inches long, are
seen in the spring, making their way up rivers, and dispersing
into the tributary streams as they proceed ; but whether the
parent Eels thus return is uncertain. It is well known that the
Eels which inhabit inland lakes and ponds, whence they cannot
escape to the sea, are able to breed without this migration ; but
it appears that their season is somewhat later, the water in such
situations being colder than that of the sea in the early spring.
Eels frequently quit the water, in warm, damp nights, and
wander over the grass ; either in quest of worms, frogs, or other
food ; or in order to change their locality. — Many of this family
are chiefly marine ; though they occasionally stray into the
mouths of rivers : this is the case, for instance, with the Conger ',
which is one of the largest of the whole order, sometimes mea-
suring six feet in length, and being as thick as a man's leg. —
The Ophisurus, or Snake Eel (so called from its strong resem-
blance to a serpent) of the Mediterranean, attains the same
length, but is not so thick. In the genus Murcena, and its allies,
the pectoral as well as the ventral fins are wanting ; and the gill-
openings are extremely small. This, too, is a Mediterranean fish ;
it was much esteemed by the ancients, who kept it carefully in
ponds ; and there is a well-known story of a cruel master, who
caused his offending slaves to be flung alive into the ponds, to
feed the Muraense. The common species grows to the length of
three feet or more ; its surface is mottled brown and yellow ; and
it is very voracious and ugly. In some of the genera nearly allied
to this, the gill-passages unite, so as to open externally by a
single orifice on the under side of the neck ; and in several of
these, we find the air-bladder almost as completely presenting
the characters of a rudimentary lung, as in the Sauroid Fishes
(§ 588).

577. The Gymnoti, or Electric Eels (§ 540), and their allies,
have been separated from the preceding family by some natu-
ralists, on account of the less complete inclosure of the gill-covers

EEL-TRIBE. LOPHOBRANCHII. 53

by the skin, and of the absence of the dorsal fin (Fig. 262). It
is to the true Gymnotus, that the electric power is confined ; and
the group includes several other genera, of which some belong to
the British seas. Of these may be mentioned the Leptocephalus,
or Morris, which is a small riband-shaped fish, with a body so
thin and transparent that its internal structure can be seen with-
out dissection ; it lurks among sea- weeds, and is very lively in
its motions. The Avnnodytes^ or Launces, — one of which is known
to fishermen by the name of the Sand -Eel, and another as the
Sand-Launce, — are remarkable for their habit of burrowing in
the sand, in which they find the worms that constitute their chief
food. They become in their turn the prey of the Salmon ; to
whose support, whilst they are in the estuaries of rivers, the
Launces are believed to contribute largely.

ORDER V.— LOPHOBRANCHII.

578. This order consists of a small group, which is separated
from all other Osseous Fishes by the structure of the gills ; which,
instead of hanging from the branchial arches in fringes of parallel
fibres, disposed like the teeth of a comb, are set upon them in
small round tufts, arranged in pairs. From this peculiar con-
formation, the name of the order, which signifies tuft-gilled, is
derived. The gills are defended by a large operculum, which is
attached by a membranous covering on all sides, except at one
part where a small hole is left for the escape of the water. These
fishes are also distinguished by having their body covered with
shields or small plates, which often give it an angular form. In
general they are of small size, and often without flesh. They
do not present many points of general interest ; but there are
certain peculiarities in their organisation, which are very interest-
ing to the Naturalist. In the Syngnaihus, or Pipe-fish, which
has a prolonged muzzle like that of the Fistularidas (§ 566), the
eggs are not deposited as in other Fishes, but are conveyed
into a sort of pouch, formed by a doubling of the skin under the
body of the male ; this pouch is under the abdomen in some

54 PIPE-FISH; HIPPOCAMPUS. — PLECTOGNATHI.

species, and at the base of the tail in others. In this pouch the
eggs become matured ; and when the fry are ready to escape, it
opens and allows them to pass out. This contrivance reminds
us of the pouch of the Marsupial Mammalia ; but there is this
striking difference, that in the latter it is the Female which affords
this protection to the young, whilst in the Pipe-fishes it -is the
Male. It has been asserted that, even after the young have
quitted the pouch, they will return to it again ; and that the
parent shows great attachment to them. The Hippocampus
(Fig. 259) has a prehensile tail, unfurnished with any finny
expansion ; and is enabled by its means to climb or hold on by
the stalks of marine plants. It is only in the dead specimen,
that the neck acquires the peculiar bend, which gives its head the
resemblance to that of a Horse, from which its name is derived.
The Pegasus, though furnished with a snout, has the mouth
beneath it ; the pectoral fins are large, and are spread out in a
wing-like manner; whence these curious Fishes have derived
their name, which signifies Flying Horses.

ORDER VI.— PLECTOGNATHI.

579. We next come to another small order, which forms a
connecting link between the Osseous and Cartilaginous fishes. It
resembles the latter, in having the upper jaw attached to the
cranium, in such a manner as to possess but little power of
motion (whence is derived the name of the Order, which means
having the jaws soldered), and also in the imperfect ossification
of the skeleton. Still, in its general conformation, the skeleton
rather resembles that of the bony fishes. The gill-lid is con-
cealed under the thick skin, as in the preceding Orders ; and
there is but a small gill-opening on either side : the ribs are
scarcely developed. This Order includes two families, which are
distinguished by the structure of their teeth. In the first of
these, the Gymnodontes, or Fishes with naked teeth, the jaws are
shaped like the beak of a Parrot ; and are composed of parallel
plates of a substance resembling ivory. These are reproduced as

GLOBE-FISH ; SUN-FISH. BALISTID^. 55

fast as they are destroyed by wear ; and they constitute very
efficient instruments for grinding down the food on which these
animals live, — which consists of Crustacea and sea- weeds. To this
family belong the Globe-fishes ; which are so named from their
power of distending themselves into a spherical form, by inflating
with air a large sac contained in the abdomen. When thus
distended, they float along the water with the back downwards,
swimming onwards by means of their pectoral fins ; and they are
covered with a series of large spines, which are raised up when
the body is thus inflated, so as to form a very efficient means of
defence. From this last circumstance, these Fishes have been
sometimes termed Porcupine-fish. There are three genera in
which this curious power exists ; the Diodon (two-toothed), in
which there is no furrow or division in the jaws, so that each
seems like a single tooth ; — the Triodon (three-toothed), in
which there is a division in the centre of the upper jaw ; so as to
divide it, as it were, into two teeth ; — and the Tetrodon (four-
toothed), in which there is a division of this kind in each jaw.
Besides these, this family contains the Orthagoriscus, or Sun-fish
(so named from its rounded form), which looks like the anterior
half of a fish cut in two in the middle. It has the power of
floating with its head and eyes above water ; but not of distend-
ing itself with air ; in this state it moves along sideways, very
slowly, however ; and appears like a dead or dying fish. The
Sun-fish (or Moon-fish, as it is sometimes called) attains a con-
siderable size ; of the short species, which is most remarkable
for its peculiarity of form, individuals have been frequently
caught measuring four feet in length, and nearly as much in
breadth, and weighing 400 Ibs. ; and it has been stated occa-
sionally to attain double that weight.

580. In the second family, that of BALISTID.&J, or File-fishes,
the jaws are armed with a small number of distinct teeth ; the
skin is either rough, or covered with very hard scales, — whence
their name, and the mouth is prolonged into a sort of pyramid.
In their general form, and in the brilliancy of their colours, they
bear a considerable resemblance to the Chaetodons (§ 556) ; and,
like them, they inhabit the seas of warm regions, keeping near

56

PILE-FISH. TRUNK-FISH.

FIG. 278.— BALISTES PENCILLIGERUS.

the surface, or in the neighbourhood of rocks. Some of them

are remarkable for the appendages with which the body is

furnished, which are
especially striking in
the Batistes pencilli-
gerus ; their use, how-
ever, is entirely un-
known.— The Ostra-
cions, or Trunk-Jishes,
should probably be
placed in a distinct
family, so remarkably
are they distinguished
by the mode in whch
the body is protected.

The head and body are covered with plates of bone, soldered

together in such a manner as to form an inflexible cuirass;

leaving only the tail, the

fins, the mouth, and a small

margin of the gill-opening,

capable of motion, — all of

which moveable parts pass

through openings of the

cuirass. The greater part FlG 279._TRUNK.FlSH.

of the vertebras also are

soldered together. There are no ventral fins, and the dorsal and

anal are small and are placed far back ; there is little flesh ; but

the liver is large, and abounds in oil. The surface is often

armed with spines. No species of these singular Fish are known

in the British seas.

57

ORDER VII.— CHONDROPTERYGII BRANCHIIS
LIBERIS.

581. We are now arrived at the true Cartilaginous fishes
(§ 525) ; of which the first order so far resembles the Osseous
group, that the gills are connected externally with a single wide
opening on each side, furnished with an operculum, or gill-cover.
All the Fishes of this order are considered by Cuvier as be-
longing to a single family ; but they may be probably better
arranged under two families, the ACIPENSERID^E, or Sturgeons,
and the CHIM^ERID^E, or Chimceras, — the former having more
affinity to the Osseous fishes, and the latter to the Sharks. The
body of the Sturgeon is more or less covered with bony plates,

FIG. 280.— STURGEON.

arranged in longitudinal rows ; and the head is armed with the
same. The mouth is situated beneath the elongated muzzle, and
is small and toothless. The air-bladder is very large, and com-
municates by a wide opening with the gullet ; and in this, and
other points of their internal conformation, the Sturgeons show
a considerable approach to the Lizards, whence they are ranked
among the Sauroid fishes (§ 588). The form of the tail is
another mark of resemblance ; for the vertebral column is con-
tinued into the upper portion of the caudal fin, the lower one
being given off from its underside, — instead of stopping short at
its commencement, and sending off the upper and lower portions
of the fin in the same manner, as in nearly all other Fishes
(Fig. 246). Sturgeons, like Salmon, ascend large rivers for the
purpose of spawning; and they are the subject of valuable
fisheries. They are more abundant in the Continental rivers
than in those of Britain ; and are particularly numerous in those

58 STURGEONS. CHIMJERIDJE. SHARKS, ETC.

which fall into the Black and Caspian seas. The common
Sturgeon attains the length of six feet ; but the great Sturgeon
has been found twelve or even fifteen feet in length, and weighing
from 1200 to 3000 Ibs. The flesh of the former is very palatable
and wholesome, resembling veal in its character ; that of the
latter, however, is not esteemed. The Sterlet is a smaller
species, about two feet long ; which is found in the Russian
rivers, and is considered a great delicacy. All the species are
valued on account of the excellent Isinglass which is yielded by
their air-bladders ; and their roe is salted and prepared by the
Russians, forming a dish termed caviare. More than 400,000 Ibs.
of this have been prepared in the Caspian fishery, in a single
year. — The CHIM.ERIDJE have the gills not entirely free at their
extremities, but partly attached, as in the Sharks ; and although
there is externally but a single gill-opening, yet internally there
are five separate passages, terminating in the common aperture.
They lay large, flattened, eggs, included in a sort of leathery
covering; in which respect, also, they resemble the Sharks.
The commonest species is known under the name of the " King
of the Herrings."

ORDER VIII.— CHONDROPTERYGII BRANCHIIS
FIXIS.

582. This order includes the two families of Sharks and
Rays ; which, though very different in external form, agree in
many points of internal structure, and particularly in having the
gills fixed at their extremities to the outer sides of the gill-cavity,
and in having a series of apertures, through which the water
passes out from each branchial arch. In these particulars they
correspond with the last order of the class, — that of Cyclostome
Fishes ; but they differ from them in having a much more per-
fect skeleton, and in having both pectoral and ventral fins. The
differences between the two families of SQUALID^E, or the Shark
tribe, and RAID^E, or the Ray tribe, chiefly consist in their
external form ; the body in the former being elongated, and the

WHITE-SHARK ; FOX-SHARK.

59

tail extremely fleshy ; whilst in the latter the body is short and
flat, the pectoral fins immensely extended, and the tail slender.
Of the true Sharks, there are several species, of which the White-

FIG. 281. — WHITE SHARK.

shark is the most notorious. It sometimes attains the length of
twenty feet, and its mouth is sufficiently wide to enable it to
receive the thigh or even the body of a Man. This species
inhabits most of the seas of warm latitudes ; but it is rarely or
never seen near our own shores. The Fox-shark, or Thresher, is

FIG. 282.— FOX-SHARK.

remarkable for the great development of the upper lobe of the
caudal fin, into which the vertebral column is prolonged (§ 581);
this being nearly as long as the entire body. This fish is occasion-
ally met with on our own coasts, and sometimes attains the entire

60 THRESHER, BLUE-SHARK, PORBEAGLE, DOG-FISH.

length of from ten to twelve feet. Its gape is not so wide, nor
are its teeth so formidable in proportion to its size, as those of
the preceding ; but its tail is a powerful weapon, and it is
exceedingly bold and voracious in its disposition. It has been
stated on good authority, that it is not uncommon for a Thresher
to approach a herd of Dolphins which may be sporting in unsus-
picious security, and by one splash of its tail to put them all to
flight, like so many hares before a hound ; yet the Dolphin is
six times the bulk of the Thresher. — The Biw-shark bears more
resemblance to the "White in its general form, but is much smaller,
not exceeding six or seven feet in length. It is very common off
the Cornish coast, and is extremely troublesome to the fishermen
during the Pilchard-fishing season, cutting their lines and nets,
and devouring the fish. — The Porbeagle belongs to an allied
genus, Lamna, which differs from the true Sharks in having a
pyramidal snout, and the gill-openings placed rather further for-
wards. Its common name seems to be compounded of Porpoise
and Beagle ; for it bears some resemblance to the former in
shape, whilst it corresponds with the latter in its habit of hunt-
ing in packs. It is occasionally met with on almost all parts of
the British coasts, being found chiefly in currents near rocky
places ; it is voracious in its habits, swallowing entire Fishes of
two feet in length. — The Notidamus, which is an inhabitant of
the Mediterranean, is the largest of the true Fishes, its length
being sometimes as much as thirty-six feet ; but it is compara-
tively harmless.

583. This family contains many other genera, more or less
departing from the ordinary type ; among these we may mention
the curious Zygcena or Hammer-headed Shark ; which resem-
bles the ordinary Sharks in the form of its body, but has its
snout prolonged into the form of a double-headed hammer, with
an eye in the middle of each extremity. It is occasionally met
with in European seas, attaining the length of twelve feet,
and larger ones are said to inhabit the tropical ocean. —
The Dog-fish is nearly allied to the Sharks ; and is probably
more abundant on our own coast than any other of the order.
Almost every one who walks along the shore may meet with its

DOG-FISH: SAW-FISH.

61

eggs, which are enclosed in flat oblong cases, with a long tendril
from each corner, by which it clings to solid bodies, or to sea-
weed. In these cases, which are commonly known by the name

283. — HAMMER- HEADED SHARK.

of " fairies1 purses," there is a fissure at each end, which admits
the free access of sea- water to the egg ; and through one of these
the young subsequently escapes. The Small Spotted Dog-fish is
the species most common on our own shores ; and it is not only
very troublesome to the fishermen by entangling itself in their
nets, but also by frightening away the shoals of Herrings, &c.,
which are migrating towards the coast. — The last fish of this
family here to be noticed, is the Pristis or Saw-fish; so named

FIG. 284.— SAW-FISH.

from the extension of its snout into a long flat blade, furnished
with a row of sharp spines, resembling teeth, on either side.
With this formidable weapon the Saw-fish attacks the largest
Whales, and inflicts very severe wounds. It sometimes attains

62 RAHXE; — STING-RAY, THORNBACK.

the length of twelve or even fifteen feet. This fish is very widely
distributed, being found in the arctic, antarctic, and tropical seas;
but it seldom approaches the shore.

584. The true Rays, typical of the family RAID^E, have the
body so flattened, that the pectoral fins seem like a continuation
of it ; and these meet in front of the snout, and are prolonged
backwards as far as the ventral fins ; thus giving to the whole
body a nearly circular form. The eyes are situated on the upper
side of the body, as in the Flat-fish (§ 564) ; but it will be ob-
served, that the plan of construction of the Rays and Skates, is
entirely different from theirs, the two margins being here com-
posed of the edges of the pectoral fins, whilst in the Flat-fish
they are formed by the dorsal and anal ; and the Flat-fish habi-
tually lying on one side, whilst the Rays, &c., lie on the abdo-
minal surface, where we find their mouth and gill-openings.
These fish live for the most part near the bottom of the water,
on beds of sand or mud. When disturbed, they glide along in
an undulating manner, with a slight motion of the pectoral fins ;
and if attacked, they defend themselves by lashing violently with
the tail, which is often furnished with sharp spines. In the
Sting-Ray (Trygon), the tail has a single
strong spine, notched on both sides. There
are several species, intermediate in form be-
tween the Sharks and Rays, by which the two
families are connected. Most of the family
are extremely voracious, feeding on Fishes and
Crustacea, and on naked or testaceous Mol-
lusks. The teeth are flattened and lozenge-
shaped ; and so powerful are the iaws, that

FIG. 285.— STING-RAY. J ,

they are capable of crushing the shell of a
Crab with the greatest ease. Some of the Rays produce their
young alive ; in those which lay eggs, these are deposited in a
horny case, like that of the Dog-fish. One of the most common
of the British species is the Thornlack ; so named from the
skin of its back being covered with thorny tubercles, variable
in their number ; this fish is taken in abundance in the spring
and summer, when it visits the shallows for the deposition of its

TORPEDO. CYCLOSTOMATA ; LAMPREY. 63

eggs, and it is an excellent article of food. The Torpedo, or
Electric Ray (§ 542), is occasionally met with on the Channel-
coast of England ; but it is more common in warmer seas, espe-
cially the Mediterranean. It is peculiar, not only from the
possession of the electric apparatus, but also on account of the
fiddle-shaped form of its body (Fig. 263). The Myliobates re-
ceives its common name of Sea-eagle, from having the pectoral
fins of extreme breadth, so that it much resembles a bird of prey,
with its wings expanded. It inhabits the depths of the ocean,
and attains a very large size ; in a specimen caught in the West
Indian seas, the length of the body was 10 feet, its greatest
breadth 13 feet, and the length of the tail 15 feet.

ORDER IX.— CYCLOSTOMATA.

585. The Fishes of this Order are the least perfect of the whole
class, in regard to the construction of their skeleton ; and are,
therefore, at the bottom of the whole series of Vertebrated ani-
mals ; which they may be correctly regarded as connecting with
the Invertebrated sub-kingdoms. So far are they from having
a jointed vertebral column, that this is replaced, in the highest
among them, by a sort of cylinder of cartilage, which represents
the bodies of the vertebraB, but which does not show any defi-
nite division into segments ; and in the lowest, this cylinder has
not even the firmness of cartilage, but consists of a membra-
nous bag, containing a gelatinous semi-fluid substance. There
are no ribs, nor are there either pectoral or ventral fins ; there is,
in some, however, a kind of fin beneath the tail, but this has no
rays. The body is usually prolonged, and nearly cylindrical ;
and terminated by a circular mouth adapted for sucking. In
the Lampreys there are seven gill-openings on each side ; there
are strong teeth in the ring formed by the pair of jaws ; and the
inner part of the disc, which may be considered as the lip, is
also beset with hard tooth-like tubercles. The tongue, which
moves backwards and forwards like a piston, and which is the
principal instrument in the act of suction, is also furnished

64 LAMPREY, HAG, LANCELOT.

with two longitudinal rows of small teeth. By means of this
sucker, the Lamprey can attach itself to the bodies of the largest

FIG. 286. — LAMPREY.

fishes ; and is able speedily to pierce through their integuments,
and to prey upon their substance. The largest species, which
attain the length of two or three feet, are marine ; the former,
which chiefly inhabit rivers, are sometimes called Lamperns.
The members of the genus Myxine, or Hag, and its allies, have
not even a cartilaginous ring around the mouth, its borders being
entirely membranous, and furnished with only one tooth. The
mouth is surrounded by eight cirrhi, or tendril-like feelers ;
which remind us of the arms of the Cuttle-fish in miniature.
This fish is destitute of eyes ; and does not seem, indeed, to
have any other special organ of sensation than these cirrhi. The
best known species is known to British fishermen under the name
of the Hag ; it is found in the interior of other fishes, whose
bodies it has entered for the purpose of devouring them ; and
it seems to attack in preference those which have been hooked,
and which, consequently, are not able to defend themselves. As
many as six Hags have been found in the skin of a single Had-
dock, on the Norway coast (where this species is more abun-
dant than our own), the flesh of which they had almost entirely
consumed. It is usually from twelve to fifteen inches in length,
and of the thickness of the little finger ; and its whole tissues
are so soft, that it would not have been supposed capable of
inflicting any serious injury. The quantity of mucus which it
can secrete from its surface is enormous ; it has been asserted,
that if a Hag be placed in a pitcher of sea- water, it will speedily
convert this into a semi-transparent jelly ; and that, tif placed
in a fresh quantity of water, it will change this in the same
manner. The most imperfectly formed of all Fish is, probably,
the Amphioxw, or Lancelot; which has, by many Natu-

LANCELOT. — GEOLOGICAL DISTRIBUTION OF FISHES. 65

ralists, been removed altogether from the Yertebrated sub-king-
doin, on account of the almost complete absence of what are
usually regarded as the distinguishing peculiarities of that group.
Nevertheless, an attentive examination of its structure shows,
that it bears a closer resemblance to the true Fishes than to
any other animals — exhibiting their conformation in (as it were)
a degraded form. It is of very diminutive size, scarcely an inch
in length, very slender, and almost transparent. The body is
compressed laterally ; and there are no pectoral, ventral, anal, or
caudal fins, but only a single dorsal fin, extending the whole
length of the body. There are no eyes, nor any vestige of any
external organ, except a mouth, which is surrounded by small
tentacula, like that of the Hag. There is scarcely any trace of
a vertebral column, or of ribs ; yet the muscles are arranged with
great regularity, on the plan of those of Fishes in general. One
of the most curious parts of its structure is the complete absence
of cerebral hemispheres, and even of ganglia of special sense ;
the spinal cord being, apparently, the only centre of its nervous
system. Thus it may be characterised as one of those " expe-
riments prepared for us by Nature ;" exhibiting to us a case, in
which the Cerebrum is never developed ; the phenomena of which
closely correspond with the results that have been obtained
by the artificial removal of that organ. (ANIM. PHYSIOL.
§4650

586. The Geological distribution of this class presents many
points of the greatest interest to the Zoologist. As might have been
anticipated from what is known of the history of the production
of the present crust of the globe, we find remains of Fishes in the
very earliest formations which distinctly exhibit the action of water,
— that is, which were deposited as sediments in the bed of the
ocean ; and this long before we have reason to believe that any land
animals existed upon the surface of the globe. But the Fishes
of this early date were, for the most part, formed upon a very
different plan from those of the present epoch, so that there are
very few of those now existing, which bear any close resemblance
to them ; whilst, on the other hand, the greater proportion of

66 CLASSIFICATION OF FOSSIL FISH.

the species now existing had no representatives among those,
which inhabited the primeval ocean. Many of the latter are
known to us only by their scaly coverings, which are frequently
preserved with the greatest perfection, when the internal skele-
ton has disappeared, — the scales having the hardness of bone or
even of enamel, whilst the skeleton was cartilaginous. — As we
ascend towards the newer formations, which are nearer the
surface of the earth, we find the character of the class gradually
changing, — the forms, which were predominant in the older
rocks, disappearing one after another, and being replaced by
others, which bear more resemblance to those now existing. It
has been discovered by Professor Agassiz, who has devoted a
large part of his life to the study of Fossil Fish, that there is a
constant correspondence between the character*of the scales and
the internal organisation of the fish ; and he has proposed that
the arrangement of the class shall be founded in the first instance
upon the form and structure of the Scales. This classification
has not yet been received amongst Naturalists, as superseding
that of Cuvier ; but the advantages which it presents, in regard
to the study of Fossil Fishes, give it a claim to our attention.
. — According to Professor Agassiz, all Fishes may be arranged
under the four following groups :

I. GANOIDIANS ; from the Greek yaros, splendour. — The
Fishes of this order are covered by angular scales, composed
internally of bone, and coated with enamel. The scales are
regularly arranged, and entirely cover the skin with an almost
impenetrable armour. — This order includes the Sauroid fish
(§ 588), of which the Sturgeons and the Lepidosteus are the
only existing representatives ; together with many other peculiar
forms, to which we have nothing at all analogous among the
Fishes now existing.

II. PLACOIDIANS ; from the Greek -rrAaf, a broad plate.—
This order contains Fish whose skin is covered irregularly with
plates of enamel, often of considerable dimensions, but sometimes
reduced to small points, like the shagreen on the skin of the
Shark, and the prickly tubercles of the Ray. — Among existing
fish, this order comprehends only the Sharks and Rays and their

FOSSIL FISH OF OLD RED SANDSTONE. 67

allies ; but these form but a very insignificant part of the species
which are to be referred to it.

The two preceding Orders are further characterised by the
peculiarity in the form of the tail, which has been pointed out
in the Sturgeons (§ 581) ; and which, among the existing fishes,
is confined to that family, with the Sharks and Rays, and the
Lepidosteus.

III. CTENOIDIANS ; from the Greek Kfet?, genitive KTZVOS, a
comb. The Ctenoid fish are covered with horny or bony scales,
jagged like the teeth of a comb on the outer edge. The Perch
and many other existing genera are examples of this order,
which contains but few fossil forms.

IV. CYCLOIDIANS; from the Greek KVKAos, a circle. — The
Fish of this last order have their scales smooth and simple at the
margin, and often ornamented at the upper surface. The Her-
rmg^ Salmon^ &c., are referred to the Cycloid order; which,
with the preceding, includes all the existing species, with the
exception of the few that have been already mentioned as
belonging to the preceding groups.

587. Now the Fish of the oldest or Palaeozoic strata belong
almost exclusively to the first of these divisions ; and of eighty
species of Ganoid fish, — which are all that have been hitherto
described, — upwards of fifty are exclusively met with in the
Old Red Sandstone formation alone. Many of the forms pre-
sented by these are most extraordinary, — being totally unlike
any with which we are acquainted among existing species, — and
indicating an obvious mixture or combination of the characters
of the class of Fish with those of the Crustacea. Indeed in
regard to the real nature of some of the species discovered a few
years since in Scotland, even Agassiz was at first undecided, —
so strong was the resemblance presented by them to certain forms
of Crustacea, especially the TriloUtes hereafter to be described
(§ 764) ; and it was not until connecting links were discovered,
in which the distinctive characters of the true Fish were more
obvious, that the nature of the first could be certainly deter-
mined. The head and body of many of these fish were covered
by large hard plates; whilst the internal skeleton, from the

F 2

68 GANOID FISHES OF OLD RED SANDSTONE.

entire absence of any remains of it, seems to have been composed
of soft cartilage. In the Cephalapsis (or buckler-head), the head
was very large in proportion to the body, occupying one-third of
its length, and being rendered of enormous breadth by two cres-
cent-shaped wings, extending backwards and outwards. In the
Ptericthys (or winged fish), the plates both of the head and body
were very large, and consequently few in number ; it was fur-
nished with a pair of wing-like fins, placed far forwards, and
terminating in a kind of hook, or strong curved point ; and the
tail, which occupied more than a third of the total length of the
animal, was straight, pointed, and covered with small tubercu-
lated angular scales. " Most probably the tail was employed as
the principal organ of locomotion ; the pointed fins being elevated
at the approach of danger, and the animal in this way rendering
itself as unapproachable and as difficult to be swallowed as its
form would admit of." The Cocosteus had a body of triangular
shape, tapering away towards the tail ; and was covered almost
entirely by a central plate, much larger than any of the others,
having a continuous ridge along the middle of the back ; it was
also furnished with a couple of defensive fins, situated near the
head, like those of the Ptericthys. The tail evidently possessed
a vertebrated structure ; and it was by this that the animal was
most certainly recognised as a Fish. — its jaws and teeth having
more the characters of the nippers of a Lobster or the mandibles
of a Beetle. The teeth were chiselled, as it were, out of the
solid bone of the jaw; just as the teeth of a saw are cut out of
a plate of steel : and the line of opening of the jaws was vertical,
as in the Articulata, instead of being horizontal, as in the Verte-
brata. Remains of this fish are found very abundantly in some
situations ; varying from a few inches to two feet in length. —
The other Fishes of the Palaeozoic epoch were, for the most part,
less widely different from those of the present day ; one remark-
able genus may be mentioned, the Holoptychius, which exceeded
most of the others in size, and was evidently adapted to prey
upon them. The name of this fish is derived from the large
undulating furrows marked upon the surface of its enamelled
scales, which give them a most beautiful appearance ; these scales,

SAUROID PISHES. 69

by their strength and magnitude, seem as if they might have
served for the armour of a Crocodile ten times the size of the
fish. Its head, also, was inclosed within bony plates, whose
upper surface was covered with rough tubercles of enamel ; and
the jaws, likewise, were composed of bone, whose outer surface
was polished, covered with enamel, and unclothed with skiri.
A row of thickly-set pointed teeth fringed the enamelled edges
of the mouth, and corresponded to the lips of ordinary fish ;
whilst within this was a second and wider range of teeth,
at least twenty times the bulk of the others. This, and some
other allied genera, were evidently the " pirates " of their day ;
the extraordinary armature of their jaws being in conformity
with the remarkable defences, with which the bodies of the fishes
that served for their prey were endowed.

588. As we pass from the Old Red Sandstone into the newer
rocks, we meet with a change in the characters of the Fish,
whose remains are imbedded in them. All those just described,
with the exception of the last, disappear ; and they are replaced
by others. Still we find that of the Fish contained in the
Mountain Limestone and the beds associated with it, a large
proportion belonged to the order Ganoidians ; but, among these,
the Sauroid fishes now predominate. These are at once dis-
tinguished by the peculiar form of their teeth; which are
marked by longitudinal furrows like those of Crocodiles ; and
which have a conical hollow at the base, in which the next
tooth is prepared, as in many Reptiles. So strong, indeed, is
the resemblance of both the teeth and scales of several of the
Fishes of this group to those of some Crocodilian animals,
that, when first discovered, they were immediately referred to
that class. The dimensions of the teeth of the genus Megalic-
thys (large fish), far exceed those of any other fishes' teeth that
have been yet examined ; one of them having been found to
measure nearly four inches in length, with a breadth at the base
of nearly two inches. The large teeth are accompanied by
several very small ones, which alternated with them, and were
distributed over the whole of the inside of the mouth. Scales of
this fish have been met with as much as five inches in diameter.

70 PLACOID FISHES OF CARBONIFEROUS SERIES.

There is some reason to think, from the character of the other
fossils with which its remains are associated, that this Fish was
an inhabitant of fresh water, like the comparatively diminutive
Lepidosteus of the present day (§ 572). The Sauroid fishes pre-
dominate in an increasing degree among the genera of the
Ganoid order, as we rise through the newer strata ; and at
last they become the only representatives of that order. It is
between the Oolitic and Chalk periods, that we find the most
remarkable change in the proportion which the Fishes of this
group bear to those of other orders ; for, whilst the Oolite
includes the remains of numerous fishes of the Ganoid order, —
many of them Sauroid fishes of great size and strength, — we find
but very few in the Chalk and later formations, and even these
are of diminished size and ferocity; so that, by this gradual
change, the order has now become nearly extinct, as already
mentioned.

589. It is in the strata of the Carboniferous order, or the
Mountain Limestone and the overlying beds of the Coal series,
that we encounter the first appearance, in any considerable
proportion, of the Fishes of the Second order, or Placoidians.
These do not depart so widely from the forms with which we
are familiar at the present day, as did the earlier Ganoidian
Fishes ; but it is interesting to remark, that the greater number
of the early Placoidians did not bear a resemblance to the Sharks
and Rays which are most abundant at the present time, but to
some that are now regarded as aberrant forms, separated from
the rest by peculiarities of conformation. This is the case, for
example, with the Cestracion Philippi., or Port-Jackson Shark ;
which has the margins and inner surface of the jaws covered
with flat pavement-like teeth, disposed in an oblique row ;
whilst the front of the moutli is armed with sharp, angular, and
pointed teeth, more resembling those of the ordinary Sharks.
The latter are evidently adapted for seizing and retaining the
food ; the former for crushing and bruising it. These teetli are
rarely found connected together in a fossil state. Now, of the
fossil Fishes presenting these peculiarities, and referred on that
account to the family Cestracionts, remains are found even in the

PLACOID, CTENOID, AND CYCLOID FISHES. 71

Palasozoic strata; they become more numerous in the Car-
boniferous series ; they are very numerous in the Lias and Chalk
formations ; but there they cease almost entirely, — the strata of
the Tertiary series scarcely containing any of them, and the
Port- Jackson Shark being the only representative of this family
at the present day. — Intermediate between these and the ordinary
Sharks was another family, to which the name of Hybodonts has
been given. The teeth of this division were stronger and
blunter than . those of the true Sharks, but were not so much
flattened as those of the Cestracionts ; and they seem to have
been adapted for cutting, tearing, and bruising substances of
considerable hardness. The Fishes of this family seem to have
made their first appearance in the later part of the Coal forma-
tions ; they were very abundant during the Oolitic period ; but
ceased entirely at the commencement of the Chalk deposit. —
Lastly, the ordinary Sharks, constituting the Squaloid family,
which are distinguished by their sharp lancet-like teeth, have no
representatives among the Fossil Fishes of older date ; but their
remains are first found in the Chalk formations, and extend
through all the newer strata down to the present time. — The
Rays, also, of the earlier periods had teeth more flattened than
those of later epochs ; and we find from their fossil remains,
that some of the forms, which are now regarded as exceptional
or aberrant, were formerly more abundant. Thus of the
Myliolatis or Eagle-Ray (§ 584), of which five species are at
present known, fifteen fossil species have been discovered.

590. The Ctenoid and Cycloid Fishes make their first
appearance in the Chalk formation ; when all the previously-
existing genera of the Ganoid and Placoid orders had become
extinct, and when the new ones that were brought into existence
were (as we have seen) far less numerous than before. There is,
then, a sort of 'boundary line at the base of the Cretaceous or
Chalk deposits, which divides the class of Fishes in a most
remarkable manner ; — all those below that line, in the order of
the strata, or (in other words) all those which existed at a period
anterior to the deposition of the Chalk, having belonged to the
two first orders, those with enamelled scales ; — whilst by far the

72 GENERAL RELATIONS OF FOSSIL FISHES.

larger proportion of those existing at a subsequent time, as at
the present epoch, belong to the two orders with horny scales,
which comprehend at least three-fourths of the 8000 living
species of Fishes known to Naturalists. Of the fossils of these
last orders, which abound in the formations of the Tertiary
period, it is sufficient to say, that they may nearly all be referred
to families which have been described as now existing ; that
many of them belong to the same genera with recent Fishes ;
but that it is doubtful if any of them are of the same species with
those now tenanting our seas.

591. The sketch here given of the principal groups of Fossil
Fishes, is sufficient to illustrate some very interesting points in
the history of this class. In the first place, we see that the first-
created Vertebrated animals so far resembled the Invertebrated
classes, as to possess a very dense external skeleton ; whilst their
internal skeleton was so soft, as not to be capable of being pre-
served ; and it appears to have been to the Crustacea, which are
among the highest of the Articulated series, that these Fishes
were most nearly related. On the other hand, among the Fishes
of the present time, the Cyclostomata, which present the cha-
racters of the Vertebrata in their most imperfect form (§ 585),
are rather analogous to the Annelida^ or Worm tribe ; with which,
indeed, some of them were actually classed by Linneeus. — We
may next observe, that the covering of dense enamelled scales,
in which all the Fishes of the earlier formations were inclosed,
rendered necessary a peculiar conformation in the mouths of
those, which were destined to prey upon them and to restrain
their multiplication. Thus we find the mouths of the predaceous
Ganoid fishes, such as the Holoptychius and its allies, and in
those of the Cestracionts and Hybodonts, a pavement-like cover-
ing of flat enamelled teeth, adapted to crush the hardest sub-
stances. But when the enamelled-scaled Fishes had given place
to those furnished with a softer covering, we find these enamelled
pavements of the jaws replaced by sharp cutting teeth, — the
predaceous Ganoids disappearing altogether, and the Cestracionts
and Hybodonts giving place to the Sharks. — What was the
purpose for which all the earlier races of Fishes were provided

GENERAL RELATIONS OF FOSSIL FISHES. 73

with the enamelled covering so often alluded to, and why these
races should have given place at a later period to others so differ-
ently constituted, we have no certain means of knowing. It has
been suggested by Dr. Buckland, that the purpose of this cuirass
may have been, to defend the bodies of the animals against waters
that were warmer, or subject to more sudden changes of tem-
perature than could be endured by animals, whose skin was pro-
tected only by such thin and often disconnected coverings, as the
membranous and horny scales of most modern Fishes. Such
changes of temperature were more frequent, there is good reason
to believe, in the earlier epochs of the Earth's history, than they
are at the present time, for reasons which will be elsewhere
explained. (See Treatise on GEOLOGY.)

592. It may be further remarked, that the history of the
Fossil Fishes most clearly proves, that the first-created forms of
Animal life were not the least perfect, — as some have maintained;
and that there is not a regular succession of new races, increasing
in elaborateness of structure, from the oldest to the most recent
formations. For among the earliest races of Fishes, we find that
those of the Sauroid family, which had many characters of eleva-
tion, held a conspicuous place ; and that, when these were
replaced by the class of Reptiles, which was called into existence
as soon as there was any land for its habitation, they ceased to
exist, and were succeeded by races of Fishes which must be
regarded as lower in the scale.

74

CHAPTER VII.

GENERAL CHARACTERS OF ARTICULATED ANIMALS.

593. THE animals of which is composed the Sub-Kingdom
ARTICULATA, not only present an internal structure which is
essentially different from that of the other three divisions of the
Animal series, but are likewise distinguished by external charac-
ters, which are usually so definite and evident, that they may be
almost always recognised at the first glance. Their entire body,
in fact*, is divided (more or less obviously) into segments ; and
seems to be composed of a series of rings placed in a line. In
some Articulated animals, this annular (ring-like) appearance
results merely from a certain number of transverse folds, which
furrow the skin, and encircle the body ; but in the greater num-
ber, the animal is enclosed in a sort of solid armour, composed

Fro. 287-— IULUS.

of a series of rings, united one to another in such a manner as to
allow them a certain degree of movement. This envelope has
uses analogous to that of the internal framework of Vertebrated
animals ; for it determines the general form of the body ; it
protects the soft parts; it gives points of attachment to the
muscles; and furnishes them with levers, by their action on
which the movements may be effected with precision and
rapidity. Hence it may be termed an external skeleton. It
must be borne in mind, however, that the hard substance
of which it is composed has no analogy in structure, or in

GENERAL STRUCTURE OF ARTICULATED ANIMALS. 75

mode of growth, with the bones of Yertebrated animals. It con-
sists, in fact, of the skin, consolidated by the deposition of horny
or calcareous matter in its substance ; and instead of being able
to grow in all directions in the manner of bone, it undergoes
very little change when it is once fully formed, and it cannot be
made to increase in size except by addition to its edges.

594. The different rings, or segments, of the body of an Arti-
culated animal, always bear a strong resemblance to each other ;
and sometimes, as in the lulus (Fig. 287), and the Scolopendra,
or Centipede, they seem like actual repetitions of each other.

Dorsal arch Dorsal oar

Dorsal member

Ventral member Ventral arch Ventral our

FIG. 288. — VERTICAL SECTION OF A SEGMENT OF AN ANNELIDE, BELONGING
TO THE GENUS AlMPHINOME.

Each ring may bear two pairs of appendages, or members ; the
one belonging to its dorsal arch, or the upper part of the seg-
ment ; whilst the other belongs to the ventral arch, or the under
part of the ring. In those Articulata in which the principle of
"division of labour" does not yet manifest itself, — that is, in
whose bodies we find a number of similar parts adapted to
perform the same functions, instead of an assemblage of dif-
ferent parts, constructed each for its own special purpose, — all the
segments are provided with these appendages, and their number
is sometimes extremely great. But in all the higher tribes, we
find the appendages of certain segments attaining a high de-
gree of development ; whilst, by a sort of compensating principle,
the others present themselves as mere rudiments, or are not even
at all discoverable. In general the appendages of the ventral
arch are alone developed ; and the variety of forms which they

76 APPENDAGES OF THE TRUNK.

present is greater, in proportion as the animal is more elevated
in the scale. Thus we find them so modified as to become
antenna, — those long, horn-like filaments, with which the head
is furnished in. Insects and Crustacea,— or to Le subservient to
mastication by being converted into jaws, or to take the form of
legs, swimming organs, &c. Of this metamorphosis we shall
hereafter notice some remarkable examples in the class Crus-
tacea. Sometimes, however, the appendages of the dorsal arch are
present throughout, and perform, like those of the ventral arch,
the functions of limbs ; of this we find many examples amongst
the Annelida. But in general, no more than two pairs pre-
sent themselves ; these are situated on the segments constituting
the centre of the body ; and they perform the functions of wings
or of analogous organs ; as we shall hereafter see, when speak-
ing of the class of Insects. The legs are generally 6, 8, 10, or
14 in number ; sometimes many hundreds may be counted ; and
sometimes they are altogether deficient ; but when they exist at
all, they are never fewer than six, which is the number that is
characteristic of the class of Insects. Sometimes instead of
distinct legs, we meet with strong bristly appendages, as in the
Earth- worm ; or bundles of such bristles, j.n the midst of which
one is occasionally a cirrhus or tendril-like appendage, constitut-
ing a sort of rudimentary leg, as in many Annelida (Fig. 288.)

595. The tendency to repetition ex-
hibited by the segments of the body,
is as remarkable in the disposition of

V^^^Hfl |

the muscles and of the nervous system, ^^ &S& ***
as it is in the arrangement of the general
envelope. In most animals of this Sub-
kingdom, each ring in its complete state
possesses a pair of nervous ganglia,
united on the central line ; and these
ganglia are connected together by a
double cord of communication, which
runs along the lower or ventral surface

of the body. In the inferior Articulata, FIG. im— NERVOUS SYSTKM
and even in the highest, previously to
the completion of their development, these ganglia are nearly

OF

NERVOUS SYSTEM OF ARTICULATA.

77

equal, and form witb their connecting filaments two chains re-
sembling knotted cords, extending from one end of the body to the
other. (Fig. 290.) But in proportion as we rise in the scale, we
see the ganglia approach one another, both sideways and length-

FIGS. 290 and 291. — Anatomy of the Caterpillar and Moth of the Privet : a, cephalic
ganglia, situated in front of the oesophagus, and giving origin to the nerves of the
eyes, &c. ; b, cords which unite these ganglia to those of the second pair, passing on
either side of the oesophagus, so as to form a collar round it ; c, first pair of 8ub-ce<-o-
phageal ganglia ; d, ganglion of the first segment of the thorax, followed in the Cater-
pillar by others at regular intervals ; e, nervous mass in the Moth, formed by the ganglia
of the second and third thoracic segments ; /, abdominal ganglia ; h, mouth ; i, trunk ;
j, oesophagus ; k, stomach ; I, intestine and biliary vessels ; m, large intestine ; n, anus ;
o, legs of the first pair ; p, legs of the second pair ; q. legs of the third pair ; r, first pair
of membranous legs, in the Caterpillar ; s, dorsal vessel ; t, first segment of the thorax ;
M, horny appendage at the extremity of the abdomen of the Caterpillar.

wise ; so that each pair unites on the central line into a single mass;
whilst the ganglia of different segments are also brought together
into one spot, and so combined as to form but one large ganglion,
— as we shall hereafter notice especially among the Crustacea.
This centralization is sometimes carried so far, in certain Crabs
for example, that there exist in the whole body but two nervous
masses, — one in the head, and the other in the thorax (Fig. 46f ).
The ganglia which we find in the head of Articulata have a

78 NERVOUS SYSTEM. LATERAL SYMMETRY.

manifest correspondence to those of certain parts of the brain in
Yertebrata. They are not the representatives of the Cerebral
hemispheres, which are peculiar to the latter ; but they ob-
viously resemble the Optic and other ganglia of special sense,
which we find even in the highest Yertebrated animals, at the
origin of the nerves that proceed to those organs, and which in
Fishes make up so large a proportion of the entire brain, as
frequently to surpass in size the cerebral hemispheres themselves
(§ 530). The ganglia of the ventral cord are so many centres of
reflex action to the different segments which they supply ( ANIM.
PHYSIOL. § 442) ; and in this respect they are analogous to the
Spinal Cord of Yertebrated animals, from which they differ in no
important particular, except in their position. Even in this,
however, there is a greater resemblance than is at first apparent ;
for there is strong reason for regarding the usual position of
Articulated animals as really inverted ; that is, for considering
what is apparently the ventral surface of the body as in reality
the dorsal, and the apparent back as the real abdomen.

596. The bulk of the body in the Articulata is made up of
the muscles, by which the several segments, and their various
appendages, are put in motion. These muscles, like the parts of
the body themselves, are arranged with great regularity and
exactness on the two sides of the median or central line ; so that
the lateral symmetry (§ 47) of the Articulata is most exact.
We shall hereafter see that this symmetry extends in great
degree also to the organs of nutrition ; which in the Yertebrata
are not arranged with the same equality. Where the 'segments
and their appendages have a similar form and action, their
muscles are but repetitions of each other ; but where, as in the
higher Articulata, the segments and their appendages are differ-
ently constructed, the muscles also are more variously arranged,
and often form a system of great complexity.

597. The development of the organs of Nutrition in Articulated
animals would seem to be altogether subservient to that of the
Locomotive apparatus ; — their function being chiefly to supply
the nerves and muscles with the aliment necessary to sustain
their vigour. The power of these muscles is so great in proper-

HABITS AND DIGESTIVE ORGANS IN ARTICULATA. 79

tion to their size, that, in energy and rapidity of movement,
some of the Articulated tribes surpass all other animals. These
movements are directed by organs of sensation ; which, although
not developed on*so high a plan as those of some Mollusca, are
evidently very acute in their powers. There are very few
instances of Articulated animals being in any way restrained as
to freedom of locomotion ; and these are for the most part found
in a single group, the CIRRHIPODA, or Barnacle tribe, which
connects this sub-kingdom with the preceding. In general they
roam freely abroad in search of food ; and they arfc supplied with
prehensile organs for capturing their prey, and with a complex
masticating apparatus for reducing it. Their actions are evi-
dently directed almost solely by instinctive propensities, which are
adapted to meet every ordinary want ; these are of similar
character in each individual of the same species, and present but
little appearance of ever being modified by Intelligence. Hence
these animals seem almost like machines, contrived to execute a
certain set of operations ; many of them, however, producing
immediate results, which even Man, by the highest efforts of his
reason, has found it difficult to attain.

598. All the Articulata, save a few of the very lowest
species, possess a distinct head at one end of the body, furnished
with organs of special sensation, and with jaws for the prehen-
sion and reduction of the food. These jaws do not open vertically,
however, as in the Vertebrata, so as to leave a horizontal
aperture ; but laterally, so as to leave a vertical aperture :
and there are frequently several pairs of them, one behind the
other, sometimes furnished with sharp cutting edges, sometimes
having their edges toothed like a saw, and sometimes adapted to
crush rather than to cut or tear. The alimentary tube frequently
passes straight along the central line, from one extremity of the
body to the other, with a dilatation near its commencement, —
the stomach : and where this is not the case, the convolutions
which the intestine makes are usually few in number. Instead
of a heart, we find a dorsal vessel (s, Figs. 290 and 291), a long
tube placed on the central line of the back, and divided into
segments, corresponding with those of the body, — each seg-

80 NUTRITIVE APPARATUS OF ARTICULATA.

ment being, as it were, the heart for its own division. The
respiratory apparatus, too, is arranged with the most perfect
symmetry. In the lower tribes, and in the Crustacea, it
is adapted to act in water ; and consists of gills or branchial
appendages, of various forms, which are prolonged from the
exterior of the body. But in Insects and Spiders, wThich con-
stitute the great majority of the class, the respiration is aerial ;
and is performed by an apparatus consisting of a set of chambers
or tubes, which are dispersed or extended through the whole
body. By this means, the air, the blood, and the tissue to be
nourished, are all brought into contact at the same points ; and
a much less vigorous circulation is required, therefore, than
would otherwise be needed. The whole apparatus of Nutrition
is comprised within a comparatively small part of the body,
in the higher classes at least ; and the bulk of the organs
composing it is never to be at all compared with that, which we
ordinarily find in the Mollusca. Thus the Liver, which in the
Oyster forms a large part of the whole substance, is often
scarcely discoverable in the Insect ; and where (as in the Crus-
tacea) its bulk is considerable, it is because the respiration, being
aquatic, is less active than usual, and is consequently not suffi-
cient to draw off the superfluous carbon from the blood ( ANIM.
PHYSIOL. § 365). The blood is usually white, as in other Inver-
tebrated classes ; and where it is otherwise (as in some of the
Annelida), it is in the liquor sanguinis, and not in the corpuscles,
that the colour exists, — these last being analogous to the colour-
less^ and not to the red corpuscles of the blood of Vertebrata.
The temperature of Articulata usually varies with that of the
air or water they inhabit ; but in the class of Insects we find
many, which have the power of generating a large amount of in-
dependent heat ; and this is strictly proportional to the quantity
of oxygen converted by them into carbonic acid, by the respira-
tory process. All the actions of the Articulata are performed
with great energy ; and at the time of the most rapid increase of
the body, the demand for food is so great, that a short suspension
of the supply proves fatal. Many of them, however, are capable
of being submitted to the influence of very high and of very low
temperatures, with little permanent injury.

CLASSIFICATION OF ARTICDLATA. 81

599. The division of this Sub-kingdom into Classes, is princi-
pally founded on the organs of locomotion ; which, as we have
seen, are so characteristic of it. We may first form two groups,
distinguished by the presence, or absence, of distinctly-articulated
members. In the former, the locomotive power is for the most
part consigned to these appendages ; and the trunk is usually
encased in a hard envelope, in which, by the union of segments
that were originally distinct, we sometimes almost lose the traces
of the characteristic division. This is especially the case with
the Crab and its allies ; in which the different parts of the body
are quite immoveable upon each other. On the other hand, in
the lower group, in which distinct members are wanting, the
locomotion of the animal is chiefly effected by the movement of
the body itself ; and this is permitted to the utmost
extent, by the softness of the integument, in which
the intervals of the articulations are scarcely
distinct from the rings themselves, — as in the
Leech or Earth-worm, — so that here, too, the
division into segments becomes indistinct, from
the opposite cause. It is in the Centipede (Fig.
292) that we have the best example of the divi-
sion of the body into segments, which is charac-
teristic of the entire group ; together with an
articulated structure in the limbs. In the classes
of Insects, Crustacea, Spiders, &c., the equality
of the segments disappears ; whilst in the Leech
and Worm tribes, the members disappear.

600. The higher division of the Articulated
series may be arranged into the following
classes : —

I. INSECTS ; characterised by the division of the
body into three distinct portions, — the head,
thorax, and abdomen ; by the possession of
FIG. 292. antenna? on the head, of three pairs of legs, and

CENTIPEDE. * .

(in general) of one or two pairs of wings ; and
by their aerial respiration.

II. ARACHNID A, including the Spiders, Scorpions > and Mites;

CLASSIFICATION OF ARTICULATA.

characterised by the division of the body into two distinct por-
tions, the cephalo-thorax (made up of the head united to the
thorax) and abdomen ; by the possession of four pairs of legs ;
by their want of antennae ; and by their aerial respiration.

III. CRUSTACEA, or Crabs, Lobsters, &c. ; distinguished by
their aquatic respiration; and by the possession of from five to
seven pairs of legs; the body sometimes divided nearly as in
Insects, sometimes even more concentrated than in the Arach-
nida, and sometimes formed on the plan of that of the Myriapoda.

IV. MYRIAPODA, the Centipede tribe ; characterised by the
want of distinction between thorax and abdomen ; by the equality
of the segments of the body, — the head, however, being very
distinct ; by the large number of legs, of which there are seldom
less than twenty-four pairs ; and by their aerial respiration.

Intermediate in some respects between the two divisions of
this Sub-kingdom, we may rank the following remarkable
group :—

Y. CIRRHOPODA, or the Barnacle tribe ; in these, there are no
locomotive members in the adult, although the young possesses
them; there are, however, a series of jointed tendril-like append-
ages, which probably serve both for respiration and for the
acquirement of food ; and the animals remain attached to one
spot, during all but the early period of their lives ; their respira-
tion is entirely aquatic.

601. In the Second division of Articulata, characterised
by the absence of articulated members, we meet with but
three classes.

VI. ANNELIDA, the Leech and Worm tribe ; characterised by
the extension of the body into numerous segments, which pre-
sent scarcely any differences from each other ; by the presence
of a distinct circulating system, and of respiratory organs ;
and by the possession of a well- developed nervous system.

VII. ENTOZOA, or Intestinal Worms, in which the Articulated
form is presented in (as it were) a still more degraded state ;
the segments being yet more completely repetitions of one
another, and often capable of existing separately ; special organs
of circulation and respiration being for the most part wanting ;

CLASSIFICATION OF ARTICULATA. 83

and the nervous system being very indistinct, — never presenting
the double ventral cord in a well-developed condition: these
have very frequently no distinct head.

VIII. ROTIFERA, or Wheel- Animalcules, a group of minute
animals, in which the Articulated structure is often very indis-
tinct, and which are especially characterised by the possession of
cilia, or little hair-like filaments, arranged in rows in the neigh-
bourhood of the mouth, and serving by their movements, both
for the acquirement of food, and for the aeration of the fluids of
the body.

84

CHAPTER VIII.

OF THE CLASS OF INSECTS.

602. THE class of Insects is pre-eminent, not only amongst
the divisions of the Articulated series, but in the whole Animal
kingdom, in regard to the number of distinct species which it
includes ; and it is probably unsurpassed by any, save the Infu-
%sory Animalcules, in regard to the number of individuals at any
time existing on the earth's surface, which belong to the nu-
merous and diversified races comprehended in it. The whole
sub-kingdom of Vertebrated animals may probably be estimated
as not containing above 30,000 species, — a number which is
surpassed by the Beetle tribe alone ; and we should be probably
not far wrong in saying, that the number of species of the whole
class, already known, exceeds that of all other animals put toge-
ther. Moreover, on account of the small size of «//, and the very
minute size of a large proportion, of the animals belonging to
this class, it is probable that the number of species already
known is far surpassed by that which remains to be discovered.
Even in our own country, new species of Insects are continually
being discovered, by the industry of observers who devote
themselves to this particular branch ; and the number at present
unknown must of course be far greater, in countries that have
been less completely explored. Of the importance of this class
in the economy of Nature, several striking proofs will be given
hereafter.

603. The tegumentary skeleton of Insects, that is to say,
the hard skin of these animals, sometimes preserves a certain
degree of flexibility ; but generally presents a consistency analo-
gous to that of horn. It must not be thought, however, that its
tissue is really of that nature ; for Chemistry teaches us that it
is composed of very^ different materials, and that a particular

EXTERNAL SKELETON OF INSECTS.

85

substance named Ckitine, forms the base of it ; but there is reason
to believe, that it possesses a definite organic structure ; and
that it consists of one or more layers of cells, in the cavities of
which this substance is deposited. We see in it a great number
of pieces, which are sometimes soldered (as it were) together ;
whilst in other instances they are united by soft portions of the
skin, and thus possess a greater or less freedom of motion.

604. The body of the Insect, as we have already said, is
divided into a certain number of rings, placed end to end ; and

- Head

Thorax

Abdomen

Antennae
Eyea

1st pair of Legs

1st pair of Wings
2nd pair of Legs

2nd paii- of Wings

3rd pair of Legs

Tibia

Tarsus

FIG. 293.— ANATOMY OF THE EXTERNAL SKELETON OF AN INSECT.

in this series of segments, we distinguish three portions, to which
are given the names of Head, Thorax, and Abdomen. The
members or appendages, which spring from the several segments,
have a structure analogous to that of the trunk of the animal :
being composed of tubes or of hollow plates, placed end to end,
and enclosing in their interior the muscles and nerves destined to
put them in motion.

86

ANTBKNJS OF INSECTS.

605. The head is formed only by a single piece ; and bears
the eyes, the antennas, and the appendages of the mouth. The
antennce constitute the first pair of members or appendages of
Insects; and are composed of a considerable number of small
joints placed end to end ; they arise from the anterior or superior
part of the head j and generally have the form of slender and

FIG. 294 — CAPRICORN BEETLE.
a, a, antennae.

FIG. 295.— PAUSSUS CORNU.

flexible horns (Fig. 294, a a) ; but their conformation varies
much, especially amongst the males ; thus they sometimes
resemble feathers, sometimes saws ; at another time small bulbs
(Fig. 295) ; and in other instances they are terminated by an
enlarged part composed of layers placed like the leaves of a book.
Their length is sometimes very considerable. We know nothing
positive regarding their use ; but it is supposed that they are

FIG. 296. — VARIOUSLY-FORMED ANTENNAE OF INSECTS.

organs of feeling, and perhaps also of hearing (ANIM. PHYSIOL.
§ 498). Other appendages, to the number of three pairs, spring

LEGS OF INSECTS. 87

from the inferior part of the head, and constitute the organs of
mastication or of suction ; we shall return to these, when speaking
of the Digestive apparatus.

606. The thorax of Insects occupies the middle part of their
body ; and bears the legs and the wings. It is always composed
of three rings, named prothorax, mesothorax, and metathorax
(Fig. 293, a, 5, c) ; and to the ventral arch of each of these seg-
ments, is fixed one of the pairs of legs. The wings arise, on the
contrary, from the dorsal arch of the thoracic rings ; but the
prothorax never bears them, and there never exists more than
one pair of these appendages on each of the succeeding rings ;
so that their number can never exceed two pairs.

607. We may distinguish, in the limbs of Insects, a haunch
composed of two joints, a thigh, a shank, and a kind of finger,
named tarsus^ which is divided into several joints whose number
varies from two to five, and is terminated by claws. Their con-
formation differs ; but, as may be readily believed, it is always
in relation with the habits of the animals. Thus the Insects
whose posterior legs present a great length (Fig. 297), usually
jump rather than walk; amongst the swimming insects, such
as the Dytiscus, the Notonecta (Fig. 298), and the Gyrinus, vul-
garly called "Whirligigs (Fig. 299), the tarsi are usually flat-
tened, fringed with hairs, and arranged like oars ; and amongst

FIG. 297.— LOCUST. FIG. 298.>-NoTONKCTA. FIG. 299 — GYRINUS.

those which can walk suspended from smooth surfaces, we find,
under the last joint of these organs, a kind of cushion or cup,
fitted to make them adhere to the body which they touch.
Sometimes, also, the anterior legs are widened like those of the
Mole, in order to enable them to dig in the ground ; the Mole-
Cricket, which often occasions considerable injury in our fields,

88

LEGS OF INSECTS.

by cutting the roots which it finds in its way, presents us with
a remarkable example of this form of structure. There also

FJG. 300. — MOLE-CRICKET.

exist some species, amongst which these same limbs constitute
organs of prehension, the leg being disposed in the manner of a
claw, and being able to bend itself back against the preceding

FIG. 301. — MANTrs RELIGIOSA.

joint, of which the edge is armed with spines. A large insect

from the South of France, the
Mantis reliyiosa, is formed in this
manner. Again, we meet with
some insects, amongst which the
anterior legs are reduced to a ru-
dimentary state, and bent back
against the thorax, no longer serving
for its movements, and easily
escaping notice, so that at first
sight we should believe these
animals were provided with only
FIO 302.-MORPHO. four legs > several diurnal Butterflies

are in this condition (Fig. 302).

608. The wings of Insects are leaf-like appendages, com-
posed of a double membrane, supported on the inside by a
more solid framework. When they are but slightly developed,

WINGS OF INSECTS.

89

they are soft and flexible ; but they soon dry up, and remain
stiff and elastic. In general there are two pairs ; we never find
a greater number, but sometimes one or other of these pairs is
wanting ; and it is always from the last two rings of the thorax
that they arise. Their form varies ; when they really serve for
flight, they are thin and transparent, except when lightly covered
with a kind of coloured dust, formed by scales of a microscopic
minuteness, such as we see amongst the Butterflies ; but often
those of the first pair become thick, hard, and opaque, and con-
stitute a kind of sheath or casing, named elytra (a, Fig. 303),

which, in a state of rest, covers
over the membranous wings (£>),
and serves to protect them ; at
other times these same wings,
still membranous at their extre-
mity, become hard and opaque
towards their base, and are then
designated under the name of
demi- casings or hemelytra. "We
are acquainted, also, with some
insects, amongst which the wings,
instead of having a leaf-like
FIG. 303. structure, are divided into a

number of membranes, barbed

along the edges, so as to resemble feathers arranged in a fan-
like manner ; this is seen in a genus allied to the Butterflies,
and known under the name of Pterophorus, or Plumed- Moth.

Fio. 304.— PTEROPHORUS. FIG. 305.— CONOPS.

Again, when the posterior wings are wanting, they are generally

90

ABDOMEN OP INSECTS, AND ITS APPENDAGES.

replaced by two small moveable threads, thickened at the end,
which are called balancers (Fig. 305).

609. The abdomen of Insects is composed of a considerable
number of rings, moveable upon each other ; we can frequently
reckon nine of these ; but at other times we cannot distinguish
so many ; this appears to depend on the union of two or more
of these segments with each other. In the perfect Insect, these
rings never bear any legs or wings ; but those which occupy the
posterior extremity of the body, often give attachment to ap-
pendages, whose forms and uses vary very much. Sometimes
they are simple bristles, or points, whose functions are not well
known; as in the Ephemera (Fig. 334) for example. Sometimes
these organs possess the form of hooks ; and
constitute a more or less powerful pair of pin-
cers, as amongst the Forficulce, or Earwigs
(Fig. 306). At other times they are so
arranged, as to act as a spring, and to enable
the animal to throw itself forwards; the
Podurce, or Spring-tails, — small insects,
which, in our climate, conceal themselves
under stones, or keep themselves on the sur-
face of still water, and which also live some-
FIG. 306— FORFICULA. times m *ne snow of the coldest regions of the
globe, show this mode of organisation.
Again, in other instances, these abdominal appendages
have a more complicated struc-
ture, and constitute an offensive
weapon, or an apparatus des-
tined to effect the deposit of
the eggs laid by the animal in
a place fitted for the development
of its young ; as examples of
these organs, we may mention

the retractile sting of the Wasps and Bees, and the piercer of
the Tenthredos, or Saw-flies. The former is composed of a
dart, formed of two sharp-pointed processes, placed within a
horny sheath, or case, and having in each a furrow (completed
into a canal by the union of the two) through which the poison

FIG. 307.— PODURA.

STINGS AND BORERS OF INSECTS.

91

flows, that is secreted by a small gland which is situated very
near. In a state of repose all these pieces are drawn within the
body of the animal ; but when the insect wishes to use it, he
causes the sheath to project, and buries it, together with his dart,
in the skin of his enemy. Sometimes it is even impossible
for him to draw it out ; the whole sting is then separated from
the body, and remains fixed in the wound. The injury which
results from this, quickly causes the death of the insect. The
male is always destitute of this weapon ; hence it may be seized
without danger : but the females, and generally the sterile
individuals, called workers, are provided with it : the puncture
causes a painful inflammation. — The borer of the Ichneumons,
of the Fcenus (Fig. 308), and of many other insects, shows an

arrangement very analogous; and
we generally observe in it a kind
of small saw, by the aid of which
the insect pierces the vegetable or
animal tissues in which it desires
to deposit its eggs. It is by thus
piercing a species of oak, in the
Levant, that the small insect,
known by the name of Cynips,
or Gall-fly, causes the formation
of the Gall-nuts, of which so
much use is made in the manu-
facture of ink, and in the prepara-
tion of black dyes. The small puncture effected by the Cynips
causes an overflowing
of the vegetable juices,
and there soon results
from this, an excres-
cence, in the centre of
which we find the eggs,
or larvae, of the insect.
610. Insects are pro-
vided with highly de-
veloped senses ; they evidently possess Hearing and Smell, as
well as Taste, Sight and Touch; but even now the seat of the sense

FIG. 308.— F(ENUS.

FIG. 309 THE INK-GAJLL INSECT, AND THE INSECT

BY WHICH IT IS PRODUCED.

ORGANS OF SENSE IN INSECTS.

of Smell has not been certainly discovered ; and amongst the
greater part of these animals, no special organ of Hearing can
be perceived. The antennas, and the appendages of the mouth,
seem to be the principal instruments for Touch ; and the former
may, perhaps, also serve for the perception of Sound. We also
know very little of the apparatus for Taste ; but the organs of
Sight have been better studied. — The structure of the Eyes is
very different from that which we have seen amongst the higher
animals. In general, the organ which at first sight appears to
be a single eye, is, in reality, formed by the aggregation of a
multitude of small eyes, each having a cornea, a vitreous body
of a conical form, a layer of colouring matter, and a separate
nervous filament. In the common House-Fly, for example, we can
reckon four thou-
sand of these dis-
tinct eyes; and some
insects are known,
which have more
than twenty- five
thousand. All these
little corneas are

hexagonal, and are FIG. 310.-Head and eyes of the Bee : a, a, antenna ; A, facets
United together SO enlarged ; B> the 8sanc with hairs growing between them.

as to form a kind of common cornea, whose surface presents a
number of divisions, resembling the meshes of a net, visible
only by the aid of a magnifying glass. (See ANIM. PHYSIOL.
§§ 573, 574). Moreover, each of the small eyes, which
altogether make up these compound organs, is perfectly distinct
from those which surround it, and forms with them a bundle of
tubes, each terminated by a nervous thread proceeding from a
bulbous expansion of the same Optic Nerve. Nearly all Insects
are furnished with two of these compound eyes, usually placed
on the sides of the head ; but sometimes they are replaced by
simple eyes ; and in other instances these two sorts of organs
exist together. The structure of simple eyes, which are known
also by the name of stemmata or ocelli, has the greatest analogy
with that of each of the elements of the compound eyes. The
simple eyes are generally united in a group, to the number of

SOUNDS OF INSECTS.

93

three, towards the top of the head. We know nothing certain
of the manner f\ which these organs act upon the light that
falls upon them ; nor of the mechanism of vision amongst
Insects.

611. Several Insects possess, in common with the higher
animals, the faculty of producing
sounds : but in general their song is
not connected with the movements of
the air in the respiratory apparatus,
as amongst the former ; and depends
upon the rubbing of certain parts of
the body against each other, or on
the movements produced in certain
special instruments, by the contrac-
tion of muscles. Thus the monoto-
nous and deafening noise of the Cicada
results from the alternate tension and
relaxation of an elastic membrane,
placed like the skin of a drum upon
the base of the abdomen ; amongst
the Crickets, there are certain parts
of the wings, which, when rubbed
against each other, vibrate with in-
tensity, and which have a very curious structure for this purpose ;
but the humming of Flies appears to depend upon the rapid exit

of the air through
the thoracic spira-
cles, during the
violent movement
of flight. Again,
there are some In-
sects that utter a
kind of cry, the
manner of produc-
ing which is not well known ; such is the Sphinx Atropos,
known under the name of the Deaths-head Moth. (ANIM.
PHYSIOL. §§ 676—679).

FIG. 311 — CICADA.

FIG. 312.— SPHINX ATROPOS.

94 NERVOUS SYSTEM OF INSECTS.

612. The Nervous system of Insects shows the general
arrangement, and the chief part of the modifications, which we
have already described in treating of the Sub-kingdom, to which
these animals belong (§ 595). It is principally composed of a
double series of ganglia, which are united together by longitu-
dinal cords ; the number of these ganglia corresponds with that
of the segments ; and they are sometimes at nearly equal dis-
tances, and extend from one end of the body to the other, whilst
in other instances several of them are connected together in such
a manner, as to constitute a single mass. The cephalic ganglia
present a very high development, and give origin

to the nerves of the Antennae and of the Eyes, &c.
The first pair of ganglia below the oesophagus sup-
plies the nerves of the mouth ; and the cords which
unite these nervous centres to the cephalic ganglia,
and which pass round the oesophagus, give off on
each side a nerve which goes back to the stomach ;
and which joining itself with that of the opposite
side, forms a single trunk, running on the central
line above the digestive canal, and having two gan-
glia in its course. The three pair of ganglia on the
ventral cord, following those which are situated im-
mediately beneath the oesophagus, belong to the three
rings of the thorax, and are the points of departure of
the nerves of the feet and the wings ; in general they
are very close together, and are much larger than
the succeeding pairs, which belong to the abdomen.

613. The manner in which Insects are nourished,

7 rlG. 313.

varies very much ; some only live on the juices of NERVOUS s\-s-
plants and animals, others feed on solid food, and
are either carnivorous or devourers of plants ; and these differ-
ences correspond with remarkable modifications in the structure
of the mouth. Amongst gnawing insects, such as Beetles,
Cockchafers, Cockroaches, and Locusts, this opening is furnished
in front with a central piece, named labrum, or upper lip (#,
Figs. 314 and 315) ; and has on each side a kind of large tooth,
moveable and very hard, called the mandible, or upper jaw (&),

BUCCAL APPARATUS OP INSECTS.

95

which serves to divide the food. Immediately behind these
mandibles is found a second pair of appendages, whose structure

FIG. 314.

HEAD OF COCKCHAFER.
a, labrum ; b, mandibles ;
c, maxillae ; d, tongue ;
e, labial palpi ; /, an-
tennae; <7, compound eyes ;
h, ocelli.

PIG. 315. — PARTS OF THE
MOUTH OF CARABUS ;— a, la-
brum ; 6, mandibles ; c,
fa* axillae ; d, labium.

is very complicated ; these are the second pair of jaws, termed
the maxillae (c). Each of these last organs has on the inside a
plate or cylinder, of greater or less hardness, generally armed

FIG. 316. — STAG-BEETLE.

with notches or hairs, and having on the outside one or two
small appendages composed of several joints, and termed maxil-

96

BUCCAL APPARATUS OF INSECTS.

lary palpi. Again, behind the maxillae is found a second pair of
appendages, whose base is supported by a central piece, called
the mentum, or chin. These appendages constitute the tongue
(d, Fig. 314) ; they are applied against the maxillae, as these
organs are themselves applied against the mandibles. We have
further to mention a second pair of jointed moveable appendages,
or palpi ; which are termed labial palpi, — the name of labiumy
or lower lip, being commonly given to the piece formed by the
union of the tongue and mentum (dy Fig. 315). The form of
these various parts differs according to the nature and consist-
ency of the food. The palpi serve principally for seizing the
food, and holding it between the mandibles whilst these divide
it. Sometimes the maxillae have an enormous development, and
form a large pair of pincers on the front of the head ; an arrange-
ment which is very remarkable among the Stag-beetles, and
other species of the genus Lucanus (Fig. 316).

614. Amongst the sucking Insects, the maxillge or the labrum
are lengthened, so as to constitute a tubular trunk ; in the

Mandible

Maxillary Palp —
Maxill

Lubial Palp

Lateral Lobes of
the Tongue

- Tongue .

FIG. 317.— HEAD OF
ANTHOPHOKA.

c d

FIG. 318.— PARTS OF THE MOUTH
SEPARATED.

interior of which we frequently find delicate filaments, perform-
ing the functions of small lancets, and formed by the mandibles
and maxillse modified to such a degree as to be hardly percep-

BUCCAL APPARATUS OF INSECTS. 97

tible. Amongst the Bees, the Anthophorse, or solitary Bees, the
Humble Bees, and other Insects known by Zoologists under the
name of Hymenoptera, the buccal apparatus * presents an
arrangement, which is in some degree intermediate between these
two extreme states. The labrum and the mandibles much resemble
those of the gnawing Insects, and offer nothing very peculiar in
their form and structure («and&, Fig.318); but the maxillae (c)
and the tongue (d) are greatly elongated; and the former have
a tubular form, and inclose longitudinally the sides of the tongue ;
so that these organs, united into a bundle, form a canal that
serves for the passage of the food, always soft or liquid, by which
these Insects are supported. This tube is moveable at its base,
and flexible during the remainder of its length ; but it is never
rolled up, as we shall find amongst the Butterflies. The man-
dibles serve only to divide the materials, of which the Hymen-
optera make their nests ; or else to seize and put to death the
prey, whose juices these Insects suck. It is also to be observed,
that there exist within the buccal cavity other solid pieces
which are wanting amongst the gnawing insects ; and which
constitute valves destined to close the pharynx, whenever the
movement of deglutition is not going on.

615. Amongst the Cicadas, the Bugs, and other insects of
the order Hemiptera, the apparatus for suction is
composed of the same elements ; but these present
a somewhat different arrangement. The mouth is
armed with a tubular and cylindrical proboscis,
directed downwards and backwards (Fig. 319),
and composed of a sheath inclosing four bristle- like
prolongations, or setae ; the sheath (#, Fig. 320)
is composed of four joints, placed end to end, and
representing the labium or under lip : at its base

Fro. 319—Buo. . 8 /'.

we perceive a conical and elongated piece, which
is analogous with the labrum ; lastly, the setce (b, c), which have
the form of fine threads, stiff and jagged at their points to }>e

* The term buccal refers to that which belongs to the mouth ; and the above
expression is conveniently applied to denote the several parts collectively, which
altogether make up the mouth, in whatever way they may be arranged.

98

BUCCAL APPARATUS OF INSECTS.

able to pierce the skin of animals or the vessels of plants, are

the representatives of the
mandibles and the maxilla)
extremely elongated. In those
Ui/ nir Hemiptera which live at the

expense of other animals, the
proboscis is usually very firm,
and folds into a semicircle
under the head. Among those
which are nourished by suck-
ing vegetables, on the con-
trary, it is nearly always thin,
and is laid when in a state of
rest against the lower side of
the thorax, between the feet.
Its length is sometimes so
considerable, that it passes backwards behind the posterior ex-
tremity of the abdomen.

616. Amongst the Flies, also, the proboscis, which is some-
times soft and retractile, sometimes hprny and lengthened, repre-
sents the under lip, and often bears palpi at its base ; a longi-
tudinal channel occupies its upper side, which incloses the setce ;

FIG. 320.— BUCCAL APPARATUS OF AN
HEMIPTEROUS INSECT.

FIG. 321 — NEMESTRINA LONGIROSTRIS.

whose number varies from two to six, their analogues amongst
the gnawing insects being the mandibles, the maxillae, and the

BTJCCAL APPARATUS OF INSECTS.

99

FIG. 322. — TRUNK OF A
BUTTERFLY ; a, head ;
b, base of antennae; c,
eye ; d, trunk ; e,
palpi.

FIG. 323. — MORPHO HSLENOR.

tongue. Sometimes this proboscis acquires an enormous length
(Fig. 321) ; sometimes on the contrary it is hardly visible. —
Lastly, among the Butterflies, which are also supported on
liquid substances, but which find them at the bottom of the

flowers, and there-
fore have no occa-
sion for instruments
to procure them,
there exist no setae
performing the func-
tions of lancets, as
among the preced-
ing ; and the mouth
is furnished with a
long tubular trunk,
coiled into a spiral,
and composed of
two slender filaments, each channelled on its internal edge, so
that a tube is formed by the adhesion of the two ; these are
nothing else than the maxillge very greatly lengthened and
modified in their form. At the base of this tube is seen a
small membranous piece, which is the representative of the
labrum ; and on each side, a small tubercle, the only vestige
of the mandibles. We also perceive the rudiments of the
maxillary palpi ; and behind is found a small triangular labium,
having two very large labial palpi, composed of three joints, and
nearly always clothed with scales.

617. The alimentary canal generally presents a very com-
plicated structure : sometimes it is straight, and has very nearly
the same diameter throughout its entire length ; but usually it
is more or less convoluted, and has several successive enlarge-
ments, and contractions. We may distinguish in it (Fig. 324),
a pharynx (a), an oesophagus (5), a first stomach or crop (c), a
second stomach or gizzard (d)9 of w.hich the walls are muscular
and often armed with horny pieces fitted to triturate the food ;
a third or true digestive stomach (e), whose texture is soft and
delicate ; a small intestine (/), a ccecum, and a rectum (g). As

H2

100 DIGESTIVE APPARATUS OF INSECTS.

we see amongst the higher animals a connection between the
nature of the food and the development which this canal acquires,
so among the Carnivorous Insects it is generally very short ;
whilst among Insects which are supported on Vegetable sub-
stances, it is usually very long.
The food which enters it, is at
first moistened with the sa-
liva; the apparatus which
secretes this liquid consists of
a certain number of floating
tubes, terminated sometimes by
small follicles or sacs, and
communicating with the pha-
rynx by their excretory canals.
A multitude of villi, with
which the digestive or chylific
stomach is generally furnished,
appear to serve for the secre-
tion of a gastric juice ; and it
is also into this cavity, that the
bile is poured. There does not
exist any liver, properly speak-
ing, among Insects ; but this
organ is replaced by long and
delicate tubes (^), which float
in the interior of the abdomen,
and open high up in the chylific
stomach. (Similar vessels, open-
ing lower down, take the place
also of the urinary glands ; for
uric acid has been found to be
secreted in them.) By one of
their extremities, the biliary

i i . , , . 324. — DIGESTIVE APPARATUS OF BEETLE ; a,

Vessels always open into the pharynx ; b, esophagus ; c, crop ; d, giz-

chylific stomach ; and the other zard ? e> chylific 8t<>mach ; /, small intes-
tine ; g, rectum ; h, biliary vessels.

extremity is sometimes free,

but sometimes fixed to the intestine, either near the first opening

CIRCULATION IN INSECTS.

101

or close to the rectum. Lastly we find, towards the extremity
of the intestinal canal, other secreting organs, that serve to
elaborate particular liquids (such as the poison of the Bee's
sting), which several Insects can throw out from the extre-
mity of their abdomen, when they are irritated.

618. It would appear to be by simple absorption, that the
chyle traverses the walls of the digestive tube and mixes with
the Blood. This liquid is watery and colourless; it is not
everywhere inclosed in vessels, but spreads itself out into the
interstices, which exist between distinct organs, or which pre-
sent themselves in the substance of their tissue. Insects are
destitute of a regular circulation. We can clearly see very
rapid currents in certain parts of the body ; but the nourishing
liquid does not perform a circle in such a way as to return
constantly to the point of its departure. There really exist
amongst these animals only vestiges of a circulating apparatus.

Fro. 325. — CIRCULATION IN INSECTS.

We see near the dorsal surface of the body a longitudinal tube
(a, Fig. 325), which performs alternate movements of contrac-
tion and dilatation, analogous to those of the heart among the
higher animals. The nourishing liquid penetrates into it by
lateral openings, furnished with valves to prevent its reflux ; and

102

CIRCULATION AND RESPIRATION OF INSECTS.

being propelled forwards by the successive contractions of its
different chambers, it passes out in front by a series of canals,
of which some convey it to the head, whilst others pass side-
ways and backwards (&), for the supply of the body with its
appendages, the legs and wings. On returning from these parts,
it re-enters the dorsal vessel, partly at its posterior extremity,
and partly by the lateral orifices already mentioned.

619. It will be observed that, in this course, there is no
special conveyance of the nutritious fluid, when rendered venous

Head.

1st Pair of Legs

1st Segment of
Thorax

— Air-sacs

FIG. 326. — RESPIRATORY APPARATUS OF INSECT

in its character by circulating through the tissues, to a particular

RESPIRATION OP INSECTS. 103

organ for its aeration. If the Respiration of Insects were effected
in the usual manner, by means of lungs, or at the external sur-
face of the body, it would have been consequently extremely
incomplete ; but the disadvantage which would appear to be the
necessary result of this great imperfection in a function so import-
ant as the Circulation, does not really exist. Nature has made
up the deficiency in the transmission of the blood, by conducting
the air itself into all the parts of the body, by the aid of a multi-
tude of canals, which communicate with the exterior, and which
ramify minutely in the substance of the organs. These air-
conveying tubes, known, as we have already said, under the
name of trachea, present a very complicated structure : we
can usually distinguish in them three coverings,
of which the middle one is composed of a carti-
laginous filament, rolled in a spiral, like an
elastic spring. Sometimes they are simple ;
but at other times they have a certain number
of large dilatations, in the form of soft vesicles,
which act as reservoirs of air. The openings by
which the air penetrates into the tracheae are
TUBE OK INSECT, called stigmata or spiracles ; they are generally
simple slits, like button-holes ; but sometimes
they have two valves, which open and shut like the leaves of a
folding-door ; and they are frequently furnished with a kind of
sieve or grating, to prevent particles of dust, &c., being drawn
inwards by the air. We usually see one pair upon the lateral
and upper part of each segment ; but they are often wanting on
the two last segments of the thorax. The means by which the
air is renewed in the interior of this respiratory apparatus,
appears to consist generally only of the movements of contrac-
tion and dilatation of the abdomen. As we have already said,
Respiration is very active amongst these animals j they consume
a considerable quantity of air in comparison with their size, and
they quickly die when they are deprived of oxygen ; but when
they are in this state of apparent death, they may remain in it a
very long time, without losing the power of being restored to life.
620. The greater number of Insects produce but very little

104 HEAT AND LUMINOSITY OF INSECTS.

heat ; but some of these animals, in certain circumstances, give
out a quantity sufficiently considerable to raise their temperature
perceptibly. This is the case with Bees, when they are
disturbed in their hives ; and it is noticed that their Respira-
tion then becomes very active. (See ANIMAL PHYSIOLOGY,
§§ 410, 411.)

621. Another most remarkable phenomenon, of which the
cause is not fully known, is the production of light ; which is
observed amongst some Insects. Of this the Lampyris, or
Glow-worm, is an example, which is well known to almost
every one who frequents our fields. The male has wings and
is not luminous ; but the female, which is destitute of them, and
which is often found on banks and hedges during the summer
evenings, sheds a phosphorescent light that is often very brilliant.

In another species of Lampyris
which inhabits Italy, the indi-
viduals of both sexes are at the
same time winged and luminous ;
but this singular property is
especially remarkable among cer-
tain Fire-flies, which live in the
warm regions of America, and

FIG. 328 MALE AND FEMALE GLOW- , . , , , n • • ,1

WORM which produce, when flying in the

darkness, a natural illumination of

the most brilliant effect ; they are often placed by women in
their hair as ornaments ; and we are told that the Indians use
them to light themselves, when they travel by night. Among
our Glow-worms, the light proceeds from certain spots situated
upon the upper part of the two or three last rings of the abdo-
men ; whilst among the Fire-flies, it comes from analogous spots
placed upon the prothorax or corslet. It appears that the insect
can vary at pleasure the intensity of this phosphoric light ; and
that it continues during a certain time, when the animal is placed
in a gas unfit for respiration, or even in a vacuum ; but that it is
extinguished in cold water.

622. The sexes are distinct amongst these animals, and there
often exist very great differences between the male and female ;

METAMORPHOSES OP INSECTS. 105

the common Glow-worm has already afforded us an example of
this (Fig. 328). Nearly all Insects lay eggs ; some of them are,
however, viviparous. There often exists at the extremity of the
abdomen of the female, a dart, a saw, or some other organ,
fitted to make holes for the reception of the eggs ; and by an
admirable instinct, the mother always lays them in a place, where
her young will find near them the food which they will require;
and yet, in the greater number of cases, this food is not the
same as she would seek for herself. During the early period of
their lives, insects change their skin several times, and nearly
always display some very singular phenomena, of which we have
already seen an example amongst the Batrachian Reptiles. The
greater number of them, at the time of their coming forth from
the egg, neither resemble their parents, nor have the form which
they will themselves acquire at a later period ; and before arriv-
ing at a perfect state, they undergo changes so considerable,
that we cannot better designate them than under the name of

623. Insects, in general, pass through three very distinct states,
known under the names of the larva state, the chrysalis state, and
the imago or perfect state ; but the changes which take place, are
not always equally great ; sometimes these changes render the
animal perfectly different, at other times they only consist in the
development of wings ; and these various degrees of transforma-
tion are known under the names of complete, and of incomplete,
metamorphosis.

624. The insects which undergo a complete metamorphosis, are
always more or less vermiform (or worm-like), when they come
from the egg, and when they are in a larva state ; their body is
long, almost entirely soft, and divided into moveable rings, of
which the regular number is thirteen. Sometimes they are com-
pletely destitute of feet ; at other times they are provided with
a variable number of these organs ; but the conformation of these
is not at all analogous to that of the same parts in the adult
animal. They have, nearly always, simple eyes, but they are
sometimes entirely destitute of them ; their mouth is usually fur-

106

METAMORPHOSES OF INSECTS.

nished with mandibles and jaws, whatever may be the form that
it will afterwards assume ; and we often see the first of these
organs serving for locomotion, as well as for seizing the food.

FIG. 329. — LARVA, PUPA, AND IMAGO OF PAPILIO MACHAON.

These Larvae also differ in their form, and are sometimes known
under the name of Caterpillars, sometimes under that of Worms.
— After having remained in this state for a longer or shorter time,
and having experienced several changes of skin, the wings begin to
be formed beneath the skin, and the animal passes into the state of
chrysalis. During the whole length of this second period of their
existence, these singular animals cease to take any food, and re-
main motionless. Sometimes the skin from which they have last
freed themselves, dries up, and forms a kind of oval case, in the
interior of which they remain shut up ; sometimes they are only

METAMORPHOSES OF INSECTS. SILKWORM.

107

covered by a thin pellicle, which lies over the external organs,
follows all their inequalities of surface, and causes the insect to
appear as if closely wrapped in bandages.

625. Before undergoing this metamorphosis, the Larva pre-
pares a defence for itself ; and shuts itself up in a case, which it
makes with silk, secreted by salivary glands, and drawn out by
the aid of spinnerets, hollowed in the lips. In other instances,
it suspends itself by means of threads, or conceals itself in some
hollow. It is, however, whilst the insect is in this state of appa-
rent repose, that active operations are going on within the body,
of which the result is the complete development of the entire
organisation. Its interior parts become soft, and by degrees
assume the shape that they will preserve ; the different organs,
with which the adult animal ought to be provided, are deve-
loped under the envelope which conceals them ; and when this
evolution is finished, it frees itself from this species of mask ;
spreads its wings, which are not long in acquiring firmness, and
becomes a perfect insect or Imago.

626. As an example of this complete metamorphosis, we can-
not make a better selection, than by taking the Bombyx Mori ;

for this insect in
its larva state pos-
sesses for us an
immense interest ;
it is the silkworm,
the rearing of
which contributes
so powerfully to
the agricultural
prosperity of the
southern countries
of Europe, and the
product of which
gives origin to so much industry and wealth. This insect came
originally from the northern provinces of China, and was not
introduced into Europe until the sixth century. The Greek
Missionaries brought some of its eggs to Constantinople in the

FlG. 330. — SfLKWORM.

108 GROWTH OF THE SILKWORM.

reign of Justinian, and, at the period of the first crusades, its
cultivation was spread into Sicily and Italy ; but it was not
until the time of Henry IV. that this branch of agricultural
industry acquired any importance in the southern provinces of
France, of which it now forms one of the chief sources of wealth.

627. The eggs of the Silkworm, when dry, have a gray-ash
colour ; and with some care they may be preserved thus during a
very long time without injury. In order that the work of incuba-
tion may commence, and that the larvae may be hatched, the
eggs must be exposed for some time to a temperature of at least
60° Fahr. After having experienced an increasing heat for eight
or ten days, they will become whiter ; and soon afterwards the
larvae will begin to come forth. These little animals, at the
time of their birth, are only about a line and a quarter in length.
Their body is long, cylindrical, annular, smooth, and commonly
of a grayish colour ; at its anterior extremity we distinguish a
head, formed by two hard and scaly tubercles, upon which are
seen some black points, which are the eyes ; the mouth occupies
the anterior part of this head, and is armed with strong jaws ;
the three succeeding rings have each a pair of small scaly feet, and
represent the thorax ; the abdomen is very much developed, and
has no members upon its two first segments, but is furnished
at the posterior end with five pair of fleshy tubercles, which
resemble stumps, and which serve as so many feet.

628. In the south of France, these worms are called magnans;
and the name of Magnanerie is given to the establishments in
which they are reared. The first care that they require after
their birth, is to separate them from their shells, and to place
them upon frames, on which they find the food adapted for their
support. For this purpose it is usual to cover the eggs with a
sheet of paper, perforated with holes, through which the worms
creep to get at the mulberry leaves placed above ; and when
they are collected upon the boughs which are covered with these
leaves, they are carried away upon the frames prepared for their
habitation. The food of the Silkworm consists of Mulberry
leaves ; and consequently it is on the cultivation of this tree,
that the capability of rearing these insects depends. The White

GROWTH OF THE SILKWORM. 109

Mulberry is the species the most generally employed for this
purpose. It is a tree which grows to the height of fourteen or
fifteen feet ; it flourishes very well in all soils, and it is culti-
vated with success even in the north of Europe ; but it never
grows wild anywhere. The Mulberry came originally from
China. Two Greek monks introduced it into Europe towards
the middle of the sixth century, at the same time with the Silk-
worm. Its cultivation was soon spread in the Peloponnesus,
and gave to this part of Greece its modern name of Morea.
Thence the Mulberries and the Silkworms were conveyed into
Sicily under the direction of King Roger, and acquired a rapid
extension in Calabria. Some French gentlemen who had accom-
panied Charles VIII. into Italy during the war of 1494, having
known all the advantages which that country derived from this
branch of agriculture, wished to bestow the same upon their own
country ; and brought some Mulberry trees from Naples, which
they planted in Provence and Dauphine. About thirty years
since, the first of these trees planted in France was still to be
seen at Allan, near Montelimart. At present the Mulberry
trees cover a large part of the south of France ; they are even
cultivated in the north ; and the success of some recent attempts
appears to show, that they might be profitably cultivated in
England.

629. Silkworms remain in the larva state for about thirty-
four days ; and during this time they change their skins four
times. The time comprised between these successive changes,
constitutes that which the cultivators call the different ages of

o

these little animals. At the approach of each change they
become dull and cease eating; but after having cast off the skin,
their hunger is increased. The quantity of food which they
consume rapidly increases. It is computed that for the larvae
proceeding from an ounce of eggs, there must be generally about
seven pounds of leaves during the first age, which lasts five days;
twenty- one pounds during the second period, which only conti-
nues four days ; seventy pounds during the third period, which
continues seven days ; two hundred and ten pounds during the
fourth age, whose length is the same as that of the third age ;

110 GROWTH OF THE SILKWORM.

and twelve or thirteen hundred pounds during the fifth period.
It is on the sixth day of the last age, that the greatest voracity
shows itself. The worms then devour two or three hundred
pounds of leaves, and when eating make a noise which resem-
bles that of a heavy shower. On the tenth day they cease
eating, and prepare themselves to undergo their first metamor-
phosis. We then see them endeavouring to climb upon the
branches of small bundles of twigs, which have been carefully
placed above the frames on which they have until then remained.
Their body becomes soft, and a thread of silk comes out of their
mouth, which they draw after them. They very soon fix them-
selves, and throw around them a multitude of threads of extreme
fineness ; and, suspended in the middle of this net- work, spin
their Cocoon, which they form by continually turning themselves
round in different directions — thus twisting round their body the
thread which comes out from the spinneret, with which the lip
is perforated. The silk, thus formed, is produced in glands,
which have much ^analogy with the salivary glands of other
animals ; and the matter of which it is composed is soft and
glutinous at the time of its first appearance, but soon becomes
hardened by the air. The result of the different twistings of
this single thread, is to cause the different threads to adhere
together, and to form an envelope, whose tissue is firm and shape
oval. The colour of the silk varies; sometimes it is yellow,
sometimes of a brilliant white, according to the variety of the
worm which has produced it ; and the length of each thread
often exceeds 1100 feet, but varies much, as does also the weight
of the cocoons. The worms proceeding from an ounce of eggs
may produce as much as 130 Ibs. of silk ; but such an amount is
rare ; and from 70 to 80 Ibs. is the usual product.

630. In general, three days and a half or four days are suffi-
cient for the larva to finish its Cocoon ; and if we then open
this envelope, we see that the animal no longer presents the same
appearance as before its seclusion. It has become of a brownish
colour, its skin resembles old leather, and its shape is oval, a
little pointed at its posterior extremity. We no longer distin-
guish a head or jaws ; but the posterior extremity is formed by

METAMORPHOSES OF INSECTS. Hi

two moveable rings, whilst in front we see an oblique band,
representing the future wings of the perfect animal. The time
during which the Bombyx remains thus shut up in a Chrysalis

FIG. 331 — CHRYSALIS OF- THE SILKWORM. FIG. 332.— SILKWORM MOTH.

state, varies according to the temperature. If the heat is from
60 to 65 degrees, they come out of it in a perfect state on the
eighteenth or twentieth day. In order to open the Cocoon,
they moisten it at one extremity with a particular liquid, which
they throw up from the stomach ; and then they violently strike
their head against the part thus softened. When the Bombyx
has thus finished its metamorphosis, it presents itself under the
form of a Moth, with whitish wings ; its mouth is no longer
furnished with jaws, as in its early state, but is prolonged into a
rounded spiral trunk ; its legs are slender and lengthened, and
its internal conformation differs as much from that of the Larva,
as its external form. Almost immediately after this second
birth, the Moths seek each other for the purpose of reproduction ;
and the females subsequently deposit their eggs, of which the
number sometimes amounts to more than five hundred for each
of these insects ; and at last, after having lived in a perfect state
for ten or twenty days, during which time they take no food,
they die.

631. Among Bees we meet with still greater changes ; since
in their Larva state they are completely destitute of legs, and
resemble small worms. It is the same with Flies, Gnats,
and a great number of other insects ; thus the vermiform animals
which swarm in putrid carrion, and which are known under the
name of Maggots, are nothing else than the larvaa of the Meat-fly.
The Gnats or Musquitoes, which fly in such large swarms, and

112

METAMORPHOSES OF INSECTS.

Fro. 333.— GNAT AND LARVA.

which render themselves so unpleasant to Man by their venomous
punctures, live in the water during their larva state. They
are then vermiform, destitute of limbs, and have the abdomen

terminated by bris-
tles and some appen-
dages arranged in a
radiated form (Fig.
333); and from their
last ring arises a long
tube, by the aid of
which the animal
draws in from the
atmosphere the air
which it requires.
To breathe by this
means, it suspends
itself as it were from
the surface of the

water, with its head downwards ; and we see it performing this
movement at short intervals. The Chrysalis continues to live in
the water, and to move about there ; but instead of breathing
like the larvse, it draws in the air which it requires by means of
two pipes, placed upon the thorax. It floats on the surface of the
liquid ; and after having completed its metamorphosis, the per-
fect insect uses the skin of the chrysalis as a boat, until its long
legs and wings have gained sufficient strength to enable it to
move on the surface of the water, or to fly away ; but if its
body happens to be submerged, as often occurs when the wind
upsets these frail barks, it is infallibly drowned.

632. The Insects with incomplete metamorphosis also pass
through the larva and chrysalis state, before arriving at the
perfect state; but here the larva only differs from the perfect
insect by the absence of wings ; and the state of the chrysalis is
only characterised by the gradual development of the wings,
which, at first folded back and concealed under the skin, then
become free; but only acquire their full development at the
period of the last change. We may mention, as examples of

METAMORPHOSES OP INSECTS.

113

insects showing this kind of metamorphosis, the Grasshopper
and the Ephemerae or Day-flies. These last display a remark-
able peculiarity ; since in general, insects change the skin for the
last time, when they pass from the Chrysalis to the perfect state ;
whilst the Ephemera experiences one more change, before arriving
at its complete form, in which it only lives for the space of a few
hours. The larva of the Ephemera lives in the water, and
differs very little from the adult, except in the shortness of its
limbs, the absence of wings, and by the row of leaf-like ap-
pendages which it bears on each side of its abdomen, and which
it uses as organs of respiration and of motion in the water. The
chrysalis only differs from the larva, by the presence of cases
inclosing the wings. At the time when these organs should be

developed, the in-
sect comes out of
the water ; and
after having flut-
tered about during
some minutes, it
takes its place upon
an elevated object,
and there performs
some violent move-
ments, by means of
which it casts away

its enveloping membrane ; it is then only that its limbs attain
their full length, and that the body acquires the colours which
it will preserve.

633. Some Insects, although undergoing considerable changes
at an early period, do not pass through the complete series of
transformations of which we have first spoken ; they appear to
stop short in their development, never possessing any wings.
The Fleas are thus circumstanced. "When they come forth from
the egg, they are destitute of feet, and have the form of small
worms of a whitish colour. These larvae are very active, and
roll themselves in a circle or a spiral. They soon become of a
reddish hue ; and after having lived in this condition during

FIG. 334. — EPHEMERA VOLGATA : LARVA, PUPA, AND IMAGO.

114 METAMORPHOSES, INSTINCTS, AND CLASSIFICATION.

twelve days, they shut themselves up in a small silky shell, of
extreme delicacy, and are there transformed into a chrysalis ; at
the end of about twelve days of seclusion, if the weather is warm,
they come out of their envelope in a perfect state.

634. Again, there are some Insects which do not pass
through any metamorphosis, and which are born with all the
organs with which they will ever be provided ; but it is only
among Apterous^ or wingless, Insects, that this mode of deve-
lopment exists. The Podura, which has been already referred
to, and the Louse, are of this kind.

635. The class of Insects, which (as we have seen) is so
remarkable for its organisation, is still more so in regard to the
habits of the animals composing it, and the admirable instincts
with which Nature has endowed a great number of them. The
stratagems which they employ to procure themselves food, or to
escape from their enemies, and the industry which they display
in their labours, astonish all those who are witnesses of it ; and
when we see them unite themselves into numerous societies, to
make up for their individual weakness, helping each other by
dividing the labour necessary for the prosperity of the commu-
nity, providing for their future wants, and often even regulating
their actions according to the accidental circumstances in which
they find themselves placed, we are confounded at encountering
amongst beings so small, and in appearance so imperfect, instincts
so varied and so powerful, and intellectual combinations which
so much resemble those of the reasoning powers. This subject
will be more fully treated of in the latter part of the present
volume. At present we must confine ourselves to a sketch of
the classification of this group ; which, on account of the immense
number of forms included in it, must be more slight than that
which has been given of the preceding classes.

636. The subdivision of the Class into Orders is founded
chiefly upon the structure of the Mouth, the conformation of the
Wings, and the nature of the Metamorphosis. Neither of these
characters must be trusted to singly ; since within the limits of
one group, we find considerable variation. Thus in almost every
order, we meet with apterous or wingless insects ; an example of

CLASSIFICATION OF INSECTS. 115

which we have already seen in the Glow-worm. Sometimes, as
in that instance, the deficiency of wings is confined to one of the
sexes — usually the female ; whilst in other cases, both sexes are
destitute of these organs. Nevertheless there is a group, con-
sisting of three small orders, in which the want of wings is the
rule and not the exception ; and the insects brought together in
these, are associated together on account of their resemblance to
each other in general structure ; — whilst, on the other hand, the
wingless insects first alluded to are left among the orders in
which they are placed, on account of their correspondence with
other insects of those orders in the structure of the mouth, the
nature of the metamorphosis, &c.

637. We may divide the Class into two Sub-classes ; the
members of the first of which (A) always undergo some degree
of metamorphosis, and are usually possessed of wings in the
perfect state ; whilst those of the second (B) undergo no meta-
morphosis, and never become possessed of wings. — From the first
sub-class may be separated one order, in which there are no
wings ; and there then remain eight principal orders, which are
classed according to the structure of the mouth and wings.

SUB-CLASS A.

Division a. — Winged insects undergoing metamorphosis.

Order I. COLEOPTEBA (Beetles). In these the mouth is
formed for mastication ; the anterior wings are converted into
hard elytra, or wing-cases ; the posterior wings are folded trans-
versely (or cross- wise) during repose; and the metamorphosis
is complete.

Order II. ORTHOPTERA (Grasshopper, Locust, fyc.). In
these also the mouth is formed for mastication ; the anterior pair
of wings is composed of a substance more resembling parchment ;
the posterior pair, when in repose, is folded longitudinally (or
lengthwise) in the manner of a fan (Fig. 369) ; and the meta-
morphosis is incomplete.

Order III. NETJROPTERA (Dragon-fly, May-jly)* In these,
too, the mouth is formed for mastication ; but the anterior pair
of wings, like the posterior, is membranous ; and the nerves of

i 2

116 CLASSIFICATION OF INSECTS.

the wings form a close reticulation or network by their inter-
lacement. The degree of metamorphosis is variable.

Order IV. HYMEN OPTERA (Bee, Wasp, Saw-fly). In these,
the mouth is still furnished, as in the preceding, with prehensile
mandibles, but the other parts are so formed as to be rather
fitted for suction than for mastication ; the wings are all mem-
branous, but the nerves do not form such a minute reticulation
as in the preceding order; the metamorphosis is always complete.

The four preceding orders, in which mandibles are always
distinctly present, form the group of MANDIBULATA; the four suc-
ceeding, in which the mandibles are wanting or are completely
changed in form, and in which the other parts are adapted for
suction, being converted into a more or less complete haustellium
or sucking-tube, are termed HAUSTELLATA.

Order V. HOMOPTERA (Cicada, Lantern-fly). In this order,
the four wings are of the same consistence, and are rather firmer
than usual, being often somewhat parchmenty in texture ; when
folded, they incline at an angle, like the roof of a house.

Order VI. HETEROPTERA (Bugs, Boat-flies). The consist-
ence of the two pairs of wings is here different, the anterior pair
of wings being of a horny or parchmenty consistence (though
generally tipped with membrane), whilst the posterior are simply
membranous ; when folded, they are horizontal, or but slightly
inclined, and sometimes lap over each other.

Order VII. LEPIBOPTERA (Butterflies and Moths). These
have the mouth furnished with a long trunk, coiled in a spiral
when not in use ; the wings are all membranous, and are covered
with minute scales, having the appearance of fine dust, but
arranged with the most perfect regularity ; the metamorphosis
is complete.

Order VIII. DIPTERA (Gnats, Flies, fyc.) In these there are
but two wings ; the mouth is furnished with a sucking-tube ; and
the metamorphosis is complete, or nearly so.

Division b. Insects undergoing metamorphosis, but destitute of
wings. This division includes but a single order.

Order IX. APHANIPTERA (Flea, fyc.) In this group, also,
the mouth is formed for suction ; and the insects composing it are
parasitic, living upon the juices of other animals.

CLASSIFICATION OF INSECTS. 117

SUB-CLASS B.

The small remaining section, consisting of Insects which un-
dergo no metamorphosis, and are destitute of wings, includes
two orders.

Order X. ANOPLOURA (Louse). These are distinguished from
the succeeding, by the absence of appendages to the abdomen.

Order XI. THYSANOURA (Spring-tails, fyc.) In these the
abdomen is furnished with false legs, or appendages, adapted for
leaping.

Besides these principal groups, there are some small interme-
diate orders, by which the former are connected. These are not
admitted, however, by all Entomologists. Thus the Earwig
tribe, which combines, in some degree, the characters of the
Coleoptera and Orthoptera, is raised by many to the rank of a
distinct order — DERMAPTERA, which leads from the first to the
second order. Again, a separate order — TRICHOPTERA, has
been formed to include the Caddice-flies, which are intermediate
between the Lepidoptera and Neuroptera. And, lastly, there is
a small order — STREPSIPTERA, or RHIPIPTERA, which includes a
small group termed Wasp-flies, intermediate, in several respects,
between the Hymenoptera and Diptera, but differing from both
in so many particulars, as apparently to require being arranged
by themselves.

ORDER I.— COLEOPTERA, OR BEETLES.

638. The insects composing this Order, all of which are known
under the common name of Beetles, are the most numerous and
best known of the whole class. The singular forms and brilliant
colours exhibited by many of the species, the size of their bodies,
the solid texture of their integuments, which facilitates their
preservation, and the nature of their habits, which makes
their capture more easy, have combined to render them an ob-
ject of peculiar attention to Entomologists, many of whom have
devoted themselves to this order exclusively. It is probable
that from 30,000 to 40,000 species of Beetles alone now exist in

118 GENERAL CHARACTERS OF BEETLES.

the cabinets of collectors ; and we may safely affirm, that at least
as many more yet remain to be discovered.

639. The conversion of the first pair of wings into elytra^ or
hard wing-cases, and the complete in closure of the second pair
by these, when the insect is at rest, constitute, as we have seen,
the distinguishing features of the Order. The elytra, when
expanded, are of little or no use in flight, generally remaining
nearly motionless ; when closed, they meet along the back in a
straight line, which is called the suture. The structure of the
mouth, in this order, has been already described. The head is
provided with two antennas, which vary in form, but which have
usually eleven joints ; the form of these often differs considerably
in the two sexes. The eyes are large and protuberant, espe-
cially in the carnivorous species, and in those, the slowness of
whose habits makes them need quick powers of sight, for the
purpose of avoiding their enemies. Of the three segments of the
thorax, the anterior one (commonly termed the corslet) greatly
surpasses the two others in size ; being so much developed at
their expense, as almost to constitute the thorax by itself. The
two latter segments are firmly united to each other, and to the
commencement of the abdomen ; and the chief movement of the
parts of the trunk upon one another, is between the first and
second segments of the thorax ; the latter being prolonged for-
wards into a sort of footstalk, which is received into a cavity in
the former, and thus serves as a kind of pivot for its movements.
The abdomen usually consists of only six or seven segments ; the
remainder of the nine, which properly form this part, being
consolidated in the last.

640. Although the characters already mentioned are applica-
ble to by far the greater number of insects included in this Order,
nearly all of them are subject to exceptions. Thus, there are
many species, in which the organs of flight seem altogether
wanting, in one sex, at least, as in the female Glow-worm ; even
here, however, the rudiments of elytra will be found. In other
instances, the elytra are fully developed, so as to cover the upper
surface of the body ; but adhere together along the suture, so as
to prevent the expansion of the wings, which are, consequent! v.

GENERAL CHARACTERS OF BEETLES. 119

never developed ; this is the case in the Blaps (Fig. 349). In
other cases, again, the elytra, instead of simply meeting along
the suture, fold over each other ; in other instances, they do not
meet at all ; and there are some species in which the wings are
folded, not transversely, but longitudinally r, as in the next order.
It is well for the Student to be aware that such exceptions exist
in this, as in every other large natural group ; however definite
its characters may generally be. In none of these instances, is
there an exception as to more than one or two of the characters
in question ; the remainder conform to the usual type.

641 . The Metamorphosis in this Order is invariably complete;
and it is thus distinguished from all that approach it in the
structure of its mouth, or in the character of the wings. The
larvce are worm-like in their aspect ; the head is usually horny,
the rest of the body soft. There is generally a pair of short
jointed legs attached to each of the first three segments, bearing
some resemblance to those of the perfect insect. Those which
possess legs are
usually active in
their habits ; but
there are others
which, leading a
retired life, and
being born in the
midst of their food
(such as the Nut
Weevil), are des-
titute of members.
The larvae of the
carnivorous species
have in general the
most robust legs ;
and in some of the
herbivorous species ^ m_LARVA PUPA> AND PERFECT STATES OF

these are replaced CBTONIA AURATA, OR ROSE-BEETLE.

by fleshy tubercles,

or pro-legs. A pair of these generally exists on the last segment

120 SUBDIVISION OF BEETLE TRIBE.

of the abdomen. Previously to undergoing its change, the larva
often forms a case for itself, of bits of earth, or chips of wood,
united by silken threads, or by gluey matter. The pupa, or
chrysalis, is inactive, sometimes even for years, and takes no
nourishment ; but the form of the future Beetle is plainly
perceived, the different parts being encased in distinct sheaths.
(Fig. 335).

642. There is much difficulty in forming a simple natural
classification of this immense tribe, on account of the great num-
ber of distinct species which it includes, and their strong general
resemblance to each other. Hence it is often necessary to resort
to characters of great minuteness as the ground- work of the
system ; and it sometimes happens that, by the adoption of such
a plan, tribes which are in reality closely allied in general struc-
ture, are placed in different groups, whilst others are brought
together which are in many respects dissimilar. No better
system, however, has yet been proposed than that of Latreille ;
who took as the basis of his classification the number of joints
in the tarsus or last portion of the foot (§ 607). The four
following sections are thus formed.

I. PENTAMERA (five-parted), in which the tarsi of all the
feet are distinctly 5»jointed.

II. HETEROMERA (differently-parted), in which the tarsi of
the first two pairs of feet are 5-jointed, and the two posterior
4-jointed.

III. TETRAMERA (four- parted), in which all the tarsi appear
to be 4-jointed. (It has lately been observed, however, that the
fifth joint exists in these, although it is very minute, and con-
cealed in one of the others.)

IV. TRIMERA (three-parted), in which all the tarsi have
three distinct joints. (A fourth of small size, however, is also
present.)

Each of these sections contains several families ; of which the
most important will now be noticed.

643. Section I. PENTAMERA. The first family of this
section consists of Beetles which are exclusively carnivorous ;
hunting after, and devouring, other insects; and being carnivorous

CARNIVOROUS BEETLES.

121

even in their larva state. These CARNIVORA are characterised
by the possession of six palpi, — there being two to each of the
maxilla? (Fig. 315), — and by the termination of the jaws in a
sort of claw or hook. Some of them are terrestrial, and others
aquatic ; in the former, the legs are adapted only for running ;
in the latter, they are modified for swimming. — The terrestrial
division of the family is composed of two very large tribes, the
Cidndelidce and the Carabidce, characterised chiefly by the form
and mode of attachment of the hook at the end of the jaws. The
Cicindelidce have the body usually of a dark or light-green colour,
varied with shining metallic tints, and with white spots upon
the elytra ; they frequent dry situations exposed to the sun, run
very quickly, fly off when they are approached, and alight again
at a short distance. The larvae burrow in the earth, forming a
cylindrical hole of considerable depth ; in the process of excava-
tion they use their jaws and feet, and load the concave back of
their heads with the grains of earth which they have detached ;
thus loaded, they ascend backwards,
resting at intervals, and fixing them-
selves to the inner walls of their
burrow by the assistance of two
hooked tubercles on the back ; when
arrived at the orifice, they jerk off
their load to a distance. Whilst
lying in ambush, the flat plate of the
head exactly stops the mouth of the
hole, forming a flat surface with the
surrounding soil. When their prey
comes within their reach, they rush
upon it with great ferocity, and seize it between their powerful
jaws ; and their voracity is even extended to larvae of the same
kind. They close the orifice of their burrow when they change
their skin, or undergo their metamorphosis into the pupa state.
There are several British species of this group ; as well as a
large number of brilliantly-coloured tropical species, of which
many are apterous.

644. The tribe of Carabidce is of very great extent ; above

FIG. 336.— CICINDELA CAMPESTRIS,
AND LARVA.

122 CARNIVOROUS BEETLES ; CARABID^J.

2000 species having been brought together by a single collector.
Their bodies are of very firm consistence,
whereby they are enabled to creep under
stones and through fissures, and are also
prevented from being injured by the
insects they attack. They prowl about
on the surface of the ground, under
stones, &c., beneath the bark of trees, or
the moss growing at their roots, in
search of their insect prey, which con-
sists chiefly of the herbivorous species of
their own order. Some of them are

FIG. 337.— CARABUS. , . ,-, . r i •. <» j-

nocturnal m their habits, feeding upon

Cockchafers and other species of herbivorous beetles that fly
abroad during the night. The habits of this tribe are not
exclusively carnivorous, however, for some species, generally
found in corn fields, are clearly ascertained to feed upon growing
grain. — Many species of this tribe are provided with a very
curious means of defence ; being enabled to exhale a very fetid
odour, and to discharge from the abdomen, to a considerable
distance, an acrid fluid, capable of producing much irritation.
In the Brachinus this fluid is so highly volatile, that, immedi-
ately on coming in contact with the air, it passes into a bluish
vapour of very pungent scent, and makes a sort of
explosion ; hence the species possessed of this power
have been termed Bombardier Beetles. The larger
species are found only in tropical regions; but the
small species represented in the accompanying figure,
is a native of England. The Bombardier Beetles for
BEETLE. faQ most part live in societies, especially in spring ;
and are found concealed under stones. Of the entire family, a
considerable proportion are found in Britain and other temper-
ate countries ; but the largest and most brightly-coloured species
are confined to warmer climates.

645 . The aquatic Garni vora form a tribe far less numerous than
the terrestrial species ; and are at once distinguished by the pecu-
liar modification of the legs, which adapts them for swimming,

AQUATIC CARNIVOROUS BEETLES; — DYTISCUS. 123

— these members being flattened, and fringed with bristles, so as
to serve as oars. They live, during their larva and perfect
states, in water ; but they quit that element to undergo their
metamorphoses, and to pass the time of their pupa condition.
The larvas have the body long and narrow, with a strong head
armed with powerful mandibles ; and they are of very active
carnivorous habits. They breathe by organs adapted for aquatic
respiration ; but the perfect insects can only breathe air, and are
obliged to come to the surface occasionally for that purpose.

The Dytiscus, the
principal genus of
this tribe, is com-
mon in fresh and
placid waters, such
as lakes, pools, or
ditches. Its larva
feeds upon other
aquatic larvse, such
as those of dragon-

flies, gnats, &c. ; and moves quickly through the water, by means
of strokes with its expanded tail. The pupas may be found buried
in the adjoining banks. The Imago also is very voracious, feeding
principally upon the juices of the animals it attacks, which are
often much larger than itself ; an individual has been kept in a
large bottle of water for three years and a half, being fed once
a week or oftener with a bit of raw beef, from which it extracted
the blood, but being able to fast for a month at a time. — The
other principal genus is the Gyrinus (Fig. 299), the common
species of which are known under the name of " Whirligigs,"
from their peculiar motion. These may be met with, from the
first fine days of spring until the end of autumn, on the surface of
quiet waters, and even upon that of the sea, often assembled in
great numbers, and appearing like brilliant points. They swim
with great agility, often curveting in a circular direction, —
whence their common name. Sometimes they remain stationary
without the slightest motion ; but no sooner are they approached,
than they escape by darting under the surface of the water, and

1 24 BRACHELYTRA. — SERRICORNES.

swimming off with the greatest agility. The four hind-legs are
used as oars, and the anterior pair for seizing the prey. When
they' dart beneath the surface, a bubble of air, like a silvery ball,
remains attached to the hind part of the body. — Numerous species
of both these genera are found in Britain.

646. The next family of the Pentamerous Beetles is that of
BRACHELYTRA, distinguished, as the name imports, by the short-
ness of the elytra ; these, which have only four palpi, contain
but a single tribe, composed of the genus Staphylinus and its
allies. These insects run and fly with equal
agility ; they are extremely voracious ; but do
not feed on living prey, deriving their nutriment
from dead and decaying animal and vegetable
matters. The majority live in the earth, amidst
manure and putrescent substances; others are
found among Fungi and rotten wood, and under
stones ; others, again, are only met with near
water ; and a few of the smallest are only found

FIG. 340— STAPHY- .

LINUS ER-ZTHROP- in flowers. Ine Iarv89 teed on the same sub-

TERUS.

stances, and in the same situations, as the perfect
insects ; and greatly resemble them in form. These Beetles, —
of which one of the largest is frequently to be seen running about
garden-walks, and is commonly known under the name of the
Devil's Coach-horse, — turn up the end of the body when touched,
bending it in all directions ; and they possess the power of emit-
ting a strong odour, which is in some instances extremely fetid,
and which serves as a means of defence.

647. The next family, SERRICORNE^, is distinguished by the
toothed or serrated form of the antennas. As in the preceding,
there are only four palpi ; but the elytra completely cover the
body. Some of this family, having the body of solid consistence,
and oval in form, have the head buried, as it were, in the thorax,
which advances on its two sides, nearly as far as the mouth.
In this manner is formed the Buprestis, distinguished for the
splendour of its colours ; many of its species having spots of
golden hue upon an emerald ground; whilst in others, azure
glitters upon the gold. The largest and most brilliant species

SERRICORNES ; — ELATER, DEATH-WATCH. 125

are found chiefly in tropical climates, which these insects appear
especially formed to inhabit ; our native species, which are not
above a quarter of an inch long, being observed to fly with the
greatest activity in warm weather. They live among trees ; and,
if an effort be made to seize them, they counterfeit death, and fall
to the ground. — The Beetles belonging to the allied genus, Elater,
are commonly called Skip-jacks ; for, when laid on their backs,
being unable to raise themselves on account of the shortness of
their legs, they spring perpendicularly in the air, so as to alight
upon their feet. This is effected by first bending the head and
anterior portion of the thorax towards the abdomen, and then
violently straightening it, so as to give a backward stroke against
the surface on which they are lying. The larva of one of the
British species, known to the farmer as the Wire-worm, does
much injury by devouring the roots of the corn. A species of
Elater, inhabiting the West Indies and South America, is one of
the most brilliant of the Fire-flies ; having two brightly-illumi-
nated spots upon the front of the thorax, and a portion of the
abdomen which is uncovered during flight being also very lumi-
nous.— Nearly allied to the Elaters is the Lampyris or Glow-
worm tribe ; of which sufficient mention has been already made.
— To the same very numerous family belong the genus Plinus
and its allies ; one species of which is well known under the
name of Death-watch. These are insects of small size and slow
movements ; many of them are destitute of wings ; and those
which possess them seldom use them as means of escape. When
touched, they counterfeit death by lowering the head, drawing

in the antennae, and contracting
their feet ; and they remain in
this position for some time. Their
colours are always obscure, and
but slightly variegated; and
they live in dark places near

FIG. 341.— ANOBIUM STRIATUAI, NATURAL ,, « «,,

SIZE AND MAGNIFIED. or uP<>n tne surface of the ground.

Of the sub-genus, Anobmm,

many species inhabit the interior of our houses, where they
do much injury in the larva state, by gnawing furniture,

126 CLAVJCORNES. — PALPICOBNES.

books, &c., which they pierce with little round holes, like those
made by a drill. Other species feed upon flowers, wafers, pre-
served specimens of natural history, &c. The curious sound
made by them — from which have arisen the superstitious ideas
that gave origin to their common name, — has been elsewhere
noticed (ANIM. PHYSIOL. § 677). The species is remarkable for
the pertinacity with which it feigns death when alarmed ; pre-
ferring, it is said, to suffer death under a slow fire, rather than
give the least sign of life.

648. The succeeding family, that of CLAVICORNES, consists
of those Pentamerous Beetles, whose antennas end in a club-
shaped enlargement. These are partly terrestrial, and partly
aquatic. They feed for the most part on animal matter, at least
in the larva state ; but a large proportion of them prefer sub-
stances which are in a decaying or putrescent condition. One of
the most interesting genera is the Necrophorus or Burying Beetle;
so named from its habit of excavating the ground beneath the
dead bodies of small quadrupeds, such as Mice or Moles ; when

they have interred the carcass, they deposit
their eggs in it, and the larvae, when hatched,
feed upon the flesh. — Another genus, which
includes a large number of species, is the
Dermesles ; of which the larvae (whose bodies
are hairy) are very voracious, feeding on the
skins or carcasses of animals, often destroying
collections of insects, and committing great
ravages in fur- warehouses.

649. The PALPICOBNES also possess antennae with a club-like
termination ; but these are never longer, and are usually shorter,
than one of the pairs of palpi. Nearly all of them are aquatic,
and have their legs adapted for swimming, somewhat in the
manner of those of the Dytiscus. The most remarkable genus
is the HydrophiluS) of which one large species, an inch and a
half long, oval, of a brown-black colour, and highly polished, is
common in the ponds and ditches of this country. It swims and
flies well, but walks badly. The eggs arc laid in a sort of cocoon,
spun by the female, and coated with a gummy matter that is

L AMELLICORNES ; — SCARABjEI. 127

impervious to the water on which it floats. The larvae, which have
a worm-like body, with six feet, and with sharp
mandibles arming the head, are very voracious ;
feeding upon Tadpoles and the young fry in
fish-ponds, and upon small fresh- water Mollusca.

650. The last family of the Pentamerous sec-
tion, the LAMELLICOBNES, is of very great extent,
as well as one of the most striking of the whole
Beetle tribe, in regard to the size of the body,
and the variety in the form of the head and thorax
in the different sexes ; and also, moreover, in those

species which in their perfect state live upon fresh vegetable sub-
stances, in respect to the brilliancy of the metallic colours with
which they are ornamented. But the majority of other species,
which subsist on decomposing vegetable matter, are of an uniform
brown or black colour; although some are not inferior in brilliancy
to the preceding. All have wings ; and they crawl but slowly
along the ground. None of them are aquatic. Their food consists
of dung, manure, tan, and particularly, in some species, of the
roots of vegetables ; whence these insects, in their larva state
especially (this being always the period of greatest voracity),
often occasion great loss to the cultivator. — This family receives
its name from the peculiar conformation of the antennae, which
terminate in a mass formed of the last three joints : these are
flattened into plates or lamellae, and are sometimes arranged like
a fan or the leaves of a book, sometimes in the manner of a
comb, and sometimes inclosing one another. The family is
divided into two principal sections, the Scarabcei and the
Lucani.

651. Of the Scarabcei, one subdivision, including the sacred
Beetle of the Egyptians (Fig. 344), feed principally upon the
excrements of various animals ; and they inclose their eggs in
balls of the same (whence they have been called Pilularii),
which they roll along with their hind feet, several often
being in company, until they reach the hole in which these
are to be deposited. Of these we have a characteristic ex-
ample among British species, in the Geotrupes stercorarius, the

1 28 LAMELLICORNES ; — SCARAB^EI.

common Dor or Shard-borne Beetle ; which is one of the com-
monest of all Beetles in this country. One of the most

FIG. 344. — ATEUCHUS (ScARA-
^EGYPTIORUM.

FIG. 346.— DYNASTES HERCULES.

FiG. 345.— GEOTRUPKS STERCORARIUS.

remarkable^amongst foreign species is the Dynastes Hercules,

a native of Brazil,
which attains the
length of 5 inches,
and of which
the male pos-
sesses an enor-
mous horn pro-
jecting from the
head, which is
opposed by a corresponding protuberance from the thorax. To
this group also belongs the Melolontha vulgaris or common
Cockchafer ; which is most destructive to vegetation in both its
larva and perfect conditions, feeding on the roots in the one case,
and on the leaves and young shoots in the
other. The larvae live for three or four
years beneath the ground; becoming lethargic
in winter, but actively voracious in summer.
Their excessive multiplication is usually pre-
vented by birds'; but if these be kept away,
they increase very rapidly, and become a
complete pest to the cultivator. The perfect
insects sometimes make their appearance in such swarms, as to

FIG. 347-— LARVA OF
COCKCHAFER.

ROSE- BEETLE ; — STAG-BEETLES.

129

devastate an entire forest. To this group also belongs the
Cetonia aurata or Rose-beetle, a very common British insect, of
which a figure has been already given (Fig. 335) ; it is about an
inch long, of a shining-green colour above, coppery-red beneath,
with white marks on the elytra. In its larva state, it frequents
rotten timber and wood, and is often met with underground in
ants' nests, where it would seem to feed upon the bits of wood
of which they are composed ; from this circumstance it is some-
times called the "king of the ants." After remaining about
three years in the larva state, it makes a sort of cocoon of chips
of wood, glued together by an excretion of its own ; in this it
passes the winter in the state of an inactive pupa, from which it
emerges in the following summer in its perfect form. The Rose-
beetle flies well, with a considerable humming noise, during the
hottest part of the day ; and goes from flower to flower (not
confining itself to Roses, but seeming to prefer them), sucking the
honey from their interior, and sometimes devouring their nectaries.

652. The Lucani, or Stag- Beetles, derive their common name
from the peculiar form of the mandibles, which are very large,
curved, and toothed, like stags' horns (Fig, 316). The Lucanus
cervus, a highly-characteristic species of the group, is one of the
largest of British insects, the males being two inches or more in
length. This species flies about in the evening, in the middle of
summer, especially round the oaks, upon the wood of which the
larva feeds ; remaining in that state

for several years, before undergoing its
final transformation. The accompanying
figure represents the Dorcus parallelipi-
pedus, or Small Stag-Beetle of this
country ; which is far less striking
than the larger species in regard to the
development of its maxillse. Some of
the exotic species of this group are very
large and splendidly coloured.

653. Section II. HETEROMERA. The
Coleoptera of the Second section, cha-
racterised by possessing five joints in the tarsi of the two anterior

FIG. 348.— DORCUS PARALLELI-
PIPEDUS.

130

MELASOMA ; BLAPS. CANTHARIS.

pairs of feet, and of only four in the posterior tarsi, entirely feed
on vegetable substances ; they are all terrestrial, and most of
them frequent dark places. — In the first family, the MELASOMA
or black-bodied Beetles, the body is usually of an ashy-brown or
black colour ; and the wings are for the most part absent, the
elytra being united along the suture. They usually live in the
ground, beneath stones, or in the sand — often also in low and
dark parts of buildings, such as cellars, stables, &c. The insects
of this tribe are very tenacious of life ; individuals having been
known to remain alive for six months without food, and pierced

through with a pin. To
this family belong the
Blaps mortisaga, a beetle
often found in dark and
dirty places about houses ;
and the Tenebrio molitor,
of which the larva, known
under the name of the ,
meal-worm, lives in corn S
and flour, whilst the per- 1 )
feet insect also frequents
bake-houses, corn-mills, &c., where it may be often found in
the eaves.

654. We may pass over the families
of TAXICORNES and STENELYTBA, as pre-
senting no points of special interest, to notice
theTRACHELiDES (wedbJ-beetles), so named
from having the head, which is triangular
or heart-shaped, carried on a kind of neck,
which separates it from the thorax. The
body is soft ; and the elytra are flexible,
and sometimes very soft. The majority
of this group live in the perfect state upon
different vegetables, devouring the leaves,
or sucking the juices of the flowers. —
Many of them, when seized, depress the head and contract the
feet, as if they were dead. Their colours are often very brilliant.
This is well seen in the Cantkaris vesicatoria, commonly known

Fto. 350.
TENEBRIO MO-
NITOR.

FIG. 349. — BLAPS MORTISAGA.

FIG. 351. — CANTHARIS
VESICATORIA.

RHYNCOPHORJE, OR WEEVIL TRIBE.

131

as the Blistering-fly, which is of a shining green metallic hue; this
insect is most abundant in Spain, but appears about midsummer
in France, and is found in great numbers on the ash and lilac,
of which it consumes the leaves. Its larva lives in the earth,
and feeds upon the roots of vegetables.

655. Section III. TETRAMERA. All the Beetles of this
group, likewise, — consisting of those which have four joints in
all the tarsi, — are vegetable-feeders. The perfect insect is found
upon the flowers and leaves of plants; the larvae are often produced
in their interior ; and, when thus hatched in the midst of their
food, their legs are commonly very imperfect. Very often the
true legs are almost entirely absent, and their place supplied by
fleshy tubercles. The first family, that of RHYNCOPHORJE, or
the Weevil tribe, is distinguished by the prolongation of the
anterior part of the head into a kind of muzzle (Fig. 352, D).
The number of species in this family is very great ; nearly four
thousand have been already collected. Many of them are
extremely destructive ; especially the Calandra c/ranaria, which
commits great havoc in granaries, both in its larva and perfect
states. The accompanying figure exhibits the history of the

development of the
Balaninus nucum, or
Nut- Weevil, whose
larva is so common-
ly found in nuts, fil-
berts, &c. The egg
is introduced by the
parent when the nut is
young and soft ; and
the wound made by it
heals over. The larva,
when it comes forth

FIG. 352.— A, a branch of the filbert tree; a, a healed f .1 fPPda

wound caused by the introduction of the egg of the nut- "

weevil ; 6, extremity of the nut ; c, exit hole of the upon the kernel in
grub ; B, the grub of the nut- weevil ; c, the pupa of the , . . . . . , , 1
same ; D, the perfect insect (Balaninus nucum). which it IS imbedded ;

and, when about to
change its state, it bores through the shell, and escapes, leaving

K 2

132

XYLOPHAGI, OB WOOD-EATING BEETLES.

FIG. 353.— 1, 2, TOMICUS TYPOGRAPHIC ; 3, 4, 5, (
HVLURGUS PJNIPKRDA (natural size and magnified).

a small round orifice. To this tribe belongs one of the most
splendid of all Beetles, theCurculio imperialis, well known as the
Diamond-beetle, which is a native of South America, and very
abundant in some parts of that country. There are small species
belonging to our own island, however, which are scarcely less
brilliant when magnified under a good light.

656. The second family of the Tetramerous Coleoptera has
received the name of
XYLOPHAGI (or wood-
eaters)^ on account of
the peculiar habits of
the Beetles composing
it. They usually live
in wood, which their
larvae pierce in every
direction ; and, when
abundant in forests,
especially those of pines

and firs, they destroy large numbers of trees in a few years.
They are destitute of the prolonged muzzle of the last order, and
have short antennae, thickened towards the tips (Fig. 353). One of
the most destructive species is the Bostrickus typographus^ or the

Typographer beetle
(so named from the
figure of its burrows),
which has at different
times ravaged the
forests of Germany.
It devours, both in
the larva and perfect
states, the soft wood
beneath the bark,
which is most essen-
tial to the vegetative
processes ; and thus
causes the death of
the tree. It was reckoned that a million and a half of pines

Fro. 35 '.—Track of Typographer Beetle.

LONGICORNES; MUSK -BEETLE. 133

were killed by this species alone in the Hartz Forest, in the year
1783; and that as many as eighty thousand individuals were
ordinarily engaged in the destruction of each tree ; whence the
whole number at work in the forest at once must have been one
hundred and twenty thousand millions.

657. Passing over the small family PLATYSOMA, which closely
resembles the preceding in structure and habits, we come to the
family LONGICORNES, distinguished by the great development of
the antennae, whicli are always at least as long as the body,
and often longer. The larvee mostly reside in the interior of
trees, or under the bark ; and are destitute of feet, or have them
very small. They are furnished with robust mandibles, and do
much injury to trees, especially those of large size, by burrowing
deeply into them. They are vegetable-feeders in their perfect
state also, and do great injury to plants ; some attacking the
leaves, and others the roots. Many of them produce a slight
creaking sound, by the friction of the joint whicli unites the

FIG. 355. — CALLICHROMA MOSCHATA.

thorax to the abdomen. Several of them are brilliantly coloured,
especially the tropical species; and some are remarkable for ex-
haling an agreeable musky odour. This is the case with a British
species, the Callichroma moschata, or Musk-beetle, which is about
an inch long, entirely green, or shaded with a blue or golden hue,

134 EUPODA. CYCLICA.

and very common upon willows. The genus Acanthocinus is re-
markable for the spiny projections
from its antennae ; and the species
represented in the accompanying
figure, derives its specific name
(which means mirror-bearing) from
its having a bright burnished disc
on each of the elytra.

658. The succeeding family
EUPODA, is composed of Beetles,
which are chiefly remarkable for FIG. 356.— ACANTHOCINUS SPBCULIFER.
their habit of feeding upon the

stems and leaves of aquatic plants, and upon those of the Lilia-
ceous tribe. One species, the Crioceris Asparagi, which is of a
blue colour, with the thorax red, and the elytra
yellowish- white, with blue markings, feeds in the
larva state, on the young sprigs of asparagus ; and
*s some^mes so abundant, as to do considerable
damage to the gardener.

659. The sixth family of the Tetramerous sec-

Fio. 35/. — CRIOCE-
RIS ASPARAGI. tion, that of CYCLICA, presents many points of

interest, on account of the singular forms, and
remarkable habits, of many of the species which it includes. The
name of the family is derived from the circumstance that, in its
typical forms, the body is of a circular or oval shape ; the insects
composing it are usually of small size, but are often ornamented
with metallic and brilliant colours ; they are generally slow in
their motions, timid, and fall to the ground when an attempt is
made to seize them, folding their antennae and legs beneath the
body ; many species leap well. The larvae have six feet, and a
soft body ; they feed, like the perfect insect, upon the leaves of
different vegetables, where they ordinarily affix themselves by
means of a glutinous secretion ; and they frequently undergo their
change into the pupa state in the same situation, the cast-skins
of the larvae being crumpled up at the extremity of the body of
the pupae . The first tribe of this family consists of the Cassi-
daricE, or Tortoise Beetles ; these have a flattened body, sur-

CASSIDARLE ; CHRYSOMELIN^E.

135

rounded by a margin, which is formed by a prolongation from
the thorax and elytra, and which even conceals the head ; and
they are able to lie so close upon the surface of the leaves, that
no part of the body or limbs is visible. Their colours are mucli
varied, and often very prettily arranged in spots, points, rays,
&c. The commonest species in this country is the Cassida mri-
dis, which is no more than l-16th of an inch long, of a green
colour, with black thighs. Its larva, which lives on thistles

and artichokes, has a
very flat body, with
spines set on the edges;
and it has the singu-
lar habit of covering
itself with its own ex-
crement, which it at-

Fio. 358.— CASSIDA VIRIDIS, IN ITS DIFFERENT STATES ; tacheS in a mass tO£e-
a, larva ; b, the same on a leaf, with its covering of ., , nrrip* nrT i

excrement ; c, pupa; d, perfect insect. tlier> ana MUM* OH a

sort of fork, arising

from its tail. The pupa, also, is very flat, with thin-toothed
appendages at the sides of the body ; and its thorax is broad, and
prolonged for wards in a rounded expansion, which covers the head.
660. In the sub-family Chrywmelince, or Golden Beetles, this
expansion of the thorax is generally wanting; the body is
usually of a hemispheric or ovate form, the base of the thorax
being as broad as the front edge of the elytra ; and the surface is
usually bespangled with the most brilliant hues, in which blue,
green, and gold, are pre-eminently conspicuous. Their motions
are generally slow, and many of them are destitute of wings. Of

the genus Chrysomela, the
C. populi is one of the com-
monest British species ; it
is of a blue-black colour, and
has red elytra, tipped with
black ; and it is found upon
the willow and poplar, in
the larva as well as in the
perfect state. As in the
preceding group, the exuviae of the larvae are found collected into

FIG. 359.— CHRYSOMELA POPULI
6, Pupa ; c, Imago.

a, Larva

136 TIM ARCHA. G ALERUCINjE. TRIMERA.

a mass, at the extremity of the body of the pupa ; 'and, in some
instances, the larva, before undergoing its transformation, attaches
itself to the leaf by a glutinous exudation. Of the apterous
group, the Timarcha is the principal genus ; and the T. l&vigata
is a common British species, varying in length from half to three
quarters of an inch, and frequenting woods, turf, and low her-
bage. It crawls slowly, and emits a reddish-yellow fluid from
the joints when disturbed ; from which circumstance it is com-
monly known by the name of the Bloody-nose Beetle. The larvae
bear a strong resemblance to the perfect insect, both in appear-
ance, sluggishness of movement, and general habits ; when dis-
turbed, they roll themselves up in the manner of a Wood-louse.
The sub-family Galerucinas^ may also be mentioned as contain-
ing the genus Haltica ; which is composed of a group of small
brightly-coloured Beetles, whose larvae devour the leaves of cul-
tivated vegetables, and occasion-
ally commit great devastations
by their numbers and voracity.
One of them occasionally attacks
the turnip in this country ; and
from its great leaping powers,
may well be designated the

FIG.360.-HALTICANEMORUM, or TUR- Turnip-flea. The Turnip-fly
NIP-BEETLE; naturalize and magnified, belongs to quite a different group.

(§ 686.)

661. Section IV. — TRIMERA. The Beetles of this section are,
for the most part, of small size, and not very numerous. Their
habits are various, a portion feeding on Fungi, and the remainder
chiefly upon Aphides. To the latter section belongs the genus
Coccinella^ of which several species are known in
this country, under the name of Lady-birds, or
Lady-cows. They sometimes appear in great pro-
fusion, and have created much alarm. It is erro-
neous to suppose, however, that they do any injury
to vegetation ; for, on the contrary, they are of great
benefit to plants, by feeding on the Aphides which
infest them ; and this they do both in the larva and perfect states.

137

ORDER II.— ORTHOPTERA.

662. In many respects the Insects of this Order resemble
the Coleoptera; and they are closely connected with that group
by the family FORFICULIDJE, or Earwig tribe, which partake of
the characters of both. But they differ from the Beetles, in the
softer covering of their bodies ; in the partially membranous
character of the anterior pair of wings, which seem intermediate
between the horny elytra of Beetles and the membranous wings
of other insects, and which do not meet when closed along the
central line of the back ; and in the fan-like manner in which
the posterior wings are folded up beneath them, which is per-
mitted by the straight direction of their veins. They differ also
in their metamorphosis ; for, whilst that of the Beetles is com-
plete, that of the Orthoptera, is only partially so, — the larva

FIG. 362 — LARVA AND PUPA OF GREAT GREEN GRASSHOPPER.

and pupa closely resembling the perfect insect in form, walking
and feeding in the same manner, and differing in little else, than
the absence of the wings and wing-covers, which are gradually
and visibly developed in the pupa. — This Order comprises
numerous well-known insects, often of large size and splendid
colours, such as Grasshoppers, Locusts, and Walking-Leaves ; —
as well as Cockroaches and Earwigs. Some of the largest of
known insects belong to it ; a few species attaining a length of
eight or nine inches, and an equal expansion of wings. Com-
paratively few of this Order are inhabitants of temperate regions ;
and it attains its greatest development, both as to the number
of species and individuals, their size, and their colour, between

138 FORFICULID.E, OR EARWIG TRIBE.

the tropics. All the known Orthoptera are terrestrial, both in
their perfect and two previous states. Some are purely carni-
vorous, and others are adapted to a mixed diet, — the Cock-
roaches, for example, being capable of feeding on almost any
kind of organised matter; but the greater number feed upon
plants. Hence from their large size, and the enormous quantity
which each individual can devour, they are among the most
destructive of all the Insect tribes, when they appear in large
numbers. This is particularly the case with the Locusts in
warm countries ; the ravages of which not unfrequently cause
famine and pestilence, both among men and beasts. Some
details upon this subject will be given in the latter part of
this volume.

663. Before treating of the true Orthoptera, we shall first
notice the family FORFICULID^E ; which has been raised by some
into a distinct order, under the name DERMAPTERA, or leathery-
winged (§ 637). The Earwigs and their allies, of which this
group is composed, have the anterior wings formed into elytra,
possessing a consistence intermediate between that of the horny
elytra of Beetles, and the parchment-like anterior wings of the
Orthoptera ; they are of small size ; and they meet, when folded
together, upon the central line, as in Beetles. The posterior
wings are folded across when at rest, as in the preceding Order,
but the part thus doubled down is itself folded in a fan-like
mode, as in the Orthoptera. These insects are further distin-
guished by the two large appendages at the posterior part of
the body, which form a pair of forceps (Fig. 306). They are
very common in damp situations, where they assemble in troops
under stones and the bark of trees ; they do much injury to
the flowers and fruits of our gardens, and they will devour the
bodies of their dead companions. Their forceps appears to serve
as an instrument of defence ; whether it answers any other
purpose is not known. Their common name is derived from the
incorrect notion, that they have a peculiar tendency to creep into
the ears of sleeping persons.

664. The proper Orthoptera may be divided into two prin-
cipal sections ; in the first of which the legs are nearly of the

SUBDIVISIONS OF ORTHOPTERA. BLATTID^E. 139

same length and adapted for walking or running, whence they
are named CURSORIA ; whilst in the second, the SALTATORIA, the
thighs of the hind-legs are of disproportionate length, and are
adapted for leaping. These two groups also differ in the
arrangement of the wing-covers and wings, when closed ; for
they usually rest horizontally in the body (and consequently
more in the manner of those of the Beetles) in the first ; whilst
in the second they meet at an angle, like the two sides of a roof.
The second section is further distinguished by the creaking
sound, which the males have usually the power of emitting, by
the friction of their legs against the body.

665. The first section may be divided into three families,
which differ considerably from each other in general form, — the
BLATTID JE, or Cockroaches ; the MANTID^E, or Mantis tribe ;
and the PHASMID^E, or Spectre insects. In the first of these, the
legs are adapted for running ; in the second, the fore-legs are
converted into claws for seizing the prey ; and in the third, the
limbs are adapted only for walking or creeping. — The BLATTID^E
are in many respects intermediate between the Forficulidae and
the more typical Orthoptera ; in fact, their general resemblance

Fio. 363. — BLATTA ORJENTALIS, MALE AND FEMALE.

to the Coleoptera occasions them to be commonly regarded as
Beetles. These well-known insects are now pretty generally

140 BLATimE, OR COCKROACH TRIBE.

diffused over temperate climates ; although most of the species
are believed to have been originally natives of tropical regions,
where only they attain their full development. They are
nocturnal in their habits, and active in their movements along
the ground ; their powers of flight are usually inconsiderable,
the wings being usually small in proportion to the size of their
bodies ; and they are extremely voracious, devouring with
avidity almost every kind of organised matter. In cold climates
the wings are scarcely enough developed, even in the male, to
raise the body from the ground; whilst in the female they
are almost entirely absent. The species which is commonest
in this country, the Blatta orientalis, is so named from its being
supposed to have been originally a native of the East Indies; it
has, however, been so long domesticated with us, that its time
and mode of introduction are uncertain. In common with most
other species of Blatta, it ejects a dark-coloured fluid from the
mouth, emitting a very disagreeable odour, of which it is diffi-
cult to get rid, and attaching itself to whatever the insect has
crept over. The tropical species are larger and more voracious ;
one of them, which attains the breadth of six inches when its
wings are expanded, is known in the West Indies by the name
of drummer, from the sharp knocking sound which it produces,
and which is sometimes kept up through a whole night by
several individuals replying to each other; and it is said to
attack sleeping persons, and even to devour the extremities of
the dead. — Notwithstanding the disgusting character which
attaches to these insects, on account of their appearance and
habits, they present several points of much interest to the
Naturalist, especially in regard to their mode of depositing their
eggs. Instead of being discharged separately, the eggs are col-
lected together and deposited at once, enclosed in a large horny
case or capsule (equalling half the abdomen of the female in
size), and generally of a more or less oval and flattened form,
like a small bean with one edge more flattened than the other
(Fig. 363, A). Along this edge there is a slit, from end to end
of the capsule ; and the plates which form the edges of this slit
are jagged or toothed, fitting closely to each other. The interior

BLATTID,E. MANTID^E, OR MANTIS TRIBE. 141

of this capsule is divided into two spaces, in each of which is a
row of separate chambers, every one of them enclosing an egg.
The capsules are attached by means of a glutinous secretion, in
such situations as the females select as most fit for their reception ;
and the slit part is strongly coated with cement, so as to be even
stronger than the other parts. In this capsule, the young larvae
are hatched ; and they immediately discharge a fluid, which
softens the cement, and enables them to push open the slit ;
through this they escape, and the slit then shuts again so closely,
that it appears as entire as before.

666. The MANTID.E are purely carnivorous insects, of which
none are natives of this country. They differ much from the
BlattidsB in the form of the body ; which, instead of being
flattened and oval, is narrow or compressed, and lengthened. The
first pair of legs is enormously elongated, and forms a very
powerful organ of attack. These insects frequent trees and
plants ; and the forms and colours of their wings and bodies are

Fro. 364.— MANTIS, tN THE ACT OF SEIZING A FLY, WITH A
YOUNG ONE JUST HATCHED.

often so adapted to those of the leaves and twigs which surround
them, as to give them remarkable power of eluding observation.
Most of the species asume, when lying in wait for their prey,
an attitude which has been mistaken by the inhabitants of the
countries where they are found, for that of prayer ; and the

142 MANTIS TRIBE. - PHASMIDJB, OR SPECTRE INSECTS.

names commonly given to the Insects are such as to express this.
Thus the best-known species, which is very common in the south
of France and Italy (Fig. 364), has received the name of
Mantis religiosa, the Praying Mantis, or Soothsayer ; and is
termed by the French prie-Dieu. This is regarded by the Turks
as an object of superstitious veneration; and many absurd stories
are on record, in regard to its habits. The peculiar attitude
in question, however, is nothing else than the position in which
the prey is most readily seized ; — the front of the thorax being
elevated, and the two fore-legs being held up together like a pair
of arms, prepared to seize any animal that may fall within their
reach. These insects are extremely voracious ; and, if kept
together without food, they will fight until one is killed, the
victor then devouring his conquered adversary. — The eggs are
included in a capsule, as in the BlattidsB.

667. The third family of the Cursoria, that of PHASMID^E,
or Spectre Insects, is also restricted to warm climates ; and
consists of a small number of extremely curious species, com-
monly known under the names of Walking- Sticks, Walking-
Leaves^ &c., from their resemblance to those objects. Their
whole structure indicates a sluggish mode of life ; they subsist
solely upon vegetables, and crawl slowly among the branches
of low shrubs, devouring the young shoots. In fact, their
mode of life bears a strong analogy to that of the Sloths among

Mammalia. Their
means of escape
from enemies con-
sist entirely in their
very close resem-
blance to the ob-
jects in the midst
of which they live.
Some of them are
destitute of wings,

FIG. m—PHASMA (BACTERIA) FRAGILIS, OR WALKING-STICK. an(* ^aVG ^1G aP~

pearance of dead
twigs ; the legs being generally extended in a straight line so as

POASMID.E ; WALKING-LEAF. 143

to look like~the lateral twigs ; whilst the absence of motion in
the Insect for a long period adds strength to the deception.
Others, which possess wings, have still the same general appear-
ance ; these organs being laid flat along the back, so as not to
extend beyond the body. In others, again, the wings have
the form and aspect of withered leaves (Fig. 366) ; whilst the
wing-covers are very short. And lastly, there are a few, in
which the wing-covers are of a brighter hue, and of larger size,
covering in the wings, and giving to the whole animal the
appearance of a fresher leaf. These curious insects are for the
most part natives of the East Indies, the East Indian Archi-
pelago, Australia, and South America. Their larvae differ but
little from the perfect insects, except in their colours and in the
absence of wings; and there are several species, as we have
seen, in which these are never developed. It not unfrequently
happens that they lose a limb by violence ; and this is repro-

FIG. 366. — PHYLLIUM SICCIFOLIUM.

duced, provided the complete growth of the animal has not been
attained. The eggs are laid separately, in the usual manner.
668. The section SALTATORIA consists of numerous species

144 SALTATORIA. — ACHETID^E OR CRICKETS.

allied to the well-known Crickets, Grasshoppers, Locusts, &c. ;
all of them being adapted, by the peculiar conformation of their
hind-legs, to move by leaping rather than by running. Besides
this peculiarity, they all agree in depositing their eggs in the
ground : and they generally effect this by means of a horny
tubular prolongation of the last segment of the body, or oviposi-
tor, such as we shall meet with in the order Hymenoptera.
There are three distinct groups in this section ; — namely, the
ACHETIDJE or Crickets; the GRYLLID^E or Grasshoppers; and the
LOCUSTIDJE or Locusts; but the differences between them are
scarcely such, as to entitle them to rank as distinct families.
The Crickets are essentially inhabitants of the ground, in which
many of them burrow, both in the larva and perfect states ; few
of them have any powers of active flight. One of the most im-
portant species of this family is the Gryllotalpa vulgaris, or
Mole-Cricket (Fig. 300), which derives its name from the pecu-
liar similarity in its anterior extremities, and from the resem-
blance in its habits, to those of the Mole. It is about an inch
and a half long, and of a brown colour. In making its burrows,
it cuts through or detaches all the roots of plants which it en-
counters ; but it does not do this so much for the purpose of
feeding upon them, as to make a passage in search of insects and
worms. The female forms, in June and July, at the depth of
about six inches from the surface, a rounded cell, smooth within,
and resembling with its gallery a bottle with a long bent neck ;
in this she deposits from 200 to 400 eggs ; and the young remain
in society for some time after they are hatched. The larvae are
at first white ; but in other respects they resemble their parents,
except in their smaller size and their want of wings ; after their
first moulting, they disperse, and soon gain their darker colours;
and they are about three years before they arrive at the perfect
state. Their wings are so little developed, that the possibility
of the flight of the inseots has been denied. It is remarkable
that the various species of this singular genus should be spread
over the whole globe. The House- Cricket (Fig. 367) is too well
known to require particular description; it takes up its abode
in the neighbourhood of the fire-places of rooms on the ground-

CRICKETS ; — GRASSHOPPERS.

145

FIG. 367.— HOUSE-CRICKET.-

floor, sometimes even burrowing into the mortar, even within a
few inches of the fiercest fires ; and here it remains during the

winter months, be-
coming torpid in
its haunts, if the
fire be discontinued.
In the summer,
however, it fre-
quently goes forth
to the gardens, and
seeks a habitation
in the ere vices of garden -walls, &c., as if it then found heat enough
out of doors. The Field- Cricket is much larger, and also rarer,
than the preceding ; it frequents hot sandy districts, in which it
forms its burrow at the side of footpaths, &c., in situations ex-
posed to the sun, to the depth of from six to twelve inches ; and
sits at its mouth watching for its prey, which is said to consist
of other insects. This is one of the most noisy of all the Crickets.
669. The Gryllidce, or Grasshoppers, are distinguished from
the preceding by the roof-like position of the wing-covers, which
in the crickets fold ho-

rizontally; but agree
with them in having
long thread-like an-
tennae, and a talc-like
spot at the base of the
wing-covers in the
males. They are dis-
tinguished, on the other FlG- 368.— GRYLLUS VIRIDISSIMUS.
hand, from the Locusts with which they agree in the first of
these characters, by the inferior robustness of the body, and the
length and slenderness of the legs and antennae. The Gryllus
viridissimus, or Great Green Grasshopper, represented in
Fig. 368, is the largest British species of this Order, and one of
the largest of our native insects ; its length being about two
inches, and its breadth when the wings are expanded being three
inches and a half. Many species of this genus are destitute of

146

GRASSHOPPERS. LOCUSTS.

wings, or have only small wing-covers. Of their voracity a
curious instance is mentioned by Mr. Westwood; who states
that on one occasion he placed a specimen of the large green
species in a box, together with one of its legs which it had
accidentally jerked off; and on opening the box the next morn-
ing, half the leg was devoured. Amongst the foreign species of
this group, there are some which bear a most singular resem-
blance to the fresh leaves of various plants.

670. The last group of this Order consists of the various
tribes of migratory Locusts, together with several which are
ordinarily ranked as
Grasshoppers, but which
agree with the Locusts
in the shortness of their
antennae, and the robust-
ness of their bodies and
limbs (Fig. 369). These
leap with much greater
energy than the preced-
ing, and have a much
longer-sustained flight.
The powers of devasta-
tion possessed by the
Locusts are almost in-
conceivable ; for they are
produced in vast num-
bers, and live in societies,
so as speedily to destroy the vegetation of the spot on which
they have settled. Thence they take their flight in vast multi-
tudes to adjoining districts ; and so great is the number of which
these swarms consist, that it is not speaking figuratively to say
that the sky is darkened by their passage. Their ravages
usually continue until they are checked for want of a further
supply of food ; for as the instinct of the Locusts leads them to
continue their flight in the same direction, they are at last
stopped either by the desert or the sea ; and sometimes a storm,
carrying them out of their course, or hurrying them on in it,

FIG. 369. — PNEUMORA.

GENERAL CHARACTERS OF NEUROPTERA. 147

effects a clearance much more speedily than any other cause could
do. Of the cause of the occasional appearance of the Locusts, in
such vast multitudes, no satisfactory explanation has been given.
Of these Insects there are several different species, which are
distributed over the tropical and the warmer temperate regions of
the globe ; and in many parts they are used as food by the
inhabitants of the countries they infest.

ORDER III.— NEUROPTEEA.

671. The Neuroptera correspond with the two preceding
Orders, in having a mouth adapted for mastication, but differ from
them as to the conformation of the wings ; the anterior as well
as the posterior pairs being here membranous and transparent.
In both pairs of wings, the veins form a very beautiful and
minute network, subdividing and uniting again, so as to divide
the whole surface into a large number of minute cells, which
much exceed in number those of the wings of any other tribe of
insects (Fig. 370). Although the posterior wings are usually
as large as the anterior, or sometimes even larger, they are occa-
sionally much smaller, and may even be altogether wanting.

675. The body of the Insects of this Order, which contains
the well-known Dragon-flies, May-flies, Ant-lions, White Ants
or Termites, and others, is generally prolonged, and destitute of
any very hard integument. These insects are of intermediate
size ; none of them exceeding in dimensions the largest Dragon-
flies of this country ; whilst none exhibit the minuteness of some
Hymenoptera and Coleoptera. They differ in the character of
their metamorphosis, as well as in their adult structure ; for in
some the metamorphosis is complete, the larva undergoing a
marked change of form; and in others there is not much difference,
except in the absence of wings, between the larva and perfect
insect. By these differences the Order may be divided into two
sections ; in the first of which the insect is active during the
whole of its pupa state ; whilst in the second, it is quiescent,
except just before its last metamorphosis. The first of these

148 LIBELLULIDJ5, OR DRAGON-FLIES,

groups may again be subdivided into three families ; — the
LIBELLULID^E or Dragon-flies ; — the EPHEMERID^E, or May-flies ;
and the TERMITID.E or White Ants. In the first two of these,
the larvae and pupaa are inhabitants of the water, and respire by
means of peculiar organs placed along the sides or at the extremity
of the abdomen ; whilst in other respects, they nearly resemble
the perfect insect. They creep out of the water to undergo the
final metamorphosis.

673. Section I. The LIBELLULID^, or Dragon-fat, are well-
known insects ; being easily distinguished by the slender form
of their bodies, their varied colours, their large gauze-like wings,
and the rapidity of flight with which they pursue other insects
on which they prey. They have a large head, of rounded form,
furnished at its sides with two very large compound eyes, and

FfO. 370. — LlBELLULA CANCELLATA.

with three ocelli, situated upon its upper surface. Most of this
tribe frequent the neighbourhood of water; and may be fre-
quently seen skimming over the surface of ponds or streams, in
search of flies, gnats, and other small insects. An American species
has been recently described by Mr. Newport, which seems to be
actually provided with branchial or gill-like appendages, even in
its perfect state ; and the habits of this insect appear to be pecu-

EARLY STATES OF DRAGON-FLY. 149

liarly aquatic. The eggs are deposited upon aquatic plants, and
the larvaa are thus produced in the element in which they are at
first to reside. The head of the pupa is remarkable for the

FIG. 371.— A, the pupa with its mask. B, the same with the mask closed, and
discharging a current of water.

singular form of the portion which takes the place of the lower
lip; this is a kind of mask, composed of several pieces, and cover-
ing the mandibles, maxillae, and nearly all the under side of the
head, when it is closed together ; but being capable of extension
and unfolding, and being furnished with a pair of sharp claws at
its upper part, so as to become the instrument by which the
animal seizes its prey. The posterior end of the abdomen, in the
early state of the Dragon-flies, is usually the seat of the respi-
ratory function. This is commonly performed by means of three
leaf-like membranous organs, which are situated inside the extre-
mity of the intestine, or sometimes within a sort of prolonged
pyramidal tail ; in using these, the animal draws a supply of
water into the rectum ; and then forces it out violently, by which
acl it also impels itself through the water. The succession of
jerks thus produced, is the chief means of locomotion of the
larvae of the Dragon-flies, and serves to distinguish them from all
other aquatic larvae; so that they are very easily recognised. Several

150 AGRIONS ;< — EPHEMERID^, OR DAY-FLIES.

species of Dragon-flies exist in this country ; the largest, which

is probably not surpassed in
size by any others, measures
two inches and a half in
length ; but the foreign
species are usually more
brilliantly coloured. — In the
Agrions, the wings stand
perpendicularly when in

FIG. 37'2.— AGHION VIRGO. . . ,

repose, instead ot horizon-
tally as in the Dragon-flies ; and the mouth is somewhat dif-
ferently constructed. The species represented in the accompany-
ing figure is of a golden-green, or bluish-green colour, with the
wings blue ; and in common with many other less conspicuous
species, it is an inhabitant of Britain.

674. The EPHEMERID^E, or Day-flies, receive their name
from the short duration of their lives in the perfect state. The
history of their early condition has been already given (§ 632).

FIG. 373 — EPHEMERA.

Their last change takes place near sunset on the fine days of
summer and autumn ; and they are sometimes produced in such
vast numbers at one time, that the ground is covered with them
after their death, and their bodies are carted away as manure.
They take no food after their final change ; and as the propaga-
tion of the race is then their only object, they die almost as soon
as it has been performed, often in a few hours after they have
quitted the water, — the duration of their lives in their previous
conditions having been two or even three years.

675. The TERMITID^, or White Ants, are terrestrial, active,
and carnivorous or omnivorous, during all their stages. In

TERMITES, OR WHITE ANTS.

151

several points of their structure, they resemble the Orthoptera ;
whilst in their habit of living in societies, they resemble a large
proportion of the Hymenoptera. There is, however, as we shall
hereafter see, a considerable difference in the duties of the several
tribes of which these communities consist. A more particular
account of their operations will be given in a later part of this
volume ; and at present it will be sufficient to say, that the larvae
resemble the perfect insect, except in the absence of wings, and are
the workers. Among the adult insects there are
some, which never acquire wings, and in which
the reproductive organs are not developed; these,
which are termed the soldiers (Fig. 374), have
the head much larger and longer than that of
the larvae, and the mandibles are very long and
cross each other ; they are far less numerous
than the larvae, and live near the outer surface
of the nest, so that they are the first to make their appearance
when it is attacked; and they are also stated to compel the
workers to labour. The winged males (Fig. 375) and females,

FIG. 374.— SOLDIER
TERMKS.

Fro. 375.— TERMES
in perfect state.

FIG. 37G — QUEEN in the winged state, and filled
with Eggs.

when they have arrived at their perfect state, quit their habita-
tion, and fly abroad during the evening or the night, in great

152

TERMITID.E. MYRMELEONID^E, OR ANT-LIONS.

FIG. 377.— Psocus

PULSATORIUS.

numbers ; they lose their wings before the morning, however ;
and the greater part of them, falling to the ground, become the
prey of birds, reptiles, &c. The females, however, are sought
by the workers, who imprison them in royal chambers, as they
have been termed, in the centre of the nest. The abdomen
subsequently attains an enormous size, from the quantity of eggs
it contains ; and these, when laid, are carefully
tended by the workers, and defended by the
soldiers. — Some small species belonging to this
family, but not at all resembling the true
Termites in habits, are found in our country;
one of them, which is found in collections of
dried plants, is remarkable for producing a slight
ticking noise; it is represented of its natural
size, and magnified, in the accompanying figure.

676. Section II. Of the division of Neuroptera in which a
more complete metamorphosis occurs, the pupa passing into an
inactive condition, the family of MYRMELEONID^E, or Ant-lions,

is one of the most re-
markable. As its pecu-
liar habits in the larva
state have already been
elsewhere described

(ANIM.PHYSIOL.§697),

they need not be here
dwelt on. When the
larva has attained its full
growth, and is ready to
assume the pupa state,

it spins a perfectly round cocoon of a silky matter, the exterior
of which it covers with sand ; and from this the perfect insect
makes its escape at the end of fifteen or twenty days. None of
this group are found in Britain.

677. The family HEMEROBIID^E, which is closely allied to
the preceding, is remarkable for the exceeding brilliancy of the
eyes in most of the species, and for the delicate structure and
varied colours of the wings. The eyes often resemble the most

FIG. 378. — MYRMELEO.

HEMEROBIIDjE. — SIALIDJE. 153

highly-polished gold ; and the wings frequently reflect the
prismatic colours ; so that, although of small size, these insects
are very conspicuous. They are for the most part inhabitants
of temperate climates; and many species abound in Britain.
They usually fly during the twilight, remaining inactive during
the day ; and they emit a very disagreeable odour when handled.
The females deposit their eggs upon plants, attaching them at
the extremity of a long slender footstalk, the base of which is
fastened to the leaf ; this footstalk is composed of a white viscid
matter, discharged by the female at the time of laying her egg,
and speedily hardening by exposure to the air. The eggs, thus
curiously fixed in small clusters, have the appearance of minute
fungi. The larvae are extremely voracious, and especially attack
the Aphides ; unlike the Ant-lions, however, these Aphis-lions
(as they have been termed) do not remain concealed in one spot,
but wander in search of their prey where it is to be found in
the greatest abundance. So ravenous are they, that they do
not require more than half a minute to suck the juices from one
of the largest Aphides ; and they not unfrequently attack each
other, the conqueror in like manner sucking the body of the
vanquished. During the summer they arrive at their full growth
in about fifteen days ; they then spin a silken cocoon, in which
they enter as inactive pupae during the winter ; and come forth
in the succeeding summer.

678. The remaining families of this Order may be very
briefly noticed. The SIALID^: are a small group of moderate or
large-sized Neuroptera, having very large anterior wings. They
are nevertheless slow and inactive in their habits, and frequent
the neighbourhood of water, in which they pass their larva
state. The ordinary species Sialis lutaria, or May-fly, is a
well-known bait with the angler, being produced during the
spring months in large quantities ; it is of a dull brown colour,
and may be found on the walls or palings near the water. The
larva is furnished with appendages for aquatic respiration,
strongly resembling those of the Ephemera ; but when arrived
at its full growth, it quits the water and burrows into the
adjoining bank, in which it excavates a sort of cell. Here it

154 PANORPID^J. RAPHIDIID^E. MAKTISPIDjE.

is transformed into a pupa, which remains inactive, with its
limbs laid along the breast, but which is lively when disturbed ;
and here, too, it undergoes its final change.

679. The PANORPID^E are known under the name of Scor-
pion-flies, on account of the remarkable conformation of the

posterior extremity of the abdomen in
the male. The sixth and seventh seg-
ments are very slender and somewhat
curved upwards, so as to constitute a
sort of tail ; whilst the eighth is greatly
thickened, forming an oval mass, armed
with a pair of forceps, and capable of
FIG. 379.-P*ANORPA COM- free motion in any direction. The species
MUNIS. represented in Fig. 379 is a very common

British insect, frequenting hedges and

woods. The Scorpion-flies are very active, and prey upon
other insects in the perfect state. The abdomen of the female is
also prolonged into an ovipositor ; by which she can deposit her
eggs in deep holes or crevices.

680. The RAPHIDIIDJE are commonly known as Snake-flies,
from the elongated form of the head and neck, and the facility
with which they move the front of the body in different direc-
tions. They are of comparatively small size, agile in their
movements, and possessing powerful jaws ; they are chiefly
found in the neighbourhood of woods and streams ; and they
prey upon other insects inhabiting the same situations. Finally,
the MANTISPID^E seem to connect this order with the preceding ;
having the mouth formed upon the plan of that of the Neurop-
tera ; but having the fore-legs converted into prehensile claws,
and the first segment of the thorax lengthened so as to elevate
them, almost exactly as in the Mantis.

681. We shall next mention the small intermediate group of
PHRYGANEID.E, or Caddice-flies, which are by some Entomolo-
gists regarded as constituting an aberrant family of the Neu-
roptera, whilst others raise them into the rank of a distinct
Order, TRICHOPTERA, — a name derived from the hairy covering

PHRYGANEID^E, OR CADDICE-FLIES.

155

with which their wings, as well as their bodies, are beset. In
this character, as also in the arrangement of the nerves of the
wings, they bear a strong resemblance to the Lepidoptera.

682. These Insects are chiefly remarkable on account of the
habits of the larvae, which are well known under the name of Cad-
dice-worms. These reside in cylindrical cases, open at each end,
to which they attach various matters, as bits of stick, weeds,
pebbles, or even small living shells, by the assistance of silken
threads, which they spin from the mouth. These cases they bear

about with them ; protruding
the three first segments, with
their legs, when they creep
forwards ; and withdrawing
these upon the slightest alarm.
They are never known to
quit these cases of their own
accord. Different species ap-
pear to prefer different mate-
rials for the construction of
their cases; but they have
A, Larva in the power of employing almost

its case ; B, grating ,- c, Imago. r * J »

any which rail in their way,

when there is a deficiency of those usually preferred. The
food of some of the larvae is vegetable ; but others prey upon
small aquatic larvae, such as those of the Neuroptera. — When
about to assume the pupa state, the larvae fix their cases to some
solid substances beneath the water, and close the two extremities
with a kind of grating, that admits of the passage of water
through the tube, which is necessary for respiration. A short
time before they are to assume their perfect form, they make
their way out, by means of the pair of hooked jaws, with which
they are then furnished, and swim about with great activity by
means of the two hind legs, crawling occasionally upon the four
first. In order to throw off their pupa-case, the larger species
crawl up plants out of the water ; but the smaller ones merely
come to the surface, and there undergo their transformation, —
using their old envelope as a boat, out of which they rise to

156 GENERAL CHARACTERS OP HYMENOPTERA.

expand their wings, much in the same manner as Gnats. The
perfect Caddice-flies run with great agility, but their flight is
awkward, — except in some of the smaller species, which assemble
in troops and fly over the surface of the water towards sunset.
They are nocturnal in their habits, and not unfrequently enter our
houses, being attracted by the light. They emit a disagreeable
smell when touched. These insects are very numerous in Bri-
tain ; no fewer than 1 90 species having been described.

ORDER IV.— HYMENOPTERA.

683. In the membranous character of their four wings, the
insects of this Order resemble the Neuroptera ; but they cannot
well be mistaken for them. The anterior wings are usually
much larger than the posterior; and the veins or nerves* are
much fewer in number than in the Neuroptera, and do not form a
close network by their ramifications, as in that Order. In some
of the minute species, the wings are almost, or even entirely,
destitute of nerves. Another character furnished by the wings
consists in the connection of the anterior and posterior wings on
each side, during flight, by means of a series of minute hooks
along the front edge of the latter, which catch the hinder mar-
gin of the other, so as to produce one continued surface on each
side.— The principal character of the Order, however, is derived
from the structure of the mouth ; for, although considered as
mandibulate insects, the Hymenoptera are much better fitted for
imbibing their nourishment by suction, than for obtaining it by
mastication (§ 614). The Hymenoptera are also peculiarly
distinguished by a prolongation of the last segment of the body
in the females, into an organ, — which is, in one division of the
Order, a sting., — and in the other, an ovipositor, or instrument for
the deposition of the eggs, usually possessing the power of boring
a hollow for their reception.

* These terms are used to mean the same things ; namely, the hard frame-
work on which the membrane of the wing is extended. They must not be under-
stood as indicating any analogy to the veins and nerves of higher animals.

INSTINCTS OP HYMENOPTERA. 157

684. The Hymenoptera are further remarkable for the great
development of their instinctive faculties, and of their locomotive
powers. It is in this order that we find the most remarkable
examples of contrivance, and of skilful adaptation of means to
ends ; but this adaptation results, it would appear, not from an
exercise of intelligence on the part of the animals themselves (as
in Man and the higher Vertebrata), but from their blindly fol-
lowing out a path laid down for them by the Almighty Designer
(ANIM. PHYSIOL. § 475). That the two classes of faculties just
mentioned should attain their highest development in the same
group (the Neuroptera may, perhaps, be included in this state-
ment), is a very remarkable and interesting fact. Considering
these powers as those which are peculiarly characteristic of the
animal kingdom, we may regard these groups of Insects as the
types or centres (§ 35) of that kingdom. As we descend the
scale, we find these powers gradually disappearing, whilst the
organs of vegetative life (which, as we have seen, are of compa-
ratively small size in Insects) gain the predominance, so that in
the Zoophytes we have an evident approach to the Vegetable
kingdom. On the other hand, as we ascend the Vertebrated
series, we find the Instincts gradually superseded by Intelligence,
which in Man becomes the sole director (at least in the well-
governed mind) of the actions, keeping the instincts in subordi-
nation ; and through his immortal soul we are connected with
that kingdom of pure Intelligence, in which we have reason to
believe that Mind exists unfettered by the imperfections of its
corporeal instruments, and of which we are encouraged to hope
that we shall ourselves be sharers, when "this corruptible shall
have put on incorruption." — The mutual adjustment of the
various instinctive actions of a large number of individuals, so
that they all work together towards a common end, like the
parts of a machine, is nowhere so remarkable as in the social
Insects, which are principally restricted to this order ; and the
Bees, Wasps, Ants, Ichneumons, Saw-flies, Gall-flies, and many
other groups contained in it, have consequently attracted the
attention of the observer of nature from a very early period.

685. The Insects of this Order undergo a complete meta-

158 METAMORPHOSIS OF HYMENOPTERA.

raorphosis ; the larvae being more imperfect than those of almost
any other tribe ; and the pupse being quite inactive. In the
greater proportion of the order they are destitute of feet, and
resemble little worms. Their support is provided for, either by
the deposition of the eggs in situations where the future grub
will be furnished with an ample supply of food — the parent
being directed to these by an unerring instinct, — or by the active
exertions of the parents, which convey to the young the food
which they have themselves collected ; or by similar exertions
on the part of a race destitute of peculiar sex (hence termed
neuters), on whom this charge more especially devolves. When

FIG. 381.— LARVAE OF BEE, NATURAL FIG. 382 — PUPA OF BEE.

SIZE, AND MAGNIFIED.

arrived at their full growth, and after undergoing several pre-
vious changes of skin, the larvae are transformed into inactive
pupae ; in which all the limbs of the future insect are visible,
encased in distinct sheaths, and folded on the under surface of
the thorax. During this part of their existence they take no
food. In their perfect state, these insects, for the most part,
take but little nourishment ; and this consists almost exclusively
of the nectar of flowers. Many of them, however, — such as the
Wasps, — attack and destroy other insects ; but these are often
destined, not for their own support, but for the nourishment of
the young. — This Order is of considerable extent, being inferior
only to the Coleoptera ; and it has been estimated to contain
one-fourth part of the whole Insect population. It attains its
greatest development in warm climates ; for, of the numerous
species inhabiting this country, the greater part are of very small
size, and some are almost of even microscopic minuteness. None
of the species attain any great dimensions ; very few of them
exceeding, or even attaining, two inches in length, or three in

CLASSIFICATION OF HYMENOPTERA. 159

the expansion of their wings. The duration of their lives, from
the hatching of the egg to the final change, is believed never to
exceed a year.

686. This Order may be primarily divided into two groups,
according to the nature of the organ in which the body of the
female terminates ; — the end of the abdomen being prolonged, in
the TEREBRANTIA, into a saw or borer for the deposition of the
eggs ; — whilst, in the ACULEATA, it is formed into a sting or
piercer connected with a poison-reservoir. In the former group,
the number of joints in the antennae is extremely variable;
whilst in the latter, it is always twelve in the female, and thirteen
in the male. The Terebrantia may be again divided into the
PHYTIPHAGA, of which the larvae feed upon vegetable matter ;
and the ENTOMOPHAGA, in which they generally feed parasiti-
cally upon living insects. The Aculeata are in like manner
divided into the PR^EDONES, or predaceous tribes, which do not
collect pollen, and in which the larvae feed upon other insects
stored up for them, or upon fluids stored up by the neuters ;
and the MELLIFERA, in which the larvaa feed upon honey or
pollen-paste, collected and stored up for them. All these have
characteristic distinctions in their adult form ; on which it would
not be accordant with the character of this work to dwell
minutely. The division of the Order into sections may be better
understood from the following tabular arrangement of them : —

I" Larvae vegetdble-
Possessiiig ovipositor — TEREBRANTIA < feeders I. PHYTIPHAGA.

[ Larvae parasitic II. ENTOMOPHAGA.

* -.7 .• * fPredaceov£inJiabits.III. PR^DONES.

{ HanwcoUecton IV. MELLIFERA.

687. Section I. TEREBRANTIA PHYTIPHAGA. The principal
family of this section is that of TENTHREDINID^, or Saw-flies, so
named from the saw-like character and action of the ovipositor.
With this instrument they make a succession of small holes in the
branches or other parts of tre^s, into each of which they insert an
egg, closing the hole with a drop of frothy fluid. The tissue in
the neighbourhood of the wound swells up from its irritation; and
sometimes becomes a kind of gall^ either woody or pulpy, accord-

'

160

TENTHREDINIOE OR SAW-FLIES ; TURNIP-FLIES.

'IG. 383 — A, extremity of the abdomen of theSawfly,
showing the two saws, c, and their supporters, d, ex-
tended ; a, the terminal joint of the abdomen ; and
b, the two internal horny sheaths. B, a small por-
tion of one of the saws very highly magnified.

ing to the parts injured, which forms the abode of the larva in
some cases, during its whole life as such, and up to its final

metamorphosis; but in
general the larvae come
forth at an earlier
period, and feed upon
the exterior of the
leaves. They greatly
resemble the Cater-
pillars of Lepidopter-
ous insects; but usually
y differ from them as to

the number of their
feet, which are either
restricted to six, an-
swering to those of
the perfect insect, or

amount to eighteen or twenty-two. In order to undergo their
change into the pupa state, they spin a cocoon, either on the
earth or on the plants on which they have fed ; but they do not
become pupas, until they have been inclosed in this for many
months, and only a few days before they come forth as perfect
Saw-flies. To this group belongs the Athalia centifolice, or
Turnip-fly, which occasionally appears in this country in such
vast numbers as to produce the greatest devastation. The larva
is twenty-two-footed, and of a greenish-black colour ; whence it
is commonly known by the appellation of the nigger^ or Hack
caterpillar of the Turnip, — to which plant it is chiefly detrimen-
tal, by devouring the leaves, and thus totally destroying the
crop in an incredibly short space of time. It was especially
abundant in the south-eastern counties of England, in the years
1835, 1836, and 1837. The appearance of the black larvae is
preceded by that of the imago, a pretty yellow and black
insect, which is first seen hovering over the turnip-fields about
the middle of May or the beginning of June ; it deposits its eggs
in the soft tissue of the leaf, puncturing the cuticle by its ovipo-
sitor ; and these are hatched in five or six days. In a few days

TENTHREDINID^E, OR SAW-FLIES. — SIRICIDjE. 161

more, a whole field has been often devastated by the voracity of
the larvae, which devour the soft tissue of the leaves, leaving only
their skeletons and stalks. The most effectual remedy for these
attacks was found to be the introduction of Ducks into the fields,
by which the plants were cleared of the larvae more effectually
than they could be by any other means. Many other species
exist, however, almost equally injurious to different tribes of
plants. Thus the Gooseberry is subject to the attacks of a
Tenthredo, of which the larvae — often amounting to as many as
one thousand upon a single tree — devour its leaves at the begin-
ning of summer. The Apple, again, suffers from the deposition
of the eggs of another species in its fruit. And the "Willow is
subject to the attacks of many species, some of which devour its
leaves, whilst others cause the production of galls by perforating
its branches. The perfect Insects of this group are of moderate
size, not exceeding an inch in length ; some of them, however,
are among the largest Hymenoptera inhabiting this country.
Their flight is usually heavy, and is attended in the larger
species with a humming noise ; it seems, however, to be more
agile in the hot sunshine. They come forth for the most part in
the spring, having passed the winter in the pupa state ; and they
usually obtain their chief supply of food from the pollen or honey
of flowers, especially those of the Umbelliferous tribe ; some of
them, however, attack and devour living insects which frequent
the same plants. The ravages of these insects are restrained
by the destruction of vast multitudes of their larvae, through the
agency of the Entomophagous, or parasitic section of this group ;
thus the Lophyrus pini, a Saw-fly which infests the Pine, is
itself subject to the attacks of at least twenty parasites, of which
fifteen are Ichneumonidae.

688. The SIRICID^E bear a strong general resemblance to the
preceding group, both in structure and habits ; but they have a
stronger ovipositor, which enables them to pierce not merely the
soft substance of trees or young shoots, but hard timber.
The larvae produced from the eggs thus deposited, usually reside
in the interior of trees, which they perforate in various directions;
often causing great destruction of the Pine forests, of which the

162

SIRICIDJE. — CYNIPID^, OR GALL-FLIES.

largest species are inhabitants. When full grown, they form
a slender silken cocoon, mixed with chips of wood, at the

extremity of the
burrow ; and here
they undergo their
final transformation .
The perfect Insects
are among the largest
of the order; they
are remarkable for
the very cylindrical
form of their bodies,
and for the hum-
ming sound which
they make when on

FIG. 384.— SIREX GIGANTEUS. j.]ie wing

689. SECTION II. — In the section of ACULEATA ENTOMO-
PHAGA, the first family, that of CYNIPID^E, or Gall-flies, rather
corresponds with the preceding in its general habits, and in the
diet of the larvae. These insects puncture, with their ovipositor,
the surface of the leaves, buds, stalks, and young stems and roots,
of various plants and trees ; and they increase the aperture by
means of the toothed edge, forming a kind of saw, with which
the extremity of this organ is armed. In this aperture they
deposit, besides the egg, a drop of fluid, which seems to be
peculiarly irritating in its character ; causing the production of
tumours or galls., of various sizes, shapes, and colours ; the solid
interior of which becomes the food of the larva when hatched.
It is a remarkable circumstance, that the very same tree should
produce, on its different parts, galls of very different forms and
of various degrees of consistency, according to the species of
Cynips by which it has been punctured. The hardest is the
common Gall-nut, which is employed in the manufacture of ink,
and also, to a far greater extent, in the process of dyeing black
(VEGET. PHYSIOL. § 399). This is produced in the Levant,
upon a low-growing species of Oak, the Quercus infectoria. It
has been recently ascertained, that the " apples of Sodom,"-

OAK-GALLS. ICHNEUMONID^. 163

which are found on the borders of the Dead Sea, and which
have been said " to appear outwardly tempting to the eye, but to
turn to ashes on the lips," — are nothing else than galls of a softer
consistence, produced from the same Oak by the attacks of
another species of Cynips. The " oak-apples," again, of our
own country, are large galls found upon the young shoots ; the
leaves sometimes produce, besides the larger galls, a multitude
of little spangled discs, of a reddish colour, which contain the
larvse of a small species of Cynips ; the parts of fructification are
sometimes attacked by a species, the galls of which hang on the
catkins like a bunch of currants ; and the root produces a large
woody gall, inhabited by a species of Cynips, of which 1100
individuals have been found in a single gall. The Oak is by no
means the only species of vegetable infected by these insects ;
but a larger number of Gall-flies appear to be restricted to it
than to any other plant. The Rose is subject to the attacks of
one species, which causes the flower-bud to be developed into a
gall in a very curious manner. — An insect, considered as belong-
ing to this family, deposits its eggs in the seeds of the most
forward wild figs of the Levant. The modern Greeks, following
a custom handed down to them by their forefathers, fasten seve-
ral of these fruits among the later figs ; and the insects escaping
from them, covered with pollen, make their way into the unfer-
tilised fruit, and thus contribute to its maturity (BOTANY, § 673).
This operation is termed caprification.

690. The family of ICHNETJMONID^E may be regarded as
peculiarly characteristic of the Entomophagous section. The
female Ichneumon deposits her eggs, by means of her sharp-
pointed ovipositor, only in the bodies of other insects, — chiefly
the caterpillars of Lepidoptera, or the larvse of the Phytiphagous
section of Hymenoptera. Some of them have a very long ovipo-
sitor, which is used to insert the eggs into the bodies of Cater-
pillars that live beneath the bark, or in the crevices of wood ;
whilst those in which this instrument is short, place their eggs
in or upon the bodies of caterpillars, to which they can obtain
easier access. They do not confine themselves to these situa-
tions, however ; but employ for the same purpose the eggs or

M2

164

ICHNETJMONIDJ?, OR ICHNEUMONS.

pupas, still preferring the larvae when they can meet with them.
The young Ichneumons, when hatched as footless grubs, — some-
times in considerable numbers in the body of one caterpillar, —
devour only the fatty parts, which are not absolutely essential
to life ; and the animal they infest may continue to exist for
some time, thus affording them a continued supply of nutriment ;
but when the Ichneumons are ready to undergo their last meta-
morphosis, they either pierce the skin and escape, or else they
kill their victim, and perform their changes within its body.
The perfect Ichneumons feed solely upon the juices of flowers,
and fly about with considerable agility in search of their nutri-
ment, or of proper situations for the deposition of their eggs.
It is in the genus Pimpla, that the ovipositor attains its greatest

development, its
length being in
some exotic spe-
cies as much as
three or four
inches ; when
not in use, it is
inclosed in two
long channelled
filaments, which
unite to receive
it like a sheath.
This family is
extremely nu-
merous. Proba-
bly more than

3000 species exist in Europe alone ; and the number peculiar to
other parts of the globe may fairly be reckoned as at least equal.
Scarcely any tribe of Insects is free from their attacks ; although,'
as already stated, the Lepidoptera are the chief sufferers. In
restraining the multiplication of many Insects, which commit
great injury against the Agriculturist, the Ichneumonidae render
essential service to Man ; and there is no mode in which they
can be said to do him any counteracting injury.

FlG. 385. — PlMPLA MANIFBSTATOR, DEPOSITING ITS EGGS.

CHALCIDIDjE. CHRYSIDID^. 165

691. The family CHALCIDID.E, or Chalcis tribe, is composed of
a great number of parasitic insects, distinguished by their
generally very minute size, (their length seldom exceeding a
line or two,) their brilliant metallic or variegated colours, and
their nearly veinless wings. Like the Ichneumonidae, they are
all parasitic upon other insects in their early states ; the majority
infesting the larvae and pupas ; but some, from their minute
size, being reared within the eggs of other insects. They are
especially destructive to Lepidoptera ; but they will also attack
the species of most of the other Orders. Not unfrequently they
deposit their eggs in various kinds of galls, formed by the agency
of the preceding families; and their progeny, when hatched,
attack and subsist on the larvae inclosed within : and there are
some species, whose larvae are parasitic upon those of other para-
sitic insects. — Lastly, the CHRYSIDIDJS, or Ruby-tailed Flies,
constitute a small group, distinguished by having the abdomen
attached to the thorax by a short peduncle or foot-stalk, and
composed of only from three to five segments, — the remainder
being formed into a tubular apparatus, capable of being drawn
together or extended like a telescope, and having a minute sting
or ovipositor at its extremity. These insects, although but of
small or moderate size, are amongst the most splendid of our
native species ; being adorned with brilliant metallic tints, —
usually blue and green on the head and thorax, and a fiery
copper-colour or ruby on the abdomen ; hence they have been
termed the humming-birds amongst insects. They may be
observed during the hottest sunshine, flying and running with
great vivacity over walls, palings, sand-banks, and occasionally
upon flowers (especially those of the Umbelliferae) and leaves.
Their economy has not been fully made out ; but there is reason
to believe that the females do not insert their eggs in the
bodies of other insects, but take an opportunity of depositing
them in the nests of the different Wild-Bees and other Hymen-
optera, during the period when the latter are provisioning their
nests for the support of their own progeny; which is thus
starved by the intruder, whose voracity is such as to require
the whole supply of food that had been prepared for the legiti-

166 PR^DONES. SAND AND WOOD-WASPS.

mate occupiers of the nest. In this habit, these insects closely
resemble the Cuckoo (§351). In many points of structure,
the Chrysididee bear a strong resemblance to the Aculeate
Hymenoptera; and they may be considered as intermediate
between the two great divisions of the Order.

692. Section III. ACULEATA PRJEDONES. The Hymenoptera
of the Aculeate division may be usually distinguished from the
Terebrantia, by the mode in which the abdomen is united to
the thorax. In the borers, it is in general closely jointed to
it, — a structure which is evidently necessary for providing the
ovipositor with the requisite strength ; whilst in the stinging
Hymenoptera it is usually connected by means of a peduncle
or foot-stalk, which is often (as in the Wasp) extremely
slender, and of which the first appearance is seen in the Chry-
sididse, as just now mentioned. — The Predaceous subdivision of
this group contains several families ; of which the most im-
portant only will be noticed in detail.

693. The CRABRONID^E, LABRIDJE, BEMBECIDJE, SPHEGIDJB,
SCIOLIDJE, and MUTILID^E, may all be considered under one
general description ; they form a group, which may be termed,
from their peculiar habits, that of Fossores, or Diggers ; and
they are commonly known as Sand and Wood- Wasps. They are
solitary in their mode of life, and consequently no neuters exist
among them. In general the females excavate cells in the
ground, or in posts, timbers, &c. ; in which they deposit —
together with their eggs — various larvae or perfect insects, and
(in some species) even spiders, which are destined for the sup-
port of their progeny when hatched. Occasionally the insects
composing this store are first stung to death ; but sometimes
they are only slightly stung, and are finally killed by the larvae
when they come forth from their eggs, — being in this manner
rendered powerless, whilst their bodies are prevented from
decomposing. The perfect insects are generally very active,
and fond of the nectar of flowers, especially those of the Umbelli-
ferous tribe. They delight in the hottest sunshine, flying and
running over sand banks exposed to the mid-day sun, and keep-
ing their wings in constant agitation; some of the tropical

FORMICID^, OR ANTS. 167

species are among the largest of the order, and their sting is very
severe. The Sand-burro wers excavate their nests, by means of
powerful brushes, with which their legs are furnished ; whilst
the Wood-burrowers use for this purpose their strong broad
mandibles, which are provided with tooth-like projections.

694. The next family, that of FORMICID.E, is composed of
the well-known and singularly interesting tribes of Ants (the
White Ants, improperly so called, belonging however to the
preceding order) ; which are distinguished from all the Hymen-
optera previously described, by their habit of residing under-
ground in numerous societies, and by the existence of neuters
among them, by which class the labours of the community are
chiefly performed. The males and females, which constitute
but a small proportion of each community, are alone furnished
with wings ; the former are the smallest. The neuters are
somewhat smaller than the males, and for the most part
resemble the females in conformation ; but the thorax is
smaller, not having to give attachment to wings. The nests
of Ants are differently constructed in the different species, but
all are very curiously and regularly arranged ; some account of
them will be given hereafter. The males and females leave the
nest, as soon as they have acquired their wings; and go
forth together into the air. The males soon die, without
entering their former abode. Of the females some return, and
deposit their eggs in the original nest ; whilst others go to a
distance, and become the foundresses of new colonies : they, too,
lose their wings at this period, sometimes stripping them off
with their own feet, in other instances being deprived of them
by the neuters. — These last not only construct the nest, but
most carefully tend the young grubs ; supplying them with
food, moving them on fine days to the outer surface of the
nest to give them heat, and carrying them back again at the
approach of night or bad weather, and defending them when
attacked by enemies. The winged Ants having all perished at
the commencement of the cold weather, the neuters only survive
the winter. Some of them are larger and rather differently
formed from the rest, and appear to be the soldiers of the com-

168

VESPID^, OR WASP TRIBE.

munity ;— -not only defending their own nests against attacks,
but actually making war upon the nests of other species of Ants
(as will be hereafter detailed), and keeping their captives in
slavery. Ants are well known to be extremely fond of saccha-
rine matters ; and they seem greatly to relish the fluid which
exudes from the bodies of Aphides and Coccidae (§ 719, 720).
Some species even collect Aphides into flocks, and keep them,
as it were, in pastures ; which they connect with their nests by
means of galleries, excavated along the stems and branches of
trees ; and they protect the eggs of these insects in their own
nests, especially in bad seasons.

695. The family of VESPID^E, or Wasps, is distinguished from
the other Hymenoptera, by the wings being folded when at rest,
throughout their entire length. In general these insects are
social ; the communities, however, being small. In such cases,
there are neuters^ or individuals of neither sex ; but these are
not destitute of wings. There are also some solitary Wasps
(whose habits resemble those of the Fossores, whilst their
general structure is more conformable to that of the Social
Wasps), among which no neuters exist. — The best-known of
the Social Wasps, such as the Common Wasp of this country,
construct their nests with bits of wood, bark, &c., which they
separate with their jaws and reduce
to a pulp ; and this pulp, when ex-
panded and dried, forms a paper-like
substance. With this are built layers
of hexagonal cells, one row being
joined to the under side of another.
The top row is attached in some
species, merely to the under side of
a branch, or to the roof of a slight
hollow, by which it may be in some
degree protected ; but in other
species, the whole comb is enveloped
in a covering, formed by several
layers of the same paper-like sub-
stance, with one or more apertures (Fig. 387 ; and AMIM,

WASPS' NESTS ; — MELLIPERA.

169

PHYSIOL. Fig. 267). Wasps feed in their perfect state
upon insects, meat, fruit, &c. ; and nourish their young with
the juices of those substances. A Brazilian species stores
up an abundant provision of honey. — The nests of the Solitary

Wasps are formed of
earth ; they are some-
times concealed in holes
of walls, in the earth, or
old wood; and some-
times they are fixed to
plants. The parents
store them with insects
or caterpillars, which

they have previously wounded with their stings. These nests
contain a succession of cells, in each of which a single egg is
deposited.

696. Section IV. The Hymenoptera belonging to the
Melliferous, or honey-collecting divisions of the Aculeata, are
known by the peculiar conformation of the hind-feet ; of which
the first joint is compressed and extended
into the form of a square plate, and pro-
vided on the inside with brush-like tufts ;
these organs are employed for the purpose
of collecting and carrying the pollen of
flowers, which is destined for the nourish-
ment of the young. — All the insects of this
tribe are commonly known by the name of
Bees ; but the tribe, like that of Wasps,

, . ft. . /, FIG. 388. — HIND LEG OK

contains two dmerent groups, — in one ot WORKING BEE.
which the species are all solitary, and there
are only two kinds of individuals — males and females — in each ;
whilst the others mostly live in societies of greater or less extent,
but are chiefly distinguished from the former by certain pecu-
liarities in the structure of the mouth.

697. Of the Solitary Bees, which constitute the family
ANDRJENIDJE, there are many curious varieties ; some of which
go under the names of Mason, Carpenter, and Upholsterer Bees,
from the materials on which they respectively work ; the first

170

SOLITARY BEES ; HUMBLE-BEES.

agglutinating bits of sand or gravel, by means of a viscid saliva,
and constructing with these a regular edifice ; the next excavating

FIG. 389 — XYLOCOPA, OR CARPENTER BEE; AND NEST.

wood by means of their powerful jaws ;— and the last construct-
ing their cells out of pieces of leaves, which they cut into the
requisite form with surprising dexterity. The purpose of these
operations is, in all instances, to form a series of cells ; in each
of which an egg is deposited, with a supply of pollen-paste for
the nutrition of the larva.

698. Of the Social Bees, or APID^E, there are two principal
groups ; the first consisting of the Humble- Bees or Wild- Bees ;
and the second of the Hive- Bees.

699. The Bombi, or Humble-Bees, of which there are many

species in this coun-
try, live in curious
habitations, which
are sometimes exca-
vated at a consider-
able depth in the
ground, and some-
times built upon
its surface, beneath
stones, &c. The so-
cieties consist, in
FIG. 390—BoMBus. some species, of about

fifty or sixty indivi-
duals ; in others of as many as 200 or 300. They contain three

HUMBLE-BEES; — HIVE-BEES. 171

kinds of individuals, — males, females, and neuters : of these
the females are the largest, and the neuters the smallest.
The females alone survive the winter ; and they employ the first
fine days in spring to commence their nests, which they very
quickly excavate, and supply with a mixture of honey and
pollen for the nourishment of the. first brood. This consists
exclusively of workers or neuters ; which, after having undergone
their transformations, assist in the labours of the nest, — both by
the construction of new cells, the collection of food, and the
rearing of the larvas. It is not until the autumn, that the males
and females are produced. The former proceed from eggs laid
by females, so much smaller than the rest, that they have been
mistaken for workers. At the commencement of winter, all but
the larger females die; these remain in a sort of chamber distinct
from the rest, rendered warm by a carpeting of moss and grass ;
but without, as it would appear, any supply of food.

700. It is in the Hive-Bees, that the arts of construction,
and the union of individuals in societies, are exhibited in the
most remarkable manner. These societies contain but a single
perfect female, commonly termed the Queen, — several hundred
males, which are known as Drones, — and about twenty thousand
Workers or Neuters. It is by the latter that all the labours of the
hive, — the construction of the combs, the collection of food, and the
nourishment of the larvae, — are performed. The accompanying
figures exhibit the relative sizes and aspects of these three kinds.
The wax of which the comb is constructed, is secreted by the

FIG. 391 — QUEEN BEE. FIG. 392 DRONK BEE. FIG. 393.— NEUTER BEE.

insects themselves, in little scales, which work out between the
segments of the abdomen. These are taken up and kneaded by
the jaws, and applied in the proper place. The cells are for the

172 HIVE-BEES. LEPIDOPTERA.

reception of the eggs, of honey and of the pollen of flowers
mixed with honey, into a paste known as bee-bread. This food
is not deposited in the cells with the eggs ; but is supplied to the
larvae by the workers, which tend them most assiduously. The
honey is stored up for the support of the adults through the
winter; a considerable proportion of the Neuters surviving, as
well as the Queen, when the supply of food is sufficient. The
Drones are killed at the end of the summer, by the stings of the
workers, being themselves unprovided with any means of defence.
The eggs are laid in the central part of each comb, which is the
warmest situation ; those which are to produce Drones have
cells constructed for them, which are
rather larger than the rest ; and those
from which Queens are to be reared,
termed royal cells, are much larger and
of different form. When so many
young Bees are produced, that the hive

FIG. 394.— ROYAL CELL. < o

is over-peopled, colonies are sent forth

with young queens in search of another habitation. Further
details on the economy of Bees have been elsewhere given
(ANIM. PHYSIOL. §§ 712 — 716) ; and others will be found in a
later part of this volume,

ORDER V.— LEPIDOPTERA.

701. This Order, characterised, as formerly stated, by the
downy covering of the wings, contains some of the most beauti-
ful forms of the whole class, as well as some of the largest.
The number of species it comprehends, is probably as great as
that of any other Order, except the Coleoptera ; and may pro-
bably rank as about one-fifth or one-sixth of the whole class.
All the insects of this Order are commonly ranked as Butterflies,
Moths, and Sphinges or Hawk-moths ; and whilst they are most
readily distinguished from all others, there is so much general
resemblance among themselves, that the difficulty of classifying

GENERAL CHARACTERS OF LEPIDOPTERA.

173

FIG. 395.— FEATHER-SCALES OK THE GOAT-MOTH.

them is often considerable. The possession of scales upon their

wings is not alto-
gether peculiar to
them, for they are
found upon the
wings and bodies
of other insects ;
but it is only in
these, that the wings
are covered with
such completelayers
of them. The scales

are generally of somewhat oval form, terminating at one end in
a kind of stalk, by which they are attached to the membrane of
the wing ; and on this they are arranged in rows, overlapping
each other like tiles on a roof. They may be easily rubbed off
with the finger, and the bare membrane is left, which is then
seen to correspond with that of the wings of other insects. The
number of scales covering the wings of the Silkworm Moth, has
been estimated at about 400,000 ; it is entirely to these that the
colours of the wings are due, which are frequently so gorgeous in
this Order. In a few species, the wings are partially, or even
almost entirely destitute of scales ; but the structure of the mouth,
and their alliance in general characters with other species, leave
no doubt that they belong to this Order. Of the peculiar adapta-
tion of the mouth of the Insects composing this Order, for swtion,
mention has been already made (§ 616) ; and they are there-
fore placed at the head of the Haustellate or Suctorial group, as
the Coleoptera are at the head of the Mandibulate insects. Of their
metamorphosis, also, an account has been given ; and it now
only remains to describe some of the peculiarities of the larvae
and pupae of this Order.

702. The first three segments of the body, in the Lepidopterous
larvae, have each a pair of simple, short, and jointed feet ; which
are the rudiments of those of the perfect insect. Behind these are
a variable number of temporary appendages, called pro-legs, which
are thick, short, fleshy tubercles, armed at their extremity with
a great number of minute hooks ; and furnished with powerful

174

MOTION OF CATERPILLARS.

muscles. There are usually five pairs of these — four of them

succeeding the true legs, and another proceeding from the last

segment of the body. Those possessing pro-legs on nearly every

, segment, crawl upon all the feet at once, after the manner of

1 the Myriapoda ; but those which have only a small number of

1 pro-legs adopt a different method. They seize fast hold of the

objects on which they are stationed, with the six true legs at

\ the fore part of the body, and then elevate the intermediate

segments into an
arch, until they
bring the pro-legs
behind close to the
others ; they then
disengage the true
feet, and retaining
hold with the pro-
legs, they thrust the
body to its full
length, and then re-

no. 396.-CATERriLLAR AND CHRYSALIS OF MAGPIE MOTH.

the

manoeuvre, which
they execute very quickly. They are called, from this circum-

FIG. 397.— 1. CATERPILLAR OF SWALLOW-TAILED MOTH (Curapteryx Sambucaria).
2. CATERPILLAR OF PRIVET HAWK-MOTH (Sphinx ligustri).

stance, Loopers or Geometers. Many of them resemble small

STRUCTURE AND HABITS OF CATERPILLARS.

175

pieces of stick in their forms and colours ; as well as in their
mode of occasionally standing fixed to twigs, by their hind legs
only, for a great length of time. Such an attitude requires a
great amount of muscular force ; and we find that the muscular
system of these Caterpillars is very complicated and highly
developed (Fig. 398). It
was stated by Lyonnet, who
devoted many years to the
study of the anatomy of the
larva of the Goat-moth, that
this contains 4041 distinct
muscles.

703. The greater number
of Caterpillars are vegetable-
feeders, most of them confin-
ing themselves to the leaves
of plants; and the correspond-
ence between the development
of the leaves and flowers of
plants on the one hand, with
that of the Caterpillars and
Butterflies which are respectively to feed upon them, cannot but
strike every one as a beautiful example of creative foresight. —

But there are some Caterpillars,
which are adapted to feed upon
such flowers, as come forth early
in the year ; and others attack
seeds, roots, and even the woody
portion of the stem. More-
over, there are a few which live
in this state upon animal matter,
such as wool, hides, leather, arid
fat. Many can digest a con-
siderable variety of alimentary materials; whilst there are others
that can only find support on some one kind, — the leaves of a
particular species of plant for example. The habits of Caterpil-
lars are extremely various. Some burrow into the substance of

FIG. 398. — DORSAL MUSCLES OF THE ANTERIOR
SEGMENTS OP THE CATERPILLAR OF Cossus.

FIG. 399— NKST OF TORTKIX.

176 CATERPILLAR AND IMAGO OF LEPIDOPTERA.

leaves, in which they excavate galleries; others envelope
themselves in the membrane of the leaf itself, which they roll
together and attach by threads, — as seen in Fig. 399, repre-
senting the nest of the larva of Tortrix viridissima (a small
nocturnal Butterfly), which is constructed upon the leaves of
the Oak. Many construct cases or sheaths, either fixed or port-
able, by agglutinating several substances together, — as is done
by the larva of the common Clothes'-Moth ; and there are some
that live in societies, dwelling together under a tent of silk,
which they spin in common, and which serves to defend them
from the inclemency of the weather.

704. The Imago, or perfect Insect, when it throws off its
last envelope and comes forth into the air, of which it is hence-
forth to be one of the gayest inhabitants, is not altogether
perfect, although capable of very soon becoming so. The wings
appear at first very slightly developed, and sometimes even
hang loosely at the sides ; and it is not until the animal
has injected their tracheee with air, — by taking several full
inspirations and then forcing it into these passages, — that they
become expanded so as to serve for flight. From that period
the body is supported by them, during by far the largest pro-
portion of their active state ; the legs being weak and used only

Fro. 400.— TORTOISE-SHELL
BUTTERFLY JUST EMERGED
FROM THE CHRYSALIS. F«». 401.-DAWAIS PLEXIPPA.

to rest upon, and one pair being sometimes undeveloped
(Fig. 401).

705. The Lepidopterous insects are divided into three

DIURNAL LEPIDOPTERA, OR BUTTERFLIES.

177

•-

sections ; which differ alike in their conformation and habits. These
are, — I. The DIURNA, Diurnal Lepidoptera, or Butterflies, which
may be at once distinguished by the vertical position of the wings
during repose; — II. The CREPUSCULARIA, or Twilight Lepi-
doptera, commonly known as Hawk-Moths, in which the wings
are horizontal in repose, and the antennas thick and club-shaped ;
— and III. The NOCTURNA, Nocturnal Lepidoptera, or Moths,
whose wings are also horizontal or inclined in repose, but
whose antennae are more slender, tapering gradually from the
base to the point.

706. Section I. DIURNA. — The first section corresponds
with the Linnaean genus Papilio ; which is now, however, very

much subdivided.
The Butterflies are
distinguished from
the other Lepi-
doptera by the
brilliancy of their
colouring, and by
the beauty of the
under as well as
the upper side of
the wings. Their
Caterpillars have usually sixteen feet ; and their Pupae are
nearly always destitute of any silken envelope, and are attached by
the tail. The Pupa of nearly every Butterfly of this group is
ornamented with golden spots ; from which circumstance the name
Chrysalis is derived : this term ought, therefore, to be limited to
the Pupa of the Butterflies ; but it is now in such general use,
as applied to all Pupae, that it is undesirable so to restrict it,
and the term Aurelia (which means in Latin what Chrysalis
does in Greek) is now employed by Entomologists to designate
these Pupae. The antennae of Butterflies are sometimes
knobbed at their extremities, sometimes of the same thickness
throughout, and sometimes taper gradually from base to point.
To the genus Vanessa, which is distinguished by the abrupt
termination of the antennae in a short knob, belong several of

FIG. 402. — ARGYNNIS PAPHIA.

178 BUTTERFLIES. CREPUSCULARIA, OR HAWK-MOTHS.

the most beautiful of the British Butterflies ; — such as the Pea-
cock (Fig. 403), the Painted Lady, the Camberwell Beauty, the
Red Admiral, the Tortoise-shell, and others. The subdivisions

FIG. 403.— PEACOCK BUTTERFLY.

of this Section bear so strong a resemblance to each other in
structure and habits, that it is not requisite to describe them
more minutely.

707. Section II. — The CREPUSCULARIA, or Hawk-Moths,
correspond with the Linnaean genus Sphinx; which derives its name

FIG. 404.— SPHINX OF THB VINE.

from the peculiar attitudes, resembling that of the sculptured
Sphinx of antiquity, into which the larva sometimes throws
itself (Fig. 397, 2)« Although the Lepidoptera arranged under

CREPUSCtfLARIA; SPHINGES, OR HAWK-MOTHS. 179

this division on account of their correspondence in structure, are
mostly twilight-fliers, this is not the case with all ; for there
are some which come abroad in open daylight, and suck the
juices of flowers with their long trunks, whilst the sun is
brightly illumining their wings. These species are observed
to be more brilliantly coloured than the rest; the body and
wings in most of the Sphinges having a dull, brownish- grey
aspect, like that of many Owls, whose habits are similar. The
wings are more downy in appearance than those of Butterflies,
as if the scales did not lie so closely upon one another. The
larvae of the Hawk-Moths have always sixteen feet ; and their
pupaa are either inclosed in a cocoon, or bury themselves in
the earth. The perfect insects make a loud humming noise in
their flight. — One of the most remarkable of this group is the
Acherontia atropos, Death's-Head-Moth (Fig. 312), which is
distinguished by the skull-like patch on the back of the thorax,
as well as by the squeaking sound which it emits. In conse-
quence of the peculiar aspect of the body, the sudden appearance
of this insect in large numbers has been commonly regarded as
ominous of evil. It is a great enemy to Bees, and enters their
hives, devouring their honey, and alarming the inhabitants so
much, that they keep aloof from it instead of attacking it,
although it has no means of defence. — The Sphinx stellatarum,
or Humrning-bird Hawk-Moth, commonly known under the
name of " Bee-bird," is one of the most beautiful of the diurnal
species ; and is remarkable for the loudness of the sound which
it produces, when feeding self-poised upon its wings, by means
of its long proboscis, which it inserts into the cups of even the
narrowest tubular flowers. It might thus be almost regarded
as the representative, in our own climes, of those feathered
beauties after which it is named, that delight the eyes of the*
observer of Nature in tropical regions.

708. Section III. The group of NOCTTJRNA, or Moths, is
by far the most extensive of the order, and includes the largest
species. In their general aspect, Sphinges and Moths are some-
what alike ; but they may be at once distinguished by the form
of the antennae, which taper in the latter from base to point.

180 NOCTURNA, OR MOTHS. HEPIALID^E ; BOMBYCID^E.

Many of them have no distinct trunk ; and in some species the
females are almost, or altogether, without wings. Sometimes
the wings can be rolled round the body ; and in a few instances
they fold longitudinally, like a fan. The greater part of these
Lepidoptera fly by night, and their colours are usually dull.
Their Caterpillars vary as to the number of their legs, from ten
to sixteen ; their pupae are of rounded form, and almost always
spin a cocoon. The large number of species belonging to this
section, and the general similarity of their form, make their
classification a matter of some difficulty. They have been
divided into ten families ; of which it will be sufficient here to
notice the most important.

709. The first family, that of HEPIALID.E, contains two
interesting genera, Hepialus and Cossus. The Moths of the
former are commonly termed Swifts, from the rapidity of their
flight, which takes place during the twilight ; the sexes vary
considerably in appearance and structure, — the male of one
species, which frequents the Hop, being pure white, whilst the
female is yellow, with darker markings. The male is commonly
known as the Ghost-Moth, from his colour, and from his habit
of hovering with a pendulum-like motion, over one spot (often
in churchyards), where the female is concealed. The genus
Cossus contains the Goat-Moth, one of the largest of British
Lepidoptera ; which has received its common name from the
goat-like character of the strong scent emitted by the larva.
This larva feeds upon the wood of willow-trees, which it per-
forates in every direction, and thus so greatly weakens the trees,
that they are often blown down with the first strong wind. It
was this larva, which was so laboriously dissected by Lyonnet
(§ 702) ; and his researches were continued upon the pupa and
imago, so as to constitute the most elaborate and complete
account of the anatomy of any Insect, that has been yet given to
the world.

710. The family of BOMBYCID^ consists of Moths allied to
that of the common Silk-worm. The pupae are inclosed in
cocoons of pure silk, frequently of very firm texture ; and they
are rarely subterranean. The prevailing hues of these Moths

BOMBYCIDJE, OR SILK-WORM TRIBE.

181

are grey or fawn colour ; and many of the larger species have
the wings ornamented with eye-like spots (Fig. 405). This

FJO. 405 — EMPEROR MOTH.

tribe contains the largest species of Lepidoptera. The Saturnia
pavonia major, found in France, has been seen to attain the
breadth of five inches across the wings ; and the Saturnia pavonia
minor, or Emperor Moth of this country (Fig. 405), attains the
breadth of 3J inches. Many of this genus are remarkable for the

FIG. 406. — SATURNIA PROMKTHKA.

contrivances they adopt for security in the Chrysalis state ; and
among the most so is the Saturnia promethea (Fig. 406), an

182

MOTHS. — BOMBYCID.E.

FIG. 407.— CATERPILLAR, LEAF-COCOON, AND CHRYSALIS
OP THE PROMETHEUS MOTH.

American species, which, previously to spinning, draws together

the sides of a leaf (within which it afterwards forms its cocoon),

and fastens its stalk
to the stem by a
strong silken web
(Fig. 407). The
genus Bombyx is
one of great in-
terest and import-
ance, as containing
the Bombyx mori,
whose larva fur-
nishes all our silk ;
as well as many
other species. Of
these, some much
resemble a bundle
of dead leaves, both

in colour and form, when their wings are closed ; such is the

Bombyx quercifolia, or Oak-leaf Moth (Fig. 408). The Cater-
pillars of another species of Bombyx

are remarkable for their curious

habits. They live in societies on the

leaves of the oak ; and spin, when

young, a kind of silken tent, divided

within into cells. They may be seen

to issue from it in the evening in a

procession, — one of them, which

seems to act as a guide, advancing

at the head, — two then following, —

then three, — then four, — and so on,

each rank containing one more than

the preceding one. Hence they have

been called processionary caterpillars.

Each spins a separate cocoon; but

they are united in regular apposition,

being laid side by side against each other.

711. The family NOCTUID^E contains a great proportion of

FIG. 408. — BOMBYX QUERCIFOLIA.

MOTHS. GEOMETRID^E ; TORTRICID^l.

183

FIG. 409. — PHAL,*ENA GROSS ULARI ATA.

the larger sombre-coloured night-flying Lepidopterous insects ;

and contains 400 British species, which bear a very strong

resemblance to each other. — The family GEOMETRIDJE, so named

from the peculiar mode of progression of its Caterpillars (§ 702),

is nearly allied to the preceding ; but the Moths it includes are less

exclusively nocturnal, and are more brightly coloured. To this

family belongs the com-
mon Magpie Moth (Fig.
409), whose larva and
pupa have been already
represented (Fig. 396) ;
also the Swallow-tailed
Moth, and many other
well-known species. — The
TORTRICID^: constitute a

numerous group, composed of minute and usually dull-coloured

Moths, whose larvse are ex-
tremely destructive to vege-

tation. One of these, known

as the Codling Moth, is one

of the most destructive ene-
mies to the Apple crops of this

country ; laying its eggs in

the eyes of the newly-formed

fruit, within which the larva

feeds, its presence being only

indicated by the premature

falling off of the fruit. —

Another species does great

damage to our apricot trees

in the early spring, by tying

the young shoots together

with threads, so firmly that

their growth is stopped, and

by devouring the young

blossom-buds. Another species (Fig. 399) feeds upon the Oak,

which in certain years it totally strips of its foliage ;Jts numbers

FIG. 410 — PYRALIS VITIS.

4, Male ; 4 a, Female ; 4 6, Caterpillar ;

4 c, Eggs ; 4 d, 4 e, Pupae.

184 TORTRIX. CLOTHES'-MOTHS ; PLUMED MOTHS.

being so great, that when the branches of that tree are sharply
beaten, a complete shower of these moths is dislodged. And
another commits great havoc in our gardens, by eating the young
leaves and buds of the roses ; the caterpillar feeding within the
bud, from which, when disturbed, it lets itself down by a thread.
One of the most destructive insects of this family is the Tortrix
vitana (the Pyrale of French Entomologists) ; whose larvae com-
mit extensive ravages in the Vineyards of some parts of France,
where they occasionally appear in very large numbers, devouring
and tying together the leaves, and preventing the development
of the grapes, by surrounding them with the silken threads of
which they make their cocoons (Fig. 410).

712. The family TINEID^E contains those little Moths, com-
monly termed Clothes' -Moths, whose larvae are so injurious to
woollen stuffs of every kind, as well as to furs, skins, feathers,
and other objects of natural history, upon which their voracity
is exercised. They use the same materials also for the construc-
tion of their moveable cases or sheaths ; which they enlarge with
the increasing size of their bodies, both by adding to their
extremities, and by slitting them along and inserting a new
piece, so as to increase their diameter. In these tubes they
undergo their metamorphoses, after closing the orifice with
silk. — The larvae of the genus Galleria infest Bee-hives, feeding
upon honey, forming galleries in the honeycomb, and enveloping
the bees in their silken webs, sometimes to such an extent as to
destroy the community.

713. The FISSIPENN.E, or Plumed Moths (Fig. 304) consti-
tute a small group, distinguished from all other Lepidoptera by
the singular division of the wing into branches or rays, of which
each pair has from two to six ; these are most beautifully
fringed at their edges, and much resemble the feathers of Birds.
They are composed of the nerves alone, without any intervening
membrane ; this last seeming to have been transformed into
the fringe. The Plumed Moths are of small size ; some of them
are diurnal and brightly-coloured; others are twilight-fliers,
and of a duller aspect. Some species have the power of folding
up the wings like a fan ; so that, when closed, they present the
appearance of a single broad ray.

ORDER STREPSIPTERA.

185

714. This is probably the place in which the small Order
STREPSIPTERA should be introduced ; although the insects com-
posing it depart so widely from the general type, that it is
difficult to say to what orders they are most nearly allied. They
are few in number ; and are parasitic in their larva state upon
other insects, especially the solitary Bees belonging to the
family Andrsenidae. The name of the Order, which means
" twisted wings," has reference to certain curious appendages,
that look as if they had
been twisted, which are
seen in front of the
wings ; these appendages
are attached to the se-
cond segment of the
thorax, whilst the wings
(of which there is only
one pair) proceed from
the third; hence they
are to be regarded as the
altered rudiments of the
anterior pair of wings, in
the same manner as the
balancers of the Diptera
are to be considered as
the rudiments of the
posterior (§ 724). The
most remarkable feature

in the organisation of these insects, is the absence of any opening
at the mouth ; although it is furnished with appendages in some
degree resembling those of the Lepidoptera. The eyes are large
and prominent, being mounted on footstalks as in many Crus-
tacea. The antennas are of singular form, being usually furnished
with an internal branch or projection nearly as long as the
antennae itself. The wings are large, and folded in a fan-like
manner ; when in motion they make a buzzing sound, which is
considerable in proportion to the size of the animal. The third
segment of the thorax, to which they are attached, is developed

411. — A, Stylops Dalii, nat. size; B, magni-
fied ; c, Andrena, with the heads of two of its
larvae exserted between the abdominal rings, a ,•
D, larva extracted and magnified.

186 STREPSIPTER A . — HOMOPTER A ,

to an extraordinary size in proportion to the rest of the animal.
The larvae appear to feed upon the fatty matter in the bodies of the
Bees and Wasps, on which they are found, without injuring their
vital parts ; and their production does not seem to cause the death
of the animals they infest. When full grown, their heads may
be seen projecting between the segments of the abdomen of the
Bee (Fig. 411, a). Here, too, they undergo their metamorphosis
into the pupa state ; remaining still inclosed in the larva-skin,
and bursting through both the larva and pupa cases, to make
their way forth as perfect insects. No distinct mouth has been
discovered in the larva, and its mode of obtaining nourishment
is unknown. Many points in the economy of these singular
insects are still uncertain; especially all that concerns their
reproduction. All the specimens yet discovered appear to be
males ; and it has not been yet ascertained when and how the
eggs are laid, or at what stage in the growth of the animals
infested by them, the parasites first make their appearance.

ORDER YI.— HOMOPTERA.

715. THE Insects of this Order are distinguished from all
others which have, like them, the mouth adapted for suction, by
possessing two pairs of wings, usually composed of a firm mem-
brane, and not covered by scales ; and by having the anterior
pair, whatever may be their consistence, of the same substance
throughout, and roof-like when folded. They present many
curious anomalies both in structure and habit ; so that it is
difficult to assign any general character that shall include them
all. It is in the structure of the mouth that there is the greatest
agreement ; this is adapted for suction, the tongue being
elongated and channelled like a gutter, and being surrounded
by delicate lancet-like organs, with which the tissues of plants are
pierced. All the Insects of this group subsist on vegetable
juices; and some of them, from the amount of damage they
commit, are very injurious to the cultivator. Some of the
females are furnished with an ovipositor, provided with several

CICADID^E, OR CICADAS,

187

toothed saws ; and with this they make incisions into the leaves
and stems of plants. This Order may be divided into sections,
like the Coleoptera, according to the number of joints in the
tarsi. These sections are only three in number : in the first,
TRIMERA, the tarsi are three-jointed ; in the second, DIMERA,
they are but taro-jointed ; and in the third, MONOMERA, they
have but one joint.

716. Section I. TRIMERA. The three-jointed division of the
Homoptera includes three families, the CICADHXE, or Cicadas,
the CERCOPID^E, or Froth-hoppers, and the FULGORIDJS, or 'Lan-
tern-flies.— The CICADID^E are the largest of the Order; one

species measuring between six and
seven inches in the expanse of its
wings. They are nearly all inha-
bitants of tropical or the warmer
temperate regions ; only one small
species having been found in this
country. They have large transpa-
rent wings, but are not very active
in their habits; being generally found
upon trees or shrubs, whose juices
they suck. The female makes a
succession of slits in the small twigs
with her ovipositor, and deposits her
eggs in these; the young larvae
soon quit their birth-place, however,
and descend to the ground, where
they increase in size and become
pupae. It is a species of Cicada
inhabiting a kind of Ash, which, by puncturing it, causes it to
discharge the sweet, slightly purgative, substance, that is known
as Manna. — Of the peculiar sound-producing powers of the
Cicadidse, an account has been elsewhere given ( ANIM. PHYSIOL.
§ 679). The ancient Greeks used the Pupae and perfect insects
as articles of food.

717. The FULGORIDJ2 bear a general resemblance to the
Cicadidas, but are generally destitute of organs for producing

Fro. 412.— CICADA.

188

FTJLGORIDvE, OR LANTERN-FLIES.— CERCOPHLE.

FIG. 413. — FULGORA LANTKRNARIA.

sound, and have the legs more adapted for leaping. Many of
them are distinguished by a curious prolongation of the forehead,
which sometimes equals the rest of the body in size. The shape
of this projection varies extremely in the different species, which
are numerous in many tropical regions. It is in it, that the

luminous property of the
Lantern-fly (Fig. 413) is
said to exist; but the
luminosity of this in-
sect,— of which one spe-
cies is a native of Guiana,
and another of China, —
is doubted by many na-
turalists, the evidence in
regard to it not being sufficient. If it really exists, it is only at
particular seasons. The Lantern-fly of Guiana seems to be an
exception to the general rule, with respect to the absence of
sound -producing powers in this Order ; for it produces, from
sun-set to sun-rise, a loud sound which has been compared with
that of a razor-grinder at work.

718. The family CERCOPIDJE consists of insects of small size ;
many of which are remarkable for the grotesqueness of the forms
they assume. Several species are inhabitants of this country,
and are known under the name of Frog-hoppers, from their leap-
ing powers ; or of Froth-hoppers, from their peculiar frothy
secretion ; or of Cuckoo-spits, from the supposed origin of this fluid.

The most singular forms,
however, are confined to
the tropics ; and exam-
ples of them are present-
ed in the accompanying
figures of two Brazilian
species, whose curious

F.G.414.-a,Bocydiumglobulare;6,B.cruciatum. appen(lages result from

an extraordinary development of the first segment of the thorax.
The insects of this family are often beautifully varied in their
colours ; they are constantly found upon plants, upon the juices

FROTH-HOPPERS. — APHID^E, OR PLANT-LICE. 189

of which they subsist in all their stages ; and some of them are
employed by certain species of Ants, for the same purposes as the
Aphides (§§ 694 and 719). The Aphrophora spumaria is one of

the best known British
species; its larva and
pupa, resembling the
perfect insect in almost
every respect save the
absence of wings, are

FIG. 415. — APHROPHORA SPUMARIA ; a, imago; found beneath a frothy

exudation,— especially

upon willow-trees; and the exudation is sometimes so abun-
dant, from the large number of these animals, that persons
walking beneath are wetted by the continual dropping of the
fluid. A species nearly allied to this, inhabiting Madagascar,
discharges a clear instead of a frothy fluid ; and this in such
quantities, that it falls to the ground in the middle of the day,
when the heat is the greatest, in a continual shower.

719. Section II. DIMERA. This section entirely consists of
minute insects ; of which the most remarkable family is that of
APHID.E, or Plant- Lice. These live in great numbers upon the
surface of plants of almost every description, and suck the
juices, by means of their proboscis, from the young shoots,
leaves, stems, and even roots. They greatly weaken its vigour,
and often distort young shoots and leaves ; some species cause
little gall-like excrescences by the irritation they produce. From
two horn-like processes at the posterior part of their bodies, a
saccharine secretion exudes, of which Ants are very fond (§ 694);
and it is either this fluid dropped on the adjacent leaves, or the
extravasated sap flowing from the wounds made by the insects,
which is known under the name of honey- dew. In many of the
species of this family, a large proportion of the individuals never
acquire wings ; in which case the Pupa is not to be distinguished
from the Larva or Imago ; whilst at certain parts of the year,
other individuals of the same species, and of both sexes, acquire
wings. The wingless Aphides, which may be seen in the
spring and early summer, are all females capable of producing

190 APHIDES, OR PLANT-LICE. — COCCIDyE.

fertile eggs ; and from these are reared the winged males and
females, which are seen later in the season. Their rapidity of
production is enormous ; nine generations having been produced
within three months, and each generation averaging 100 indivi-
duals. Hence it may be calculated that, from a single Aphis,
10,000 million millions may be generated in that short period.
It is not surprising, then, that an immense amount of damage
should be done by them, notwithstanding their very small size.
Many of the blights so injurious to the gardener and the agricul-
turist, consist really of Aphides ; although from the minuteness
of the insects themselves, they frequently escape observation.
The Aphis Roscs^ or Rose Louse, is one of those best known to
the gardener ; whilst the one most destruc-
tive to the property of the cultivator on a
larger scale is the Aphis Humuli, or Hop
Fly. Of the extent of its influence on the
**' production of that vegetable, some idea
may be formed from the fact, that the duty paid to the English
government on its growth, has varied from 468,OOOJ, to 15,400/.
in different years, almost entirely from the absence of this insect
in the former case, and its presence in the latter ; and the differ-
ence in the actual value of the crop is, of course, far greater.

720. Section III. MONOMERA. The third section contains
but one family, that of COCCID.E, sometimes called Scale Insects.
These, although ordinarily of very small size, are amongst the
most injurious to vegetation of the whole tribe. Like the last,
they are remarkable for their powers of propagation ; and when
they once gain possession of a plant or young tree, its death is
almost certain, — the minute size of the larvae rendering it almost
impossible to exterminate them. They furnish, however, some
very important products. The bodies of many species are deeply
coloured through their whole substance, and yield dyes of great
value ; the richness of which seems to depend upon the nature
of the plant on which they feed. The Coccus of the ancients
was a native of the Levant; but that which furnishes the
Cochineal so highly valued at the present time, was originally
confined to Mexico, where it feeds on the plants of the Cactus

COCCID^E, OR SCALE INSECTS; COCHINEAL. 191

tribe ; it has been introduced, however, along with its proper
food, into Spain and Algiers, as well as into the hothouses of
this country. About 800,000 Ibs. weight of Cochineal are
annually brought to Europe ; each pound of which contains about
70,000 insects. The Lac of the East Indies, which is extensively
employed in the composition of varnishes, the making of sealing-
wax, &c., is the product of another species of Coccus. The
species which inhabit our own country, are important rather on
account of the damage they commit, than the benefit they afford
to Man. The bark of many of our trees often appears warty,
by reason of a great number of small oval or rounded bodies,
like a shield or scale, which are fixed to them, and in which no
external traces of the insect are to be observed. These, however,
are larvae belonging to the tribe in question. Some of them are
females ; others young males, which are similar to them in form.
At a subsequent period, they all undergo singular transforma-
tions. The males fix themselves to the plant, and pass into the
pupa state, in which they remain completely at rest ; and at
last emerge as winged insects, — coming out of their cocoons
backwards, with the wings extended flatly over their heads.
The females, on the other hand, remain attached to the plant,
and increase in size, in consequence of the development of a large
number of eggs in their interior ; but they undergo scarcely any
other change. The eggs are deposited between the lower side
of the body, and the surface to which it is attached ; the latter
having been previously covered with a sort of cottony secretion.
The parent then dies, and her body dries up and becomes a solid
cocoon, which covers the eggs. Here the eggs are hatched ; and
the young larvae, which are at first active in their habits, quit
their envelope, and ascend to the extremities of the branches ;
there they affix themselves by their sucking-beak, gradually
increase in size, and lose their activity. In this condition they
pass the whole winter ; and it is not until the succeeding spring,
that the characters of the sexes, which are henceforth to be so
distinct, begin to show themselves.

192

ORDER VII.— HETEROPTERA.

721. THESE Insects bear a close general resemblance to those
of the last Order ; but are distinguished by the characters of the
anterior pair of wings, which are tough at their bases and mem-
branous only towards their points, and which fold nearly hori-
zontally, partly overlapping each
other. The mouth is formed nearly
on the same plan as that of the
Homoptera; being adapted solely
for suction. By far the greater
number of the Insects of this Order
^ee<^' ^ke the preceding, upon the
juices of plants ; but some of them
prey upon other arid weaker Insects ;
FIG.417-PENTATOMA. ™& a few species (of which the

numbers, however, sometimes mul-
tiply to a great extent) suck the juices of larger animals. The
majority of this Order are found in tropical climates ; and the
species that inhabit those regions, are mostly ornamented with a
great variety of beautiful colours and markings, which often vie
with those of the most splendid of the Beetle tribes. Many
species, however, are of aquatic habits ; and these are all of an
obscure or black colour. Nearly all the terrestrial species have
the power of emitting, when they are suddenly alarmed or
touched, a powerful odour ; which is of a pleasing character in
some species, but which in others (as the common Bed-bug) is
very disgusting. Many of them seem to eject a poisonous fluid
into the wound which they make for the purpose of suction.
In some species, the wings are altogether undeveloped ; or the
upper pair is wanting. The insects of this Order continue active,
and require food, during all the stages of their existence. They
may be divided into two sections, distinguished by their resi-
dence, and by the modifications of their structure in accordance

CIMICID^J, OR BUG-TRIBE; — HYDROMETRID^J. 193

with it; — theGEOCORis,E,or Land-Bugs; — and the HYDROCORISJE,
or Water-Bugs.

722. Section I. GEOCORISJE. This section contains a large
number of families ; nearly all of which, however, bear a strong
general resemblance to that which includes the common Bugs, —
the CIMICID^E. Some of the tropical species attain considerable
size, being described as of the bulk of a Cockchafer ; and they
are much dreaded by the inhabitants of the regions they infest.
Many of the Geocorisse, however, are vegetable-feeders ; and
it is among these, that the most brilliant colours are exhibited.

FIG. 418.— HALYS. FIG. 419.— CIMEX LKCTULA'RIUS.

The common Cimex lectularius, or Bed-bug, and its allies,
never possess wings. — There is a curious group of very long-
legged insects, which, though placed in this section, leads to the
next ; this is the family HYDROMETRID JD, some species of which
may be met with on almost every pond or stream, skimming
along the surface, and turning rapidly about, with the greatest
ease and velocity. The form of the body strongly resembles
that of a London wherry ; the hind feet conjointly act as a
rudder ; and the motion is given by the two middle feet, which
do not, however, dip into the water, but merely brush along its
surface. The body is clothed on the under side with a fine
coating of hairs, forming a sort of plush ; which is evidently
serviceable in preventing it from coming in contact with the
water.

723. Section II. Of the HYDROCORISJS, or true Water-

194

HYDROCORIS.E, OR WATER-BUGS.

FIG. 420. >— NOTO-

NECTA.

Bugs, there are two families only. The NOTONECTID^E, or Boat-
flies, live almost entirely in the water, where they
feed upon other aquatic insects ; these they seize
by means of their fore-legs. The legs of the
hinder pair have a fringe of bristles along their
edge ; by which the surface, with which they
strike the water in swimming, is greatly increased.
Their general form is extremely well adapted for
rapid progression in water ; and it is from the
peculiar aspect and movement of the body, that
they have received the name of boat-flies or water-boatmen.
The insects of this family swim on their backs ; and the arrange-
ment of all their organs has reference to this position. When
stationary at the surface of the water, as is much their custom in
calm hot weather, they very quickly obtain intelligence of the
approach of danger, by means of their eyes, which are so placed
that they are able to see both above and below the surface ;
and then, by a single stroke of their paddles, which are commonly
stretched out at . full length, they descend out of sight. Their
motions are very quick in the element they are chi«Hy formed to
inhabit ; whilst on land they are scarcely able to walk. They
can fly well ; but they rarely exercise this power. The larva and
pupa only differ from the imago in their
smaller size, and in the deficiency of wings.
When they descend into the water, the
Notonectidse carry down a supply of air for
respiration, in a hollow which exists beneath
the wings, when these are folded together. —
The NEPID^E, or Water- Scorpions, receive
their name from the scorpion-like form of
their fore -legs, which are efficient instruments
for seizing their prey. They are in most
respects similar in structure and habits to
the insects of the preceding family ; but
their motions are much slower, their legs
not being so advantageously formed for
swimming. The species represented in the accompanying figure
is a verv common inhabitant nf Aiir nnnrls

FIG. 421. — NEPA

CINKREA.

195

ORDER VIIL— DIPTERA.

724. THE two-winged insects constitute one of the most
extensive Orders in the whole Class, not only in regard to the
number of distinct species, but also from the occasional excessive
multiplication of individuals of the same species. Many of them,
also, have been constant attendants upon Man in all ages. They
do not attract attention, however, from their size, for there are
few that exceed an inch in length ; nor is it on account of their
beauty, for the majority of them are of dull colours ; their forms,
too, are rarely elegant ; and of the habits and metamorphoses of
a large proportion of them, very little is known. They owe the
notice they have attracted, chiefly to the habits of certain species;
which affect Man and the Domestic Animals, in various ways,
both in their perfect and early states. However annoying these
may be, it must not be forgotten, that other Diptera are of
extreme service, in cleansing the surface of the earth of vege-
table and animal impurities; and the carcass that is full of
maggots would be much more prejudicial in its decomposition,
than it is when principally eaten up by these voracious creatures.
The mouth in the insects of this order is formed for suction, as
already described (§ 61 6) ; but there are considerable varieties
in the mode in which this is accomplished. Behind the wings
are found a pair of moveable slender bodies, termed halteres, or
balancers ; these are probably the representatives of the second
pair of wings. They are kept in continual motion, and are
usually present even when the true wings are not developed.
The Diptera all undergo a complete metamorphosis, as far as
respects the comparative structure of the Larva and the perfect
Insect ; the former being generally cylindrical footless grubs,
with no representatives of legs, except in a few species. But in
many there is no proper transformation into the Pupa state ; the
skin of the larva not being thrown off, but hardening and con-
tracting, so as to form a kind of cocoon. "Within this, the body of

o2

196

METAMORPHOSIS AND SUBDIVISION OF DIPTERA.

FIG. 422 — LARVA, PUPA, AND IMAGO OF STRATIOMYS
CHAMELEON.

the larva is found, at first apparently but little altered, except

that it has become de-
tached from the skin, to
the inside of which the
organs peculiar to the
larva, such as the parts
of the mouth, remain
adherent. Shortly after-
wards, the inclosed being
assumes the form of a
soft and gelatinous mass,
in which none of the
parts of the future insect
remain visible ; some
days afterwards, how-
ever, these organs become distinct, and the insect has then assumed
the real state of pupa, though without having yet thrown off its
larva skin. When ready to escape, it scales off the anterior end
of its case, like a cap. Many larvee, however, do throw off their
skins when assuming the perfect state, and some form a regular co-
coon. The duration of life in the perfect state is usually very short.
725. In subdividing this Order, we first separate from it a
small but remarkable group, which forms the transition to the
more aberrant orders of the class, especially the Aphaniptera.
Some of them are entirely destitute of wings ; and yet in their
general structure they correspond with the Diptera. They are
distinguished from all other insects by their curious mode of
reproduction. Not only are the eggs hatched within the body
of the parent, but the Larvae are retained there until they have
been transformed into Pupae, in which state they come forth to
the world. Hence this section has received the name of PUPI-
PARA. It contains two families, all the species of which are
parasitic. The HIPPOBOSCID^E, sometimes called Forest Flies^
are of small size, covered with bristles, and frequently destitute
of wings. They are known by the French under the name of
Spider-Flies. They reside upon quadrupeds and birds, running
with great agility, and often sideways, burying themselves

SUBDIVISIONS OF DIPTERA. — CULICID^E, OR GNATS. 197

amongst the hair or feathers. That which is parasitic on Sheep
is known as the Tick. One minute species infests the Hive- Bee;
and this is remarkable, not only for being destitute of wings, but
of eyes also. In the other family, that of NYCTERIBIID^E, the
general form still more nearly approaches that of Spiders. The
group contains but a small number of species, all of which are
parasitic upon Bats, and are termed Bat-Lice.

726. The remaining Diptera, constituting by far the larger
proportion of the class, may be subdivided into four sections.
In the first, NEMOCERA, the antennae are composed of six joints ;
whilst in all the remainder, the antennae are short, not having
more than three distinct joints. In the second, NOTACANTHA,
the last division of the antennas is really composed of two; the
proboscis does not project much from the mouth, and is furnished
with only two lancets. In the third, TANYSTOMA, the antennae
have really only three joints, the last being usually terminated
by a seta or bristle. And in the fourth, ATHERICERA, the
antennas are only two- or three-jointed, and the proboscis is
capable of being withdrawn into the mouth.

727. Section I. NEMOCERA. To this division belong the two
families of CULICHXE and TIPULID.E ; the former known as the

FIG. 423. — CULEX PIPIENS, female, natural size and magnified, with head of male.

Gnat tribe, the latter as the Harry Long-legs. Both are
remarkable for their beautifully-tufted antennae ; but the former
are distinguished by the length of the proboscis. Gnats are
well known to abound chiefly in damp situations ; the reason
being, that their larvae are inhabitants of the water. In this
state they are very active, swimming with great agility, and
often descending ; bu^ coming to the surface to breathe, which

I

198

CULICID.E, OR GNAT-TRIBE. TIPULID^I.

they do head downwards, the respiratory orifice being at the end
of a very prolonged spiracle arising from the end of the abdomen.
When the final transformation occurs, the skin of the pupa,
which is being cast off, serves as a kind of raft, which prevents
the perfect insect from being immersed in water, and thus wetting
its wings. The Mosquitoes, which infest many countries, espe-
cially in warm latitudes, or during the brief but hot summers of
some colder ones, differ but little from the common Gnats. They
sometimes appear in such swarms, especially in marshy districts,
that they can be only kept off by fire. Their rapid multiplica-
tion is easily understood, when it is known that their whole
series of metamorphoses only occupies three or four weeks in
summer, so that there may be several generations produced in
the course of one season ; and that each female lays several
hundred eggs. — The TIPULID^E also have feathered antennae, but
their proboscis is very short. Some of them very strongly

resemble Gnats, both in the
larva and perfect states ;
such are the Midges, of
which one species is repre-
sented in Fig. 424. In
another group, there is a
strong resemblance to the
Cynipidee, or Gall-flies ;
both in their minute size,
veinless wings, and mode
of life. Their larvaa are
terrestrial, and are very
commonly developed within a sort of gall, produced by the punc-
ture made by the parent in the tissues of plants, when depositing
its eggs. Some species make their puncture in the young sprigs,
others in the leaves, and others in the flowers ; and there are
several which are extremely injurious both to the Gardener and
the Agriculturist. Thus the Wheat crops of this country are often
seriously injured by the Cecidomyia Tritici ; the eggs of which
are deposited by the female in the centre of the corolla, where the
larvae are hatched ; and it is probably by devouring the pollen,
that they are most injurious to the plant. Another species,

FIG, 424. — CHIRONOMUS, with its Pupa and
Larva, magnified.

TIPULID^E. NOTACANTHA. TANYSTOMA. 199

C. destructor, is known in America under the name of the Hessian
Fly ; this attacks the lower part of the stem of the wheat. The

Fio.425— CECIDOMYIA DKSTRUCTOR, andC. TBITICI, with the Larvae
of the latter feeding in wheat flowers, magnified.

proper Tipulce, or Harry Long-legs, are the largest species of
the family. Their larvae generally live in the earth, in the rotten
parts of trees, &c., and many of them do great mischief by feed-
ing upon the roots of grass and corn.

728. Section II. NOTACANTHA. The second Section of the
Diptera contains three families, STRATIOMID^E, BERID.E, and
CCENOMYIDJE, which do not attract much attention, although
some of the species contained in them are very abundant. They
are mostly small but gaily-coloured insects ; and are most nume-
rous in moist situations, in which the larvae are generally pro-
duced. Some of the larvae, as that of Stratiomys Chamceleon
(Fig. 422), are completely aquatic; and respire, like the larvae
of the Gnats, by extending their tails to the surface, the spiracle
or breathing-pore being in that situation. They mostly feed
upon vegetable, rather than upon animal, juices.

729. Section III. TANYSTOMA. The insects composing the
third section have usually a more perfect mouth, than those of the
other divisions ; and they are also remarkable for the structure
of the head of the larvae, which possess two claw-like appen-
dages, by which they attach themselves to the substances that
afford them support. Many of the perfect insects are eminently
carnivorous or insectivorous ; as are also some of the larvae.
There is a genuine metamorphosis in this group ; the larva-skin
being cast off at the entrance of the animals into the pupa-state.
In this state they much resemble the perfect insect ; the limbs
being inclosed in distinct sheaths, and folded on the breast.

200 TABANID^J, OR GAD-FLIES. — BOMBYLIIDJE.

The perfect Insect escapes from the pupa-state by means of a
slit along the back. To this group belongs the family TABANID.E,

or Gad-fly tribe; which com-
prises some of the largest Di-
pterous insects, and which is
pre-eminently distinguished for
the tormenting powers which
different species possess. They
pierce the skins and suck the
blood of various Quadrupeds,

FIG. 426— TABANUS BOVINUS. .

both wild and domesticated ;

and do not spare Man himself. They chiefly abound in woods
and pastures ; and the buzzing noise which they make, has
obtained for them the designation of " the breeze." The insect
of which Bruce has spoken, in his Travels in Africa, under the
name of Zimb, is probably a species of this family. He describes
it as attacking cattle in so dreadful a manner, that, unless imme-
diately driven to the sands, they forsake their food, and run
wildly about the plains, dreading even its very sound, until they
die, worn out with fatigue, fright, and hunger. The Camel, and
even the thick-skinned Elephant and Rhinoceros, are said to be
subject to this enemy.

730. The family BOMBYLIID^E are distinguished by their
very long proboscis, with which they suck the nectar from
flowers. They fly with great
rapidity, and hover over
flowers without settling ;
making at the same time a
loud buzzing noise with their ^
wings. Some of them have
a remarkably Bee-like form.
The family ANTHRACID^E,
which is nearly related to
the preceding, is chiefly
composed of exotic species,
which are generally large or
of moderate size, often covered with hair, and beautifully coloured.
They fly in the sunshine with great agility ; and subsist, like

ATHERICERA ; — SYRPHID.E, OR WASP-FLIES. 201

the preceding, upon the juices of flowers. In general the pro-
boscis is comparatively short ; but in a few instances, as in the
Nemestrina longirostris, it is of extraordinary length (Fig. 321).
This section also contains several other families of less interest
and importance ; among them we may mention the ASILID./E,
which live by rapine, seizing Flies, Tipulae, Humble- Bees, and
even Wasps, and sucking their juices.

731. Section IV. ATHERICERA. The Dipterous insects of
the fourth tribe are principally vegetable-feeders in their perfect
state, only a few being carnivorous or insectivorous ; but their
larvse are generally extremely voracious, and will devour almost
any kind of soft animal matter. This section includes the Flies
strictly so called, the Bot-flies, and many other tribes. — The first
family, that of SYRPHID.E, bears an extremely close resemblance
to the Humble-Bees and Wasps, in the nests of which some
species among them deposit their eggs ; this resemblance is evi-
dent in the accompany-
ing figure, which repre-
sents the Eristalis, or
Drone-fly (A), and the
Anthophora retusa^ or
Spring Wild-Bee (B),
two insects which differ
entirely in their habits,

FIG 428,— DRONE-FLY AND SPRING WILO-BEE. J

— the former being the

very personification of luxurious idleness, doing nothing but sip
the nectar from the brightest flowers and bask in the sunshine
on the leaves, — whilst the latter toils all day long, either in the
construction of the nest, or in provisioning it with pollen paste.
The wisdom of the Creator has provided the insects of the former
group, as a check upon the too great increase of the latter ; for
the larvae of the Syrphidae, when hatched in the nests of the
Bees, destroy their larvae, and live at their expense. Some
species restrain, in a similar manner, the excessive multiplication
of the Aphides. The perfect insects feed almost solely upon
flowers, preferring those of the Composite ; and they delight to
hover immoveably over certain spots, to which they will return,

202 MUSCID^, OR FLY-TRIBE; — MAGGOTS.

if disturbed, a considerable number of times. Above a hundred
species inhabit Britain. In a few of them the larvse are aquatic,
and the posterior part of the body is prolonged into a respiratory
tube, whence they have received the name of " rat-tailed" larvas.
732. The form and habits of the family MUSCIDJE, or Fly
tribe, are generally known. The family is an extremely nume-
rous one, above 1700 species having been recorded as existing in
Europe, of which about half are natives of this country ; and
there are probably at least as many more, which have not been
described. The strong general resemblance which exists among
all the species, together with their small size, makes it difficult
to discriminate them readily. The larvae of these insects, com-
monly known as maggots^ are soft, worm-like, footless grubs,
possessing on the head a couple of retractile hooks, by which
they can cling to the substances on which they feed. They
devour various substances, both animal and vegetable, living,
recently dead, or far advanced in putrefaction. The eggs are
deposited by the female (as in other instances) in the neighbour-
hood, or in the very substance, of the food which is adapted for
the support of the larva, however little this may be to its own
liking. Some of these larvas are remarkable for their leaping
powers, — whence they are commonly termed " hoppers." This

is especially the case
with the larva of
the Piophila casea,
or Cheese-hopper ;
whose mode of
springing into the
air is very curious.

FIG. 429.-1. The CHEESE-HOPPER preparing to spring.- When preparing to
2. Natural size of the Larva.— 3, 4. The Fly to which leap, it first raises
it is transformed : natural size and magnified.

itselt on its tail ;

in which position it is enabled to balance itself, by means of
some prominent tubercles on the last segment of the body. It
then bends itself into a circle ; and having brought the head
towards the tail, it stretches out the two hooks of the mouth,
fixing them into two cavities at the other extremity of the body.

203

It then contracts the body from a circular to an oblong figure ;
the contraction extending in a manner to every part of the body.
It now suddenly lets go its hold, and straightens the body, with
such violence, that the noise produced by its hooks is very
perceptible. The height of the leap is often from twenty to
thirty times the length of the body ; exhibiting an energy of
motion, which is particularly remarkable in the soft Larva of an
Insect. A Viper, if endowed with similar powers, would throw
itself nearly a hundred feet from the ground. The learned
Swammerdam, who devoted much attention to the anatomy and
habits of this creature, observes — " Now let the sharpest geniuses,
and men of the greatest penetration and learning, judge if a
creature, on the fabric of which there plainly appears so much
art, order, contrivance, and wisdom, nay, in which is seen the
hand itself of the Omniscient God, could possibly be the pro-
duction of chance or rottenness." This observation refers to the
idea formerly entertained almost universally, that the Maggots,
which make their appearance in the midst of decomposing
matter, are the results or products of that decomposition. Ex-
periments devised for the purpose, however, have clearly shown,
that there is here no exception to the general rule ; for that, if
the parent Insects be carefully excluded, no maggots will make
their appearance in a decomposing mass of any description. —
Of the voracity of the larvas, and the rapidity with which they
undergo their transformations and propagate their kind, some
idea may be formed from the estimate of Linnaeus,— that three
Flesh-flies and their progeny would devour the carcass of a dead
Horse more speedily than a Lion would do. If this estimate is
at all exaggerated, it is probably not much so. Hence we see
the vast importance of these Insects in the economy of Nature ;
for they are called into existence just in proportion to the
demand for them, — the eggs of the parent not being developed,
unless they are deposited in a fit situation, so that the number
of individuals will not be increased unless there is matter for
them to feed on, — whilst, on the other hand, the rapidity of the
growth and metamorphoses of these Insects is greatly increased,
by the warmth that promotes the decomposition of the sub-
stances, which they are destined to remove.

204 CESTRID^E, OR BOT-FLIES.

733. The (ESTRID^E, or Bot-flies, are a family very remark-
able in regard to their structure and habits. The perfect insects
resemble large Meat-flies in form, are very hairy, and have these
hairs coloured in rings, like Humble Bees ; but they are seldom
seen, the duration of their lives being very short in this condition.
Their chief peculiarity consists in the
absence of any proper mouth in the
Imago (in which respect there is an
analogy with the Strepsiptera, § 714),
and in the peculiar habitation of the
Larva. This is always found in
living animals, — its situation, how-
FIG. 430.-(EsT«us AND LARVA. everj varymg with the species ; and
almost every herbivorous animal having one or more peculiar
to it. The egg is, in some cases, deposited by the parent in
situations where the larva may burrow into the flesh ; there
it occasions inflammatory tumors, the fluids contained in which
afford it nourishment. These have an evident analogy, there-
fore, to the Cynipidas, which produce Vegetable galls. In other
instances, the eggs or larvae, existing upon spots which the animal
is in the habit of licking, are conveyed by the tongue into the
mouth, whence they pass into the stomach. There they remain
until full-grown ; and then they quit the body (as do also those
which inhabit the flesh), and fall to the ground, beneath the sur-
face of which they undergo their transformations. The larvie
of one species, which inhabits the Sheep, are found in the frontal
sinuses of the skull. Man is subject to the attacks of one or
more species ; which do not, however, inhabit this country.

205

DIVISION II.— APTEROUS INSECTS.

734. BESIDES the foregoing Orders, we must include three
others in the Class of Insects, on account of their correspondence
with it in general structure ; although they present only one, or
even neither, of the two characters which have been stated to be
its peculiar distinctions, — namely, the presence of wings in the
perfect state, — and the metamorphosis.

ORDER IX.— APHANIPTERA.

735. OP the three Apterous orders, this one undoubtedly
approaches nearest to the true Insects ; for we find in it a
metamorphosis, and even rudiments of wings ; whilst the struc-
ture of the mouth most nearly approaches that of the Diptera.
The Fleas and their allies,
which constitute this order,
resemble the Diptera also in
their suctorial habits ; and
feed exclusively upon animal
juices. Their larvae come
forth from the egg in the state
of minute worms, possessing
considerable activity, and FlG. 43i._THE FLEA. (Puiex irritant.)
feeding upon animal matter,

in the midst of which the eggs were deposited by the parent.
They afterwards enclose themselves in a small cocoon of silk,
which is often covered with dust ; and in this they undergo their
change into the Pupa state. In the Imago, the rudiments of
wings are visible, in the form of little scales, attached to the
second and third segments of the body ; there is, however, no
proper distinction of thorax and abdomen. — The Common Flea

206

APHANIPTERA, OR FLEA-TRIBE. — -ANOPLTJRA, OR

is known to every one. There is a very curious species, of more
minute size, in the West Indies; which is commonly known
under the name of Chigoe or Jigger. This burrows beneath the
skin of the foot, and soon acquires the size of a pea, by the
enormous growth of the abdomen when distended with eggs.
If these eggs remain to be hatched beneath the skin, great irrita-
tion, and even very troublesome sores, are sure to result ; and it is
consequently necessary to extract the insect entire, with great
care, as soon as the indication of its presence is given by a slight
itching or tingling.

ORDER X.— ANOPLURA.

736. THE Insects of this Order, — the Louse and its allies, —
are regarded with the greatest disgust by the common consent of
civilized Man ; because their presence on the body is usually an
indication of a gross want of cleanliness of habit. Most of the
lower animals, however, are infested with one or more species ;
from the attacks of which they are not able to defend themselves ;
and Man is subject to a peculiar disease, which seems much to
favour their production. They undergo no metamorphosis ; and
their generations succeed
each other very rapidly.
They are destitute of the
true compound eyes ; but
have one or two minute
ocelli on each side of the
head. The legs are short,
and terminated by a strong
nail, or by two opposing
hooks ; whereby these ani-
mals can easily fasten
themselves to the hairs of

quadrupeds, or the feathers of birds ; of which animals they
suck the blood, and upon the bodies of which they pass their
lives; attaching their eggs, too, upon these cutaneous appendages.

FIG. 432 — a, THE COMMON LOUSE; b, magni-
fied ; c, one of the legs magnified ; d, eggs ;
e, ditto magnified.

LOUSE-TRIBE. THYSANOTJRA. LEPISMID^E.

207

The number of species is very considerable ; for it would appear
that almost every quadruped and bird has a kind almost peculiar
to itself, — the same Louse not being found upon different animals,
except upon such as have analogous characters and habits ;
whilst one animal frequently supports two or more species of
these parasites.

ORDER XI.— THYSANOURA.

737. IN the Insects of this Order, — which resembles the
preceding in neither having wings, nor undergoing metamor-
phosis,— there is a remarkable diversity of structure, especially
in regard to the mouth. Some of them possess as complex a
buccal apparatus as the Mandibulate Insects ; whilst in others
there is scarcely a perceptible opening. The same is the case
with regard to the eyes; these organs
being fully developed in some, and almost
rudimentary in others. — The Order
contains two families. In the first, the
LEPISMID^E, the abdomen is furnished
on each side with a row of moveable
appendages, like false legs ; and is termi-
nated by long pointed bristles, of which
three are usually most remarkable. —
The Machilis has long antennas, consist-
ing of a great number of joints ; its palpi
also are very large; and its eyes are
composed of numerous facets, and occupy
nearly the whole head. It frequents
stony places, and leaps well with the aid
of the appendages to the tail. The
Lepisma, — of which one species is known
under the name of the Sugar Louse, from
its aspect and habits, — has the eyes very
small, composed of few facets, and wide
apart ; its body is flat, and is terminated
by three threads of equal length, not fitted to assist in leaping.

FIG; 433.— MACHILIS.

208 THYSANOURA. — PODURID^.

— In the P.ODURIDJS, the appendages to the sides of the abdomen
are wanting ; but the extremity of it is prolonged into a forked
tail, by which these insects can execute very surprising leaps.

This, when not in action, is bent
forwards beneath the abdomen ;
an<^ it is by the sudden ex-
tension of it, that the leap is
produced. From this con-
f \ formation, the Poduras are

Fro. 434.-PODUHA. commonly known under the

name of Spring -tails. The

scales with which their bodies are covered, are objects of
great interest to the Microscopist ; for they have a most
elaborate and minute structure, which can only be made out by
instruments of the best quality ; hence they are very valuable
test objects.

CHAPTER IX.

OF THE CLASS OF ARACHNIDA.

738. This class is composed of Articulated animals, which
have a great analogy with Insects,

and which are equally fitted to live in
the air ; but which are distinguished
from them at the first glance, by
the general form of the body, and by
the number of limbs; and which
differ also from those animals, in
several important particulars of their
internal structure. All the Arach-
nida have the head united with the
thorax, and are destitute of antennas ;
they have four pairs of legs and no
wings ; most of them breathe by
means of air-sacs, instead of by pro-
longed tracheae ; and nearly all of
them have a complete circulating
apparatus.

739. The tegumentary skeleton of Arachnida is generally
less firm than that of Insects ; and their body is composed of two
principal parts, nearly always distinct : — one called the cephalo-
thorax, because it is formed by the head and the thorax united
into a single mass ; — the other termed the abdomen, and com-
posed sometimes of a series of distinct rings (such as we see in
the Scorpions — Fig. 447), and sometimes of a soft globular mass,
without any evident divisions (as is the case among the ordinary
Spiders— Fig. 442).

740. The organs of locomotion are all fixed to the cephalo-
thorax, and consist of eight legs, very similar to those of Insects,
and nearly always terminated by two hooks. In general their

FIG. 435 — MYGALE.

210

ORGANS OF SENSE IN ARACHNIDA.

length is considerable and they easily break ; but, as amongst the
Crustacea, the stump, after being healed, produces a new limb ;
which grows by degrees, and becomes similar to the one of which
the animal had been deprived. The Arachnida never present
any vestige of wings : and their abdomen is always entirely
destitute of locomotive appendages.

741. Upon the anterior portion of the cephalo-thorax, we
find the mouth and eyes. These last organs are always simple,
and of considerable number. We may generally
count eight, and in each of them may be distin-
guished a transparent cornea, behind which is found
a crystalline lens, and a vitreous humour ; then a
retina formed by the termination of an optic
nerve, and an envelope of colouring matter. —
Nothing is known regarding the instruments by which the
sense of hearing operates in the Arachnida; but there are
numerous proofs of the existence of such a faculty amongst
these animals ; and it would even appear that certain of them
are sensible to the charms of Music. — The sense of touch is
exercised principally at the extremities of the legs, and by the
appendages with which the mouth is furnished.

FIG. 436.

Fie 437.— SECTION OF THE CEPHALO-THORAX OF A MYGALE, showing the arrangement of the
nervous sytem : ct, cephalothorax ; m, mandible ; g, moveable hook which terminates
it • b mouth ; «, oesophagus ; e, stomach ; ab, origin of abdomen ; c, cephalic ganglion ;
t, ganglionic mass of the thorax ; ca, cords which unite it to the abdominal ganglia ;
no, optic nerve ; y, eyes.

742. The nervous system of the Arachnida presents very
great differences; sometimes (amongst the Scorpions for ex-

NERVOUS SYSTEM AND HABITS OF ARACHNIDA. 211

ample) it is composed of a series of eight ganglionic masses,
united together by double cords of communication, and forming a
chain extended from one end of the body to the other, in nearly a
uniform manner ; in other instances (as amongst the Spiders, &c.)
we find all the ganglia of the thorax united into a single mass
(£, Figs. 437 and 439), whence two cords proceed backwards,
which go to a single abdominal ganglion. In other respects,
the general arrangement of these parts is always the same.
The anterior ganglia, situated before or above the oesophagus,
and most commonly considered as representing the brain of these
animals, give origin to the optic nerve in front, and are con-
tinuous behind with the collar of nerves surrounding the oesopha-
gus ; the other ganglia are situated below the alimentary tube, and
send nerves to the limbs, to the appendages of the abdomen, &c.

743. The Arachnida are carnivorous, but in general confine
themselves to sucking the juices contained in the bodies of their
victims ; and in order to enable them more easily to effect the
capture of animals of whose strength they would be afraid,
Nature has endowed many of them with a poisonous apparatus.
The greater part are supported on Insects, which they seize whilst
alive ; some of them, however, live as parasites. Among the
first, the mouth is supplied with a pair of mandibles, furnished
with moveable hooks, or formed like a pair of pincers, — with a
pair of thin or lamellated maxillae, each bearing a large feeler
more or less resembling a leg, — and with a lower lip. Amongst
the parasitical Arachnida, the mouth has

the form of a small trunk, from which
there issues a kind of lancet formed by
the maxillae.

744. The moveable hook of the
mandibles has a small opening near its

extremity, which is the orifice of the .

excretory canal of the poison-gland al- labrum ; ma, maxm* ; P,

, , ., ,. P, , . , maxillary palpi ; m, man-

ready mentioned; and the liquid, Which dibles ; g, hook terminating

it pours into the bottom of the wounds the mandibles-
made with the mandibles, almost immediately causes the destruc-
tion of the animal attacked ; but it is too weak to injure Man.

p2

212

POISON- APPARATUS, AND DIGESTIVE SYSTEM.

745. Certain of the Arachnida are provided with another
poison apparatus, destined for the same use, and serving equally
as a weapon of defence : such is the hook by which the abdomen
of Scorpions is terminated (Fig. 44^j).^| This sting has beneath
its point several openings, which communicate with a poison-
gland ; and the sting of these Arachnida often proves mortal,
even to animals as large as Dogs. The large Scorpions of warm
countries are fatal even to Man, but the sting of the species
which inhabit Europe never appears to be mortal ; there usually
results from it a local inflammation more or less violent, accom-
panied by fever and depression, and sometimes by vomiting,
pains in the whole body, and trembling. To overcome these
attacks, physicians advise the use of ammonia (or spirit of harts-
horn), administered internally as well as externally ; and the
application of emollient substances to the wound.

746. The intestinal canal is generally very simple ; but has
sometimes csecal appendages, which penetrate even into the
interior of the limbs. In general, tubes analogous to the biliary

Fro. 439. — ANATOMY OF MYGALB : ct, cephalothorax opened below, and giving attach-
ment to the limbs, whose first joints are exhibited ; pa, legs of the 1st pair ; p, palpi ;
m, mandibles; ab, abdomen; t, thoracic nervous mass; a, abdominal ganglia; po,
respiratory sacs ; *, stigmata ; I, leaf-like folds in the interior of one of these laid
open ; ov, ovaria ; or, orifice of oviducts ; ma, muscles of the abdomen ; an, anus ;
/, spinnerets.

vessels of insects open into the intestine near the anus; but
amongst some of the Arachnida, such as the Scorpions, there
exists a liver composed of four glandular clusters. It is also in

RESPIRATION AND CIRCULATION 0? ARACHNIDA. 213

the neighbourhood of the anal opening, that we find the secret-
ing glands of the silky matter ; and also the spinnerets, by
whose aid several of the Arachnida weave for themselves webs,
which are often very extensive and of extreme delicacy.

747. The respiration of the Arachnida is aerial, like that of In-
sects, and is sometimes effected by means of tracheae ; but among
the greater part of these animals, and especially amongst the
Spiders and Scorpions, it is concentrated in certain vesicles lodged
in the abdomen, and called pulmonary sacs. These last organs
have in their interior a multitude of membranous plates, arranged
like the leaves of a book : and they thus bear a stronger resem-
blance to internal gills, than to true lungs. Each sac receives the
air by an opening situated on the lower side of the abdomen ; and
there are sometimes two, sometimes four, or even eight of these
stigmata. Certain Arachnida possess at the same time both pul-
monary sacs and tracheae; the Segestria are thus formed.
Others, such as the Pseudo- Scorpions and Mites, are provided
with tracheae only. These tubes have the

same structure as in Insects ; and the air ai
penetrates to them by two very small
stigmata, situated on the lower side of the
abdomen.

748. The blood is white among all the
animals of this class. The pulmonary
Arachnida are furnished with a complete
circulating apparatus. The heart, situated
on the back, has the form of a long vessel,
and gives origin to different arteries ; the
blood after having traversed the body is

returned to the pulmonary sacs, and arrives FIG--MO.-HEARTOF A SPIDER :

. a, border of the abdomen ;

at the heart after following a course Similar c, heart ; ar, large artery,

to that which it traverses in the Crustacea rio^extrfmit
(ANIM. PHYSIOL. § 292). Amongst the nary vessels.
Arachnida whose respiration is effected only by the aid of tracheaa,
the apparatus for circulation is but little developed ; there appears
to be only a simple dorsal vessel, without arteries or veins.

749. The Arachnida lay eggs like Insects ; and the male
differs in general from the female in the form of its maxillary

214

INSTINCTS OF ARACHNIDA.

palpi, whose use appears to be very important ; a great number
of these animals envelop their eggs in a cocoon of silk ; and
sometimes the mother remains with her young family to protect
it, and even carries the young ones on her back when they are
too weak to walk. All these animals undergo several changes
before they arrive at adult age ; and certain of them experience
a species of metamorphosis, for there are some, whose limbs
consist at first of only three pair, and which acquire a fourth at
a period more or less advanced.

750. The Arachnida are endowed with varied instincts, which
are sometimes not less remarkable than those of Insects; and we are
perhaps even to attribute to them higher faculties; for some animals
of this class are capable of undergoing a kind of education, and
give evidences of a certain degree of Intelligence. Several of them
use particular stratagems to carry off their prey ; and others
display singular industry in the construction of their habitations.
We have elsewhere had occasion to speak of the remarkable nest
of the Mygale ( ANIM. PHYSIOL. § 700) ; and the webs which our
garden Spiders spread with such admirable regularity, are
equally curious. The silk with which these animals thus con-
struct retreats for themselves, spread snares for their prey, and
form cocoons for their eggs, is secreted by an apparatus situated
in the posterior^ part of the abdomen. This apparatus consists

of several bundles of vessels, twisted
together, and terminating in minute
apertures, which are pierced at the
summit of four or six conical or
cylindrical projections, called spin-
nerets^ and situated at the end of
the tail. The gluey matter thrown
out through these pores, acquires
consistency by its contact with the
air, and consists of threads of an
extreme fineness, and a length not
less remarkable ; by the help of its
feet, the animal collects a number of

these threads into a single cord ; and each time that, in balancing
itself, the spinnerets touch the body upon which it rests, it there

FIG. 441.— NEST OF MYGAJLB.

INSTINCTS AND CLASSIFICATION OF ARACHNIDA. 215

fastens the end of one of these threads, of which the opposite ex-
tremity is still inclosed in the secreting apparatus, and of which it
can consequently increase the length at pleasure. The colour and
thickness of these threads vary greatly ; a Mexican Spider forms
a web composed of red, yellow, and black threads interwoven
with astonishing skill ; and it has been calculated that ten thou-
sand threads from the pores of a single spinneret of some of our
common Spiders do not equal in thickness one of our own hairs ;
whilst among other species inhabiting warmer climates, they form
such strong webs, that they are sufficient to stop small birds, and
even Man has to use some effort to break them. The manner
in which Spiders employ their skill in working, is subject to no
less variation ; some of them are satisfied with spreading their
threads irregularly ; others weave a web, whose meshes are of
extreme regularity. Sometimes we see them motionless in the
middle of their web, watching for their prey ; at other times
they conceal themselves in a retreat, which they construct very
near, and which has in some instances the form of a silky tube,
in others that of a small cup.

751. The ARACHNIDA are divided into two orders, according
to the structure of the organs of respiration and circulation.

I. The Pulmonary Arachnida; which are principally charac-
terised by the existence of pulmonary cavities, and by a vascular
apparatus ; but we may also recognise them by other peculiari-
ties of structure ; thus the number of their eyes is six, eight, or
even still greater, and we also find two, four, or eight stigmata
on the under part of the abdomen. The general form of these
animals varies ; some, as the Spiders, have a globular body, with
spinnerets at its extremity, and the palpi small ; — whilst in other
instances, as the Scorpions, the body is lengthened, and composed
of several rings, the palpi large, extended like arms, and armed
with pincers; and the abdomen is not terminated by spinne-
rets, but usually by the poisonous apparatus.

II. The Tracheary Arachnida; which have no pulmonary sacs,
but breathe by tracheae like Insects, and appear to have no com-
plete vascular apparatus for the circulation of the blood. Some of
them have no eyes ; and amongst those which possess these organs,

'216 ORDER PULMONARIA. — SPIDERS, ETC.

we never find more than two or four. Some of these animals,
known under the name of False- Scorpions, very much resemble
Spiders, and are remarkable for the length of their limbs ; others
have the mouth formed for sucking, and constitute the family of
AcaridcB, or Mites.

ORDER I.— PULMONARIA.

752. By the characters just now stated, this order may be
divided into two sections ; — the ARANEIDA, or Spiders, having
small foot-like palpi, not terminating in pincers ; and the
PEDIPALPI, or Scorpions and their allies, having very large palpi,
which terminate in pincers or large hooks.

753. Section I. ARANEIDA. The Arachnida of this group
all agree, more or less closely, with the common Spider, in their
form and structure. Their cephalothorax appears as if composed
of but a single segment, and is covered with a sort of horny
buckler, usually of oval form ; the abdomen is appended to it by
a very short footstalk, and usually consists of a soft and tumid
mass. The eyes are nearly always eight in number ; although
there are sometimes but six. The mandibles terminate in a very
sharp moveable hook, which is pierced near its extremity by a
small aperture, serving as a passage for the poison secreted by a
gland lodged in the preceding joint. The legs are inserted
almost in a circular manner around the cephalothorax (Fig. 439) ;
they are all of nearly the same form ; and each of them is com-
posed of seven joints, the last being armed with two hooks,
which are commonly toothed like a comb. The pulmonary sacs
in this order are only two in number, or may even be reduced to
a single one ; they are placed near the base of the abdomen, and
their position is indicated externally by a brownish or whitish
spot. All the members of this section are provided with spin-
nerets ; but it is only in a comparatively small number, that we
find the power of constructing silken webs of any great extent.
The ARANEIDA are divided by M. Walcknaer, who has made
this group his especial study, into families, according to the

CLASSIFICATION OF SPIDERS. HUNTING SPIDERS.

217

arrangement of the mandibles and eyes, which corresponds very
remarkably with their respective modes of life. These families,
and their principal subdivisions, are as follows : —

I. VENANTES, incessantly run-
ning or leaping about the
vicinity of their abode, to
chase and catch their prey.

II. VAGANTES,wanderingabroad, "|
and incessantly looking out 1
for prey. No fixed residence V
except at the period of ovi- j
position. J

III. ERRANTES, prowling about
the neighbourhood of their
nests, or near the threads
which they throw out to
catch their prey.

IV. SEDENTES, spinning large
webs to entrap their prey,
lying in wait in the middle
or at the side.

V. NATANTES, swimming in
water, and there spreading
their filaments to entrap
their prey.

LATEBRICOLJE, hiding in holes and fissures.
TUBICOL*:, inclosing themselves in silken tubes.
CELLULICOL.E, sheltering themselves in small

cells.

CURSORES, running swiftly to catch their prey.
SALTATORES, leaping and springing with agility

to seize their prey.

LATERIGRADJE, walking and running sideways or
backwards ; occasionally throwing out threads
to entrap their prey.

, going abroad, but making a web for
their nests, whence issue threads to entrap
their prey.

FILITELE, going abroad, but spreading long
threads of silk about the places where they
prowl, in order to entrap their prey.

TAPITEL^E, spinning great webs of a close texture,
and dwelling therein to catch their prey.

ORBITEL.SE, spreading abroad webs of a regular
and open texture, either circular or spiral, and
remaining in the middle or on one side to
catch their prey.

RETITEL.E, spinning webs of an open meshwork,
and of an irregular form, and remaining in the
middle or on one side to seize their prey.

AQDITEL.*:, spreading filaments in the water to
entrap their prey.

754. The first family, that of the VENANTES, or Hunting-
Spiders^ may be naturally divided into two groups; the first
being more sedentary, and the second more active. At the
head of the first group stands the tribe of LATEBRICOUE, which
consists of the genus Mygale (Fig. 435) and its allies ; these are
the largest of the whole family, some of them occupying, in a
state of repose, a circular space of six or seven inches in diameter.
They form their nests in the slits of trees, beneath the bark, in
the cavities of stones and rocks, or on the surface of the leaves
of various trees. Some of them burrow deeply into the ground,
choosing dry shelving situations exposed to the sun, and con-

218 MYGALE. — RUNNING SPIDERS.

structing subterranean cylindrical galleries, often two feet deep,
and so tortuous that it is difficult to follow them. These they
line with a silken tube, forming at its entrance a moveable lid,
composed of silk and earth, attached to the silken lining by a
sort of hinge ; and this is adapted, by its size, situation, and
weight, to close the opening so precisely, as scarcely to allow its
entrance to be distinguished from the neighbouring soil, — shutting
of itself when the Spider enters its retreat or passes out of it.
"When an attempt is made to open it from without, the Mygale
holds it down firmly with its hooked feet. The Mygale [spins
a sort of cocoon around its eggs, enclosing a hundred or more ;
they are hatched within it, and the young undergo their first
changes before quitting it. The various species of this group
are inhabitants of tropical and the warmer temperate climates ;
it is only in the former, that we find those of largest size. — The
TDBICOL^E and CELLULICOL^E are not sufficiently distinct from
the preceding, to require particular notice. They are mostly of
smaller size, and inhabit temperate climates, where they may be
considered as representing the Mining Spiders.

755. The tribes of CURSORES, or Runners -, and SALTATORES,
or Leapers, forming the second division of the Hunting-Spiders,
are distinguished by the activity with which they pursue their
prey. The former, which are sometimes called Wolf-Spiders,
have the legs adapted for running, and live mostly upon the
ground. Those of the genus Lycosus dwell in holes which they
have formed, lining their inside with silk, and increasing their
size as they grow. Some of them take up their abode in holes of
walls, where they make silken tubes ; the outside of which they
cover with earth or sand, and in which they moult or hybernate,
having first closed the entrance. The females also lay their
eggs in these tubes ; inclosing them in a silken cocoon, or egg-
case, which they carry about with them when they go out to
hunt. The young ones fasten themselves, as soon as they are
hatched, upon the body of their parent ; and there remain
attached, until they are sufficiently strong to seek their own
food. These Spiders are very voracious, and defend their habita-
tions and young with great courage. A species of this genus,

TARENTULA. — LEAPING SPIDERS. 219

the Tarentula, — so named from the city of Tarentum, in Italy,
in the neighbourhood of which it is common, — is very celebrated
on account of its reputed venomous powers. Like all the
Spiders, it has a poison-gland in its mandibles ; but the idea that
its wounds are followed by death, or by a complaint termed
Tarantism, which can only be cured by the aid of music and
dancing, has originated in the imagination only. — Some species
of the genus Dolomedes live upon the tops of trees, upon the
leaves of which they make a funnel-shaped silken nest ; whilst
others inhabit plants in the neighbourhood of water, on which
they find their prey, — running upon its surface with surprising
quickness, and even entering it without being wetted. — The
Spiders of the tribe of SALTATORES, or Leapers, have, as might
be anticipated from their name, the legs fitted rather for leaping
than for running. One of these is very common in summer upon
walls and windows exposed to the sun ; and its habits may be
watched with much interest. It moves in short leaps, and stops
suddenly at intervals, raising itself upon its legs, as if to survey
the neighbourhood. "When it discovers a fly, or especially a
gnat, it approaches it cautiously until within leaping distance ;
when it darts upon it, — not fearing to take even a perpendicular
leap, because it always at the same time suspends itself by a
thread, which it winds off as it advances. This thread also
serves to suspend it in the air, and enables it to mount up again
to the spot from which it leaped, or to sustain it whilst the wind
carries it from place to place. Many species of this group
construct, amongst leaves, under stones, &c., silken nests, in the
form of oval sacs, open at each end ; into which they retire in
order to take rest, to moult, and to take refuge against the
inclemency of the weather. If menaced with danger, they
quit these retreats, and run off very rapidly. Some species
construct, with the same material, a kind of tent, which serves
as the birthplace of their posterity, and in which the young
reside for some time with their parent.

756. The family VAGANTES, or Wandering Spiders, consists
of the single tribe LATERIGRADA ; the name of which (meaning
Side- Walkers) expresses the curious power which they possess,

220 WANDERING SPIDERS. — PROWLING SPIDERS.

of moving sideways. They conduct us towards the web-spin-
ning Spiders, in using their silken threads, not only for the
construction of habitations for themselves or of envelopes for
their eggs, but also for the purpose of entrapping prey. The
threads, however, are not arranged with any regularity, but are
laid singly. These Spiders generally remain at rest, with the
legs spread out, upon the leaves or stems of plants ; running,
however, with great rapidity, in pursuit of their prey, when it
comes within their reach. Others, however, live in rocky
places ; and have the feet so formed, that they can adhere even
to very smooth surfaces, in any position of their own bodies.
They usually construct very elaborate cocoons for the protection
of their eggs. Those which live among plants affix the cocoons
to the leaves, and draw together their edges so as to conceal
them. Those, on the other hand, which live upon rocks, usually
conceal the cocoon within their own dwelling-place ; which is
an oval conical tent, something like a Limpet in form, attached
at its base to the rock, but having an aperture at each end,
furnished with a kind of valve through which the animals go in
and out. The outer covering of this tent is composed of a sort
of yellowish taffety, thin (like the skin of an onion), but resist-
ing ; whilst the inner covering is soft and pliant.

757. The Spiders of the faniily ERRANTES, or Prowlers, are
divided into two groups, chiefly according to the situation in
which they throw out the silken lines for the entanglement of
their prey. The first tribe, that of NITIDEL^E, contains species
that only prolong these threads from their nests, which are
formed under stones in holes of walls, the hollows of leaves, and
similar situations. These species much resemble those of the
last tribe in their habits ; but differ in many points of structure.
—In the second tribe, the FILITEL^J, the threads are spread
about the places, in which these Spiders prowl in pursuit of their
prey. Among these, the Clotko, which inhabits Egypt and the
South of Europe, is remarkable for the curious habitation which
it constructs for its young. This is a kind of limpet-shaped
cocoon, about an inch in diameter, of which the circumference
has seven or eight festoons ; the points of these festoons being

PROWLING SPIDERS ; CLOTHO. SEDENTARY SPIDERS. 221

alone fixed to the stone by means of threads, whilst the edges
are left free. This singular tent is at first composed of only
two folds, between which the Spider takes its station. But
subsequently it adds additional folds ; and when the period of
reproduction arrives, it weaves another apartment, of a softer
texture, expressly for the reception of the sacs of eggs, and of
the young when hatched. The inside of its habitation is
singularly clean. The bags in which the eggs are placed, are
about one-third of an inch in diameter ; and there are from four
to six of them in each habitation. The eggs are not deposited
until the end of December or January ; and they are enveloped
in fine down, to guard them from the cold. The parent creeps
in and out beneath the edges of the festoons ; and supplies her
young with food, for some time after they are hatched. "When
they are able to dispense with maternal cares, they quit their
common habitation, and form separate abodes; and the parent
dies within her tent.

758. The last family, SEDENTES, or Sedentary Spider •*, contains
all those species with which we are most familiar, from the annoy-
ance they cause us by the construction of their webs in our
houses and gardens. — Of the first tribe, TAPITEL^E, — which con-
struct a sort of tapestried web of close texture, within which they
dwell and wait for their prey, — the common House-spider is a
characteristic example (Fig 442). — The Spiders of the second
tribe, ORBITEL^E, have the abdomen larger, softer, and more
coloured than the preceding ; they make their webs with regular
meshes ; arranged in concentric circles crossed by straight radii ;
and they usually remain stationary in the centre, in a reversed
position (Fig. 443). Many species, however, construct for
themselves a cavity or cell, which is sometimes horizontal and
sometimes perpendicular, near the edges of the net. Of this
group, the genus Epeira is the principal ; of which several
species abound in our gardens, especially during the autumn. The
eggs are deposited by the parent at the commencement of cold
weather, in angles of the ceilings of rooms, passages, &c., near
gardens ; they are enveloped in a loose white web ; and are
hatched in the spring of the following year. Some species of

222

HOUSE SPIDER; — GARDEN SPIDER.

Epeira inhabit the neighbourhood of running streams, and feed
upon aquatic insects. Another is remarkable as being nocturnal

FIG. 442.— TEGENARIA DOMESTICA, OR HOUSE-SPIDER.

in its habits. The natives of New Holland and the South Sea
Islands, when in want of other food, are said to devour a species

of Epeira. — The
RETITEJLE bear a
close resemblance to
the preceding, both
in the aspect of their
-n \ i i bodies, and in the
construction of their
webs ; but these are
not formed on a
regular plan, the

FIG. 443.-EPEIRA DIAUEMA. threads crossing in

all directions and
leaving irregular meshes. "When their prey is entangled in

SEDENTARY SPIDERS. — WATER SPIDERS.

223

FIG. 444. — MALMIGNATTE.

their web, they whirl threads around it, so as to secure it
effectually. They take great pains in the
preservation of their eggs, and do not leave
them until they are hatched. In one
common species which frequents our
dwellings, the female gums her eggs into
a rounded body, unprotected by a cocoon ;
and this she bears about in her jaws.
Other species live out of doors, and con-
struct their webs among trees. To this
group belongs the Malmignatte, an inhabit-
ant of Tuscany and Corsica; which is
reputed to be very venomous.

759. The last family of Araneidee, the NATANTES, or Water-
Spiders, closely resembles the preceding in structure ; and should
scarcely, perhaps, be separated from it. They live entirely

upon or beneath the
water ; and are ena-
bled, by the hairi-
ness of their bodies,
especially on their
under surface, to en-
tangle and carry
down with them a
supply of air for
their respiration. One very interesting species, the Argyroneta
aquatica, or Diving Spider, not only employs its silken threads
to entangle its prey, but forms with it an oval bag, of such
close texture that it is impervious to air or water; this is attached
by threads to aquatic plants, at a considerable depth below the
surface ; and its under side is open, like that of a Diving Bell ;
so that the Spider can freely pass in and out. Here it retreats
to devour its prey ; and here, too, it constructs its egg-case, and
even passes the winter. The mode in which it fills this with air,
when about to take up its residence in it, is very curious. The
hairs upon its body entangle so large a quantity of air, as to
render it quite buoyant ; in order to descend to its bell, there-
fore, it is obliged to creep along the stems of aquatic plants; and

445. — DIVING SPIDER.

224 DIVING SPIDERS. — PEDIPALPI.

when it has arrived there, it gets beneath its lower edge, and
allows the bubbles of air which it had entangled to ascend into
it. Then returning to the surface of the water, it brings down
a fresh supply of air ; and in this manner it gradually fills the
bell, which then presents a beautiful silvery or glistening appear-
ance, when seen beneath the surface of the water. This process
is strikingly analogous to that, which was first employed to
renew the air in Diving Bells ; barrels of air being sent down by
means of weights, and their air being allowed to pass into the
bell, by means of a flexible pipe, when they had been sunk to a
lower level.

760. Section II. PEDIPALPI. This section is distinguished
by the large size of the palpi, which resemble extended arms,
and which are furnished at their extremities, either with moveable
hooked claws, or with a pair of pincers, composed of two fingers,
one fixed and the other moveable, like those of Crabs and
Lobsters. The abdomen is composed of very distinct segments ;
and is destitute of spinnerets at the tip. The entire body is
encased in a hard skin. The cephalothorax is composed of a
single piece, and is furnished with six or eight ocelli or eyelets.
The number of pulmonary sacs is four in one of the two families
of which the section is composed, and eight in the other. In the
first of these families, THELYPHONIDJE, the general form is that
of the Spiders ; so that the species included in it are commonly
ranked as such. They are, however, at
once distinguished by the large size of the
palpi, and by the absence of spinnerets.
They differ from the Scorpions, on the
other hand, in the form of the abdomen ;
and in the absence of a sting at its extre-
mity. The tarsi of the two fore-legs differ
from the others in a remarkable degree ;
being composed of numerous joints, so

FIG 446.— PHRYNUS RENI- ® , ,

FORMIS, reduced. slender and prolonged as to resemble

threads, and being destitute of the usual

hook at its extremity. These Arachnida inhabit only the

hottest parts of Asia and America ; very little is known of

their habits.

SCORPIONID^, OR SCORPION TRIBE. 225

761 / With the characters of the second family, SCORPIONID^E,
or the Scorpion tribe, we are much more familiar. It is espe-
cially distinguished from the preceding by its eight breathing-
pores ; but also by its long-jointed abdomen (the hinder part
forming what is commonly called the tail), terminated by a
venomous claw or sting. The abdomen is composed of twelve
segments ; six of which are broad, forming the posterior part of
the body, whilst the other six form the tail. Between the thorax

and abdomen
there is no dis-
tinct division.
In these par-
ticulars, — the
evident divi-
sion of the body
into segments,
the want of
separation be-
FIO. 447.— SCORPION. tween the tho-

rax and abdo-
men, the multiplication of the respiratory sacs, — as well as in
others, the Scorpionidae show an evident approach towards the
Myriapoda. The Arachnida of this tribe inhabit the warm
countries of both hemispheres, living on the ground, hiding
themselves under stones or other bodies (generally in dark and
cool places), and sometimes taking up their abode in the interior
of houses. They run quickly, and curve the tail over the back.
They can turn it in all directions, and employ it as a weapon of
offence or of defence. Their usual food consists of "Wood-lice and
various Ground-Insects, such as Carabi, Weevils, Orthoptera, &c. ;
these they seize with their pincer-like palpi, and then prick them
with their stings, so as to render them powerless before proceeding
to devour them. They are also particularly fond of the eggs of
Spiders and Insects. It is only in the larger species of Scorpion,
which are five or six inches long, and inhabitants of tropical
countries, that the poison is sufficiently powerful to do any
serious mischief to Man ; and although the effects of the sting

226 SCORPIONS. SUBDIVISIONS OF TRACHEARIA.

of these are severe, they are seldom, if ever, fatal, except in
persons previously unhealthy. It is not generally known, that a
small species of Scorpion exists in our own country, as well as on
the Continent of Europe; and this has afforded to European
Naturalists an opportunity of watching its hahits. The female
resembles that of the Spiders in her attention to her young ; these
she carries on her back for several days, at first not quitting her
abode ; and she afterwards takes care of them for the space of a
month, by which time they are enabled to shift for themselves.

ORDER II.— TRACHEARIA.

762. THE Arachnida of this order present a 'much stronger
resemblance to the class of Insects, than do any of the preceding ;
for they are characterised not merely by the nature of their respi-
ratory organs — which consist of ramified tracheae, instead of pulmo-
nary sacs — but also by the imperfect development of the circulating
apparatus, as well as by a certain degree of metamorphosis,
which has been observed in several of them. They may be
divided into three families, according to the form of the thorax
and abdomen, — these characters being preferred, on account of
their being more easily recognised, in the minute animals of
which the group consists, than those founded on the structure of
the mouth and the mode in which the food is obtained. These
families are ; — I. The PsEUDo-ScoRPioNiD^:, or False- Scorpions -,
are so named from the strong resemblance which some of them
bear to the preceding group ; these have the abdomen very dis-
tinct from the thorax, and marked with rings ; and are furnished
with large palpi, which are either formed like feet (Fig. 448), or
furnished with pincers (Fig. 449) : — II. The PHALANGID.E, or
Harvest-men, which may be regarded as representing the Spiders
in the Tracheary Order; they have the thorax and abdomen united
into one mass, but the latter does not exhibit any division into
rings ; the palpi are thread-like ; — and III. The ACARID^E, or
Mites, which have the abdomen united to the thorax, but alto-
gether unmarked by rings (Fig. 452).

PSEUDO-SCORPIONID.fi. PH AL ANGIDJE.

227

Fio. 448.— GALBODES INTREPIDA.

763] The general form and aspect of the PSEUDO-SCORPIONI-
D2G will be best understood from the accompanying figures, which

represent two of
the principal spe-
cies. .The Ga-
leodes is found in
the warmer tem-
perate and the
tropical regions,
principally of the
Old World. They

run with great quickness, erect their heads when surprised, show
signs of resistance, and are reputed to be venomous. The
Chelifer strongly resembles a small Scorpion deprived of its tail ;
and one species, which inhabits herbaria, old books, &c., — feed-
ing upon the minute insects which fre-
quent such situations, is commonly known
under the name of Book- Scorpion. It
runs quickly, and often sideways, like the
Crabs or the Laterigrade Spiders. The
effffs are united into a mass, which is said

oo

to be carried about under the abdomen.

764. Here has been placed, by many
Naturalists, a very curious group, the
PYCNOGONID.E; which departs very widely

from the other Arachnida, both in the structure of the body, as
well as in the residence, which is exclusively marine. It
appears to be destitute of any special Respiratory apparatus;
and cannot, therefore, be referred with certainty either to this
class or to the Crustacea, by characters derived from the mode
in which this function is performed. On the whole, however,
its analogies seem to be rather with the latter class ; with which,
therefore, it will be described (§815). It may be regarded
as connecting the Arachnida and Crustacea.

765. The PHALANGID^E, or Harvest-men, have two thread-
like palpi, terminated by a small hook ; the legs are long and
slender, and when detached from the body, they show signs of

Q2

FIG. 449.— CHELIFER
FASCIATUS.

228

PIIALANGID^. ACARID.E, OR MITES.

irritability for a few moments. The majority of them live upon
the ground, upon plants, or at the roots of trees, and are very

FIG. 450. — PHALANGIUM CORNUTUM. FIG. 451. — GONVLEPTES ACANTHURUS.

active in their movements ; others hide themselves between stones,
or in moss, and are less agile.

766. The ACARIDJE, or Mites, have the mouth formed rather
for suction than for mastication ; its various pieces not being sepa-
rate, as in the other Arachnida, but more or less enveloped in a
sort of sheath formed by a prolongation of the lower lip ; the
maxillary palpi, however, are generally free, and their extre-
mities are commonly armed by a small pair of pincers. Some
of these animals have four or two eyes ; others have only a
single one ; and there are several which do not possess any.
They are nearly all of very small size, and multiply with great
rapidity. Many of them come forth from the egg with only
six legs, and may be considered to bear, in this state, a strong
resemblance to parasitic insects ; they do not acquire their addi-
tional pair until after the first moult, which thus becomes a sort
of metamorphosis. The Acaridae are very widely, — in fact
universally. — distributed. Some of them are of wandering
habits ; and amongst these, some are found under stones, leaves,
the bark of trees, in the ground, the water, or upon various
articles of food, such as meat and old dry cheese, and upon putrid
animal matters. Others subsist as parasites upon the skin, and
in the flesh of different animals ; often greatly weakening them
by their excessive multiplication, and producing most violent
itching. Other kinds of Mites are parasitic upon Insects ; and

ACARI, OR MITES ; RICINI^E, OR TICKS.

229

FIG. 452. — ACARUS DO-
MKSTJCUS, or CHEESE-
MITE, magnified.

many Beetles which feed upon decaying substances, are entirely
covered by them. The Acari, or True Mites,
have the legs adapted for walking; and
some of them are of active habits. The com-
mon Cheese-Mite is familiar to every one ;
and there are many other species which
nearly resemble it in structure and habits,
but which feed upon different substances. To
this group belongs a small species, which appears to be the
occasion of one of the most disgusting diseases of the skin, — the
itch. It is scarcely visible to the naked eye ; but when exa-
mined under the microscope, it is seen to have an oval body ; a
mouth of conical form, armed with
several bristles; and eight feet, of
which the four anterior are terminated
by small suckers, that enable it to
adhere firmly to any solid bodies,
whilst the four posterior are termi-
nated only by bristles. Some of this
Acari have the power of spinning
webs, and are commonly ranked with
the Spiders ; one of these is well-
known as the Red Spider in hot-
houses, where it greatly injures the
plants by covering the leaves with
its webs. — The Ricinice, commonly
known as Ticks, are usually desti-
tute of eyes, but have the mouth
provided with lancets, that enable them to penetrate more readily
the skins of animals whose blood they suck. They are usually
of a flattened, round, or oval form ; but they often acquire a
very large size by suction, and become distended like a blown
bladder. They are found in thick woods, abounding in brushwood,
briars, &c., and attaching themselves to plants with the two
fore legs. They fasten upon dogs, cows, horses, and other
quadrupeds, and even upon the tortoise ; and they bury their
suckers (which are often furnished with minute recurved hooks,

FIG. 453. — SARCOPTES SCABIEI, or
ACARUS OF THE ITCH.

230 HARVEST-BUGS.— HYDRACHN^E, OR WATER-MITES.

as in the Ixodes, Fig. 454,) so firmly in their skin, that they
can hardly be detached hy force, — the portion of skin to which

FIG. 454. — IXODES FIG. 455.— a, HYDRACHNA GLOBULUS ;

PLUMBEUS, AND ITS b, magnified ; c, young larva ; d, pupa.

BEAK, magnified.

they are attached coming away with them. It is probably the
young of a species of this group, which is commonly known as
the Harvest-Bug ; this is very common in the autumn, upon
grass or other herbage; and insinuates itself into the skin
at the roots of the hair, producing a very painful irritation. In
this state it possesses only six legs. — Lastly, there is a tribe of
Acaridae, the Hydrachnce, in which the legs are covered with
hairs, in such a manner as to adapt them for swimming ; these
are all, during a part of their lives at least, parasitic upon
various Water- Insects, such as the Dytiscus, the Nepa, &c.
These Water-Mites undergo a more complete metamorphosis
than any of the preceding ; for the larvae have a very large
head, and six legs ; whilst the pupae have but a single pair of
legs, with which they attach themselves to the bodies of
insects, and present the appearance of an oval bag with a narrow
neck.

CHAPTER X.

CLASS OF CRUSTACEA.

767. CRUST ACE A. are Articulated animals, respiring by Iranchice
or external gills, or by the general surface, and possessing
a circulating apparatus, and separate sexes. Crabs and Lob-
sters are the types of this group ; but a great number of animals
of a much less complicated structure, and of a different external
form, are also classed with these ; for as we descend the
natural series formed by these animals, we see the same general
plan of structure gradually modified and simplified. The
lowest Crustacea are even so imperfect, that they can only exist,
attached like parasites, on other animals : whence most Natura-
lists have placed them with the Intestinal Worms.

768. The tegumentary skeleton of Crustacea generally pos-
sesses a very considerable degree of firmness. It has nearly
always a stony hardness ; and indeed contains a very consider-
able proportion of carbonate of lime. We may look upon this
solid envelope as a kind of epidermis ; for beneath it we find a
membrane like the true skin of higher animals ; and at certain
times it detaches itself and falls off, in the same manner as the
epidermis of Reptiles separates itself from their bodies (§ 471),
and as we have also seen the enveloping membrane of the larvae
of Insects renew itself several times. We can easily understand
the necessity of this change, in animals whose whole bodies are
inclosed in a solid case ; which, not being able to grow like the
interior parts, would oppose an invincible obstacle to their
development, if it could not be thrown off, as soon as it has
become too small to lodge them commodiously. Thus the
Crustacea change their skin during the whole time of their
growth ; and it would seem that the greater part of these
animals grow during their whole life. The manner in which

FIG. 456. — SANDHOPPBR.

232 BODY OF CRUSTACEA. DIVISION INTO SEGMENTS.

they free themselves from their old shell is exceedingly singular.
In general they manage to get out of it without occasioning the
least change in its form ; and when they have quitted it, the
whole surface of their body is already clothed in a new casing, —
which, however, is still soft, and does not acquire its requisite
solidity for some days.

7^9. The body of Crustacea is composed of a series of rings,

more or less distinct. Sometimes
most of these segments are simply
articulated one with the other, so
as to admit of a considerable de-
gree of motion, as in the Sand-
hopper ; sometimes they are
nearly all soldered together, and
are only distinguished by furrows
situated at their line of juncture ;
lastly, in other cases, their union

is still more close, and it is only by analogy that we are led to con-
sider the trunk, resulting from their juncture, as made up of several
rings, rather than of one only. Hence result, as we can easily under-
stand, very great differences in the form of these animals; and if we
compare with each other a Woodlouse (Fig. 457), a Sandhopper
(Fig. 456), and a Crab (Fig. 458), we might be at first led to be-
lieve them formed according to types en-
tirely different ; but a deeper study of
their structure shows, that the compo-
sition of their tegumentary skeleton is
essentially the same, and that the dif-
ferences lie almost entirely in this, —
that most of the rings being quite dis-
tinct and moveable in the Woodlouse,
are grown together in the Crab, and
that certain analogous parts do not
present the same proportions in both
animals. Thus in the Woodlouse and

Sandhopper we find a distinct head (c) followed by a thorax
composed of seven rings similar to each other (J1 J2), and each

Fio. 457. — ONISCUS, OR

WOODLOI'SR.

BODY OF CRUSTACEA. DIVISION INTO SEGMENTS.

233

ring provided with a pair of legs (/?, pp,) : and at the posterior
part of the body we see an abdomen, also composed of seven seg-
ments (as), whose size
diminishes rapidly,
but whose form is
nearly the same as in
the thorax. In the
Crab (Fig. 458), on
the contrary, the head
is not separated from
the thorax ; and it
forms, with the whole
middle part of the
body, but a single
mass, covered by a
large solid buckler

FIG. 458. — CANCKR PAOURUS, Linn., with the tail of the Q^JJgjJ ^Q CCLTdDCHCQ
male, a ; and of the female, b. •*

The abdomen, at first,

escapes observation ; for it is bent down under the thorax, and
is of small size. Yet it is easy to show, that in the Crab, as in
the Woodlouse, there are seven very recognisable thoracic rings,
and that the carapace is not a new part introduced instead of
the former, but merely the dorsal portion of one of the rings of
the head, so extremely developed that it has encroached upon
all the neighbouring rings.

770. In other animals of the same class, the general form of
the body differs still more widely from those of which we have
just spoken. Thus the Limnadias are inclosed between two oval
shields, joined like the valves of an Oyster, and it is only after
having raised this moveable cuirass, that we first perceive the
annular structure of the body (Fig. 490) ; the Cypris (Fig. 495),
which abounds in stagnant waters, presents a similar arrange-
ment : but the rings of which its body is composed, are
still more difficult to recognise. Lastly, we may advert to the
Lernem, which at their adult age present the strangest forms ;
but which, in the earlier part of their existence, possess a regular
annular structure (Figs. 501, 502). This comparative study of

234

LATERAL APPENDAGES OF CRUSTACEA.

the tegumentary skeleton is of great interest as a department of
Philosophic Anatomy ; one of whose most important branches
has reference to those modifications, to which Nature subjects
the same organic elements, in order to adapt them to various
purposes, and to create different animals from analogous mate-
rials ; but the limits we have assigned ourselves, do not permit
us to dwell longer on this subject.

771. The lateral appendages of the different rings constituting
the body, are in general very numerous, and present consider-
able differences in their conformation and uses ; — both when we
consider those in the different parts of the same individual, and
when we compare them in distinct species. Those of the first
pair are generally subservient to the animal functions, and sup-
port the eyes or constitute the antennae ; the next surround the
mouth, and serve for the prehension or division of the food ;
those of the middle part of the body constitute the legs for loco-
motion; and those whicji are placed behind have various
uses, but are generally subservient to respiration or reproduc-

pm

FIG. 459. — PRAWN : — as, antennae of the first pair ; at, antennae of the second pair ;
I, laminar appendage covering its base ; r, rostrum, or frontal prolongation of the
carapace ; y, eyes ; pm, external foot-jaw; p', first thoracic member; p", second
thoracic member ; fp, false legs, or swimming members, of the abdomen ; n, tail-fin.

tion ; lastly, this long series ordinarily terminates by one or
several pairs of members, which serve as fins.

77*2. The head, or rather the cephalic portion of the body,
carries the eyes, the antennas, and the appendages of the mouth.

LATERAL APPENDAGES OF CRUSTACEA.

235

It is sometimes divided into several distinct rings, as in the
ScillcB ; but in general there is no separation, and it is formed
of a single piece, which seems to represent seven segments joined
together. Sometimes it is moveable, and distinct from the
thorax (Fig. 458) ; sometimes, on the contrary, it is joined to
this second part of the body, which in its turn is composed of
distinct rings, articulating with each other in some species, but
in others united into a single mass.

773. Of the antenna, there are nearly always two pair;
and they are generally thread-like, and very much elongated
(Fig. 459, as and ai). The legs originate by pairs from the
different thoracic rings ; and they often amount to seven pairs,
as for example in the Woodlouse (Fig. 457), and Sand-hopper
(Fig. 466) ; but in other instances, as we see in Crabs (Fig. 458)
and Cray-fish (Fig. 471), their number is reduced to five pairs ;
those appendages, which in the former constituted the four
anterior legs, being subjected in the latter to other uses, and
transformed into organs of mastication (§ 775). There are also
very great differences in their structure : in some Crustacea
they are leaf-like, membranous, and fitted for swimming only
(Fig. 490) ; in others they look like little columns jointed
together, and adapted for walking only ;
in others, while yet remaining appro-
priate to this last kind of locomotion,
they are destined to be used also as so
many little spades for digging in the
earth, and then they are enlarged and
laminated at the end (Fig. 460) ;
lastly, in others, they end in pincers,
and thus become instruments of
prehension, at the same time that
they fulfil their ordinary functions in
locomotion (Figs. 471 and 505). In
swimming Crustacea, such as Cray-
fish, Lobsters, Prawns, &c. (Fig. 459),
the abdomen generally attains a con-
siderable development, and ends in a
large fin, in such a manner as to become the principal agent in

FIG. 460. — HIPPA.

236

NERVOUS SYSTEM OP CRUSTACEA.

locomotion ; but in those which are destined to walk rather than
to swim, this part is generally very small and bent under the
thorax. In the Crabs, for instance, this portion of the body is
reduced to almost nothing, and forms a sort of moveable append-
age, which is seen on the inferior surface of the body beneath
the legs (Fig. 458).

774. The Nervous System of Crustacea consists of a double
series of ganglia, situated on the ventral surface of the body,
near the central line. In general their number corresponds
to that of the distinct segments composing the body ; and the
first pair is always
placed on the head, in
front of the oesophagus,
where it forms a sort of
brain. The arrange-
ment of the thoracic
and abdominal ganglia,
however, varies con-
siderably; sometimes
they are placed at equal
intervals, and form,
with their cords of
communication, a chain
extending from one «nd
of the body to the
other ; sometimes they
approach one another
more or less closely ;
and sometimes they
are united, forming a

single mass, situated about the middle of the thorax (Fig. 461, t).
It may be remarked that this concentration of the nervous
system becomes more and more complete, as the animal acquires
a higher organisation. The Crustacea have in general but very
limited faculties ; and none among them present much to interest,
as to their habits. The eyes are formed nearly in the same manner
as in Insects ; sometimes they are simple, but in general they
are compound ; and in all the most perfect Crustacea, these

FIG. 461.' — NERVOUS SYSTEM OF CRAB (Maia) : ca,
upper part of the shell laid open ; a, antennae ;
y, eyes ; e, stomach ; c, cephalic ganglion ; no, optic
nerves ; co, oesophageal collar ; ns, stomato-gastric
nerves ; t, thoracic ganglionic mass ; np, nerves of
the legs ; na, abdominal nerve.

ORGANS OP SENSE OF CRUSTACEA. 237

organs are situated on moveable footstalks (Fig. 462) ; an

FlG. 462. — PODOPHTHALMA.

arrangement which we do

not see in any other division of
Articulated animals. — In many
Crustacea, there is an apparatus
for hearing, situated at the base
of the external antennas, and
composed of a small membrane,
under which we find a sort of
vestibule filled with liquid, and
inclosing the termination of a

F,GM63.-Anterior part of the inferior particular nerve. This COUSti-

surface of the body of a Crab (Maia) : r

ai, internal antennae; a, external tuteS the simplest form of an

antennae; y eyes; o, organ of hear- A ,., , .

ing; m, feet-jaws; b, mouth ; p, base Auditory apparatus. (ANIM.

of the anterior limbs; r entrance to PHYSIOL. § 512). We know

the respiratory cavity ; s, sternum. % ,

nothing positive concerning the
senses of Smell and Taste in these animals.

775. Most Crustacea subsist on animal substances ; but they
present great differences in their regimen, some being only nour-
ished upon' liquid matters, whilst others feed upon solid aliment ;
and we observe corresponding differences in the formation of
their mouths. In masticating Crustacea there is in front of
this opening a short transverse lip, followed by a pair of man-
dibles, by an inferior lip, by one or two pairs of jaws properly so
called, and generally by one or three pairs of auxiliary jaws, or
feet-jaws, which serve principally for the prehension of food

238 MOUTH AND DIGESTIVE APPARATUS OF CRUSTACEA.

(Fig. 472). In suctorial Crustacea, on the contrary, the mouth
is prolonged into a sort of beak, or trunk, as we have already
seen in Insects of the same habits. In the interior of this tube,
we find thin and pointed appendages, which perform the office
of little lancets ; and on each side we commonly see organs,
which are analogous to the auxiliary jaws of masticating
Crustacea, but which are so formed as to serve to fix the
animal on its prey.

776. The digestive canal extends from the head to the pos-
terior extremity of the abdomen ; and is composed of a very
short oesophagus, a large stomach (<?, Fig. 466) generally armed
interiorly with powerful teeth, of a small intestine, and of a
rectum. In some Crustacea, the bile is secreted by biliary

/ b c aa fl b1

FIG. 464.— ANATOMY OF A CRAB ; the greater part of the carapace having been
removed ; p, portion of its lining membrane ; c, heart ; as, ophthalmic artery ; act, abdo-
minal artery ; b, branchise in their natural position ; &', branchiae turned back to show
their vessels ; fl, lower portion of the shell ; /, appendage of the foot- jaw ; e, stomach ;
m, muscles of the stomach ; fo, liver.

vessels, like those of Insects ; but in general there is a very
voluminous liver, divided into several lobes, and composed of a

CIRCULATION AND RESPIRATION OP CRUSTACEA. 239

multitude of small tubes terminating in follicles, and grouped
round a ramified excretory canal, whose extremity empties
itself on each side into the intestine near its commencement
(jfo, Fig. 464.)

777. We know as yet nothing of the manner in which the
chyle passes from the intestine into the circulating apparatus.
The blood is colourless, or slightly tinged with blue or lilac ; and
coagulates easily. This liquid is put in motion by a heart,
situated on the median line of the back, and composed of but

FIG. 465. — CIRCULATING APPARATUS OF LOBSTER ; a, heart ; b and c, arteries to the
eyes and antennae ; d, hepatic artery ; e and /, arteries to thorax and abdomen ; gg,
venous sinus ; h, gills ; i, branchial veins.

a single cavity of variable form (Fig. 465, a). Its contraction
propels the blood into the arteries, which distribute it to all
parts of the body. The veins are very incomplete, and are
formed chiefly by passages left between the different organs, and
lined by a thin layer of areolar tissue ; they end in large cavi-
ties near the base of the legs (Fig 466, s,) from which the blood
is conducted to the respiratory organs, whence it returns to the
heart by very distinct canals termed branchio-cardiac vessels.

778. Crustacea are almost all essentially aquatic; their
respiration is nearly always effected by gills ; and when these
organs are absent, their place is supplied by the skin of certain
parts of the body, generally of the legs. In other respects,
the arrangement of the respiratory apparatus varies consider-
ably. Thus in the Crabs, Cray-fish, and all other Crustacea
of analogous organisation, the gills consist of a considerable

240

RESPIRATORY APPARATUS OF CRUSTACEA.

number of pyramids, — each composed either of a number of
minute cylinders placed like the hairs of a brush, or of little

lamellae piled one on
like the
book. —

fvb

the other
leaves of a
These organs are fixed
by their extremities
to the inferior border
of the arch of the
flanks (Fig. 466) ;
and are inclosed in
two large cavities,
situated at the side of
the thorax and shut in
between the carapace
and the arch just men-
tioned, an arrangement which is not found in the other divisions of
this class. The respiratory cavity communicates with the exterior

st

FJG. 466. — VERTICAL SECTION OF A CRUSTACEAN, SHOW-
ING THE COURSE OF THE BLOOD ; c, heart; t, venous
sinus ; va, vessels conducting the venous blood to the
gills ; ve, vessels which collect the aerated blood from
the capillaries of the gills ; vb, branchiocardiac vessels ;
/, carapace ; st, sternum.

FIG. 467. — RESPIKATORY APPARATUS OF PRAWN ; a, rostrum or beak ; b, carapace; c,
base of antennae ; d, base of abdomen ; e, base of legs ; /, gills ; g, dotted line, marking
the turned-in border of the portion of the carapace that covers in the gills, which has
been removed in this preparation ; h, canal for the exit of the water from the respira-
tory chamber ; i, its valve ; j, its extremity.

by two openings ; that which serves for the entrance of the
water is situated between the base of the legs and the side of

RESPIRATION OF CRUSTACEA.

241

the carapace ; the other, destined for the exit of the water, is
placed at the sides of the mouth (Fig. 467). The renewal of
the water in contact with the gills, is effected by the movements
of a large valve, situated near this last opening, and formed by
lamellated appendages of the second pair of jaws (Fig. 467, *)•
In other Crustacea, the Scilla for instance, the gills are formed
of feathery tufts ; and instead of being inclosed in the thorax,

FIG. 468. — SCILLA ; y, eyes ; a, antennas ; pi, first pair of legs ;
p2, second pair of legs ; p9, three last pairs of thoracic legs ; pa,
abdominal pro-legs ; &, gills ; g, fin-like members.

they float freely on the exterior, and are fixed to the abdominal
members. In others, as the Sandhoppers, the gills are replaced
l>y membranous vesicles fixed at the base of the legs, beneath
the thorax. Lastly, in the Isopod Crustacea, the respiration
is effected by means of false abdominal legs, which present a
leaf-like and membranous aspect.

779. A small number of these animals are formed to exist
in air ; but they constitute an exception to what has been said,
relative to the difference in the structure of the breathing appa-
ratus of terrestrial and aquatic animals : for, instead of being pro-
vided with lungs or tracheaB, they respire by gills like the former ;
but these organs are placed in such a manner, as to be surrounded
by that degree of moisture, which is necessary for the exercise of
their functions. The Land-Crabs, which are met with in different
parts of the globe, but which chiefly abound in the Antilles,
offer a remarkable example of this anomaly. Instead of living
in the water like ordinary Crustacea, these animals are terrestrial;

242 RESPIRATION AND REPRODUCTION OF CRUSTACEA.

and although provided with gills, some among them are speedily
suffocated by submersion in water. Indeed, their respiration
is so active, that the small quantity of oxygen dissolved in the

water cannot suffice for
their wants ; but in the
air they find this gas
in abundance ; and an
arrangement similar to
that which we have
met with in certain
Fish (§ 538), permits
them to remain out of

FIG. 469. — LAND CRAB.

the water without their

gills becoming so dry, as to be unfit to perform their functions.
Sometimes there is, at the bottom of the respiratory cavity, a
sort of basin, destined as a reservoir for the water necessary to
supply the requisite moisture to the gills. In other instances, we
find in the lower arch of this cavity a spongy membrane, which
seems to serve the same purpose. Most of these Land-Crabs
commonly inhabit moist woods, and hide themselves in holes
which they dig in the soil ; but the localities which they prefer
vary according to their species. Some dwell in low marshy
lands, near the sea ; others in w coded hills far from the shore ;
and these last at certain periods quit their habitual dwellings
for the sea. The Woodlice also are terrestrial Crustacea,
whose respiration is effected by means of leaf-like plates, which
are situated under the abdomen, and which, in other animals
formed nearly on the same plan, fulfil the functions of gills.

780. All Crustacea are oviparous. The female is generally
distinguished from the male by the more enlarged form of the
abdomen ; and after having laid the eggs, she carries them for
some time, suspended under that part of her body, or even
inclosed in a sort of pouch, formed by the appendages to the
legs. Sometimes the little ones swim about in this pouch, and
remain there until they have undergone their first moult.
The young do not in general undergo true metamorphoses;
but sometimes they acquire, with advancing age, a larger

METAMORPHOSES OF CRUSTACEA. 243

number of legs ; there are some which change their form com-
pletely during the first part of their life. This is the case, for •
example, with the common Crab,
whose early condition is represented
in the accompanying figure. It is
remarkable, however, that in other
animals of the same Order, such as the
Cray-fish, the change of form is so in-
considerable, as not to deserve the name
of metamorphosis. Hence we perceive that
the degree of this change cannot be em-
ployed as a character in the subdivision
of the Class, as we have seen that it may
be in Insects. Of a large proportion of
Crustacea, however, the early form is
unknown. The metamorphoses of some
FIG. 470.— EARLY FORM OF THE of the lower tribes are even more ex-
traordinary than those of the higher

(Figs. 496 and 497, 501 and 502) ; being frequently such, as
appear to remove the adult altogether from the class, to which
the larva evidently belongs.

781. The early condition of many of the higher Crustacea
bears a strong resemblance to the permanent forms of the lower.
This is in no point more remarkable, than in the character of {he
respiratory apparatus. Thus in the earliest period of the develop-
ment of the Astacus flumatilis, or River Cray-fish, no trace of
gills can be discovered; but as the embryo within the egg
approaches maturity, temporary gills are developed in the form
of leaf-like expansions, occupying the situation of the extremities
of the maxillary appendages, which are the first developed of all
the members. These soon subdivide, and one part assumes a
cylindrical form, and seems no longer to belong to the apparatus ;
whilst branchial filaments begin to appear on the other — which
are subsequently prolonged into complete gills. During this
interval, the thoracic extremities have made their appearance ;
and they also become furnished with branchial appendages. At
a subsequent time, a narrow groove or furrow is seen along the

244 SUBDIVISIONS OF CRUSTACEA.

under edges of the thorax ; the margins of which, after no long
period, are prolonged so as to meet each other and enclose the
gills, — openings being left for the entrance and exit of water,
which are at first large, but which subsequently become contracted
to the proper size.

782. The Class of Crustacea may be divided into three natural
groups or Sub-Classes, characterised by differences in the conform-
ation of the mouth, as follows : —

I. MAXILLOSA, or Masticating Crustacea, whose mouth is
furnished with mandibles and maxillae adapted for mastication.

II. EDENTATA, Toothless or Suctorial Crustacea, whose mouth
is composed of a tubular beak armed with suckers.

III. XYPHOSURA (so named from the Sword-like appendage
with which they are furnished, Fig. 505), whose mouth has no
appendages peculiar to it, but is surrounded by legs, whose bases
perform the office of jaws.

783. The group of MAXILLOSA comprehends the greatest part
of the class ; and includes all those, whose organisation is most
complicated and perfect. These Crustacea do not live on the
juices of other animals, as do those constituting the suctorial
group ; but they are habitually nourished on solid food. They
vary greatly in external form, in their number of legs, and in the
structure of their respiratory apparatus ; and they may be
divided by these characters .into four Sections, containing nine
Orders. —

A. The first Section, PODOPHTHALMA, includes all those
having the eyes mounted upon foot-stalks, and moveable. They
are almost always furnished with distinct branchiae ; their feet are
partly formed for walking, and partly for prehension ; and the
thorax is covered with a carapace, formed by the great develop-
ment of one of the rings. This Section includes the two first
Orders :—

I. DECAPODA, possessing five pairs of thoracic extremities, and
having the gills enclosed in a special respiratory cavity, on each
side of the thorax.

II. STOMAPODA, having the gills external, and a variable
number of extremities.

SUBDIVISIONS OF CRUSTACEA. 245

B. The second Section, EDRIOPHTHALMA, consists of those
Crustacea, whose eyes are sessile (that is, not mounted on a foot-
stalk), and whose branchia3 are not distinct organs, but are
united with the extremities, which are commonly seven on each
side, and adapted for walking. This Section contains the three
succeeding Orders : —

III. AMPHIPODA, in which the thoracic members are subser-
vient to respiration ; and which have the abdomen well developed,
and furnished with six pairs of appendages.

IV. L^MODIPODA, in which there is the same provision for
respiration, but which have the abdomen undeveloped.

V. ISOPODA, in which the abdomen is well developed, and
has members, similar in form to the rest, subservient to
respiration.

C. The third Section, BRANCHIOPODA, is characterised by the
absence of any special organs for respiration ; their place being
supplied by the flattening of the anterior pair of legs into thin
plates, which are subservient to that function. This Section
contains two Orders : —

VI. PHYLLOPODA, in which the body is either shell-less, or
enclosed in a simple carapace, and furnished with a large number
of appendages.

VII. CLADOCERA, in which there is a carapace in the form of
a bivalve shell.

D. The fourth Section, ENTOMOSTRACA, is composed of Crus-
tacea in which there are no branchiae, nor any organs destined
to supply their place. The eyes are sessile, and are commonly
united into a single mass. This Section also contains two
Orders : —

VIII. OSTRAPODA, which has the body inclosed in a sort of
shield resembling a bivalve shell.

IX. COPEPODA, in which there is no such envelope.

It is in the Order Isopoda, that we find, in the equality of
the segments and of their appendages, as well as in the aerial

246 ORDER DECAPODA ; GENERAL CHARACTERS.

respiration of many species, the nearest approach to the class
MYRIAPODA; and in some members of the Entomostracous
section, we find a considerable approximation to the higher
ROTIFERA.

SECTION A.— PODOPHTHALMA.

ORDER I.— DECAPODA.

784. In this Order we find the highest general organisation,
the largest size, and the most varied habits, which we anywhere
meet with among Crustacea ; it is the one most useful to Man ;
and also most interesting to the Naturalist. The Lobsters,
Crabs, Cray-fish, Prawns, Shrimps, — in fact, nearly all the
species that are ever used as food, — belong to it. Their growth
is slow ; but they ordinarily live a long time. Their habits are
mostly aquatic ; but, in consequence of the manner in which
their gills are inclosed, none of them are killed at once by being
withdrawn from the water ; and some of them pass the greatest
part of their lives in air. They are naturally voracious and
carnivorous : and the first pair of legs is transformed into a pair
of powerful claws, by which they seize their food and convey it
to the mouth, — the claw of one side usually having a sharp edge
for cutting, whilst that of the other is provided with a blunt
rounded edge for bruising. The form and size of the claws,
relatively to the rest of the extremities, varies greatly in the
different species; thus in the Cray -fish (Fig. 471), they only
seem like legs somewhat enlarged ; whilst in the Crabs
(Fig. 475), they commonly seem to be distinct organs. It is
in this group, that we find the mouth furnished with the most
complicated set of appendages ; and we may trace in these a
gradual transition from the form of jaws to that of legs. This
is shown in the accompanying figures, which represent the
under surface of the Cray-fish, and the series of feet-jaws sepa-
rately displayed. — This Order is divided into three sub-orders,

ORDER DECAPODA. BRACHYOURA.

247

according to the development of the abdomen ; these are : —
I. The BRACHYOURA, or short-tailed Decapods, to which the
name of Crabs is commonly applied ; — II. The MACROTJRA, or
long-taikd, such as the Lobster, Cray-fish, £c. ; — and III. The

FIG. 471.— CRAY-FISH ; a and 6, antenna ;
c, eyes; d, organ of hearing; e, external
feet-jaws ; /, first pair of thoracic mem-
bers ; g, fifth pair of thoracic members ;
7/, abdominal false-legs ; i, tail-fin ; j,
anus.

FIG. 472. — MA STICATOKY APPARATUS, com-
posed of six pairs of appendages ; a, man-
dibles ; 6 and c, first and second pairs of
maxillae ; d, e, f, three pairs of feet-jaws,
gradually approaching the form of the or-
dinary limbs.

ANOMOURA, in which the condition of the abdomen is inter-
mediate. Each of these sub-orders is divided into families;
but it will be sufficient here to notice their principal forms.

785. The BRACHYOURA may be considered as ranking at
the head of the whole Order, in regard to the concentration
and high development of their nervous, circulating, respiratory,
and secreting systems. They are formed for walking rather

248

MACROUROUS DECAPODS ; — CRABS.

than for swimming ; and they are consequently usually found
upon the shore, or even quite inland, rather than afloat. The

FIG. 473.— CARCINUS MJENAS, (Common small edible Crab), upper side, and under side
of the body with the limbs cut short ; a, lateral antenna ; b, intermediate antenna : c,
eye ; d, outer foot jaw ; e,f, g, h, i, base of the five pairs of legs ; k, tail ; I, sternum.

tail or post-abdomen is shorter than the thorax, and possesses
no appendages or swimmerets at its extremity ; it is folded in

FIG. 474.— MAIA.

a state of rest beneath the thorax, where it is lodged in a hollow

MACROUROUS DECAPODS ; — CRABS.

249

fitted to receive it ; and in the female it is furnished with four
pairs of double filaments, analogous to the sub-abdominal swim-
ming appendages of the long-tailed Decapods, and used for
carrying the eggs. The claws, or first pair of legs, are alone
furnished with pincers ; the ordinary legs having only simple
pointed terminations. — In the Maia (Fig. 474) and other allied
genera, the body has very much the form of that of some Spiders,
and the legs are very long ; whence these Crabs are commonly
termed Sea-Spiders by the fishermen. — The Cancer pagurus, or
common large edible Crab, belongs to a group distinguished by
the very great breadth of the carapace, which, in this species,
sometimes amounts to as much as twelve inches ; it is much
arched at the sides, and each border has nine festoons. This

Crab is captured, by sinking
pots, baskets, or nets, baited
with decaying animal mat-
ter, to a considerable depth
along the rocky coast. Du-
ring the summer months it
is very abundant, especially
where the water is deep;
but in winter it is rarely to
be found, and it is supposed
to burrow in the sand, or to
retire to the deeper parts of
the ocean. The Carcinus

Mcenas, or small edible Crab, is very active in its habits, run-
ning with considerable speed ; it is caught, however, in large
numbers, but is principally eaten by the lower classes, being
less esteemed than the preceding as an article of food; its
breadth seldom exceeds three inches. There are several other
species of this group, which are used as food in different parts
of the world, where they take the place of the preceding. — The
Podophthalma, which is extremely remarkable for the length of
its eye-bearing foot-stalks (Fig. 462), belongs to a group of
Crabs distinguished by the flattened form of the last pair of
legs, which are used as oars, and enable the animal to swim
with facility.

FIG. 475 — CANCER PAGURUS.

250

BRACHYOUROUS DECAPODS. LAND-CRABS.

FIG. 476. — THELPHUSA.

786. Of the group of Brachyourous Decapods formed to live
at a distance from the sea, there are many species; some of

them inhabiting fresh
water, whilst others form
burrows in the ground,
even at a distance from
water. Of the genus
Thelphusa, one fresh-
water species, a native
of the rivers of Southern
Europe, was well known
to the ancients, who
often represented it upon
their medals ; the Greek
monks eat it uncooked,

and it is a common article of food in Italy during Lent.
Another species, which inhabits India, has been thus noticed by
Bishop Heber in his Journal : — " All the grass through the Dec-
can generally swarms with a small Land- Crab, which burrows in
the ground and runs with considerable swiftness, even when en-
cumbered with a bundle of food as big as itself; this food is grass,
or the green stalks of rice ; and it is amusing to see the Crabs,
sitting, as it were, upright, cut their hay with their sharp
pincers, and then waddling off with their sheaf to their holes,
as quickly as their side-long pace will carry them." They have
been found on the table-lands, at an elevation of nearly 4000 feet
from the sea ; and there is reason to believe that they do not,
like the West Indian Land- Crabs, perform an annual migration
to the sea, for the purpose of depositing their eggs. — The
Gecarcinus, or Land-Crab of the Antilles (Fig. 469), is remark-
able for its nocturnal and burrowing habits, and for the
migrations it executes ; when the season arrives for the depo-
sition of the eggs, it moves towards the sea in large com-
panies, taking the most direct line, and seldom permitting any
obstacles to interrupt its progress. — Some of the Land-Crabs
are remarkable for the inequality in the size of their claws ; the
larger is used to close up the mouth of the burrows ; and it is

CRABS. ANOMOUROUS DECAPODS; HERMIT-CRABS. 251

sometimes held up in a beckoning attitude, whence these Crabs
have acquired the name of Calling-Crabs. — Nearly allied to
these, which are all inhabitants of tropical regions, are some
small native species, termed Pea-Crabs, which reside, at least
during a part of the year, inside various bivalve shells, such as
Mussels, &c. The ancients believed that the Pea-Crab lives
on the best terms with the inhabitant of the shell in which it is
found; and that it not only warns it of danger, but goes
abroad to cater for it ; this, however, is an absurd fiction.

787. The Decapods of the section ANOMOURA are intermediate
between the Short-tailed Crabs, and the Long-tailed Lobsters and
Cray-fish ; not having the abdomen reduced to the almost rudi-
mentary state, which it presents in the former ;
neither having it converted into a powerful
organ for swimming, as in the latter (Fig. 477).
There is nearly always a pair of appendages
attached to its last segment ; and these have,
in some instances, important uses. This section
includes the Hippa (Fig. 460) and its allies,
constituting the family HIPPID^E; and also the
family PAGDRID^E, or Hermit- Crabs, which
are very peculiar as to both their conformation
and their habits. The tail, or post-abdomen,
FIG. 477.— REMIPES is of large size, but its envelope is little else
than a membranous bag, entirely unpossessed
of the usual hardness of the Crustaceous inte-
gument, and presenting no division into segments. The thorax
itself is not very firm ; and it is only on the claws, which are of
large size, that we find the true calcareous envelope. For the
protection of their soft tails, the Paguridce resort to various arti-
ficial methods. Many of them seek univalve shells, in which
they take up their abodes ; attaching themselves to their interior
by a sucker, with which the tail is furnished at its extremity,
and also holding by the three pairs of appendages, or false legs,
which it bears at its hinder portion. When they are feeding or
walking, the head and thorax project beyond the mouth of the
shell ; but when they are alarmed they draw themselves in,

252 HERMIT-CRABS. — MACROUROTJS DECAPODS.

closing the mouth with one of the claws, which is much larger
than the other, and holding to the interior so firmly, that they
will rather be torn asunder than quit their attachment. As they
increase in size, they are obliged to change their habitation for a
more commodious one ; and the way in which they accomplish
this is very amusing. They may be not unfrequently observed
crawling slowly along the line of empty shells, &c., left by the
last wave ; and as if unwilling to part with their old domicile
till a new one has been obtained, they slip their tails out of the
old house into the new one, again betaking themselves to the
former, if the latter is not found suitable. In this manner they
not unfrequently try a large number of shells, before they find one
to their liking. There are several species of various sizes, which
are inhabitants of our own shores ; they feed, for the most part,
upon dead fish, and all kinds of garbage thrown upon the shore.
The Birgus, an allied genus of tropical regions, has the tail some-
what more protected, but still soft ; this does not lodge in shells,
but retires to rocks, or hides itself in burrows in the earth. The
best-known species, Birgus latro, inhabits the Isle of France,
and lives upon cocoa-nuts ; it burrows at the roots of the trees,
and feeds upon the fruit which falls from them ; and it is even said
to climb the trunk, to obtain a further supply.

788. The MACROURA, or long-tailed Decapods, are dis-
tinguished not merely by the length of the tail, but by having
it terminated by a sort of fin, expanded laterally, and consisting
of five pieces (Fig. 478). This is a very powerful instrument
for motion in water, serving, by its vertical strokes, to propel
the animals through the liquid ; and we consequently find the
Crustacea of this Section much more frequently swimming in the
water than walking on its bottom or on the shore. This Section
is a very extensive one, and contains the largest species of the
whole class. The Lobsters, Cray-fish, Prawns, Shrimps, &c.,
of which the group is chiefly composed, are sufficiently well
known to need no description. We may notice, however, the
Palinurus, or Spiny Lobster, one of the largest animals in the
class ; which was known to the Romans under the name of
Locusta. This is distinguished by the very large size of its

MACROUROUS DECAPODS. — PALINURTJS. 253

lateral antennae ; which are beset, like the body, with sharp
points. The legs are all single-fingered ; not even those of the

FIG. 478. — PALINURUS.

first pair being furnished with pincers. This animal frequents
deep waters, especially off rocky shores ; and it only approaches
the coast at the return of spring, to deposit its eggs, which are
numerous, minute, and of a bright red colour. The common
English species not unfrequently weighs 12 or 14 Ibs., when

254 GALATHEA. ORDER STOMAPODA.

loaded with eggs. — The Galathea, a genus somewhat allied to the
preceding, and of which two small species are common on our
own coasts, is remarkable on account of the vast numbers in
which it sometimes appears ; the Galathea gregaria having been
seen by Sir Joseph Banks, during his voyage round the world,
to accumulate in such multitudes, that the surface of the water
appeared as if saturated with blood.

ORDER II.— STOMAPODA.

789. THE name of this Order is derived from the mode in
which the feet approach the mouth, in many of the animals
composing it ; not only the foot-jaws, but also part of the
thoracic extremities, being directed towards it (Fig. 480). The
number of legs is variable ; but there are generally from twelve
to sixteen, — one or more pairs of the feet-jaws of the Macrourous
Decapods being here developed as true legs. The general
form of the body bears considerable resemblance to that of the
Cray-fish and its allies ; the abdomen being much prolonged,
the tail-fin much expanded laterally, and the appendages beneath
the abdomen being developed and used as fin-feet. There are,
however, some considerable differences in their structure ; which
are quite sufficient to separate the Stomapods as a distinct Order.
The branchiae, instead of being inclosed in a cavity beneath the
thorax, are attached to the abdominal appendages, and hang
freely in the water (Fig. 468) ; the heart has more the form
and characters of the dorsal vessel of Insects ; the integuments
have little solidity, and are sometimes membranous and trans-
lucent ; and the nervous system is arranged in a less concen-
trated manner. — All the Stomapods are marine ; and the largest
species are only found in tropical climates. As they are
inhabitants of deep waters and the open sea, rather than of the
shores, their habits are but little known ; but from the confor-
mation of some of the Order, they may be regarded with proba-
bility as very voracious.

790. As connecting this Order with the last family of the

STOMAPODA. - MYSIS, OR OPOSSUM-SHRIMP. 255

preceding, we may first notice the curious genus Mysis^ or

Opossum-Shrimp ; which bears, in its general form, so strong a

resemblance to the ordinary Shrimps, that it has been usually

placed with them. It is distinguished, however, from the true

Decapoda, by the external position of its branchiae ; as well as

by other characters. In regard to the number of the feet, it

holds a very interesting intermediate

place between the Decapods and the

ordinary Stomapods ; for the last

pair of feet-jaws is developed into

true legs, making their number

twelve in all; and the other two

pairs have much more the form of

ordinary legs, than in the Decapods.

Each of the legs has a lateral ap- FIG 479._MYSIS VuLOARIS> about

, which is SO much developed twice the natural length : a, one

,., , ,. , , of the bifid legs.

as to appear like a second limb ; and

thus, reckoning-in the feet-jaws, which also possess similar
appendages, we may say that the Mysis has no fewer than 32
legs. The common name of this curious little animal is derived
from the peculiar conformation, which enables it to afford a
special protection to the eggs. The female has a large concave
scale, attached to the inner division of each of the posterior legs ;
and these, overlapping one another, form a pouch, which is
capable of being considerably distended. Into this pouch the
eggs are received, when they quit the ovarium ; and here they
continue until the young are so nearly developed, that they pre-
sent a very close resemblance to the parent. The parent then
opens the valves of the pouch, and sets free the whole brood at
once into the surrounding element; and these usually seem
to remain associated with the community, from which they
sprang. Although sparingly distributed in the seas of Europe,
these little animals inhabit some parts of the Arctic ocean in
amazing numbers; constituting the principal food of the pro-
digious shoals of Salmon, which resort thither in the months of
July and August, and upon which the inhabitants of Boothia
depend in great degree for their winter store of provisions ; and

256 ORDER STOMAPODA. — SQUILL A MANTIS.

serving also as one of the chief articles, on which the "Whalebone
Whale is supported.

791. The Squilla, which is sometimes termed " Sea Mantis,"
from the resemblance of its powerful claws to those of that
Insect (§ 664), may be regarded as the type of the Order. Its
carapace is small, and only covers the anterior half of the thorax ;
— the posterior being formed of rings like those of the abdomen.

FIG. 480. — SQUILLA MANTIS.

The members which, in their position, correspond with the
external feet-jaws of Decapods (Fig. 480, a), are here developed
into enormous claws, terminating in a sharp hook ; in the
typical species, Squilla mantis, the last joint or finger is furnished
with six sharp projecting spines ; and the preceding joint, or
hand, is furnished with three sharp spines, and is hollowed at
its edge into a groove, into which the finger shuts, in such a
manner as to render this claw a most efficient instrument of
prehension. The other foot-jaws, and the three first pairs of
thoracic members (£>), share in this conformation ; being fur-
nished with a sharp moveable finger, and a hand armed with
spines, against which the finger closes ; and these are directed
towards the mouth, in such a manner as to hold the prey against
it, in the most efficient manner. The three posterior pairs of
legs, which are attached to the annulated (or ringed) portion of
the thorax (c), are furnished with a brush instead of a hook at
their extremities, and more resemble the abdominal swimming
legs. The tail is expanded into a broad fin. Thus we see that
the locomotive apparatus of this animal is partly adapted for
prehension, and partly for natation (or swimming), and not at

ORDER STOMAPODA; — PHYLLOSOMA, OR GLASS-CRAB. 257

all for walking. This species is probably the largest of the
Order ; its length being about seven inches. It is common in
the Mediterranean.

792. To this Order also belongs a very curious genus, the
Phyllosoma, or Glass-Crab. Its scientific name, which means
leaf-bodied, as well as its common designation, refer to the
remarkable peculiarity of structure by which it is distinguished ;
the whole body being flattened like a leaf, and almost as trans-
parent as glass. It is composed of a large oval plate, which
represents the head, and bears the two eyes, mounted on
long footstalks, at its anterior extremity ; of a second plate,
in part covered by the preceding, and giving insertion to the
thoracic legs ; and of an abdomen which . is always short, and
in some species undeveloped. The legs, six in number, are very
long and slender ; they are bifid or divided into two, like those
of the Mysis ; and are adapted for swimming only. These
curious creatures are inhabitants of the tropical parts of the
Atlantic and Eastern Oceans.

793. It is scarcely possible to avoid being struck by the
analogy presented by this Order, to the Orthoptera among
Insects. The resemblance of the Squilla to the Mantis has already
been noticed ; and the correspondence of the Phyllosoma to the
leaf-like species of the same order (§ 653), is scarcely less
remarkable. We may also point out the many resemblances
between the Decapod Crustacea, and' the Coleopterous Insects.
They occupy a corresponding position, in being at the head of
the mandibulate series of their respective classes ; they are both
also pre-eminent in regard to the hardness of their integuments ;
and in both there is an adaptation of the extremities for walking,
rather than for swimming or flying- — which are actions analogous
to, each other (ANIM. PHYSIOL., § 663).

258

SECTION B.— EDRIOPHTHALMA.

ORDER III.— AMPHIPODA.

794. Passing on to the group of EDRIOPHTHALMA, — which is
distinguished by the absence of peduncles supporting the eyes,
and by the union of the respiratory organs with the locomotive

members, — we have to first notice the
Order AMPHIPODA, in which the
abdomen is well developed, but the
respiratory organs are connected with
FIG. 481.— GAMMARUS PULEX. the thoracic limbs only. These organs
consist of membranous vesicles, at-
tached to the base of the legs, of which some traces present them-
selves in the preceding Order ; the continual renewal of the
water in contact with them is accomplished by the constant
movements of the first three pairs of abdominal pro-legs. The
thoracic legs are fourteen in number, consisting of the ten which
are characteristic of the Decapods, with the addition of two pairs
of feet-jaws, — only one pair of these last organs being here left
in its original form. The legs are partly directed forwards,
and partly backwards, from which the name of the Order is
derived. The abdomen is much developed, and is composed of
seven segments, — the last, however, being a mere rudiment ; the
appendages of the three preceding divisions are often united into
a sort of bundle, constituting an organ which is of great service
in leaping. These Crustacea are all of small size ; but they
frequently present themselves in very large numbers. Some of
them are inhabitants of the sea and shores, whilst others are
abundant in our streams. The greater number of them are very
agile leapers.

795. The common Talitrus locusta,OT Sand-hopper (Fig. 456),

AMPHIPODA; — SAND-HOPPER, &c. 259

is a very characteristic example of this Order. It is extremely
abundant on our shores ; and may often be seen in vast numbers
on the sands, especially when the sun is shining upon them and
the tide is retreating. The whole surface of the sand, or rather
the air for a few inches above it, appears as if alive with them ;
for they are incessantly leaping to an elevation, which is, for their
minute size, very considerable, as if they were in the height of
enjoyment. They burrow in the sand ; and seldom enter the
water. Their food probably consists of the minuter animals, and
of the decomposing animal and vegetable remains, which are
left in the sand by the sea. The Gammarus pukx (Fig. 481),
which is nearly allied to the preceding in structure and in
its leaping powers, is an inhabitant of fresh water brooks;
being especially abundant in those, in which there is an accu-
mulation of decaying vegetable matter. The Corvphium is

remarkable for its very long
antennae, and for its pre-
daceous habits. It is very
abundant on the coast of
La Rochelle, where it forms
extensive burrows in the

Fio. 482. — COR YPHIUM LONGICORNE; a, terminal -, , , . ..

segment of the tail. sand> — Onl7 making its ap-

pearance, however, at the

beginning of May. It keeps up a continual war with the Anne-
lida, which inhabit the same neighbourhood ; and also attacks
Mollusca and even Fishes, as well as dead animal matter.
Scarcely anything is more curious, than to observe these creatures
at the rising of the tide assembled in myriads, moving about in
all directions, beating the mud with their arm-like antennae, and
mixing it with water in order to discover their prey. If they
meet with Annelids even ten or twenty times their size, they
unite together to attack and devour them ; and the carnage does
not cease, until the whole of the mud has been turned over and
examined. It is said that they sever the byssus, by which the
Mussels are fixed (Fig. 591) ; so as to cause them to fall, and thus
to enable them to be more readily attacked. They are in their
turn devoured by Fishes and by many Shore-Birds. The Crustacea

260

ORDER L.EMODIPODA ; CAPRELLA.

of a portion of this Order are parasitic in their habits ; attaching
themselves to the bodies of Fishes ; and having the mouth more
adapted for suction.

ORDER IV.— L^MODIPODA.

796. The Crustacea of this Order resemble the preceding in
the conformation of the respiratory organs ; but differ from all
the other Edriophthalma, in the want of development of the
abdomen. The number of legs varies considerably in the different
species. The body is composed (with the head) of eight or nine
segments, of which seven may be furnished with members ; but
not unfrequently some of the appendages are undeveloped. This
Order is divided into two Sections, according to the form of the
body; the Filifor-
mia, having the
body long and
thread-like, and the
legs also long and
slender (Fig. 483);

whilst in the Ovalia, Fie. 483.— CAPRELLA PHASMA.

the body is shorter

and broader, and the legs shorter and stouter (Fig. 484). Of
the former group, the Caprella phasma is a characteristic exam-
ple ; it is found among marine plants,
creeping along in the same manner as the
Geometer, or Looper-Caterpillars (§ 700),
often bending itself back with great rapidity,
and applying its antennae to various parts of
the body. It has five pairs of legs, of which
the second is the largest; these are not disposed,
however, in a regular, but in an interrupted
series, the second and third segments of the
thorax having only the respiratory vesicles.
In an allied genus, there are also ten legs, disposed in a con-
tinuous series ; and in another, all the fourteen are developed.

FIG. 484— C YAM us BA-

L^NAKUM.

CYAMUS. ORDER ISOPODA. 261

The Cyamus and its allies, belonging to the second division of
the Order, appear to be mostly parasitic in their habits. The
Cyamus, commonly termed the Whale-Louse, attaches itself, by
means of its strong claws, to the surface of the body of the
Whale; which is sometimes so completely covered by these
parasites, that the individuals thus infested may be easily
recognised at a considerable distance by their white colour.
When the parasites are removed, the skin of the Whale is found
to be deprived of its epidermis.

ORDER V.— ISOPODA.

797. These Crustacea bear a general -resemblance to the
Amphipoda ; but their bodies are flattened horizontally, instead
of being compressed vertically, and the abdomen is not terminated
either by appendages adapted for leaping, nor by an expanded
fin for swimming, as in that group. The thorax nearly always
consists of seven segments, and is furnished with seven pairs of
appendages adapted for walking (Fig. 456) ; but the respiratory
organs are not attached to them, but are developed as expansions
of the extremities of the pro-legs, which are attached to the
abdominal segments. These organs, which have usually an oval
form and a membranous texture, are sometimes suspended freely
beneath the abdomen ; but they are occasionally covered in by
little scales, which fold over and protect them. The females
usually have large plates attached to the base of the thoracic
legs, which form, by their meeting, a pouch in which the eggs
and young are matured ; others have a membranous bag in this
situation. The newly-hatched young have only six thoracic
segments and six pairs of legs, — acquiring an additional segment
and pair of legs at the time of their first moult.

798. Of this Order, the principal part is aquatic ; but one
group is terrestrial. Many of the former are parasitic upon other
animals, — very frequently upon larger Crustacea; this is the
case with the Bopyrus, which is parasitic upon the common
Prawn, affixing itself beneath the carapace, upon the branchiae,

262

ORDER ISOPODA ; LIMNORIA, WOOD-LOUSE.

and producing an evident swelling externally. Between eight
and nine hundred young ones have been observed beneath the
body of a single female ; and the parent has the instinct to set
them free in situations frequented by the Prawns. — Of those
marine Isopods which are not parasitic, the most worthy of notice
is the Limnoria terelrans ; which, although not more than a
sixth of an inch in length, is, through its boring habits, and its
powers of multiplication, exceedingly destructive. It pierces
timber in different directions with astonishing rapidity, appa-
rently for the purpose of feeding upon it, as in its stomach are
found minute particles of the wood. It is found in different
parts of the British Ocean, attacking wooden piles, immersed in
water, in our dock-yards, bridges, flood-gates, chain-piers, &c. ;
and perforating them in the most alarming manner.

799. It is in the terrestrial species, that we find the most
remarkable provision for the inclosure of the respiratory organs ;
these being completely folded over, by plates developed from the

abdominal members ; and
the anterior plates being
perforated with a row of
small holes, through which
the air gains access to the
gills within. Like the Land
Crabs, these terrestrial Iso-
pods (of which the common
Wood-louse is a very familiar
example), for the most part
frequent damp situations;
inhabiting dark and con- 1
cealed places, such as cellars, \ >
caves, holes in walls, the un-
der-side of stones, &c. They feed upon decaying animal and vege-
table matter, and come forth from their retreat in damp weather.
They crawl slowly, except when alarmed ; and they have the
power of rolling themselves into a ball, so as to expose on the
outside nothing but the plates of the back, and to conceal the
appendages of the underside of the body.

FIG. 486. — ARMADILLO

PUSTULATUS.

FIG. 485.— ANILOCRA.

ORDER ISOPODA ; TRILOBITES. 263

800. The order Isopoda is probably the situation, in which
we are to place the remarkable fossils known under the name of

A

V

B

FIG. 487 — CALVMKNK FIG. 488. — A, ASAPHUS KXPANSUS. B, THE SAMK

BiUMENBACHH. ROLLED UP.

Trilobites-t from the three lobes into which the body is divided
lengthways (Fig. 487). These are found in the very earliest of
the formations that contain fossils at all ; and they appear to
have ceased to exist, before the creation of Mammalia. They
resemble the Isopoda in the equality of their segments, as well as
in the tri-lobed division of the body, which is presented by some
of the recent species of that order ; and also in their tendency to
roll themselves into a ball (Fig. 488). Their exact situation,
however, cannot be known, until some information has been
gained in regard to their extremities, of which no remains have
yet been discovered. It is probable that these were very short ;
in which respect they would correspond with those of certain
parasitic Isopods; but they may have been soft and membranous,
and formed for swimming, like those of the Phyllopoda. They
bear no inconsiderable resemblance externally to the Chiton
among Mollusca (Fig. 584) ; and could probably, like them,
draw the border of the shell completely down to the surface on
which they were adherent. Their Articulated character, how-
ever, is fully evidenced by the nature of their eyes, which have
the compound structure peculiar to that Sub-Kingdom. This
has been so perfectly preserved in many specimens, that the
facets may be counted with the aid of a magnifying-glass ; and
as many as four hundred have been found to exist in a single
specimen.

264

SECTION C.— BRANCHIOPODA.

ORDER VI.— PHYLLOPODA.

801. We are now arrived at the third Section of the class, —
that of BRANCHIOPODA ; in which the union between the legs
and respiratory organs, which we have seen to be gradually
taking place in the preceding Orders, becomes more complete, —
there being now no distinct gills, and the anterior legs being
converted into respiratory organs, by an expansion of their sur-
face. Hence the name of the group ; which means " gill-
footed." In the greater part of this and the succeeding groups,
the body is inclosed in a sort of horny shell ; which sometimes
appears composed of but a single piece, and in other instances
is formed like the shell of a bivalve Mollusk : — hence they are
commonly known as Entomostracous Crustacea (this term
meaning, inclosed in a shell). The eyes are generally placed near
each other ; and are sometimes so close, as to run together (so to
speak) into one mass. The foot-jaws are all converted into
true legs, being, like them, adapted for swimming ; and even
the antennas sometimes become locomotive organs. The number
of legs varies greatly ; reaching in some
species to above a hundred ; but being
commonly much less. All these animals
are aquatic, and most of them inhabit fresh
water. They are for the most part extremely
active in their habits ; and are all of small size,
some of them being even of microscopic minute-
ness. This active locomotion is doubtless in

riQ. 4oy« — -v/YCLOPS

VULOARIS, magnified. part connected with the act of respiration, and

serves to produce a constant interchange in the

water in contact with the surface of the body, and especially

PHYLLOPODA ; — LIMNADIA ; APUS. 265

with the branchial expansions of the legs. Even when the animals
are at rest, these last organs are seen to be in rapid motion.
The eggs are arranged in a mass in a cavity beneath the back of
the shell, or are inclosed in a common envelope, and carried in
one or two bunches or masses at the base of the tail (Fig. 489).
802. The Order PHYLLOPODA includes those Branchiopoda,
whose body, sometimes naked or shell-less, and sometimes
inclosed in a shield-like carapace or in a bivalve shell, is divided
into a great number of segments, nearly all of which are
furnished with leaf-like appendages, or gill-feet. They vary
considerably in their conformation ; some of them being provided
with a certain number of simple swimming feet, placed behind
the gill-feet ; but of the latter there are always at least eight
pairs, and sometimes their number amounts to sixty pairs. The
first division of the order includes those, which have the. body
protected by a horny shell. This is the case with the Limnadia
(Fig. 490), which has a bivalve shell, and bears a considerable

FIG. 490.— LIMNADIA. FIG. 491.— APUS MONTAGU;.

resemblance to the Daphnia (§ 804), except in the form and
number of the feet; and in the Apus (Fig. 491), which has a
simple shield-like shell, and in which the feet are very numerous,
but all except the anterior ones are extremely small. These last
are extremely remarkable for the power which their eggs possess,
of retaining their vitality for several years, when the waters in
which they are deposited have been dried up. They inhabit
lakes, pools, and ditches, and are often found in vast numbers,
especially in the spring and beginning of the summer. They are
sometimes raised into the air by whirlwinds, and scattered again

266

PHYLLOPODA ; BRINE-SHRIMP ; BRANCHIPUS.

like rain. Their eggs are of a red colour, and fall to the bottom
of the water, when set free from the egg-cases which the parent
bears near its tail. When first hatched, the young differ con-
siderably from their parents, having but one eye, four legs, no
tail, and the shell covering only the front half of the body.
These little Crustacea are said to feed upon young Tadpoles.
They swim well on the back, and burrow in the sand, elevating
their tails in the water.

803. In the species included in the second division of the
Order, there is neither bivalve shell, nor any trace of a shield-
like carapace ; but the body is entirely soft. It is usually much
prolonged, and composed of a large number of segments ; but
the branchial appendages or gill-feet do not exceed eleven pairs.

To this group belongs the
curious Artemia salina, or
Brine-shrimp ; a small Crus-
tacean, about half an inch in
length, commonly found in the
salt-pans at Lymington, when
the evaporation of the water is
considerably advanced. The
accompanying figures represent
the progressive stages of its
development. " Nature having

constructed it with members solely adapted for swimming, it
seems to be in perpetual quest of prey, gliding with an almost
even motion through the water, and moving with equal indif-
ference on the back, belly, and sides ; the shape of the animal,
the undulating movements of its fins, and the glossy appearance
of its coat, render it an object
of a very interesting descrip-
tion.""— Nearly allied to this is
the Branchipus ; of which the
several species are found, often
in great numbers, in small pools, especially after heavy rain ;
sometimes even in those which are left on the uneven surfaces of
stones, — the eggs, which are inclosed in a strong shell, seeming

FIG. 492.— ARTBMIA SALINA, in different
stages.

FIG. 493. — BRANCHIPUS STAGNALIS.

CLADOCERA ; DAPHNIA, OR WATER-FLEA. 267

to have been transported by the wind. The Branchipi generally
swim on their backs ; and their short lamellar feet, which are
unfit for walking, are then kept in an undulatory motion, that
sends forward a current of water, along a channel hollowed in
the lower side of the body, to the mouth, and thus supplies the
animal with food. At other times, they swim more forcibly, by
alternate lateral strokes of the tail upon the water.

ORDER VII.— CLADOCERA.

804. The Order CLADOCERA consists of those minute Crus-
tacea answering to the foregoing description, which have the
body inclosed in a bivalve shell. These belong, for the most
part, to the genus Daphnia ; of which the common species,
Daphnia pulex (which has also received the name of Monoculus
from its single eye), is commonly termed the Arborescent Water-
Flea, from its power of leaping, and from the branching form of
its antennae, which serve as oars. It is very abundant in many
ponds and ditches, coming to the surface in the mornings and
evenings, and in cloudy weather ; but seeking the depths of the
water during the heat of the day. It swims by taking short
springs, and feeds on minute particles of vegetable substances,
not however rejecting animal matter when offered. There are
several curious points, relative to the propagation of these little
animals, which are worthy of notice. After the eggs leave the
ovaries, they remain in a large cavity between the body and the
shell ; here they usually attain their complete development, —
the young coming forth into the world, in a form very nearly
resembling that of the parent. From the transparency both of
the eggs and of their containing envelope, the whole process of
development may be distinctly seen. At first the eggs are
quite round, and seem as if made up of a multitude of minute
globules. The shape then alters a little, becoming oval; and
these globules augment in number ; but as yet no trace of any
body is perceptible. A little afterwards, we see a black spot in
the centre, which is the eye, and which is the first organ visible.

268 ORDER CLADOCERA ; DAPHNIA.

The other organs then begin to show themselves ; but it is not
until near the end of the fourth day, that any motion is per-
ceptible. They come forth into the world, at the end of the fifth
day, with the tail curved up within the shell ; and very shortly
after birth, this tail maybe seen to spring forth with a sudden jerk,
and to assume its natural position. In a short time afterwards,
the animal acquires the perfect form, and it speedily increases
in size, — throwing off its envelope, and acquiring a new one, at
short intervals. In summer these moultings are frequently
seen to be performed every two days ; but in colder weather,
several days elapse between them. They do not cease with the
full growth of the animal, but continue during its whole life.
The purpose of this may be, to prevent the animal being injured
by the tendency of its shell to become overgrown with parasitic
Animalcules and Confervas ; for weak and sickly individuals
may be frequently seen so covered with these growths, that their
motion and life are soon arrested, the animals apparently not
having strength enough to throw off their envelope.

805. After the third or fourth moulting, the young Daphnia
begins to deposit its eggs in the cavity of its back ; these may
be frequently seen there, as early as the tenth day of its separate
existence. Soon after the young are born, another moulting
takes place ; and the egg-coverings, which have been left in the
cavity, are thrown off with the shell. In a very short time after-
wards, another brood of eggs is seen in the cavity ; these are
soon hatched, and another moult takes place ; and these pro-
cesses continue to take place through the whole season, until the
weather becomes severe. All the Daphnice then seem to be
destroyed ; none having their existence prolonged through the
winter. There is, however, a very curious provision for perpetu-
ating the race. At particular seasons, the Daphnia may be
found with a dark opaque substance on the back of the shell.
This has been termed the ephippium, from its resemblance to a
saddle. When examined by the microscope, it is seen to be of
a dense texture, and to be composed of a mass of hexagonal cells ;
and to contain two oval bodies, which are capsules opening like
a bivalve shell, each inclosing an ovum covered with a horny

DAPHNIA; POLYPHEMUS.— ORDER OSTRAPODA. 269

envelope. This is first seen after the 3rd moulting ; after the
4th it passes into the open space in the back ; and at the 5th it
is thrown off with the shell, and remains floating on the surface of
the water, until the temperature rises sufficiently to hatch the eggs.
The ephippial eggs which are deposited in the summer are pro-
bably developed during the same season ; but those which are
laid in the autumn remain undeveloped during the winter, being
protected by their peculiar envelopes ; and it is by the action of
the returning warmth of spring upon them, that the new gene-
ration of Daphniae is produced in the next year. They may be at
any time hatched, however, by artificial warmth. " These two
species of eggs," says an attentive observer of the processes now
described, " produced by the same being, offer a very singular
example in the history of animals, and show with what wisdom
Nature provides for the preservation of even her smallest
creatures."

806. The Polyphemus has, like the Daphnia, oar- like
antennas, divided into two branches. It
is remarkable for the large size of its
head, which is almost entirely occupied
by a single enormous eye (Fig. 494.) It
swims on its back or sides, giving to its
FIG. 494.-POLYPHKMUS antennae and legs quick and repeated

STAR NORUM, magnified. , '. ..1,1

motions, and executing with the greatest
ease all kinds of evolutions.

SECTION D.— ENTOMOSTRACA.

ORDER VIII.— OSTRAPODA.

807. We are now arrived at the last group of Masticatory
Crustaceans; in which we lose all trace of organs peculiarly
adapted for respiration, — the feet not being modified for this
purpose, as in the last Section, but being expressly formed for
swimming, each member being terminated by two oars composed

270 ENTOMOSTRACOUS CRUSTACEA.— OSTRAPODA.

of two or more joints. There is considerable resemblance, except
in the conformation of the mouth, between some of these and
the Suctorial Crustacea hereafter to be described, It is to this
group, that the term Entomostracous has been restricted by later
Naturalists ; but it is commonly applied to the minute Branchi-
opodous Crustacean just described, and even to the Limuli
(§ 816), as well as to these — all agreeing in the inclosure of the
body in a single or bivalve shell.

808. In the Order OSTRAPODA, the body does not exhibit a
division into distinct rings, and is altogether inclosed between
the two valves of a bivalve shell. This shell is furnished with
a hinge, like that of a bivalve Mollusk ; and can be closed in
such a manner as to envelop the animal completely ; but the
valves are in general sufficiently wide apart, to allow the extremi-
ties of the antennas and feet to pass out between them. There
are two pairs of antennae ; of which the first (#, Fig. 495) is
slender, whilst the second (b) is large, directed
downwards, and adapted for swimming. The
mouth is situated near the middle of the inferior
surface of the body ; it is furnished, besides an
FIG. 495.— CYPRIS upper and lower lip and a pair of mandibles, with

VIDUA, magnified. . of which the posterior

carries a large flapper-like appendage, that is probably to be
regarded as a branchial organ. The true thoracic feet are only
four or six in number. The body terminates in a bifid tail ;
and the eggs are lodged, as in the Daphniae (to which these
animals bear a strong general resemblance), in a cavity between
the back and the shell. The principal genus of this Order is the
Cypris, which, like the Daphnia and the Branchippus, is an
inhabitant of pools and streams; and strongly resembles the
former of these, in regard to its moultings and the deposition
of its eggs. The young are not born alive, however ; for the
mass of eggs, including about twenty-four, is attached by
the fema|e to water-plants, with the aid of a glutinous secre-
tion, — an operation which lasts about twelve hours. There are
but two pairs of legs in this genus, of which the posterior does
not make its appearance outside the shell ; being bent upwards

ORDER OSTRAPODA ; CYPRIS. 271

to give support to the ovaries. The food of these little animals
consists of dead (but not putrid) animal matter, conferva, &c. ;
but they will not attack living animals that are well and strong,
although they are often seen to attack worms, &c., when
wounded and weak, and even to prey on one another. When the
ponds and ditches in which they live dry up in summer, they
bury themselves in the mud, and thus preserve their lives as long
as the mud retains any moisture, — becoming as active as ever
when the rain falls, and again overflows their habitations. After
long-continued droughts, however, when the mud becomes very
dry and hard, they perish ; but the race is then kept up by the
eggs, which are capable of resisting this influence. These little
creatures are very lively ; being almost constantly seen in
motion, either swimming by the united action of their antennae
or anterior feet, or walking upon plants and other solid bodies
floating in the water. When alarmed, they draw their antennaa
and legs within the shell, and close its valves so firmly, that
there is no possibility of opening them. An allied genus, Cythe-
rina, distinguished by the possession of three pairs of legs, is an
inhabitant of salt water.

809. There is abundant evidence of the former existence of the
minute Crustacea of this group, to an enormous extent ; and
their size was much greater. The largest existing species of
Cypris does not exceed one-sixteenth of a line in length. But
in certain strata of the Secondary and Tertiary formations, which
appear to have been deposited by fresh water, we find layers,
sometimes of great extent and thickness, which are almost en-
tirely composed of the fossilized shells of Cyprides, many of
them exceeding a line in length ; and in the Chalk, which was a
marine deposit, the remains of bivalve Crustacean shells, proba-
bly belonging to the genus Cytherina, are frequently to be
found in great abundance.

272

ORDER IX.— COPEPODA.

810. The Entomostraca of this Order bear a strong resem-
blance in the general form of their bodies to the Edriophthalma ;
they have no carapace, nor bivalve shell, like that of the last
Order ; and their envelope is of membranous or soft consistence.
The head is large, and distinct from the thorax ; and the body is
distinctly divided into several segments, of which the thorax pre-
sents from three to five, and the abdomen two or more. The num-
ber of legs is always at least eight or ten ; and the abdomen is ter-
minated by a bifid tail adapted for swimming. The first pair of
antenna is long, slender, and many-jointed ; those of the second
pair are sometimes wanting, and sometimes developed into swim-
ming-legs. The mouth is furnished, besides the mandibles and
maxillse, with two or three pairs of feet-jaws ; of which the pos-
terior are usually very large, and furnished with a set of feathery
bristles, which almost cover the remainder of the buccal appa-
ratus. In one division of the Order, we find the two eyes quite
distinct ; in the other they form but a single mass on the median
line. The eggs are contained, when they quit the ovarium, in
two capsules borne at the base of the tail (Fig. 489) ; and the
young, when they first emerge from them, present a form differ-
ing greatly from that of the parent, which is only attained
after several moults (Figs. 496, 497). The Cyclops is a very
common genus of this Order ; belonging, as its name implies, to

FIG. 496 — LARVA OF THE CYCLOPS. FJO. 497.— CYCLOPS.

the single-eyed division of it. This genus contains numerous
species ; of which some belong to fresh water, whilst others are

ORDER COPEPODA ; — CYCLOPS. 273

marine. The fresh- water species abound in the muddiest and
most stagnant pools, and often too in the clearest springs ; the
ordinary water with which London is supplied frequently con-
tains great numbers of them. The marine species are to be
found, often in immense abundance, in small pools on the sea-
shore, within high-water mark, living among the sea-weeds and
corallines ; and others inhabit the open ocean, where, by the
luminous properties they possess, they assist in producing its
phosphorescence. Their vast numbers are the less surprising,
when the extraordinary rapidity of their multiplication is known.
It has been calculated by Jurine, who attentively observed their
habits, that from one female, 4,442 millions of young might be
produced in a year. The time occupied in the transformations and
development of the young, varies according to the season ; and
this variation appears to depend, according to the experiments of
Mr. Baird,* not only on temperature, but also on the degree of
light, the metamorphosis being retarded by darkness, as in the
Batrachia (§ 483). The Cyclops is carnivorous, feeding upon
Animalcules that are brought to the mouth by the action of
the feet-jaws, which create a whirlpool in the surrounding water;
and in this manner they even devour their own young. In their
turn they fall victims to the larvae of aquatic Insects, the Water-
spiders, and other aquatic animals, which thus restrain their
multiplication within due bounds. Owing, probably, to the
softness of their envelopes, they do not resist drought as well as
many other Entomostraca ; but they seem capable of resisting
almost any degree of cold, and they have been immersed for
some time in spirit of wine, without losing their vitality.

811. All these minute Entomostraca furnish very interesting
objects for Microscopic examination ; and the study of their
development and habits will abundantly repay the most diligent
observation. Except during the winter, there is probably not a
pool of water in this country, that does not contain some species
of them.

* " Magazine of Zoology and Botany," Vol. I., p. 316. A large proportion
of the facts here stated respecting these and other Entomostraca, are derived from
Mr. Baird's highly interesting and valuable papers in that journal.

274 SUCTORIAL CRUSTACEA.

812. We next pass to the Sub-Class of Suctorial Crustacea,
in which the mouth, instead of being furnished with mandibles
and maxillae adapted for the division of solid aliment, is prolonged
into a beak, and can only receive liquid substances. Still among
the Crustacea, as in Insects, the parts which compose the Mandi-
bulate mouth of the preceding Orders, may be recognised in the
Haustellate or Suctorial mouth of those we have now to consider.
The proboscis is formed by a prolongation of the upper and lower
lip ; and it is generally accompanied by a pair of long appen-
dages, which evidently correspond with the mandibles of the
preceding Orders, and which serve to make the punctures into
which the proboscis is inserted. Other appendages, found at its
base, are the representatives of the maxilla and feet-jaws of the
Mandibulate Orders ; and these are frequently developed as
hooks, by which the animal attaches itself to its prey. Many
of the Suctorial Crustacea bear a strong resemblance in their
general form to the Cyclops and other Copepoda. The body
is usually divided, at its anterior part at least, into distinct
segments ; and there are generally four pairs of legs, each fur-
nished at its extremity with two oar-like expansions. The
resemblance is often strongest in the early stages of development ;
— the young Lerncea, for example (Fig. 502), being scarcely
distinguishable from the young Cyclops (Fig. 496). But in their
advance towards maturity, the Suctorial Crustacea frequently
undergo the most extraordinary changes ; so that, if we were to
attend to their adult forms alone, we should be tempted to
exclude them from the class altogether, — in so small a degree
do they present its distinguishing characters. This group is
divisible into three Orders ; of which the first two are parasitic,
and the last free.

X. SIPHONOSTOMA. In this Order, the mouth is armed with
styliform mandibles ; the thorax is composed of several distinct
joints, and bears three or four pairs of swimming-feet ; and the
feet-jaws are well developed.

XI. LERKLEIDA. The mouth in this Order, as in the preced-
ing, is armed with piercing mandibles ; but the thorax exhibits
no division into segments ; and both the feet-jaws and the true
legs are undeveloped.

SUCTORIAL CRUSTACEA ; — SIPHONOSTOMA. 275

XII. ARANEIFORMES. This very curious group, which was
formerly ranked among the Arachnida, has the feet adapted for
walking, and well developed ; but the mouth is unpossessed of
distinct mandibles.

ORDER X.— SIPHONOSTOMA.

813. The Crustacea of this Order are all parasitic upon Fishes,
aquatic Batrachia, &c. ; and many of them are known under the
name of Fish-lice. Their general characters may be understood
from those of the two genera Argulus and Caligus, which will
be briefly described. The Argulus has
its body covered with an oval shield, which
does not extend, however, over the poste-
rior part of the abdomen. There are four
pairs of legs, somewhat resembling those
of the Branchiopoda, and adapted for
swimming. The tail also is a kind of
Fro. 498-AKGULus FOLIA- Swimmeret. On each side of the beak

CEIJS. 1, the animal mag-
nified; 2, one of the large or proboscis, there is a large short cylin-

^Sr?7£&a drical appendage, terminated by a curious
length. sucking-disc ; and there is also a pair of

larger jointed members, terminated by prehensile hooks. These
two pairs of organs, enabling the animal to attach itself firmly
to that on which it lives, are probably the representatives of the
feet-jaws. The eggs of the Argulus are deposited upon floating
bodies, like those of the Cyclops ; and the young, when they
first come forth, bear a strong resemblance to those of that genus.
Their swimming organs consist of the oar-like antennae and feet-
jaws; the true swimming legs, and the suckers and hooks on
the feet-jaws of the adult, not making their appearance until
after several moultings. These Crustaceans may be regarded as
in several respects intermediate between those of the preceding
Order, and the true Suctorial Crustacea ; for they have, even in
the adult state, much more locomotive power than the generality
of the latter ; and are not unfrequently met with swimming freely
in the water.

814. The Caligus (Fig. 499) is much more strange in its form

276

SUCTORIAL CRUSTACEA ; — CALIGUS.

Its body is composed of two principal portions ; the anterior one

covered by the oval
shield or carapace
(Fig. 500, a); the
d e posterior, forming the
termination of the tho-
rax and the rudimen-
tary abdomen, is di-
vided into rings. The
first pair of antennae is
reduced to the condi-
tion of small flattened
plates, in some species
bearing a sucker. The
antennae of the second
pair (b) also are short,
and composed of only
two joints. At c is
seen a sucker, formed
by the labrum, and

FIG. 499,-CALiGus. FIG. SOCK-UNDER SIDE OF CALIGUS. inclosing the mandi-

bles. The maxillae

(d, e) are represented by two pairs of rudimentary appendages,
situated at the sides of the sucker, one of them terminated by
horny claws directed backwards. The feet-jaws (/, g, h), to the
number of three pairs, are instruments of prehension, by which the
animal attaches itself ; and behind the last pair of these, there is
a forked appendage on the central line (i)9 which probably assists
in the same object. There are four pairs of thoracic legs ; of
which the first three (j9 k, I), formed for swimming, are situated
beneath the carapace ; whilst the last (m), which comes forth
behind it, is rather adapted for walking. The abdomen forms
but a single segment ( p ) ; and is furnished with a pair of small
fin-like appendages (q). One of the most curious parts in the
structure of this animal, is the pair of long tubes (r), which are
attached to the sides of the abdomen of the female ; these appear
to be receptacles for eggs, and to be analogous to the capsules of
the Cyclops, &c. (Fig. 489).

277

ORDER XI.— LERN^EIDA.

815. The animals of this Order depart so widely from the
ordinary form of the Crustacea, that, until their early state was
known, they were ranked among the lower Articulata. In their
adult state, there is an almost complete absence of members or
appendages ; and those which remain are destitute of joints,
being merely fleshy lobes serving to attach the animal to
the surface of that on which it lives. They all bear a more or
less close resemblance to the Lerncea, an animal which is not
unfrequently found on the eyes and gills of Fish. The form of
the adult is displayed in Fig. 501 ; which
shows its long suctorial trunk or proboscis
(a) ; its short thorax (&), bearing the pair of
legs (c), by which the animal is attached;
its large abdomen (d), and its two egg-
capsules (0). The legs are united to each
other at their extremities ; and bear a kind
of sucker (/), which is applied to the surface
attacked by the animal, and assists in retain-
ing it there. The whole anterior part of the
body, however, is usually buried in the sub-
stance of the part, from the juices of which
the Lernasa derives its nutriment. — However
dissimilar the form and characters of this
creature appear, to those of even
the preceding group, yet its con-
nection with them is made evident in two ways.
In the first place, there are numerous parasitic
species, which depart less from the ordinary type ;
forming a gradual transition from the Suctorial
Crustacea of the last order, to the highly-aberrant
FIG. 502.-LARVA form presented by the Lernsea ; so that, if the latter
is excluded, it would be difficult to say where the
line is to be drawn. And again, the early forms of the Lernaea
(Fig. 502) so strongly resemble those of the Cyclops and other

FIG. 501 — LERN^A.

278 ARANEIFORM CRUSTACEA; — PYCNOGONIDA.

Entomostracous Crustacea (Fig. 496), that it would be im-
possible to show any decided difference between them. This
is a very interesting example of the importance of becoming
acquainted with the whole Natural History of an animal, whose
place in the scale is at all doubtful.

ORDER XII.— ARANEIFORMES.

816. This is a very remarkable group, which is only referred
to the position here assigned it, because it can scarcely be placed
in any other, — at least without a more exact knowledge of its
internal structure and development. It consists of the small
family PYCNOGONIDA ; which, in regard to the general form of
the body, and the completeness of the extremities, seems to take
rank rather with the higher Crustacea, or with the Arachnida.
With the latter they have been commonly associated, on account
of the number of their legs ; but they differ in the absence of
breathing pores, by which the want of in-
ternal respiratory organs may be inferred ;
and in their marine residence. There is
reason to believe that the digestive cavity
is not confined to the narrow body ; but
that it sends prolongations into the legs, —
as it does into the rays of the Star-fish ;
and from this circumstance, as well as from
the absence of a respiratory apparatus, the circulating system may
be regarded either as incomplete, or as altogether wanting, — the
respiration being provided for, as in the lower tribes of Crustacea,
by the exposure of the fluids of the body to the surrounding
medium. Further, the residence of these animals would seem
to remove them from the Arachnida ; for they are all marine,
many being found amongst plants or stones on the sea-beach,
and others being dredged up from deep water. Their minuteness
renders it difficult to ascertain many points of their structure ;
and much is still to be learned respecting them. Various species
exist on our own coasts. Their motions are remarkably slow
and apparently difficult ; and it is obvious from this circumstance,

SUCTORIAL CRUSTACEA , — PYCNOGONIDA .

279

as well as from the conformation of the mouth, that their prey
must consist of either dead animal matter, or of living animals
as defenceless as themselves.
The females are distin-
guished by the possession
of a pair of spurious legs
(Fig. 504), placed in front
of the rest, and appropriated
to the purpose of holding
and carrying the eggs.
These are collected into
globular masses, enveloped
with a thin skin or mem-
brane,each mass being firmly
adherent to the limb. There
are several of these masses
in most species of the
tribe ; but in Pycnogonum itself, the eggs form a single broad
square membrane laid under the body. — The proboscis of these
curious animals, which seems to refer them to the group of
Suctorial Crustacea, is really the entire head ; and the organs
which have been usually described under the name of palpi and
mandibles, as appertaining to it, are in reality appendages of the
thorax, and must be considered as metamorphosed Jegs ; so that
the Pycnogonidae really have seven pairs of legs, like the Crus-
tacea to which they are most nearly allied.

FIG. 504. — NYMPHON GROSSIPES, and under side
of its Beak.

There now only remains to be considered the third sub-class
of the Crustacea ; which consists of but a single Order.

ORDER XII.— XYPHOSURA.

817. Although this group only contains a single genus, the
Limulus, or King-crab, yet the structure of this departs so
widely from that of all the Crustacea we have hitherto con-
sidered, that it cannot be referred to the same Order, or even

280 ORDER XYPHOSURA; — LIMULUS OR KING-CRAB.

the same Sub-Class, with any of them. The Limuli, — which are
Crustacea of considerable size, sometimes attaining the length of
two feet, — have their bodies divided into two parts ; of which
the anterior, covered by a large semicircular shield (0, Fig. 506),
bears the eyes, the antennae, and six pairs of legs, which sur-
round the mouth (5), and are used both for walking and for

FIG. 505 — LIMULUS.

FIG. 506.— UNDER SURFACE OF LIMULUS.

mastication ; whilst the posterior portion of the body, which is
covered by another shield of a somewhat triangular shape,
bears on its under surface five pairs of swimming legs, of
which the last is furnished with gills ; and this triangular shield
terminates in a long pointed process (</). Now when we com-
pare the appendages to the head and body of these animals, with
those of ordinary Crustacea, it is evident that the first pair of
the legs surrounding the mouth of the Limulus represents their
mandibles; that the second and third pairs represent their
maxillae ; the three following pairs of legs their feet-jaws ; and
the five pairs of swimming-members, abdominal fin-feet, — the
true thoracic legs being altogether absent. Besides the pair of
compound eyes, characteristic of the Crustacea in general, the
Limuli have a pair of small simple eyes, placed anteriorly, near

LIMULI. — GEOGRAPHICAL DISTRIBUTION OP CRUSTACEA. 281

the central line. — The Limuli are confined to the shores of
tropical Asia, the Asiatic Archipelago, and tropical America.
As the best-known species comes from the Mollucca Islands, they
are sometimes termed Molucca Crabs. Of their habits very
little has been ascertained. They appear to prefer the neigh-
bourhood of sandy shores, and it is said that when kept from
the water, they bury themselves in the sand, in order to avoid
the violent heat of the sun, which causes them speedily to perish.
They feed upon animal flesh. The long horny process of the pos-
terior shield is not developed in the young animal ; which also
wants the posterior or branchial members. This process is used
by some of the Malays as a point for their arrows ; the wounds it
makes being dangerous, like those made by the spines of many
Fishes, on account of their jagged character. On the coast of
America, where the Limulus is known as the Casserole Fish,
the shell is employed as a ladle for water. — Fossil remains of
this genus are not uncommon in the Secondary and Tertiary
strata ; and it may be further remarked that, in several particu-
lars, the TriloUtes may be regarded as having been probably
analogous to it.

Geographical Distribution of Crustacea.

The extensive study of this large and important class, by
M. Milne-Edwards, has enabled him to arrive at some very
interesting conclusions in regard to its Geographical Distribution.
An outline of these will be here introduced, because they would
probably serve, with some modifications, to represent the general
facts relating to the distribution of other Classes.

818. It has been pointed out, in the preceding sketch of
the principal forms of the Crustacea, that different species have
different localities, or residences assigned to them (as it were),
on the surface of the globe. We have seen that some are exclu-
sively confined to fresh water, — that others are inhabitants of the
brackish water of estuaries, — that others take up their abode on
the shore, where they are periodically covered and left dry by
the tide, — that others frequent the shallow waters in the neigh-
bourhood of the shore, — that others are found near the bottom
of the deeper waters, at no great distance from land, — that others,

282 GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA.

again, roam freely through the open sea, — and finally, that others
are only to be met with on the dry land, at a considerable dis-
tance from the shore. Thus we see that each species has an
appropriate kind of residence, for which it is peculiarly adapted
by its organisation and habits ; but it may be further stated, that
each species has an appropriate place of residence, which is very
much determined by the temperature of the region. It is true
that there are many species very extensively distributed ; but
this results from their being adapted, by some peculiarities of
structure and habit, which we cannot detect, to sustain life
under a considerable variety of external conditions (§ 13). The
extent to which even these species are distributed, however, will
depend, in great part, upon the locomotive powers with which
they are endowed, either in their adult or their young states ; and
also (in regard, at least, to all but the freely-swimming marine
species) to the continuity of a line of coast, from one point to any
other, along which their migrations may be effected. The
existence of constant or periodical currents, too, — such as the
Gulf Stream of Mexico, — will often affect the distribution of
species ; thus it is probably to this cause, that we are to attribute
the presence of some American Crustacea on the shores of the
Canary Islands.

819. The following are the general principles arrived at by
M. Milne-Edwards in regard to the influence of Temperature on
the Geographical Distribution of Crustacea.

I. The different forms and modes of organisation of these animals
manifest themselves more, in proportion as we pass from the Polar
Seas towards the Equator. — Thus, on the coasts of Norway,
where there is frequently a vast multiplication of individuals of
the same species, the number of species is very small ; but the
latter increase rapidly as we go southwards. Thus the number
of species of Crustacea of the first two Orders, known to exist on
the coast of Norway and the neighbouring seas, is only sixteen ;
but eighty-two are known to be inhabitants of the western shores
of Britain, France, Spain, and Portugal; one hundred and fourteen
are known in the Mediterranean Sea; and two hundred and two in
the Indian Ocean. A similar increase may be observed in fol-
owing the coast of the New World, from Greenland to the

GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA. 283

Caribbean Sea ; the number of species of Decapods in the former
region being only twelve, whilst in the latter it is seventy-one.

II. The differences of form and organisation are not only more
numerous and more characteristic in the warm than in the cold
regions of the globe ; they are also more important. — The number of
natural groups, which we find represented in the Polar and Tem-
perate Regions, is much smaller than that of which we find types
or examples in Tropical Seas. In fact, nearly all the principal
forms, which are met with in colder regions, also present them-
selves in warm ; but a very large proportion of the latter have
no representatives among the former. Thus, of the three primary
groups, into which the Class is at first subdivided, the Xypho-
sura are altogether wanting beyond the forty-fourth degree of
latitude. Again, the Brachyourous and Anamourous Decapods
appear to be altogether excluded from some of the most northern
regions that have been explored. Of the family of Squillidae
(§ 791 ), so highly characteristic of the Order Stomapoda, it is
rare to meet with any members, north of the forty-fifth degree
of latitude. And the curious group of Phyllopoda is restricted
within a still nearer neighbourhood of the Tropical Region.

III. Not only are those Crustacea, which are most elevated in
the scale, deficient in the Polar Regions ; but their relative num-
ber increases rapidly as we pass from the Pole towards the
Equator. Thus the Brachyoura, which must be considered as the
most elevated of the whole series, are totally absent, as we have
just seen, in some parts of the arctic region ; and we find their place
taken by the far less complete Edriophthalma, with a small num-
ber of Anomourous and Macrourous Decapods. In the Mediterra-
nean, however, the Decapods surpass the Edriophthalma in regard
to the number of species ; and the Brachyourous division predomi-
nates over the Macrourous, in the proportion of two to one.
And in the East and West Indies, the short-tailed are to the
long-tailed Decapods, as three, four, or even five, to one. — Again,
the Land-Crabs, which are probably to be regarded as taking
the highest rank among the Brachyoura, are only to be met with
between the tropics. And of the flumatile Decapods (those
which inhabit rivers, brooks, and lakes), a large proportion
belong in tropical regions to the elevated type of the Brachy-

584 GEOGRAPHICAL DISTRIBUTION OF CRUSTACEA.

oura ; whilst all those found in the temperate and arctic zones
belong to the Macrourous division.

" IV. When we compare together the Crustacea of different
parts of the world, we observe that the average size of these
animals is considerably greater in tropical regions, than in the
temperate or frigid climes. The largest species of the arctic and
antarctic seas, are far smaller than those of the tropical ocean ;
and they bear a much smaller proportion to the whole number.
Further, in almost every group, we find that the largest species
belong to the equatorial regions ; and that those which represent
them (or take their place, as it were) in temperate regions, are
of smaller dimensions.

V. It is where the species are most numerous and varied, and
where they attain the greatest size, — in other words, where the
temperature is most elevated, — 4hat the peculiarities of structure,
which characterize the several groups, are most strongly manifested.
Thus the transverse development of the cephalo-thorax, which is
so remarkable in the Brachyourous Decapods (the breadth of the
carapace of the typical Crabs being much greater than its length
from back to front), is carried to its greatest extent in certain
Crustacea of the Equatorial region; and the same might be
stated of the characteristic peculiarities of most other natural
groups. Further, it is in this region that we find the greater
part of those anomalous forms, which depart most widely from
the general structure of the Class.

VI. Lastly, there is a remarkable coincidence between the
temperature of different regions, and the prevalence of certain
forms of Crustaceous animals. Thus there are few genera to be
met with in the West Indian seas, which are not represented in
the East Indian, — the species, however, being usually different.
The same may be said of the genera inhabiting the temperate
regions of the globe ; — similar generic forms being usually met
with in the corresponding parts of the Old and New World, and
of the Northern and Southern Hemispheres, although the species
are almost invariably different.

CHAPTER XI.
OF THE CLASS OF MYRIAPODA.

820. The Class Myriapoda is the lowest in which we meet
with articulated members, or distinct jointed legs, as well as with
an articulated body. These legs are intermediate in conforma-
tion between the more highly-organized legs of Insects, and the
simple bristle -like appendages possessed by some of the Anne-
lida ; and this is exactly the place to which we should refer the
animals of this class, from a regard to their general structure.
For, on looking at the form of their bodies, we see that they are
distinguished by a uniformity in the character of their segments,
nearly as great as that which prevails in the Annelida ; so that
an lulus (Fig. 511) might almost be likened to an Earthworm,
provided with a stiffer integument and with slender legs : —
whilst, on the other hand, the adaptation of the respiratory
organs to breathe air with regularity and energy, the complexity
of the masticating apparatus, the possession of distinct eyes, and
many other characters, indicate their affinity with Insects ; in
which class, indeed, some Naturalists comprehend them. They
differ from insects, however, not merely in the absence of wings,
but in the great multiplication of the segments, which are nearly
always twenty-four at the least, each provided with a pair of
legs ; and also in the absence of any line of division between the
thorax and abdomen. As we have already seen(§ 797)> there
are certain Crustacea which bear a considerable resemblance to
them in regard to the equality of the segments, and general orga-
nisation ; but these are characterized by their branchial respira-
tion, and the number of their segments is usually much inferior.

821. The covering of the body of these animals is firm, and
of a somewhat horny character, resembling that of many Insects.
The division into segments is very distinct ; a flexible membrane

286 GENERAL CHARACTERS OF MYRIAPODA.

being interposed between each pair of firm rings or plates. This
is obviously required by the condensation of the rest of the integu-
ment ; since, if it were otherwise, the body would not have the
power of bending in any direction. The legs are covered with
the same kind of integuments, and are jointed in a similar manner;
each terminates in a single claw or hook. Sometimes two pairs
of legs seem to be present on each segment (Fig. 507) ; but this
results from the fact, that two adjacent segments are soldered (as

it were) together, so
as to appear but one,
— as is made evident
by the existence of a
similar doubling of all

FlG. 507- — POLYDESMUS. ,,

the other organs in

each division, and by the existence of a deep groove which runs
across it, marking the line of union. The first segment or head is
furnished with a pair of compound eyes, resembling those of Insects,
but less complicated in their structure ; and also with a pair of
jointed antennae. The mouth is adapted for mastication ; and
possesses a pair of mandibles, followed by a lower lip, and by a
pair of appendages somewhat resembling the feet-jaws of Crus-
tacea. On the side or under surface of the body may be observed
a row of minute pores, a pair usually existing on each segment ;
these are the stigmata, or apertures for the admission of air to
the respiratory organs, which consist of tracheae or air-tubes
resembling those of Insects. These tracheae, however, do not so
completely unite into a system, as in that class (§ 619) ; for
those of the several segments have but little communication with
each other. — The character of the other organs strongly resem-
bles that of the similar parts in Insects, though not so highly
developed. The alimentary canal runs straight, or nearly so, from
one end of the body to the other ; and possesses a few glandular
appendages, in the form of a long tube very imperfectly developed.
The circulation is carried on by the aid of a long dorsal vessel,
which extends along nearly the whole length of the body. The
nervous system presents a multiplication in its ganglionic cen-
tres, corresponding with the multiplication in the number, and

GENERAL CHARACTERS OP MYRIAPODA. 287

the similarity in the character, of the segments. — The Myria-
poda cannot be said to undergo any proper metamorphosis, like
that of Insects and some Crustacea ; since the young one, at its
emersion from the egg, possesses the form and most of the gene-
ral characters of the parent ; but there is a gradual increase,
during the period of growth, not merely in the size of the body,
but in the number of segments and legs ; and in one division of

the class (the lulidae),
the young, when it first
issues from the egg, is
altogether unprovided
with legs, these not mak-
FIG. 508.— TRANSFORMATIONS OK IULUS; ing their appearance until

after the first moult,

although they are found beneath the outer skin when it is
stripped off. A considerable number of moultings takes place
before the animal acquires its adult characters ; and this does
not happen, in some species, until after the lapse of two years.

822. This Class is divided into two Orders, which differ con-
siderably from each other in form and development.

I. CHILOPODA, consisting of the Centipedes and their allies ;
in which the body is flattened, and the legs well- developed,
constituting the principal instruments of locomotion. They run
with facility ; and are carnivorous in their habits.

II. CHILOGNATHA, consisting of the lulus, or Millepede,
and its allies ; in which the body is cylindrical, and the legs less
developed. They move slowly; and feed upon decomposing
organic matter.

ORDER I.— CHILOPODA.

823. This Order is the one, in which the greatest resemblance
to Insects may be traced. It consists of the Centipede and other
carnivorous Myriapods, possessing strong and active limbs, vary-
ing in number from fifteen to twenty-one pairs, by the aid of
which they can run with considerable rapidity ; and they are

288

ORDER CHILOPODA

CENTIPEDE AND ITS ALLIES.

able, owing to the flexibility of their long and jointed bodies, to
wind their way with facility among the lurking-places of Insects,
against which they carry on an unrelenting warfare. <5f their

FiG. 509. — SCOLOPJBNDRA, OR CENTIPEDE.

carnivorous propensities, the structure of the mouth affords suf-
ficient evidence. It is provided, not merely with a pair of
horny jaws resembling those of Insects, but with a pair of strong
sharp claws, formed by an enlargement of the second pair of
legs, and perforated at the top with a minute aperture, through
which a venomous fluid is probably instilled into the wounds
made by them. Small insects seized in these claws are seen to
die very speedily; and in warm countries the bite of the large
species of Centipede is a source of great irritation to man, —
being reputed to be more injurious than that of the Scorpion,
although it is seldom fatal. The application of Ammonia
(Hartshorn) is the most effectual remedy for the pain of the bite;
and the internal employment of the same remedy seems the best
antidote to the effects of the poison upon the constitution. The
last pair of legs usually undergoes some modification in this
Order ; being directed backwards so as to form a kind of double
tail ; and not being used for walking, except when the animal is
walking backwards. The European species of this Order seldom
exceed three inches in length ; but they are by no means uncom-
mon, if sought for in the
right situations. They
frequent dark places,
hiding themselves under
stones, beneath the bark
of trees, in the ground,
and in the hollows of
ripe fruit, — situations that are the resort of the Insects on
which they feed. The tropical species not unfrequently attain

Fro. 510>-a, LITHOBIUS FORCIPATUS; 6, GBOPHILUS

LONG1CORNI8.

ORDER CII1LOGNATHA ; MILLEPEDE, ETC. 289

a length of from twelve to fifteen inches ; and it is stated by
Ulloa, that they have been seen at Carthagena exceeding a yard
in length and five inches in breadth, and that the bite of these is
mortal. It is doubtful, however, whether this statement can be
fully relied on.

ORDKR II.— CHILOGNATHA.

824. This Order, consisting of animals having a general resem-
blance to the lulus or common Millepede, is the one most nearly
allied to the Annelida, not merely in external form, and in
the imperfect development of the legs, but also in the structure
of the internal organs. The body of the lulus (of which one of
the commonest species is known as the Gaily- worm) is long and
cylindrical ; its number of segments is between forty and fifty ;
and many of these bear two pairs of almost thread-like legs,
which arise close to the middle line, along the inferior surface of

FIG. 511.— IULUS.

the body. These are scarcely large or strong enough to support
its weight ; so that the animal moves but slowly, and seems
rather to glide or crawl, like a serpent or a worm, than to walk.
When at rest, the body is rolled up in a spiral form ; so that the
feet, being concealed in the concavity
of the spire, are protected from injury;
whilst the firmness of the rings of the
body enables them to resist consider-
able pressure. — The mouth of the
lulidcB strongly resembles that of the
Larvae of many Insects, being fur-
nished with a pair of stout horny
mandibles, with sharp toothed edges ;
and by means of these, they are enabled to divide with facility

Fro. 512. — IULUS, with the body
coiled up, and the front of the
body unrolled, with the an-
tennae magnified.

290 IULUS, POLYDESMUS, GLOMERIS.

the portions of decaying vegetable matter, on which they usually
feed. These animals are very harmless to Man, not being pos-
sessed of any poisonous organs ; and they may be regarded as
positively benefiting him by the removal of substances whose
decay would otherwise be noxious. The common lulus of thig
country seldom much exceeds an inch in length ; but there is a
South American species, lulus maximus, which attains the
length of seven inches. — The Polydesmus (Fig. 507) corresponds
with the lulidse in general structure and habits, but has the
body remarkably flattened. — The Glomeris bears a strong resem-
blance to the Woodlice (§ 799), in its oval form, and its habit
of rolling itself into a ball ; it is also remarkable from
its small number of segments, those of the body being
only twelve, as in Insects. The under surface of
the body, which is concave, has a row of small scales
on each side, which has been compared to the lateral
lobes of the Trilobites and some of the Isopod Crus-
tacea. Altogether the resemblance of this animal to
GLOMERIS that group is very striking ; the chief difference being
in the nature of the respiratory organs. — The animals
of this Order are remarkable for their power of emitting a dis-
agreeable odour, when they are alarmed. This seems to result
from a peculiar secretion, poured out from the stigmata or respi-
ratory orifices ; and it may be regarded as a means of defence,
which replaces the poison apparatus of the Centipedes.

CHAPTER XII.

OF THE CLASS OF CIRRHOPODA.

825. The Barnacles and their allies, composing this class,
have so many characters in common with the Moliusca, that they
have been generally regarded as belonging to that Sub-kingdom.
The body and its appendages are themselves quite soft ; and
the skin has the loose spongy muscular character, which corre-
sponds with the mantle of the Mollusks (§ 868). From its sur-
face is secreted a shell, composed of several pieces, but not
differing in general aspect from multwalve shells (§ 870) belong-
ing to that division. Further, these shells are either themselves
firmly united at their bases to rocks or solid masses, or they are
attached by a long peduncle or foot-stalk ; so that the conditions
in which the animals exist, closely resemble those to which we
observe the Moliusca peculiarly adapted.

826. On the other hand, when we examine the animal itself,
we find that it is perfectly

symmetrical in form ; a cha-
racter but rarely observable
amongst Mollusks that are
inclosed in shells of similar
nature (§ 864) . The body is
prolonged, and exhibits an
imperfect division into seg-
ments ; and from each of these
arises a pair of appendages on
each side, which possess some-
what of a jointed structure.
These cirrhi^ or tendril-like
organs, are long tapering
arms, fringed with cilia, or

FIG. 514. — SHELL OF
THE BARNACLK.

FIG. 515.— BODY OF
THE BARNACLK.

little hair-like filaments, by

292 GENERAL CHARACTERS OF CIRRHOPODA.

the continual vibration of which, currents are produced in the
surrounding water, that serve to bring food to the animal, and
a fresh supply of fluid for the aeration of the blood by means of
the gills, which are situated at the base of these appendages. In
this conformation, there is an evident analogy with many Crus-
tacea. Further, the mouth is furnished with lateral jaws, which
no Mollusca possess ; and the Nervous System consists of a double
cord, with a pair of ganglia in each segment of the body, pre-
cisely as in the Articulata in general. The most interesting
proof, however, that the Cirrhopoda belong to this division, is
derived from the history of their development. On their libe-
ration from the egg, they present a form much more analogous
to that of some of the Entomostracous Crustacea, than to that of
the adult animal, which they only acquire after a series of
metamorphoses.

827. The young of the Balanus (§ 830) is inclosed in a
bivalve shell, of which the valves are united by a hinge along
the back, and open along the lower margin, for the protrusion of
a large and strong anterior pair of prehensile limbs, provided with
an adhesive sucker and hooks, and of six pairs of posterior legs,
adapted for swimming. The form of the animal thus bears a
strong resemblance to that of the Daphnia (§ 804) ; and its
movements, too, are similar, consisting of a succession of jerks.
A pair of compound eyes, supported on a peduncle, is seen on the
anterior and lateral part of the body. Nearly all these organs
are thrown off together ; and the animal assumes an entirely
different form and condition. It first attaches itself to a neigh-
bouring surface by a layer of calcareous matter, which is subse-
quently to become the base of its new shell ; the valves which
surround its body are gradually developed on its envelope or
mantle ; the new ciliated arms begin to grow within ; and the
eyes disappear, the animal being henceforth destitute of the visual
sense. — The form of the young Lepas is different, having more
resemblance to that of the Cyclops (Fig. 496). The body is not
inclosed in a bivalve shell, but its back is covered by an expanded
shield, like that of Argulus (Fig. 498) ; it has a single eye, not
stalked ; and three pairs of members, of which the anterior is

GENERAL CHARACTERS OF CIRRHOPODA. 293

simple, whilst the two posterior are bifid. — Hence, if their
early state be alone considered, the Cirrhopods might be regarded
as an aberrant order of Crustacea ; but the complete change of
form which they exhibit in their passage towards the adult state,
involving the development of so many new parts, to which we
find nothing analogous in the class of Crustacea, seems to remove
them to a greater distance than even the aberrant Lerneida
(§ 815).

828. The Class is divided into two principal groups, differing
in many of their characters, though agreeing in those which have
been hitherto described.

I. PEDDNCULATA, or LEPADID^:. This Order, including the
Lepas or Barnacle and its allies, consists of those Cirrhopods
which are attached by a long fleshy peduncle or foot-stalk;
their form is flattened at the sides ; and the opening through
which the cirrhi are protruded is along one edge. The mantle
is sometimes cartilaginous ; but in general it is covered by five
calcareous pieces, of which the two principal ones resemble the
valves of a Mussel or other Bivalve shell.

II. SESSILIA, or BALANID^E. In this Order are associated
those which attach themselves at once by their basis, like the
Balanus, or Acorn-shell, so common on our rocky shores. In
these, also, the shell is composed of several valves; but these
are united into a cylindrical or somewhat conical tube, which is
attached at one end, and open at the other to give passage to the
arms, &c.

ORDER I.— PEDUNCULATA.

829. Of the common Barnacle, and its allies, which together
make up this Order, some species are common in nearly all seas.
Most of them fix themselves to wood in preference to anything
else ; so that a piece of timber, which has been for sometime
floating in the ocean, is almost sure to be partly covered by them,
and ships1 bottoms, if not protected by copper, are rendered so
foul, as greatly to impede their rate of sailing. This will be

294

ORDER PEDTINCULATA ; BARNACLE, ETC.

easily understood, when it is borne in mind how greatly the
friction will be increased, when the water, instead of being
ploughed by a smooth surface, is held (so to speak) by excre-
scences, such as those represented in Fig. 516. The commonest
species, Pentalasmis anatifera, is the one respecting which so
many absurd stories were formerly told (Vol. I. p. 16). The
peduncle sometimes grows to the length of two or three feet ; and
it possesses a considerable degree of contractility, enabling the
animal, by its means, to change its place, in some degree, by the
shortening, extension, or bending, of the footstalk. A large log
of timber covered with these animals, twisting and diverging in
all directions, and so close as to hide the surface of the log, is a
curious sight, — looking like an enormous collection of Serpents.

FIG. 517. — CINERAS CRANCHII.

FIG. 51fi.— Group of BARNACLES, attached to a ship's
bottom.

In the Cineras, the mantle has somewhat of a cartilaginous tex-

ORDER SESSILIA ; BALANUS AND ITS ALLIES. 295

ture ; and the valves do not cover the whole surface. In the
Otion, there are only two small valves, with the rudiments of
three others.

ORDER II.— SESSILIA.

830. The shell of the Balanus^ commonly known as the "Acorn-
shell," and met with almost everywhere on our shores, is formed
on a very different plan. It consists of six principal valves, of
a triangular shape, — the base of each triangle
being at the bottom, and the apex or point at
the top. Within these, however, is another
set of six smaller triangular valves, arranged in
??$^ j118^ the opposite direction, so as to fill up the
space between the preceding, and to give to the
whole shell somewhat the form of a cone with
the top cut off. The aperture of the shell is closed by an
operculum, or lid, composed of two or four pieces ; this the animal
can apply to the orifice, in such a manner as to close it com-
pletely, when its body is entirely drawn within the shell.
The growth of this shelly box is provided for by additions to the
edges of the several plates of which it is composed ; these addi-
tions increasing the size of the whole, without altering its form.
Between the internal and external layers of each valve, there is
a regular cancellated, or minutely-chambered structure, like that
of Bone (ANIM. PHYSIOL. § 47) : and this appears to be filled,
as in it, with a sort of marrow. No structure resembling this
has been found in any Mollusca. It is especially developed in
the Coronula, a genus allied to the Balanus, which is only found
attached to the back of Whales and Turtles.

CHAPTER XIII.

OF THE VERMIFORM CLASSES.

831. We are now arrived at the lower division of the Arti-
culated Sub-kingdom, in which there is an absence of articulated
members, and a general inferiority in the structure of the animals
composing it ; so that, as we descend, we lose one after another
of those characters, by which this group is distinguished.
Nevertheless, the lateral symmetry (§ 47) of the body is almost
uniformly preserved ; and it is only in the very lowest that we
meet with any approach to the circular arrangement of the parts
of the body, which is characteristic of the Radiata. The Ner-
vous System cannot be traced in the simplest animals of this
division ; but wherever it can be detected, it presents the same
essential characters as in the higher classes, — consisting of a
double cord running along the ventral surface from one extremity
of the body to the other, and studded with ganglia at intervals.
These ganglia are smaller, in proportion as they are more nume-
rous ; and their size diminishes, too, with the diminution of the
locomotive powers of the animal. The cephalic ganglia, or those
which are placed at the anterior extremity of the body, above the
oesophagus, are usually larger than the rest ; especially when
they are connected with organs of special sense, such as eyes and
antennae. But as we descend through this series, we find the
eyes disappearing, and then the antennae ; so that the head is
only marked by its being the situation of the mouth ; and the
cephalic ganglia are then scarcely to be distinguished from the
rest.

832. The body of these animals is generally long, slender,
and more or less cylindrical ; it is frequently divided into dis-
tinct segments ; but these are only marked externally by a
folding or wrinkling of the integuments ; and there does not

GENERAL CHARACTERS OF VERMIFORM ARTICULATA. 297

exist any proper tegumentary skeleton or hard envelope, as in
most of the higher classes of Articulata. In the lowest mem-

FJG. 519 — LEECH.

bers of the class, indeed, we cannot even trace an integument
distinct from the contained tissues; all being alike soft, and some-
times almost jelly-like. Even here, however, the division into
segments is most distinctly marked, by the repetition, in each
segment, of nearly all the organs of the body ; so that the
animal is much more capable of sustaining severe injuries, than
is the case in the higher classes ; and it has also greater power
of repairing them, new segments being developed to replace
those which had been lost. The greater number of the Vermi-
form or Worm-like Articulata are aquatic in their habits, living
either in water or in moist situations ; and as a general rule, their
respiration is performed either by gills, or by the general surface
of the body. They have usually a distinct circulating appara-
tus ; which serves not only to convey the nutritious fluid through
the several tissues, to whose growth it is to contribute, but also
to carry it to the organs in which it is to undergo aeration.
This apparatus consists, as in Insects, of a dorsal vessel, running
along the greater part of the body, and contracting from behind
forwards, so as to expel the blood through the branches which
proceed from its anterior extremity ; the fluid then flows back-
wards through the body, affording nutriment to its several parts
in its course ; and it is then made to flow over the walls of the
alimentary canal, so as to take up from its cavity any new
materials, which may have been prepared for it. The pro-
visions for carrying it through the respiratory organs vary
greatly, in proportion to the variety in the arrangement of the
respiratory organs themselves, which we shall see to be great,
as it is in the Mollusca : but there is not unfrequently a distinct
contractile cavity, or respiratory heart (ANIM. PHYSIOL. § 281),
for propelling the blood through every pair of gills, as in the

298 VERMIFORM ARTICULATA. CLASS OF ANNELIDA.

Crustacea (§ 777). In the lowest Articulata, however, no
dorsal vessel, or impelling organ of any kind, can be discovered ;
and the circulating system consists merely of a network of
capillary vessels, occasionally merging into larger trunks ; the
blood being propelled through it by the continual movements of
the body itself, which act upon it in somewhat the same manner
that our own changes in position do upon our venous circulation
(ANIM. PHYSIOL. § 279).

833. This group may be regarded as especially represented
by the class ANNELIDA ; which contains, with the Leech and
Earthworm, a great number of marine animals less gene-
rally known. In the ENTOZOA, we find the characters of the
Articulated series in their lowest state of development. And in
the ROTIFERA, we meet with peculiarities of form so great, that
the affinity of the minute animals it contains to the preceding
classes, is by no means apparent without a careful examination.

CLASS OF ANNELIDA.

834. The Annelida may be characterised as possessing an
elongated body, marked by transverse lines that divide it into
numerous segments : and usually furnished with a series of loco-
motive appendages in the form of bristles, sometimes implanted
on fleshy tubercles ; but not with articulated members. They
have a complete apparatus for circulation and respiration ; and

FIG. 520.— NEREIS.

the ventral chain of nervous ganglia may always be distinguished.
— Of the appendages, which often combine the functions of loco-

LOCOMOTIVE APPENDAGES OF ANNELIDA. 299

motion and respiration, there are frequently two pairs in each
segment ; one belonging to its upper or dorsal portion, and the
other to its lower or ventral (Fig. 594) : but in other in-
stances the two appendages on the same side are united (Fig.
527), We usually then find, in the marine Annelida, that
the ventral portion is chiefly devoted to
locomotion ; and the dorsal to respiration.
Thus, in the Eunice, we find, at the under
part, a fleshy tubercle (tf), furnished with a
tuft of bristles, and below it a rudimentary
cirrhus, or tendril-like organ (i) ; whilst
the upper part of the appendage is formed
by a branchial tuft (ft), and by a long
FIG.52L-GILL-TUFTOF slender cirrlms(c). This last sometimes

EUNICK. x '

exhibits a trace of articulation, as in the
Syllis (Fig. 522, a). In other cases, however, these appen-

FIG. 522. — SYLLIS WONILARIS, with one of its locomotive organs and setigerous appendage
attached thereto.

dages are only represented by a few short stiff hairs, as in the
Earthworm,; and in other instances, as the Leech> there is no
trace of any members or appendages to the body. The bristly
tufts of the Nereidans and their allies are useful to them in
various ways ; they serve them in part as instruments of attack
and defence, the bristles being usually sharp, and sometimes
barbed at their extremities, so as to attach themselves with force
to soft substances ; they assist, also, in their movements over
solid surfaces, taking hold, as it were, of the rock on which the
animal is crawling, so that the hinder part of the body is pre-
vented from slipping back, when the anterior part is pushed
forwards ; and they also aid in its movements through the

300 GENERAL CHARACTERS OF ANNELIDA.

water, serving in some degree as oars by which it is propelled.
In some instances, indeed, we find the tufts replaced by flattened
plates, which are specially adapted for this last purpose. Where
there are no locomotive appendages, the extremities of the body
are usually furnished with suckers, which give important assist-
ance in locomotion, — as in the well-known Leech. But in one
tribe of this class, the animal, in its adult form at least, enjoys
very little power of locomotion, being confined within a shell,
which it constructs for itself, and which is attached .to some
solid support.

835. The first segment, which constitutes the head, is usually
provided with one or more pairs of imperfectly-formed eyes ;
and also with several appendages analogous to the cirrhi of the
other segments, which are considered as antennae or tentacular
cirrhi. The mouth, which is situated on the lower side of the
head, is constructed on a very different plan in the several divi-
sions of the class : being sometimes furnished with one, two, or
three pairs of hard horny jaws, with toothed or pointed edges ;
sometimes having a sort of trunk, which can be pushed out or

drawn in (Fig. 523), and which
bears a pair of small tooth-like
jaws at its extremity ; and some-
times being situated in the centre
of a flattened sucker, and armed
with an apparatus of little saws,

FIG. 523. — HEAD AND TRUNK OK GLY- ,-, T , /T-,. ronx mi

CERrs; c, anterior portion of the as m the LeeC" (Fig. 532). The

body ; t, head ; tr, trunk ; 6, opening alimentary canal is usually simple

of the mouth ; m, m, jaws.

in its form, passing in a straight

line from one end of the body to the other ; and not exhibiting
any distinction of stomach or intestine. It is often furnished
with a number of little saccular appendages, placed along the
greater part of its length ; these are probably secreting organs,
as we do not find any others which can be regarded as having
that character. Many of the Annelida are remarkable for the
red colour of their blood ; this colour is not given, however, by
red corpuscles, but exists in the liquor sanguinis (ANIM. PHY-
SIOL. § 229). Sometimes, however, the blood has rather a

DEVELOPMENT OF ANNELIDA. 301

greenish tint ; and in many instances it is colourless, as in the
Annelida in general.

836. Little is known of the history of the development of the
Annelida ; but there appears to be considerable variation in the
amount of change they undergo after coming forth from the egg.
The Nereidans, in their early stage, seem to bear a very close
resemblance to Infusory Animalcules ; for they are described as
consisting of a simple disc, surrounded with two rows of vibratile
cilia, which serve for locomotion, and for the acquirement of
food. The mouth, which is situated near the edge of the disc, leads
to a short, straight alimentary tube, which terminates in a sort of
cone projecting from its lower side. In a short time this conical
projection begins to increase in length, and to show a division
into segments ; and by a gradual increase in the number of these,
the body is at last formed. At the same time, the formation of
the head takes place by a gradually-increasing projection of the
other surface of the disc. Whilst the head and body are being
developed, this first-formed disc remains for a time as a sort of
appendage on each side of the head ; but it finally disappears. In
the Leech and Earth- Worm, on the other hand, the development
of the young seems to be nearly complete, by the time that they
leave the egg. — We find in this group the first appearance of that
gemmiparous mode of reproduction, which is especially charac-
teristic of Zoophytes (ANIM. PHYSIOL. §§ 723-730). The
accompanying figure represents the mode of propagation of the

FIG. 524.— NEREIS PROLIFERA.

Nereis prolifera ; in which a young one is formed from the hinder
part of the body of the parent, its head being produced by a
conversion of one of the segments of its body ; and this is gra-

302 PROPAGATION AND CLASSIFICATION OF ANNELIDA.

dually detached by a narrowing of the preceding joint. Pre-
viously to its separation, however, the young one often forms
another bud from its own hinder part, in a similar manner; and
even three generations have been seen thus united. — From observa-
tions recently made on another Marine Worm, in which a similar
occurrence takes place, it would appear that the buds thus
detached are, like the flowers of Plants, destined to Reproduc-
tion only; for whilst the parent continues to grow, to obtain its
food, and to develope new buds from its hinder portion, these
buds do not seem to grow into new individuals like their parents,
— but, although possessing a head, mouth, and alimentary canal,
they do not take in nourishment, their functions being restricted
to the laying of eggs, from which new Nereids spring. — Some-
thing analogous to this is met with among the Entozoa ; the
posterior segments, containing the ova, being detached from the
rest of the body, and thrown off altogether.

837. This Class is subdivided into Orders, according to the
differences in general conformation and habits exhibited by the
tribes which compose it ; arid especially by the character and
distribution of the respiratory organs. The first Order, DORSI-
BRANCHIATA, includes those which have the branchial appendages
or gill-tufts disposed regularly along the body, sometimes extend-
ing along its entire length, and sometimes restricted to the
segments about the middle. This Order has been also denomi-
nated Errantia, from the active habits of the animals composing
it. — II. In the next, TUBICOLA, we find worm-like animals
inhabiting fixed and permanent residences, like the testaceous
Mollusca. The disposition of the gill-tufts around the head, and
the absence of them along the body, is the principal character
which distinguishes the animals themselves from those of the first
Order. — III. In the third Order, TERRICOLA, the body is desti-
tute of all external appendages, except some minute and almost
imperceptible bristles ; for the respiratory organs are here deve-
loped internally, the animal being usually formed to crawl upon
the ground, instead of swimming through the water. — IV. And
in the last, SUCTORIA, the body is destitute even of these bristles,
but is furnished with a sucker at each extremity.

ORDER DORSIBRANCHIATA ; NEREIS, ETC. 303

ORDER I.— DORSIBRANCHIATA.

838. Of the foregoing Orders, the Dorsibranchiata appear,
on the whole, to possess the most complete structure, as well as
the most varied faculties ; and they also exhibit the forms most
characteristic of the class. The head is almost always quite

distinct from the trunk, and is furnished with one
or two pairs of minute eyes, which are seen as black
or reddish specks upon its upper side ; and it is also
provided with several pairs of appendages (Fig. 525),
as well as with complex instruments of mastication.
These Marine Worms do not attain any considerable
dimensions upon our coasts, rarely exceeding a few
inches in length ; but in tropical climates, species
FIG. 525.— HEAD are to be met with of comparatively gigantic pro-
SEGM^NTS™ portions, having their bodies composed of 400 or
500 segments, and occasionally measuring four feet
from one end to the other. They generally crawl with facility,
and swim rapidly ; their chief habitations are among rocks and
masses of shells ; but some of them bury themselves in the sand,
forming a sort of burrow, lined by mucus secreted from their
bodies, which they quit in search of their prey. They are all
carnivorous, and live on various small marine animals.

839. The NEREIDS, commonly known as Sea-Centipedes
(Fig. 520), may be regarded as characteristic examples of this
group. They are distinguished by having the gills in the form
of leaf-like appendages or laminse, which are traversed by a net-
work of vessels ; and every segment has, on either side, two
tubercles, two cirrhi, and two tufts of bristles. They have none
of that venomous power, which their name might be supposed to
indicate ; but they are extremely voracious, and thread the
most intricate passages and crevices among rocks and stones,
in pursuit of their prey. In their turn, they are devoured by
Fishes. — The Eunice is nearly allied to the Nereides ; but has
gills composed of filamentous tufts (Fig. 521, 5), instead of leaf-

v2

FIG. 526. — EupHROSiNE LAUREATA.

304 DORSIBRANCHIATA ; EUNICE, ARENICOLA, APHRODITA.

like plates. — The Eunice gigantea of West Indian seas is the
largest Annelide known; sometimes measuring four feet in
length. There are smaller species upon our own coasts. — In the
Amphinome, the gills have the form of branching or arborescent
tufts ; and these are disposed along the whole of the body. They
are frequently coloured very brilliantly. — The allied genus
Euphrosine has thess branchial tufts very much developed ; and

the body, instead of
being long and narrow,
has a broad and oval
form. — The Arenicola,
or Lob- worm, is an
animaFwell known on
our coasts ; being sought
for by Fishermen, who
use it as a bait. Its

gills, like those of the preceding genera, have an arborescent
form ; but they are disposed on the middle part only of the
body. As its name imports, it lives in the sand, in which it
burrows to the depth of twelve or eighteen inches : its situation
may be known by a little coil of sand, which is seen on the
spot beneath which it is to be found. The Arenicola is one of
the Annelidans most distinguished by the red colour of its circu-
lating fluid ; and this colour is peculiarly seen in the branchial
tufts, which have a beautiful crimson hue during the life of the
animal. — The Aphrodita is an animal well known on our coasts
under the name of " Sea Mouse;" probably on account of the
large quantity of silky hairs with which it is covered. These
hairs are of a very brilliant metallic lustre ; and their colours
vary with the play of the light ; so that this animal is scarcely
surpassed by any, in beauty of colouring. The back is furnished
with two rows of large membranous scales, which somewhat
resemble the elytra of Insects ; these inclose the gills ; but they
are themselves concealed by the hairy covering just mentioned.
The form of the body much resembles that of the Euphrosine
(Fig. 526). A large number of Aphroditse are not unfrequently
thrown up on our coasts after a gale of wind. In many species,

APHRODITA, PERIPATUS. ORDER TUBICOL^E. 305

the lateral setee or bristles exhibit a beautiful structure, which
admirably fit them for weapons of defence, being barbed on each
side at their tips ; and each of these barbed setee is inclosed in
a smooth horny sheath, composed of two blades. — Lastly, we
may mention a very curious genus, Peripatus^ which is probably
to be placed in this order, although it is a resident on land. In

some respects it
bears a resem-
blance to the
lulidze (§ 824),
having legs adapt-
ed for walking,

FIG. 527 — PERIPATUS IULIFORMIS.

which present

some appearance of articulation or jointing ; but in the softness
of its body, and in the termination of the legs in tufts of bristles,
it evidently corresponds with the Nereidans.

ORDER II.— TUBICOL^E.

840. The animals of this order never attain to the same
dimensions with the preceding ; and more is known of the casings
which they form, than of the structure of the animals themselves.
One of the commonest of these is the shelly tube exuded by the
Serpula ; which is formed of calcareous matter, resembling that
of the shells of Mollusca, and apparently secreted from the sur-
face of the body in a similar manner. In fact, it is often scarcely
possible to distinguish between the shell of a Serpula and that of
a Vermetus (Fig. 583). The tubes of the Serpulse (Fig. 528) are
generally found clustering in masses, attached to the surface of
stones, shells, or other bodies, which have been immersed for any
length of time in the sea ; they are usually more or less contorted
in form, varying in this respect according to the position in
which they grow ; but they are always closed at one end, which
tapers to a point, the wide end being open to give exit to the
head and mouth of the inhabitant. The animal which forms
this shell, and resides in it, has its branchial filaments or gill-
tufts all assembled round the head ; where they form a pair of

306

ORDER TUBICOL^E; — SERPULA, SPIRORBIS.

FIG. 528 — GKOUP OF SERPULA.

most elegant fan-like appendages, which usually possess very
brilliant colours. At the base of each
series, there is a fleshy filament ; and
one of these, on the right or left side
indifferently, is prolonged and dilated at
its extremity into a flat disc, which fits
to the mouth of the shell, and serves to
close it when the animal is withdrawn
into the tube. The body of the animal
is composed of a great number of seg-
ments ; but these are for the most part
unprovided with any appendages. The
anterior segments, however, which are
much thicker than the rest, are furnished
on each side with bundles of stiff bristles.
The largest species of this, as of the
preceding groups, are found in tropical
regions, where they usually form their

habitations in the midst of Corals, and lengthen their tubes as the
Coral is built up around them ; their length is sometimes as much
as three feet ; and their expanded gill-tufts are of extremely vivid
colours, strongly resembling the most brilliant Carnations in
general aspect. These are usually extended beyond the mouth
of the shell, in order to obtain the full influence of the water,
for the aeration of the circulating fluid ; but if they be touched,
they are immediately drawn in, and the mouth of the tube is
closed by the disc just mentioned. Numerous smaller species
are found on our own coasts ; and some of these are remarkable
for the brilliant hues of their expanded gills. — A minute white
spiral shell may be frequently seen upon the flat fronds of sea-
weeds ; this is the Spirorbis, the animal of which is nearly allied
to that of the Serpula. The food of these Annelids probably
consists of Animalcules and small marine animals ; together, per-
haps, with particles of dead animal matter, which are brought
towards the mouth, by the currents created by the cilia on the
branchial tufts : their masticating apparatus is much less complete
than that of the Dorsibranchiata.

841. Besides the Serpulae, we have to mention several other

TUBICOL^E J TEREBELLA, AMPHITRITE, PECTJNARIA. 307

animals of this group, which do not form their tubes by a calca-
reous exudation from their own bodies, but by cementing together
particles of shell, sand, small pebbles, &c., by means of a gluti-
nous secretion. We may first notice the Sabella, which seems
to have some power of exuding calcareous matter; and forms its
shell partly of this material, and partly of granules of clay or
fine mud. In the arrangement of its gill-tufts, it bears a strong

resemblance to the Serpula.
The Terebella forms its tube
entirely by the agglutina-
tion of grains of sand, pieces
of shell, &c. ; and some
species live in groups, so

FIG. 529.— TEREBELLA MEDUSA, in its tube. that their clustering-toge-

ther forms solid masses,

which may go on increasing to a considerable size. The gills are
here smaller, and are placed behind the head, having the form of
small arborescent tufts ; and the head is furnished with numerous
tentacula, which are capable of being greatly extended. These
probably assist the gills in the aeration of the blood, as they pre-
sent a large surface to the water ; but their chief use appears to
be the prehension of food. The shelly tubes usually have little
branches near their summit, through which the gills and the ten-
tacula pass out. The Tubicolee of the genus Amphitrite are
distinguished by their large
golden-coloured setee, disposed
in a comb-like series, or in a
crown, or in one or several
ranges on the front of the head ;
these probably serve them for
defence, and may give assistance
in locomotion. Many of these
animals, belonging to the sub-
genus Pectinaria, are less con-
fined to one spot than the pre-
ceding; their tubes, which are FlG' ^.-TEKKBELLA
composed of fine grains of sand cemented together with great
regularity, are simple cones open at both ends, and not attached ;

308 PECTINABIA. — ORDER TERRICOL.E.

and they carry these about with them, when roaming in search of
food. It is perhaps in consequence of their locomotive powers,
which give them a greater facility of selection, that they construct
their shelly tubes with so much more regularity than other
Annelidans. These tubes, usually about two inches long, may
be frequently picked up on our shores. Some of this group,
however, are fixed like the other Tubicolas, and form their tubes
less regularly. Their bodies are doubled up, as it were, within
these envelopes ; so that the intestine terminates in a tube which
is curved back over the head.

ORDER III.— TERRICOLJE.

842. The Annelidas of this Order have a cylindrical body,
tapering to a point at its extremities, and furnished only with
several rows of bristles ; these are frequently invisible to the
naked eye, but may be distinguished by the resistance they make
when the finger is passed along the body from behind forwards,
— their points being directed backwards, in order to give the
animal a firm hold of the earth through which it is boring. The
head of these animals is not distinct from the body ; and they
have neither eyes, antennae, mandibles, cirrhi, nor external gills.
Their bodies, however, are distinctly divided into segments ; and
these are marked by minute spots on each side (Fig. 531, «),
which are apertures leading to small respiratory sacs, on the
walls of which the blood is submitted for aeration to the influ-
ence of the air or water received into them. This Order includes
only two principal groups ; the Earth- Worms and the Naids, —
the former being inhabitants of the land, and the latter of the
water.

843. The Earth- Worms, which nearly all belong to the genus
Lumbricus, generally live beneath the surface of the ground, either
perforating the dry soil, or burying themselves in mud, where
many of them lead a semi-aquatic life. When the Worm is
boring, it insinuates its pointed head between the particles of the
earth amongst which it penetrates like a wedge ; and in this
position, the anterior part of the body is fixed by the spines or

ORDER TERRICOL^J; EARTH-WORMS. 309

bristles, of which there are four pairs on each segment (Fig.
531, b). The hinder parts are then drawn forwards by a shorten-
ing of the body, — a movement which the spines do not oppose ;
this swells out the anterior segments, and forcibly dilates the
passage into which the head had been already thrust. The
spines upon the hinder rings then take a firm hold upon the
walls of the hole into which they have been drawn ; .and this
part of the body being now made a fixed point, the head is again
forced forwards by the powerful contraction of another set of
muscles ; and by a repetition of this process, the animal easily
makes its way through substances, which it would at first have
seemed impossible for it to penetrate. The muscles, by which
this action is performed, are disposed in two series ; the arrange-
ment of which is very characteristic of the Articulata in general,
though it is less obvious in the higher classes, whose locomotion
is chiefly effected by the action of the extremities. The muscles
of one series are longitudinal in their direction, passing from
segment to segment, and serving by their contraction to draw
the segments together, in such a manner as to shorten the body,
at the same time increasing its diameter. The muscles of the
other series have a contrary direction, forming rings round
the body, and tending by their contraction to diminish its
diameter, and consequently to increase its length.

844. The burrowing of Earth-worms is a process exceed-
ingly useful to the Gardener and Agriculturist; and these
animals are far more beneficial to Man in this way, than they
are injurious by devouring the vegetables set in the soil. They
give a kind of under-tillage to the land, performing the same
below ground that the spade does above for the garden, and the
plough for arable land ; and loosening the earth, so as to render
it permeable to air and water. It has been lately shown, that
they will even add to the depth of soil ; covering barren tracts
with a layer of productive mould. Thus, in fields which have been
overspread with lime, burnt marl, or cinders, these substances
are in time covered with finely-divided' soil, well adapted to the
support of vegetation. That this result, — which is commonly
attributed by the farmers to the " working-down " of the
materials in question, — is really due to the action of the Earth-

310

ORDER TERRICOL.E ; EARTH-WORM.

worms, appears from the fact that, in the soil thus formed, large
numbers of " worm-casts " may be distinguished. These are
produced by the digestive process of the Worms ; which take
into their intestinal canal a large quantity of the soil through
which they burrow, extract from it the greater part of the
decaying vegetable matter it may contain, and reject the rest in
a finely-divided state. In this manner, a field, manured with
marl, has been covered, in the course of 80 years, with a bed of
earth averaging thirteen inches in thickness.

845. It is commonly supposed that the Earth- Worm may
be multiplied by the division of its body
into two pieces, of which each will
continue to live. This does not, however,
appear to be the case with regard to the
common species. If it be divided across
the middle, when in motion, each part
will continue to move for a time ; but
only the piece which bears the head will
be found alive after a few hours. This
forms a new tail ; and soon shows little
sign of injury. But if the division be
made near the head, the body will re-
main alive, and will renew the head ;
and the head, with its few attached
segments, will die. — There appear, how-
ever, to be some species, in which this
reproductive power is sufficiently great
to produce a new head and body from
even a small portion of the original ;
so that above twenty individuals have
been produced in this manner, by the
division of a single one into as many
parts. This power is even greater in the
Naids ; which also produce buds, that
separate from the parent by spontaneous
division, as in the Nereis prollfera
(§ 836). — The propagation of the Earth-
worms presents some other very remarkable peculiarities. The

FIG. 531. — LUMBRICUS TER-
RESTRIS, OR EARTH-WORM ; 6,
anterior segments magnified,
showing the bristles directed
backwards ; c, egg enclosing
two young ; ^.escape of young
worm from the egg.

EARTH-WORM, NAIS. ORDER SUCTORIA. 311

ova, when they have been fertilised, quit the ovarium, not by
oviducts or passages leading outwards, but by finding their way
into the loose tissue of the body, beneath the muscular layer ;
through this they are propelled by a series of strong undula-
tions, until they reach a sort of receptacle, in which they undergo
the first part of their development, and within which, in some
species, the eggs are hatched, so that the young come forth alive.
The eggs are provided with a curious valve-like structure at the
end through which the young worm emerges ; and it is remark-
able that, in a great number of instances, two embryos may be
observed in a single egg.

846. The genus Nais is nearly allied to the Lumbricus ; but
the worms which it includes are aquatic in their habits, living
in holes which they perforate in mud at the bottom of water.
Some of them have small black points upon their heads, which
have been regarded as eyes.

ORDER IV.— SUCTORIA.

847. This Order contains the common Leech and its allies,
which are all animals of aquatic habits, but not all agreeing in
its blood-seeking propensities. The group derives its name, as
already stated, from the suckers which terminate the two ex-
tremities of the body, and which constitute its chief means of
locomotion ; for having fixed its anterior extremity, the animal
draws the posterior one close up to it, by bending its body, — and
then, fixing the latter, re-advances the first, by straightening
and extending the body. In this manner the Leech can advance
much more rapidly over solid surfaces, than the Earth- Worm
can by its crawling movement ; and it can also swim with
facility.

848. The Leech, in its general structure, bears a considerable
resemblance to the Earth- Worm ; but differs as to the conforma-
tion of its mouth and digestive apparatus, which are in accord-
ance with its suctorial habits. Its mouth is situated in the
middle of the cavity of the anterior sucker ; and three little

312 ORDER SUCTORIA; LEECH.

cartilaginous bodies, usually called teeth, but more properly jaws,
are seen to be disposed around it, in such a manner that the

FIG. 532.— HIRUDO OFFICINALIS.

three edges form three radii of a circle. Each of these has two
rows of minute teeth at its edge, so that it resembles a small
semi-circular saw. It is imbedded at its base in a bed of
muscle, by the action of which it is worked, in such a manner as
to cut into the skin, — a sawing movement being given to each
piece separately. It is in this manner that the tri-radiate form
of the leech-bite is occasioned ; each ray being a separate little
saw. The lacerated character of the wound is very favourable
to the flow of blood ; which is further promoted by the vacuum
created by the action of the sucker. The alimentary canal is
straight ; but is furnished, at its posterior portion, with a large
number of little sacs, or caeca, opening from it. The operation
of digestion is extremely slow, notwithstanding the rapid and
excessive manner in which the Leech fills its stomach ; a single
meal of blood will suffice for many months ; nay, more than a
year will sometimes elapse, before the blood has passed through
the alimentary canal in the ordinary manner, during all which
period so much of the blood as remains undigested in the sto-
mach continues in a fluid state. — Leeches are furnished with
eight or ten simple eyes, which may be detected by the aid of
a magnifying-glass, as a semicircular row of black points, situated
above the mouth upon the sucking surface of the oral disc ; this
position is evidently calculated to render these organs of use in
the discovery of food. Each of these visual specks would seem
to be merely an expansion of the extremity of a nerve, derived
from the cephalic ganglia, spread out beneath a kind of cornea
formed by the delicate and transparent cuticle, and having
behind it a layer of black pigment ; nothing like a crystalline
lens can be discovered ; so that the vision of these animals must

LEECH, GORDIUS. CLASS OF ENTOZOA. 313

be extremely imperfect. — The greater number of the Leech tribe
are inhabitants of fresh water ; some, however, are only found
in the sea ; others live in moist situations near stagnant water,
pursuing Earth- Worms, &c. ; and there is one small species,
entirely terrestrial, which inhabits the woods of -Ceylon, and
attacks men and horses that are passing through them, in such
a manner as to become, from its great voracity, one of the most
troublesome pests of that fine island.

849. As connecting this order with the next, we may here

place the genus Gor-
dius, a long thread-
like Worm, scarcely
exhibiting any marks
of articulation on its
FIG. 533.-GORDIUS AQUATICUS. body, and having no

distinct respiratory or-
gans. Its various species inhabit fresh and stagnant waters,
mud, and marshy grounds ; and are commonly found with their
long bodies coiled up into complex knots, — whence the name of
the genus. The mouth is a simple pore at the anterior extremity
of the body, which is conical ; the tail, on the other hand, which
has been mistaken for the mouth, is bifid (Fig. 533, «).

CLASS OF ENTOZOA.

850. This class derives its name from the peculiar mode of
existence of the animals composing it; most of them being
inhabitants, during their whole lives, of the bodies of other
animals, generally of higher organisation, from the juices of
which they derive their nourishment. Many of these possess a
distinct worm-like form (Fig. 534) ; the body being much pro-
longed and exhibiting a division into segments, and the mouth
being situated at one extremity. These, therefore, evidently
belong to the Articulated series. There are others, however,
which, in their general form, the simplicity of their organisation,
and the circular arrangment of the organs about the mouth, seem
to approximate more to the Radiata (Fig. 536).

314 PLANARIA. ENTOZOA PROPER.

851. There is a very interesting group, consisting of the
genus Planaria and its allies ; which is placed in this class on
account of its general conformity with it in structure ; although
not agreeing as to the residence of the animals composing it, —
these not being inhabitants of the bodies of other animals,
but swimming freely in waters of the ocean, as well as in
streams and ponds, and crawling upon their banks, or upon
floating substances. The body is flat, and three or four times
as long as it is broad. "Within its soft tissue are channelled
out, not only a complex digestive cavity, but also a system of
vessels which absorb fluid from its walls, and convey it through
the system. The stomach opens, not by a mouth at one end,
but by a sort of sucker projecting from the middle of the body ;
and through this the Planaria imbibes the juices of various
aquatic animals which it attacks ; mastering even the most active
little worms (such as the Nais) by twisting its body round
them. — The most curious part of the economy of these animals
consists in their power of reproducing parts that have been lost,
and of repairing injuries ; which seems to be almost as great as
that of the Hydra among Polypes. They may be divided into
three parts ; of which the first shall contain the two minute spots
which are believed to be eyes ; the middle one the sucker ; and
the posterior one the reproductive apparatus; and in a short
time, each part will develope itself into a new individual, perfect
in all its parts. It may be partially split longitudinally from
either extremity, so that two heads, or two tails, or both in com-
bination, may be formed, all uniting at the middle point, but
each being complete in itself.

852. The proper ENTOZOA do not present many points of
general interest ; although their peculiar relations to Man, and
the numerous varieties of structure which they present, render
them objects of much scientific interest to the professed Naturalist
and Physiologist. For obvious reasons we shall here content
ourselves with a very general sketch of the group. — It may be
divided into two primary Sections, according to the degree of
development of the principal organs. In the first and highest
of these, the STERELMINTHA, there is a distinct intestinal tube

ENTOZOA ; — STERELMINTHA. 315

with an orifice at each end, floating freely in an abdominal cavity,
as in higher animals ; and there are also traces of a nervous and
muscular system, more or less developed. This division evi-
dently approximates to the Annelida. — In the lower division,
CCELELMINTHA, there is no distinct alimentary canal ; the
cavities for the reception of food, as well as those for other pur-
poses, being, as it were, channelled out of the soft, almost homo-
geneous, tissues of the body. Some of these, too, preserve the
Worm-like form ; but in others this can scarcely be traced.

853. SECTION I. STERELMINTHA. A characteristic ex-
ample of this group, possessing a very distinct nervous system, is

presented by the
Linguatula tce-
nioides(Fig. 534);

FIG. 534,-LiNWATULA TVEmoiDEs. a W°rm which

infests the frontal

sinuses of the horse and dog. — The Ascaris lumbricoides, or
Round Worm of the human intestines, also belongs to this group.
It infests not only man, but many of the lower animals ; and
sometimes occasions severe disease, and even death. It derives
its second or specific name from its resemblance to the Earth-
worm. The short active Thread-worms, sometimes infesting
the lower part of the intestine, and giving rise to great irrita-
tion, but not to such severe consequences as the preceding, con-
stitute another species of the same genus. — We may also notice
the Filaria, or Guinea-worm, which burrows in the flesh of
man and other animals in warm climates ; if undisturbed, it will
often continue its operations for a considerable time without
much uneasiness ; but if disturbed, it sometimes occasions the
most excruciating pain. When it shows itself externally, it
must be extracted very slowly and carefully, for fear of breaking
it ; since, if this should occur, the part remaining in the body
would retreat and continue to exist in its previous situation,
re-forming the remainder. This Worm grows to the length of
several yards.

854. SECTION II. CCELELMINTHA. A characteristic example of
this group, in which the worm-like form is preserved, with a
considerable degree of complexity of organisation, is the Tcenia

316

ENTOZOA ; — CffiLELMINTHA.

Solium, or Tape-worm. The body of this animal is distinctly
divided into joints or segments; which sometimes amount to
several hundred ; the whole animal occasionally attaining the

FIG. 535. — TiENiA SOLIUM.

length of ten feet. These segments are all connected by the
nutritive canal, which runs from one end to the other ; but
the reproductive apparatus is repeated in each division. The
head is small, and possesses a double circle of small hooks. Its
existence is essential to the life of the body, which dies if the
head be broken off; but if some of the joints remain attached to
the head, it continues to grow and form new ones. — The so-called
Eels of vinegar and sour paste are referrible to this group, in
regard to the simplicity of their structure and their worm-like
form ; although their habitation is so different. There is also
a little worm-like animal closely allied to these, which is found
in diseased ears of wheat, and which possesses remarkable
tenacity of life, being revived by moisture after having been

dried for almost any length of
time. — The accompanying figure
represents one of the Entozoa, in
which the Vermiform aspect is
almost completely wanting. This
animal possesses a head much re-
sembling that of the Tape-Worm;
but instead of having a long jointed
body, it dilates behind into a large
bag, which contains only fluid. It
does not frequent the cavities of the body, like the Intestinal

FIG. 536.— CYSTICERCUS CBLLTILOS^: ;
a, head enlarged.

ROTIFERA, OR WHEEL-ANIMALCULES. 317

Worms ; but is found in the areolar issue, and in the substance
of the various membranes. It is not uncommon in Man ; but
frequently multiplies to a great extent in the Pig.

CLASS OF ROTIFERA.

855. The class of ROTIFERA, or Wheel- Animalcules and their
allies, is probably to be regarded as belonging to the Articulated
division of the animal kingdom ; although the characters of that
group are by no means distinctly marked in it. That these
beings possess a structure much more complex than that of the
Infusoria, to be hereafter considered (Chap. XX V.), there can be
no doubt whatever. That this complexity of structure was for
a long time overlooked, was owing to the minute size of the
animals in question ; scarcely any of them exceed a line in length,
and many are less than -^-^ of' an inch. Nearly all the species
of this class are aquatic in their habits, some living only in salt
water, others frequenting stagnant ponds, and others appearing
in vegetable infusions, where they generally succeed animal-
cules of inferior organisation. A few, however, can live in
moist earth.

856. The great transparency of the bodies of the ROTIFERA
permits their general structure to be easily recognised. They
have usually an elongated form, similar on the two sides. At
the anterior extremity, we observe one or more rows of vibratile
cilia, usually arranged in a circular manner. When these are in
motion, an appearance as of revolving wheels is produced, from
which the class derives its appellation ; and this is particularly
evident in one of its commonest forms, usually known as the
Wheel- Animalcule, which possesses a circular row of cilia on
each side (Fig. 537, #)• In many species we find a prolonga-
tion of the body in front, extending beyond the ciliary apparatus;
this, which sometimes bears one or more red spots, that are
believed by Ehrenberg to be eyes, may be regarded as a head
(Fig. 537, a). The body is covered by a double envelope, both

318

ROTIFERA, OR WHEEL-ANIMALCULES.

layers of which are extremely thin and flexible in some species ;
whilst in others the outer one seems to possess a horny consist-
ence, and may even contain siliceous or flinty matter, like the
sheaths of the lower Infusoria. In the former case, the whole
integument is drawn together in a wrinkled manner, when the
body is shortened ; in the latter, the sheath acts as a kind of
cell, into which the head and ciliary apparatus can be completely
retracted. These last would
seem to have some relation with
the Polypifera ; and we shall
hereafter see that the affinity
may be regarded as very close.
On the other hand, the former
present an external resemblance
to the Vermiform tribes ; which,
also, will be found to increase on
a closer examination : and there
are also species, of which the
sheath bears a strong likeness to
that of some Entomostracous
Crustacea (§ 807). Hence we
may regard this group as con-
necting the Articulated classes
with the Zoophytes.

857. As a characteristic illus-
tration of the class, we shall select
the common Wheel- Animalcule,
Rotifer vulgaris. The body,

PTrrpnrlpfl nn«?<;p<*<?p<? prmsi Frs- 537— WHEEL ANIMALCULES ; A,
ie<1>> P°S ' with the wheels expanded ; B, with the

length in proportion to wheels folded up and drawn in ; a, the

* •*- 1~«~ J ...-A-U i.l-_ „ „««.*« . »» *U^ «/U-,l~ .

its diameter, and has much of the
Vermiform or Worm-like aspect;

this is increased When a Slight dular apparatus surrounding it ; i, young

ones nearly complete ; k, eggs ; I, tail.

contraction draws the external

membrane, which is here thin and very flexible, into transverse
wrinkles, that seem to indicate the segments of the trunk. The
posterior extremity is prolonged into a tail, possessing three

head with the eye-spots ; b, the wheels ;
c, water-siphon ; d, masticating appara-
tus; e, salivary glands; f f, intestinal
canal ; .17, its dilated termination ; Ji, glan-

STRUCTURE OF WHEEL- ANIMALCULE. 319

joints, each of which has a pair of prongs or points. These
joints can be drawn up within each other, like the sliding-tubes
of a telescope. Within the external integument there are four
longitudinal bands running from end to end ; these are probably
bundles of muscular fibre, by the contraction of which the body
may be shortened. The cilia are disposed in two circles, form-
ing what are termed the wheels. By the successive vibration of
these, the appearance of a continual rotation is produced ; and
their action creates rapid currents in the surrounding fluid, by
which the supply of food is obtained. A sort of whirlpool is
created by each wheel, which brings towards the mouth the
minute animalcules and other particles floating in the neighbour-
hood ; and those which are not swallowed, are carried off by a
return-current. Between the wheels, the head is occasionally
protruded, bearing the two red spots supposed to be eyes ; and
on its under surface there is a projecting spike (c), which is
observed to be tubular, and which is believed to act as a syphon
for the introduction of water into the general cavity, for the
purpose of respiration. In the organisation of the alimentary
canal, we observe a striking resemblance to that of the Ascidiform
Polypes (Chap. XXI Y.) The oesophagus terminates in a sort of
gizzard, provided with regular teeth at its entrance (d). These
teeth are two in number on each side, and are fixed upon hard
jaws, moved by powerful muscles, so as to work between each
other. All the food which is swallowed is submitted to their
action, before it enters the first stomach ; and when the cilia are
in operation, these jaws are always in regular movement. From
the first stomach there passes off in the Rotifer a long straight
intestine (/,/), which terminates without any dilatation except
near its close (#), just at the commencement of the tail. But in
many other Rotifera we find the gizzard opening into a larger
cavity, which may be regarded as the true digestive stomach.
Near the termination of the intestine is the opening of the pas-
sages, by which are extruded the eggs (&), that are formed in the
large ovaria. These eggs often attain so great a degree of deve-
lopment, while yet within the body of the parent, that the ciliary
movements of the embryo may be seen ; and the young may be

z2

320 STRUCTURE OF WHEEL-ANIMALCULE.

said to be born alive, being capable of active locomotion, and ot
obtaining their own food, as soon as they quit the body of the
parent. Besides the longitudinal muscular bands, we observe
transverse lines crossing the body at intervals, which might be
supposed to possess the same character, and to contribute to the
elongation of the body, by contracting upon the contents of
the visceral cavity. But Ehrenberg gives strong reasons for the
belief, that these are blood-vessels, passing off from a trunk
which runs along the back, like the dorsal vessel of Insects
(§ 618). Nervous ganglia are suspected to exist in this animal
in the neighbourhood of the eyes ; but they cannot be seen in
this species as distinctly as in some other Botifera.

858. This Animalcule, from the activity of its habits, and
the variety of the movements it performs, is one of the most
interesting objects which commonly present themselves to the
microscopic observer. Sometimes it fixes itself by its forked
tail to some solid basis, and then sets its wheels (as they appear)
into rapid revolution ; at the same time bending its flexible body
in various directions, so as to create currents in different parts
of the surrounding water. In this manner it draws into its
gullet the unfortunate Animalcules which have been affected by
the whirlpool it has created ; just like (it has been amusingly
remarked by Spallanzani) a certain species of Whale, which, after
having driven herrings into a bay or strait, by a blow of its tail
produces a whirlpool of vast extent and great rapidity, which
precipitates them down its open mouth. The food thus taken
in passes at once towards the stomach, and is submitted to the
action of the jaws at its entrance, by which it is broken down.
By keeping a Wheel- Animalcule for a few days in pure water, it
will become almost perfectly transparent in every part, and its
alimentary canal will be completely emptied. If some water
containing the green or red Cercarioe, or any other small coloured
animalcules be then added, its voracity will be very amusingly
exhibited. They will be very distinctly seen passing into the
alimentary canal, as fast as the animal can masticate them ; and
this will become distended with their coloured substance. It can-
not be questioned that the ciliary movement is here entirely

STRUCTURE OF WHEEL- ANIMALCULE. 321

subject to the will of the animal. When satisfied with the sup-
ply of food it has obtained, the movement of its wheels no longer
continues ; and the lateral projections on which they are situated
then usually fold themselves inwards, so as to conceal them.
The form of the animal— the head still projecting — then closely
resembles that of a Leech ; and the movements which the Rotifer
performs in this condition, are by no means unlike those of that
animal. Sometimes it detaches itself altogether, and swims
freely through the fluid, as if in search of a new pasture. In
other instances it attaches itself by the head, which is furnished
with a sort of sucker for the purpose ; and then, by shortening
the body, draws up the tail into close proximity with it. It
then attaches the tail, and, detaching the head, extends the body
so as to project the head to a considerable distance, where it
takes a new hold of the surface upon which it thus creeps. The
rapidity and precision with which these movements are executed,
display a considerable amount of muscular energy on the part
of the animal, as well as of that capability of adapting its opera-
tions to circumstances, which indicates sensations of some acute-
ness. When the body is elongated to its full extent, the intestinal
canal runs nearly straight ; and the eggs, which may usually be
seen by its side, lie apart from one another. But, when the body
is contracted, the alimentary tube becomes serpentine, and the
eggs by its side, appear to be in close contact. The great amount
of muscular contractility, and the flexibility of the integument in
this animal, enable it thus to contract itself more than most of
its class. It is not unfrequently seen to assume quite a globular
form ; and this is its usual aspect when it dies, or when the water
evaporates. — The reproduction of the Rotifer is not accomplished
by spontaneous subdivision, or by the production of buds, such
as we shall see to occur in the lower Infusoria ; it takes place
only by eggs, in the manner already mentioned. Although not
many eggs are produced at once, yet these so speedily become
capable of producing others in their turn, that the multiplication
of these beings takes place with extraordinary rapidity. A cal-
culation, made by Ehrenberg, from data furnished by experiments
upon another species, will be presently given (§ 861).

322 TENACITY OF LIFE IN ROTIFER A.

859. The capability which these Animalcules possess, of
being revived, after having been entirely dried up, or desiccated^
is one of the most curious points in their history ; since no other
animals of an organisation so complex, appear able to preserve
their vitality under the same treatment. The fact was first
observed by Leeuwenhoek ; and it has been since confirmed by
other observers. Ehrenberg doubts, however, whether a com-
plete desiccation could have taken place ; thinking it impossible
that the animal should survive it. The following statement of
my own experience on the subject may not, therefore, be unde-
sirable. In the summer of 1835 I placed a drop of water, con-
taining a dozen specimens of the Rotifer vulgaris, on a slip of
glass ; and allowed the water to dry up, which it did speedily,
the weather being hot. On the next day, I examined the glass
under the microscope, and observed the remains of the animals
coiled up into circles, — a form which they not unfrequently
assume when alive, — but so perfectly dry that they would have
splintered in pieces if touched with the point of a needle, as I
had before observed in similar experiments. I covered them
with another drop of water ; and in a few minutes ten of them
had revived, and these speedily began to execute all their regular
movements with energy and activity. After they had remained
alive for a few hours, I again allowed the water which covered
them to dry up ; and I renewed it on the following day with the
same result. This process I repeated six times ; on each occasion
one or two of the animals did not recover ; but two survived to
the last; and with these I should have experimented again,
had I not accidentally lost them. — It is possible that the species
on which Ehrenberg and other foreign naturalists have experi-
mented, may not be the same as that which I and other English
observers have used. Something, too, appears to depend upon
the season and the general condition of the animal ; for, on
repeating the experiment in subsequent years, I have found the
results extremely variable, — not more than one or two sometimes
recovering, out of a large number that had been dried up. It is
interesting to remark, that, whilst, in the embryo which is being
developed from the egg, the rotatory and masticating organs are

WHEEL-ANIMALCULES ; HYDATINA.

323

the first parts which exhibit motion, they are the last to revive
after this kind of resuscitation.

860. We observe, then, in the Rotifer vulgaris, a very manifest
tendency to the Vermiform character, exhibited in the elongated
shape of the body, the position of the
eyes and mouth at one extremity of it,
the narrow, straight, intestinal canal
having its second orifice near the other
extremity, and the mode of locomotion
when the tail is detached and the
operation of the wheels suspended.
This tendency, however, is not so
marked in some species of the class,
which are inmanyrespectsmore highly
developed than this; — for example,
the Hydatina senta^ an animalcule
not uncommon in vegetable infusions.
Here the body is somewhat funnel-
shaped ; and the cilia are arranged
around the wide mouth, in two con-
centric rows. The outer row consists
of a simple continuous circle, arranged
upon the edge of the body ; but the
inner one is made up of eleven groups
of cilia, attached to distinct muscular

lobes. The integument appears to consist, as in the Rotifer, of
two membranes, both of which are soft and flexible. To the inner
one are attached four pairs of longitudinal muscles, by which
the chief movements of the body are performed. The tail has
separate muscles for its retraction or protrusion ; and others are
seen at the large extremity of the body, which fold up the ciliary
apparatus. The distinction between the muscles and the sup-
posed vessels is here well marked ; and there can be little doubt
that the true function of the latter has been assigned, even
though no subdivision or re-union can be traced (on account
of the minuteness of the whole object) between the transverse

FIG. 538.— HYDATINA SENTA ; a,
rows of cilia ;'Jb, muscles of the ]
jaws ; c, stomach ; d, enlarged
termination of the intestine ;
e, anus ;/, salivary glands ; g,
ovaria ; h, dorsal vessel.

324 STRUCTURE AND REPRODUCTION OF HYDATINA.

branches. The mouth is situated in the centre of the large
extremity of the body; it leads, through a short oesophagus, to
the first stomach or gizzard, the jaws at whose entrance are pro-
vided with five or six pairs of teeth. Into this cavity a pair of
secreting casca open ; and between the termination of these is
the commencement of the intestinal tube ; the upper part of
which, being very distensible, may perhaps be regarded as a
second stomach, since in this the digestive process is principally
performed. The intestine terminates, as in the Rotifer, near the
posterior part of the body ; and the oviducts open into the dis-
tended extremity of its tube. The nervous system is here easy
to be distinguished. It consists of a kind of circle surrounding
the oesophagus, on which three pairs of ganglia may be observed.
From the lower pair there proceeds a double cord, which passes
along the ventral surface of the body to its opposite extremity.

861. The reproductive powers of the Hydatina are very remark-
able. The number of eggs contained in the ovarium at once is
never large,seldom exceeding three or four; but they are frequently
deposited and renewed, and themselves soon arrive at maturity.
The following experiment is related by Ehrenberg : — " On Nov.
21, I placed in a jar a young Hydatina containing an egg nearly
mature. I added for its food a drop of liquor containing Monads.
On the morning of the 22nd, the egg had been deposited. On
the 23rd I met with four individuals, of which two were fully
developed. On the morning of the 24th, there were twenty.
The observation ceased at this point ; as it became too difficult
to count the numbers which thus rapidly increased. In a space
of 72 hours, twenty individuals had been formed — one only
having been employed as the stock ; and at this rate of increase,
the numbers would be, at the end of ten days, 1,048,576; and this
number would be quadrupled in another day. Even if only two
instead of four were produced daily by each individual, a million
would be called into existence in twenty days ; and on the
twenty-fourth day, we should have 16,777>216 animalcules."
When we consider, in connection with this rapid increase in
number, the curious power of revivification possessed by these

REPRODUCTION OF ROTIFERA. 325

beings, it is 'obvious that we need not have recourse to the
idea of spontaneous generation,* to account for their sudden
appearance in various situations, and for their speedy multiplica-
tion wherever the condition, in regard to food, temperature, &c.,
is favourable.

* This term refers to an i»!ca which has been entertained at various times, that
animals of low organisation may of themselves originate, by the accidental meeting
of particles adapted to form their structure.

CHAPTER XIV.

OF THE MOLLUSCA IN GENERAL.

862. QUITTING now the Articulated series, — which we have
seen to terminate in very simple forms of structure, that lead us
towards the Zoophytes, — we return to a higher point in the
Animal scale, to descend in like manner through the Molluscous
series. Looking only at the general complexity of structure
exhibited by these groups of Animals respectively, we might have
some difficulty in deciding which should rank the highest ; since
in the Articulata we observe one set of organs far more highly
organised than in any of the Mollusca ; whilst the converse holds
good as to another set of organs in the Mollusca. But when we
look at the respective characters of these organs, we cannot
reasonably hesitate longer. It is the organs of animal life that
are so highly developed in the ARTICULATA ; whilst it is in the
development of the organs of nutritive or vegetative life only, that
they are surpassed by the MOLLUSCA. In the Animal scale,
therefore, we may justly regard the Articulata as ranking on the
whole above the Mollusca. To the consideration of the latter
group we shall now proceed.

863. The range of animal forms comprehended in the sub-
kingdom MOLLUSCA is so great, that it would be difficult to
include them by any character common to all. We encounter
but few traces of the circular disposition of organs around the
mouth, which is characteristic of the .Radiated tribes ; and we
seldom meet with any thing that even approaches to the elon-
gation of the body, still less to the division into segments, which
has been noticed among the Articulata. This will be compre-
hended, when it is borne in mind that the body of the Mollusca
is almost entirely occupied by the organs of nutrition ; and that
the organs of sensation and locomotion are entirely subservient to

GENERAL CHARACTERS OF MOLLUSCA. 327

the supply of these. We find in the lowest tribes of this group,
li ving beings which are fixed to one spot during all but the
earliest period of their lives ; and which scarcely possess within
themselves so much power of movement, as that enjoyed by the
individual polypes in a mass of Coral ; and yet these exhibit a
complex and powerful digestive apparatus, a regular circulation
of blood, and an active respiration. But we nowhere find,
throughout the whole animal kingdom, that the conformation of
these organs governs the shape of the body ; they rather adapt
themselves to the type which predominates in its structure, and
which is principally manifested in the disposition of the loco-
motive organs. Thus, the stomach of the Star-fish sends a
prolongation into each ray; whilst in the Articulata, on the
other hand, we find the digestive cavity prolonged into a tube,
in accordance with the form which the body there possesses.

864. Thus we see that, in regard to external shape and
arrangement, the apparatus of Organic life has no definite plan
of its own ; and in the Mollusca there is an absence of any
general type, to which it may be made conformable. Hence the
shape of the body varies extremely in those classes, in which it
is entirely or principally composed of these organs; and no
general character can be given, which shall apply to all, or even
a large part, of the animals composing them. There is often an
entire want of every kind of symmetry ; that equality of the two
sides, which is peculiarly characteristic of the higher animals,
being deficient ; as well as the radial arrangement of parts seen
in the lower. But this is only the case, where there is no
development of a head ; that is, of a prominent part on which
the mouth is situated, and which also bears the organs of sensa-
tion, if any exist. In the higher Mollusca, which possess not
only sensory tentacula, but eyes, and even organs of smell and
hearing, we find these disposed in a symmetrical manner ; so
that the head (where it exists), or the part peculiarly concerned
in animal life, presents a bi-lateral equality of parts, even where
the remainder of the body wants it. In the more active species
among the higher classes, we find this bi-lateral symmetry
extending in many instances through the whole body ; evidently

GENERAL CHARACTERS OF MOLLUSCA.

bearing a pretty close relation with the degree of locomotive
power. It is most evident and complete in the CEPHALOPODA ;
many of the animals in which class are adapted to lead the life
of Fishes, and resemble them in the general form of the body
and in the structure of many individual organs.

865. As a group, however, the MOLLUSCA are .to be
characterised rather by the absence, than by the possession, of a
definite form ; and there is a corresponding absence of any
regular organs of support, by which such a form could be main-
tained. The name they have received designates them as soft
animals ; and this they are pre-eminently. The Shell, where it
exists, 'is to be regarded rather in the light of an appendage
designed for the mere protection of the body, and deriving its
shape from it ; than as a skeleton, giving attachment to muscles,
and regulating the form of the whole structure. Where tT e
body is entirely inclosed within it, as in the lower bivalve
Mollusca, no locomotive powers whatever, except such as depend
on the passage of water through the respiratory tubes, are
enjoyed by the animal. It is only where the body is uncovered
by a shell, or a portion of the body can be projected beyond it,
that any active movements can be executed ; and the muscles
concerned in the performance of these do not make the shell a
fixed point, as is done by those of Articulated or Vertebrated
animals in regard to their skeletons, but are entirely unconnected
with it.

866. Hence we see that the shell of a Mollusk is, when
considered in reference to its functions, a very different organ
from that of a Crustaceous animal, although formed in somewhat
the same manner. Its frequent absence might of itself lead us
to suspect its want of importance to the living structure. In one
whole class of Mollusca it is entirely deficient ; and in three others
it is frequently absent. In only one it is universally present.
When speaking of the anatomical conformation of the body,
therefore, we may leave the shell pretty much out of considera-
tion. Before the animals which produce them had been properly
studied, Naturalists founded their classification of Mollusca upon
the shells only ; and the greatest confusion thus resulted. Shells

GENERAL CHARACTERS OP MOLLTJ3CA. 329

of very similar aspect are often produced by animals extremely
unlike each other,* and living in different conditions — as, for
instance, fresh and sea water. And shells of very dissimilar
character in the eye of the mere Conchologist, often belong to
animals closely allied. In fact, the form of the shell taken
alone is a character as purely artificial, as the number of stamens
and pistils in a flower ; and will lead to a classification as far
removed from a natural plan. But when the principal divisions
have been formed upon other grounds, the conformation of the
shell will often afford valuable subordinate characters ; and the
Naturalist seeks to employ these as much as he safely can, on
account of the facility with which he can apply them to the study
of those fossil remains, from which all traces of the animal itself
have disappeared. The softness of the entire body of the Mol-
lusca prevents us from recognising its form and structure after
death, in any other way than by the shell ; but upon this, it
must be remembered, entire reliance cannot be placed, since it is
liable to great variation, in accordance with the circumstances of
the individual) whilst it is by no means certain that there are
constant differences in its form in distinct species.

867. The only tribe of Mollusca which presents anything
that corresponds to the internal skeleton of the Vertebrata, is
that of the Cuttle-fish. There is in their bodies a cartilage,
partly inclosing the nervous centres in the head, and sending
prolongations along the back, for the protection of the large
nervous cords which traverse it, and for the attachment of the
muscles by which it is moved. These last are especially deve-
loped, where the body is spread out into fin-lil^e processes,
resembling those of Fishes, by the stroke of which active move-
ments are produced (Fig. 540).. This skeleton is almost as
highly organised, as are the lowest forms of that internal skeleton
which is characteristic of Vertebrata (§ 585).

868. In all the Mollusca, the soft body of the animal is

* The impossibility of founding a correct classification upon the characters
afforded by the shell only, is made at once apparent by comparing the shell of a
Serpula (Fig. 528), -with that of a Vermetus (Fig. 583). Between these two
shells, there is no essential difference ; yet the animals which form them belong,
not merely to different families, but to different sub-kingdoms.

330 MANTLE AND SHELL OF MOLLTJSCA.,

inclosed in a spongy elastic skin, with which muscular fibres are
interwoven ; this is termed the mantle. This envelope is fre-
quently not applied closely to the surface of the organs contained
in it ; especially among the lower classes, in which the space
thus left constitutes a respiratory chamber. It has apertures for
the admission and exit of the surrounding water, to effect the
aeration of the blood ; and, when the mouth is not capable of
being projected beyond it, the same current furnishes the supply
of food. These apertures are sometimes extended, for particular
purposes, into proboscis-like tubes (Fig. 597). Where the head
is capable of being protruded, there is usually an opening in the
mantle for the purpose ; and another for the foot, where it
exists as a separate organ.

869. The mantle is chiefly interesting, as being the portion of
the body alone concerned in the formation of the shell. Some-
times this envelope is secreted from nearly the whole surface ;
sometimes from only a small part of it. As the same general
statements in regard to the constitution of this body will apply
to all the Mollusca, its origin and essential characters may
advantageously be described, previously to the more detailed
account, which will be given of the several classes, in which its
leading peculiarities of form will be noticed as they occur. Shells
are formed, like bones, of a combination of earthy and animal
matter. The former consists entirely of carbonate of lime,
which is usually deposited in a crystalline condition. The
latter is composed of layers of membrane, alternating with the
mineral matter; and of cells inclosing it. The cellular structure,
which seems to be of the nature of Epithelium (ANIM. PHYSIOL.
§ 39), is generally found upon the surface. If the carbonate
of lime be removed by the slow action of a weak acid, the
animal matter will remain, sometimes in the form of a continuous
membrane, but sometimes only as a flaky mass, easily shaken
into separate portions. The shell is most solid and massive in
those species which lead an inactive life ; and it attains greater
weight in the Conchifera, in which every species forms a stony
covering, than in the Gasteropoda, whose powers of locomotion
are somewhat greater, and in which the shell is often absent,

FORMATION OP SHELL OF MOLLTJSCA. 331

and is frequently composed, where it does exist, of nothing but
a thin horny plate, destitute of calcareous deposit.

870. As the mouth of the shell is always at its widest part,
and as, in extending it, the cavity is enlarged as well as its
entrance, there is evidently no necessity for such a division into
separate plates, with a provision for the individual growth of
each, as we have seen in the Cirrhopoda (§ 830) ; nor for the
periodical exuviation and renewal which is performed by the
Crustacea. In order to adapt its size to the progressive increase
in the bulk of the body, new layers are deposited from the mantle
at intervals, each of which usually lines the previous one, and
extends beyond it. The portion which thus projects is generally
thicker and firmer than the rest of the new layer ; since that part
which is deposited within the previous layers is protected and
supported by them. And the corresponding part of the mantle
is also thicker and more spongy, so as to possess almost a glan-
dular texture. At this part of it, indeed, are situated the glands,
by which the colouring matter is secreted, that gives to the
exterior of the shell its beautiful and variegated tints ; these are
wanting in that portion of the mantle, which merely forms the
lining to the older layers. In general we find each new layer
in immediate apposition with the last ; but this is not always
the case. The animal forms it upon the mould, as it were, of
its own body ; and if this has shrunk, or changed its form, so as
not to occupy the whole cavity of the shell, a space will inter-
vene. This is remarkably shown in the Spondylus varius, or
Water- Clam, a section of whose shell exhibits a regular series
of chambers thus formed ; and these are usually filled with
water. In the common Oyster such spaces may often be ob-
served ; but they possess no regularity. The animal always
appears inclined to adapt its shell to the form of the body, by
reducing its cavity if necessary, as well as by extending it ; and
thus an Oyster, which has been kept without food, and wThose
body has thereby shrunk, so as not to fill .the interior of the
shell, will expend its last energies in forming a new layer
adapting the interior surface to its altered condition. The
texture of the shell varies considerably in the different tribes of

332 LOCOMOTION OF MOLLTJSCA.

Mollusks ; and it often furnishes characters in classification,
which are equally useful witli those derived from its form.

871. The means of locomotion possessed by Mollusca are
usually very limited ; and the absence of any constant and
regular provision for this function, is an additional evidence how
little it enters into the general plan of the group. We have
seen in the Articulated series, that, wherever members or instru-
ments for locomotion exist at all, they have the same character
and situation, — being developed from the several segments of
the body, with more or less complete uniformity. Now among
the lowest Mollusca we shall find, that some tribes are entirely
fixed, during all but the earliest period of their lives ; that in
others, although the body is not fixed, it has no other means of
movement than that afforded by the respiratory currents, which
cause it to advance gently through the* water, without (as it
would appear) any voluntary control on its own part. In many
animals inhabiting Bivalve shells (i. e. Shells which are formed
of two parts or valves, united by a hinge) there exists what is
termed a foot ; which is nothing else than a fleshy tongue-like
projection, sometimes enabling the animal to leap upon hard
surfaces, sometimes used as a boring apparatus, sometimes em-
ployed as a sort of fin for swimming, and sometimes chiefly
useful as the instrument for producing the lyssus, a sort of cord
by which the animal attaches itself to rocks, &c. — In the animals
inhabiting the greatetf number of Univalve shells, there is no
such projecting foot; but the under side of the mantle is thick-
ened into a fleshy disc, which, by its contractions and expansions,
serves as an instrument of progression. This is well seen in the
common Snail. Among the animals allied to these in structure,
but not possessing a shell, the whole mantle is muscular ; and
by the contractions and expansions of its different parts, the
general movement of the body is effected. This is especially the
case with the aquatic species of this group ; some of which are
thus enabled to swim with considerable rapidity. — Again, in
the Mollusca of the Cuttle-fish tribe, we find this method
replaced by others, which are more efficient, but which are
entirely different in their character. This group is distinguished

ORGANS OF LOCOMOTION AND SENSATION. 333

by the presence of a set of arms or members disposed in a cir-
cular or radiating manner around the mouth ; and these arms
are frequently the chief instruments of locomotion, as well as of
the prehension of food, being furnished with a strong connecting
membrane, that forms a sort of circular fin, by the aid of which
the animal swims backwards (Fig. 545). In other members of
this group, the arms are less developed, but the body is elon-
gated into a fish-like form ; and it is furnished at its edges with
fins much resembling the dorsal and anal fins of Fishes, and
supported by the cartilaginous internal skeleton already men-
tioned (Fig. 540). From this general sketch it is evident that
the appendages for locomotion do not possess, in the Molluscous
series, anything like the same regularity of development which
they manifest in the two preceding ; and that locomotion forms
a much smaller part of the life they are destined to lead. In
fact, the word sluggish, which is founded upon the well-known
habits of a naked (or shell-less) terrestrial Mollusk, very well
expresses the general character of the group in this respect.

872. The amount of development of the organs of sense
in Mollusca, varies as much as the character of the locomotive
apparatus. Thus in the highest class, comprehending the Cuttle-
fish and its allies, the head is furnished with a pair of large
well-formed eyes, constructed upon the general plan of those of
Vertebrata. There is also an apparatus for Hearing, much
resembling that which exists among the lowest Fishes ; and
there is reason to believe that an organ of Smell is also present.
The senses of Taste and Touch appear to be very acute. It is
in such animals, that we should expect to find the organs of
sensation most developed, on account of their rapid locomotion
and voracious habits. In the Gasteropods, which are not so
much distinguished in these respects, we find the organs of sense
less developed ; but it is seldom that either of them is altogether
absent.* Descending lower, however, we no longer find these
organs situated upon a prominent part of the body ; nor are they
usually placed in the near neighbourhood of the mouth. This

* An apparatus for hearing, though of a very simple kind, has lately been
detected in a large number of this class.

334. NERVOUS SYSTEM OF MOLLTJSCA.

is usually furnished, indeed, with feelers or tentacula, which are
nothing else than prolonged lips, and which serve to distinguish
and select the food ; but the eyes, if any are present, are gene-
rally placed elsewhere, in such a position as to be of the most
effectual guidance in the movements of the body. In the lowest
Mollusca, we lose all traces of any special organs of sense ; and
it appears as if the sense of feeling, possessed in all probability
by the body in general, but peculiarly by the lips or tentacula,
is the only one through which the animal can receive any inform-
ation of its condition.

873. The conformation of the Nervous System is very much
what might be anticipated from the facts just stated. It by no
means displays the same complexity, or seems to possess the
same importance as a prominent feature in the composition of a
Molluscous, as it does in that of an Articulated animal ; and its
arrangement is not marked by any regular characters, but varies
with the disposition of the organs with which it is connected.
Thus we have a single ganglion, or a pair of ganglia, situated in
the head, where this exists as a distinct part ; and these ganglia,
which seem to be the principal seat of the instincts of the animal,
serve to direct those movements which are not reflex. The gills,
the pharynx, the foot, and other organs, usually have their own
distinct ganglia ; and these, which are all connected with the
cephalic ganglia (those situated in the head), seem to be the
centres of the reflex actions of the several parts ( ANIM. PHYSIOL.
§ 439, and ZOOLOGY, § 53, and Figs. 35 and 36). In the
lowest Mollusca we find but a single ganglion, which seems in
some degree to combine all the functions just mentioned, but to
be particularly connected with the respiratory apparatus.

874. The Mollusca are, for the most part, extremely vora-
cious ; and are not particular in their selection of food. It is in
those which possess most power of locomotion, that we see (as
might be expected) the greatest exercise of choice ; those which
are dependent for their aliment upon the casual supplies brought
by the sea, being obliged to take what they can thus get.
Their digestive apparatus is always highly developed. We
uniformly meet with a large liver ; and frequently with salivary

CIRCULATION AND RESPIRATION OF MOLLUSCA.

335

LJL.-A

glands, and organs of mastication. There is frequently a com-
plete gizzard, or muscular stomach, for the reduction of the
food, when this is not acccomplished in the mouth ; and the
intestinal tube is often of considerable length, and much convo-
luted, or rolled together. The blood is colourless or nearly so ;
and circulates, in all Mollusks, in a regular system of arteries
and veins, issuing from a heart, which is usually muscular or
nearly so, and possessed of two cavities, one of them a receiving
cavity or auricle, and the other an impelling cavity, or ventricle

(ANIM. PHYSIOL. § 257).
The accompanying figure
will give an idea of the usual
mode in which the Circula-
tion is carried on in this sub-
kingdom. The blood (which
has returned from the gills
in an aerated state) is pro-
pelled, by the ventricle, #,
through the main systemic
artery, b ; after passing
through the capillaries of
the system, it is collected
by the systemic veins, /,
into a large trunk, which
again subdivides into the
branchial arteries, g; these
convey the blood, now ren-

FIG. 539.— CIRCULATING APPARATUS OF DORIS. — » 7

a, ventricle; b, main artery or aorta ; c, auri- dered VeUOUS, to the gills, £,

where it is aerated; and
after returning thence by the
branchial veins, d, it enters the auricle, c, whence it passes
again into the ventricle, a. — The Respiration of Mollusks is almost
always aquatic ; being carried on by the aid of gills, which expose
a large surface of blood to the water at once. These gills are
sometimes altogether exterior to the body (Fig. 569) ; sometimes
they are inclosed between folds of the mantle (Fig. 572) ; and
sometimes the respiratory surface is altogether internal. In this

AA2

i ; d, branchial veins ; e, vessels of the gills ;
/, systemic veins ; g, branchial arteries ; h,
tentacula.

336 CLASSIFICATION OF MOLLUSC A.

last case it may be so disposed as to admit the flow of water
introduced from without over its surface, as we shall see among
the Tunicated Mollusks ; or it may be adapted to expose the
blood to the influence of air, as is the case among the Terrestrial
Gasteropods (the Snail, Slug, and their allies), which are the
only Mollusca not aquatic.

875. In the classification of the Mollusca, the system of
Lamarck will be generally followed, with some modifications
rendered necessary by the researches of others. The Sub-
Kingdom may be first divided, like that of Articulata, into two
principal sections ; — the first including all those which have a
distinct head> or (in other words) which have the mouth situated
on a prominent part of the body, furnished with organs of special
sense ; — the second comprehending those in which no such head
exists, the mouth not being capable of being projected beyond
the body, and no organs of special sense being present. The
former may be termed Cephalous, and the latter Acephalous
(or headless) Mollusks. The Cephalous Moliusks are usually
divided into the three following classes : —

I. CEPHALOPODA, which have feet or tentacula arranged in a
circular manner around the head, as in the Cuttle-fish tribe.
It is in this group, that we find the nearest approach to the
Vertebrata.

II. PTEROPODA, a small but interesting class, characterised by
the possession of a pair of wing-like expansions of the mantle,
which serve as fins, and enable them to swim through the water
with great velocity.

III. GASTEROPODA, which form the most extensive group of
the whole Sub-Kingdom. These have a single foot, or muscular
disc for locomotion, formed by a thickening of the mantle on the
under surface of the body. Whilst the animals of the two pre-
ceding classes are entirely marine, there are species among these
which are adapted to live in fresh water, and even on land.

We are probably to add to these the group of HETEROPODA,
which has been usually ranked as an Order of the preceding, but
which has been lately found to differ from them so much in
internal structure, as well as in external form, as to be entitled

CLASSIFICATION OF MOLLUSCA. 337

to rank as a distinct Class. They are especially distinguished
by the form of the foot ; which, instead of being a horizontal
disc, is compressed vertically, so as to form a fin, which is turned
upwards, like the dorsal fin of Fish, instead of being situated on
the under side of the body.

876. In each of the foregoing Classes, we observe a consider-
able variation in regard to the relative size, and even the very
existence of the Shell ; for, whilst there are some species in all of
them, which are entirely destitute of this protection (such being
called naked Mollusks), there are others which possess it in a
slight degree, having it generally concealed in a fold of the
mantle ; whilst in others, again, it completely envelopes the body
when they desire to withdraw themselves under its protection.
In nearly every case, the Shell, where it exists, is Univalve ;
that is, composed of but one piece. — In the -Acephalous Mollusks
on the other hand, we find two very distinct groups ; in the first
of which the shell is always present ; whilst in the second it is
as invariably absent. The first is therefore named Conchiferous,
or shell-bearing; and the latter Tunicated, — the shell being
replaced by a leathery or membranous tunic. The Conchiferous
Acephala, with scarcely an exception, have Bivalve shells ; and
they are again divided into two classes, according to the arrange-
ment of their respiratory organs.

IV. LAMELLIBRANCHIATA, having the gills arranged in four
lamella, or riband-shaped folds, which run parallel to the edges
of the shell. To this group belong all the ordinary Bivalves.

V. PALLIOBRANCHIATA, having the respiratory surface formed
by the mantle itself. The animals of these shells differ in several
other important particulars from the preceding. This class is
very small at present, in comparison with the other Bivalves ;
but in the more ancient periods of the earth's history, a very
large proportion of the Bivalve Mollusks seems to have belonged
to it.

VI. TUNICATA, a group including all those Acephalous Mol-
lusks which are destitute of a shell. In this class, we find many
points of structure, which lead us towards the higher Zoophytes.

CHAPTER XV.

OF THE CLASS OF CEPHALOPODA.

877. THE Cephalopoda unquestionably constitute the group
of highest organisation in the Molluscous sub-kingdom. They
are characterised by the possession offset, or locomotive organs,
around the head ; whence their name is derived. But these feet
have no analogy either with the fleshy disc of the Gasteropods,
or with the feet of Articulata or Vertebrata. They are, in fact,
prolonged tentacula, or lips. In the Nautilus (Fig. 548), which
approaches the nearest to Gasteropoda, they are very numerous,
and are evidently feeble as instruments of prehension ; whilst
they would seem, from the distribution of their nerves, to be
more concerned in sensation. On the other hand, this animal
possesses a single fleshy disc, evidently analogous to that of the
Gasteropods, on which it probably crawls, when moving along a
solid surface, in a position analogous to theirs. In some of the
Cephalopoda the feet are much prolonged, and of great power ;
and are evidently very important organs both of locomotion and
prehension (Fig. 543). But in those forms which approach
most nearly to Fishes, we find them again reduced in size, very
much in proportion to the elongation of the body ; and it is by
the latter, and the fin-like expansions with which it is provided,

that progression is then
chiefly accomplished (Fig.
540). There are Fishes
which possess tentacular
F,G.540.-CALAMARY. prolongations of the lips,

which are evidently analogous to the arms of the Cephalopoda ;
and this is one among the many interesting points, by which a
transition is effected between these two classes. The Nautilus
is the only one amongst existing Cephalopoda, in which the prin-

GENERAL CHARACTERS OF CEPHALOPODA.

339

cipal part of the body is contained within a. shell. Animals of
this kind were formerly much more abundant. At present the
naked species, as they are termed — in which the shell is rudi-
mentary, and is inclosed between folds of the mantle instead of
being external to the body — are the chief inhabitants of our
seas. In some of these, the shell still retains considerable size
and density, as the common pounce-bone ; but in the long slender
species, which swim by the movements of the whole body, it is
necessarily flexible ; and here we find it very narrow, and com-
posed of a light horny substance, so as to bear some resemblance
to a feather.

878. The trunk of these animals is inclosed in the mantle ;
which is shaped like a bag, sometimes nearly spherical, some-
times more or less
elongated ; inclosing
all the viscera, and
being only open in
front (Fig. 541, o).
The head, projecting
from this opening, is
round, and generally
provided with two
large eyes, of a struc-
ture very similar to
those of Vertebrated
animals. The mouth
is situated in the
centre of the circle of
arms ; and is armed
with a pair of horny

mandibles, which have very much the form of the Parrot's beak.
—The arms are sometimes all of equal length, as in the Octopus
(Fig. 545) ; and sometimes two are much longer than the rest,
as in the Calamary. — Cephalopods are essentially aquatic, and
breathe therefore by gills. These organs are concealed beneath
the mantle in a particular cavity (Fig. 541), the walls of which
dilate and contract alternately, and which communicates with

FIG. 541.— GILLS OK POULP.

340 RESPIRATION AND CIRCULATION OF CEPHALOPODA.

the exterior by two openings — one like a slit (o) for the entrance
of the water — the other, for the exit of water and excrements,
formed like a tube or funnel (t). Each gill (I) is shaped like a
prolonged pyramid ; and is composed of a great number of mem-
branous lamellag, placed transversely, and fixed on both sides of
a central stalk. The number of gills varies ; and this difference
is characteristic of two great divisions, of which this Class is
composed. In the Poulp, Cuttle-fish, and Calamary, there
exists but a single pair ; whilst in the Nautilus there are two.

879. The heart is situated between the gills, on the median
line of the body, and is composed of a single ventricle only (c,
Fig. 542). The blood from the gills flows into this ventricle

vv av a cs
FIG. 542. — ORGANS OF CIRCULATION AND RESPIRATION IN CUTTLE-FISH.

by branchial veins (vb), whose openings are provided with valves;
it then enters the arteries (as, &,) which spring from this organ,
and is distributed into the body. This liquid then returns into
a large vena cava (vc) ; which, when arrived near the heart,
divides itself into two branches (ab) to enter the gills ; lastly,
these vessels, when arrived at the base of the respiratory organs,

RESPIRATION AND DIGESTIVE APPARATUS.

341

generally present remarkable dilatations (c6), interwoven with
muscular fibres, so as to form two contractile reservoirs, perform-
ing the functions of pulmonary hearts. This arrangement is
observable in all Cephalopods with two gills ; but does not exist
in those which are provided with four. It may be regarded as
a transition-form between the heart of the lower Mollusca, which
is altogether systemic (§ 874) ; and that of Fishes, which is
entirely respiratory (§ 535).

880. The digestive apparatus is very complicated. The
mouth is surrounded by a circular lip ; and the parrot-like jaws
are put in motion by powerful muscles.. There are well-developed
salivary glands, several stomachs, and a voluminous liver ; the
intestine terminates in the branchial cavity, at the base of the
funnel by which the water is ejected, and communicates with a
very singular secreting organ, which, in the dibranchiate (two-
gilled) Cephalopods, produces an abundance of a black liquor,
commonly termed its ink. The

duct of this gland opens near
the anus; and, when the animal
is in danger, it expels this liquid
through the funnel in sufficient
quantities to hide the animal
from the view of its enemies,
by mingling with the surround-
ing water. It is the ink of
one of these animals, the Cuttle-
fish, which is employed in
painting, under the name of
Sepia ; and several authors
look upon Indian Ink as an
analogous substance. — The
four-gilled Cephalopods present
nothing of this kind.

881. The arrangement of the Flo< 543._LoLiGopsis.
organs of locomotion, which

are fixed around the mouth, varies in different divisions. In the
two-gilled Cephalopods, there is a crown of large fleshy tentacula,
whose internal surface is provided with suckers, by means of

342

NERVOUS SYSTEM OF CEPHALOPODA.

which the animal fixes itself with great force to any body which
it embraces. In the Poulp we find eight of these appendages,
and in the Cuttle-fish ten. Sometimes two of them are expanded
into flattened mem-
branes, as in the Ar-
gonaut (Fig. 546) ;
or are elongated so as
to become filiform^
or threadlike, as in
the Calamary, and
particularly in the
Loligopsis (Fig.
543). In the four-
gilled Cephalopods
these appendages are
quite slender, and
unprovided with
suckers; but they
are extremely nu-
merous (Fig. 548).
882. Most Mol-
lusca of this class
are remarkable for
the development and
perfection of their
eyes, which are ex-
ceedingly like those
of Vertebrated ani-
mals. Many possess
also an apparatus
for Hearing ; but
this organis reduced
to a little membra-

nous sac repre-
senting the vesti-
bule, and receiving
a nerve (ANIMAL
PHYSIOL. § 512).

FIG. 544. — a, nervous collar embracing the oesophagus,
the passage of which is marked by the bristle s ; c, ner-
vous mass, apparently analogous to the Cerebrum of
Vertebrata, from whose under side proceed connecting
cords to two ganglia situated in front, which send nerves
to the mouth, lips, pharynx, &c. ; b, tentacular ganglia,
sending nerves to the arms ; 0, optic nerves ; g, sub-oeso-
phageal ganglion ; v, great nerve of the viscera, of which
one of the branches possesses an elongated ganglion, r,
and enters the gills ; m, another branch, having the same
origin, and furnished with a star-shaped ganglion, e, that
sends nerves to the mantle.

Lastly, the nervous system of these animals

NERVOUS SYSTEM AND LOCOMOTION OF CEPHALOPODA. 343

is more complicated than that of other Mollusks; and the different
ganglia, situated around the oesophagus, tend more to unite in a
single mass. The nervous collar thus formed is composed of a
pair of cephalic ganglia, whence originate the optic nerves ; of a
pair of ganglia, situated more in front, but beneath the oasopha-
gus, and furnishing the tentacula with nerves ; lastly, of a pair
of thoracic ganglia, supplying the mantle with nerves, and
sending backwards two cords on each side, which are themselves
furnished with ganglia, whence proceed nerves that supply the
mantle, gills, heart, £c. It is evident from this description,
that the nervous system of the Cephalopods approaches that of
the lower Fishes in many particulars ; especially in the almost
complete concentration of the nervous centres in the region of the
head, and in the presence of the rudiments of a cerebral mass.
If the cords that proceed backwards from the sub-cesophageal
ganglion had been united on the central line, instead of diverging
from each other, they would have presented a strong analogy in
position, as well as in function, to the Spinal Cord of Vertebrata.
883. Cephalopods are almost exclusively marine in their
habits; only a few of them, such as the Octopus or Poulp
(Fig. 545), ever quitting the water to prowl along the shore in
search of food. When thus moving, they walk in what may be
considered an inverted position ; the mouth being downwards,
and the opposite extremity of the body being directed upwards.
When swimming, the Poulp moves backwards through the
water, propelling itself by the alternate contractions and exten-
sions of the circular fin, which unites the bases of the arms. But
the long slender-bodied Calamaries (Fig. 540), in which the arms
are short, swim much more after the manner of Fishes ; striking
the water, by means of the fin- like expansions of the mantle
along the back and abdomen, with such force as occasionally to
raise themselves out of the water. The Nautilus (Fig. 548)
seems more limited in regard to its means of locomotion ; since
its arms are not long enough to serve as efficient instruments for
this purpose, and it has no other means, except a fleshy disc,
which resembles that of the Gasteropods, and which enables the
animal to crawl along solid surfaces in an inverted position.

344 HABITS OF CEPHALOPODS.

884. The animals of this Class are extremely voracious in
their habits ; and seldom, if ever, devour anything but animal
food. They chiefly prey upon small Fishes and Crustacea ; arid
seem especially destined to restrain the too rapid multiplication
of the latter. Winding its arms around the body and limbs of
even a powerful Crab, and securing them all by fixing its suckers
upon their surfaces, the Cuttle-fish can pick the shell to pieces
with its powerful mandibles, and extract the contained flesh,
without fear of injury; — an action which no animal of any
other Class could attempt. The firm armour, and powerful
crushing jaws, of the more ancient Fishes, might have enabled
them likewise to feed upon Crustacea; but no such Fishes now
exist. The Common Cuttle-fish, and the Calamaries or Squids,
are often very troublesome to fishermen, by following shoals of
fish into the nets, devouring large quantities of them, and watch-
ing an opportunity to dart away before they can themselves be
seized. In their turn, they become the prey of the larger Fish
and of Cetacea. They are much used as baits in the Newfound-
land Cod Fishery ; and in the stomachs of the smaller Cetacea
great numbers of the undigested horny Mandibles are frequently
found, indicating (of course) that at least a corresponding num-
ber of the Cuttle-fish have been devoured by them. — Some
species of this class attain a considerable size. The Onychoteuthis,
the suckers on whose two long arms are furnished with hooks at
their edges, has been known to attain the length of six feet ; and
it is much dreaded by the natives of the Polynesian islands, who
are said to have been attacked by it, when diving for shell-fish.

885. The Class of Cephalopoda may be divided into two
Orders, according to the number of the gills (§ 878) ; — the
DIBRANCHIATA, or two-gilled, including the Cuttle-fish, Argo-
naut, and their allies, having only one pair of those organs ; —
and the TETRABRANCHIATA, or four-gitted, including only the
true Nautilus among the existing Cephalopods, but comprehend-
ing a vast number of species now extinct, possessing four of
those organs. The latter of these Orders is the one most allied
to the Gasteropoda, both in the structure of the shell, and in the
conformation of the animal.

345

ORDER L— DIBRANCHIATA.

886. The species of the Dibranchiate Order are extremely
numerous ; and they frequent every part of the ocean, from the
arctic to the equatorial regions, — some preferring the neighbour-
hood of the shores, whilst others are found only in the open sea.
None of them possess more than ten arms, and a part have only
eight ; the latter are considered as forming the highest group,
being the most removed from the Tetrabranchiate Order. In
only one genus, the Argonauta, do we find the body inclosed in
an external shell ; in all the rest, the shell, or that which repre-
sents it, is internal, or rather is included between two folds of
the mantle ; and it serves rather as an organ of support, than as
a protection to the animal.

887. To the Octopod, or eight-footed family, belongs the

FIG. 545. — OCTOPUS OR POULP.

common Octopus or Poulp (Fig. 545), which is common on the
southern coasts of Europe, and which is occasionally met with
on our own shores. This animal is the Polypus of ancient

346 OCTOPUS OR POULP.

Naturalists ; who were quite unacquainted with the animals to
which the name is now restricted. (Indeed this name was first
conferred on the Hydra and its allies, on account of their simi-
larity in form, and in the position of their prehensile arms or
feet, to the animal previously known under that appellation.)
The common Poulp has arms six times the length of its body ;
and each of these is furnished with 120 pairs of suckers. Every
sucker is composed of a circular adhesive disc composed of a
muscular membrane ; this has a thick fleshy circumference, and
presents a number of lines radiating towards the circular orifice
of an inner cavity, situated beneath the central part of the disc.
In this cavity is a moveable circular piston ; which, when the
sucker is not in action, appears level with the circular aperture;
but which, when the disc is closely applied to any object, is
strongly drawn back, so as to increase the size of the cavity and
produce a vacuum in it ; — forming, in fact, an air-pump of the
most precise and beautiful construction. When the animal
releases its hold, it relaxes the muscles that drew back the
piston ; and the vacuum is then made to cease. The whole
apparatus might be compared to a boy's leather-sucker, with an
exhausting syringe fitted to its centre.

888. It may be noticed, as a curious example of reflex action,
that the nervous trunk supplying .each arm of the Octopus, is
furnished with a series of ganglia, corresponding in number and
position with the suckers. A part of the trunk passes over the
whole series of ganglia without entering them, — precisely as in
the case of the ventral cord of the Articulata ( ANIM. PHYSIOL.
§ 442) ; and this sends branches into each sucker, so as directly
to convey to them the influence of the cephalic ganglia, and thus
to cause them all to contract at the will of the animal. On the
other hand, each sucker receives nervous filaments from its own
ganglion ; and may be made to contract, when stimulated to do
so, by the contact of a solid substance, even though the arm is
entirely separated from the body. Hence, when a Cuttle-fish
has fixed itself upon any animal, it may be cut into pieces with-
out the suckers relaxing their hold ; since the muscles of every
sucker are called into action by the reflex properties of its own

OCTOPUS OR POTJLP. — ARGONAUT. 347

ganglion alone. The conformation now described is common to
the whole Order.

889. In regard to the Poulp it has been justly remarked,
that " there is something strange and uncouth in the aspect of
this creature ; its long flexible arms moving and curling in all
directions ; and its large eyes, which stare with fixed gaze,
rendering it even repulsive." Even a cursory observer would pre-
dict it to be ferocious and carnivorous ; and its actual character
harmonises with its appearance. Woe to the Fish that is
infolded within the tenacious grasp of its arms. Resistance is
vain ; for the suckers adhere with such tenacity, that they may
sooner be wrenched off than unfixed. Closer and closer to the
mouth is the victim brought ; until, being firmly secured as in a
vice, the work of demolition commences. — Although the largest
Octopi of which we have any account that is entirely free from
doubt, do not measure above 4 feet between the ends of the arms ;
yet the inhabitants of several parts of the warmer regions of the
globe confidently assert, that much larger ones are to be met
with. These are said to extend their arms out of the water, and
thus to lay hold of men, or of the masts of small vessels. The
inhabitants of some of the islands in the Indian Archipelago are
said to affirm, that Cuttle-fish are often seen two fathoms
(12 feet) broad over their centre, with arms nine fathoms
(54 feet long) ; and are stated to provide themselves with axes,
whenever they go out in boats, from their fear of being seized
by these monsters. Allowing for a great deal of exaggeration
in tliese accounts, it is still probable that Octopi exist in the
open sea, of much larger size than any with which we are
familiarly acquainted.

890. A very interesting species of the Octopod group is the
Argonauta, commonly called the " Paper-Nautilus," from the
whiteness and delicacy of its shell. As the animal has little in
common with the true Nautilus, it would be much better if the
latter designation were entirely abandoned, and that of " Argo-
naut" substituted for it. The shell is not chambered, as in the
true Nautilus ; but possesses one spiral cavity, into which the
animal can withdraw itself entirely. The animal, however, has

348

ARGONAUT, OR PAPER-NAUTILUS.

no muscular attachment to its shell ; whence it has been sup-
posed by many Naturalists to be a parasitic inhabitant, which

546.— ARGONAUT, OR PAPER NAUTILUS.

had taken up its abode within it ; the shell, from its resemblance
to that of the Carinaria (Fig. 901) being imagined to have
been really formed by an animal allied to that genus. It has
been lately proved, however, by the interesting experiments of

ARGONAUT. BELLEROPHON. 349

Madame Power (who has kept a number of these animals in a
kind of cage inclosed from the sea in the bay of Messina), that
the shell increases regularly with the growth of the animal ; and
that the Mollusk possesses the power of repairing the shell when
injured, in a manner corresponding to its original formation ;
whence no reasonable doubt can exist, that the Argonaut is the
real construction of it.

891. Of the eight arms of the Argonaut, six taper gradually
towards the extremities ; but two are expanded into wide mem-
branous flaps. From very early times, this animal has been
reputed to swim on the surface of the sea, using its arms as oars,
and spreading these expanded membranes as sails, so as to be
wafted along by the wind. But it is now known by accurate
observation of the living animal, that this is altogether a fiction
(though an interesting one) ; and that the expanded membranes
are spread over the sides of the shell, meeting along its keel or
edge, and completely inclosing it. It is by these, indeed, rather
than by the surface of the body itself, that the calcareous
secretion is poured out, for the enlargement or reparation of
the shell. It will be observed that there is a double row of
suckers along the edge of each of the expanded arms ; and by
these suckers they are held in close contact with each other along
the keel of the shell. When the animal withdraws its whole
body into the shell, the exterior of the latter is about half
uncovered, the expanded arms also being partly drawn in. By
the action of the arms, the Argonaut can swim backwards in
the same manner as other Octopi ; and it can also creep along the
bottom of the sea. — There is a fossil genus, Bellerophon, abundant
in the mountain-limestone formation ; which, from the charac-
ters of its shell, is regarded as nearly allied to the Argonaut.

892. The Decapod family, which, besides the eight ordinary
arms, has two longer and slenderer ones, presents many points
of approach to the Tetrabranchiate Order. This affinity is indi-
cated, not merely by the increased number of the external arms,
but by their smaller size in proportion to the body, by the
frequent development of a second row of small tentacula within
the others, and by several internal characters, especially the

350

LOLIGO, SPIRULA, BELEMNITE.

development of a chambered shell, of which we find some traces
in most of the different forms included in it. To this group
belong the Loligo, or Calamary (Fig. 540), already several
times noticed ; the common Sepia, or Cuttle-fish, whose body
is more bulky in proportion to its length ; the Loligopsis, so
remarkable for the length of its additional pair of arms (Fig. 543);
and several others having the same general form. In all these,
the only rudiment of a shell is a straight flat body, sometimes
broad and firm, as in the Cuttle-fish (forming the pounce-bone,
which may be picked up on every coast), sometimes slender and
horny, as in the Loligo. — There is an existing genus, however,
in which a chambered shell exists, very
strongly resembling those of the Ammo-
nite (Fig. 549) in general form, but com-
pletely inclosed by the animal, so as to
become altogether internal ; this is the
Spirula, an inhabitant of tropical seas,
whose delicate little shell may be picked
up on almost any sandy shore in warm
latitudes. The animal has not yet been
very carefully examined ; but it is known
to possess no more than ten arms ; whence
its position is fixed as belonging to this
group, rather than to the succeeding
Order.

893. With this family we are to asso-
ciate an extremely interesting genus, the
Belemnite, whose remains abound in
several of the older rocks, especially the
Lias and Oolite. The shell consists of a
conical chambered portion, implanted (as
it were) into a corresponding hollow of a
long solid sheath, tapering to a point at
its lower extremity (Fig. 547). The
conical chambered portion extends con-
siderably beyond the hollow of the stony
sheath ; but the border of the latter seems to have been prolonged

FIG. 547 — BELEMNITES;

a, large extremity, showing
the insertion of the cham-
bered cone into the sheath.

BELEMNITE. 351

forwards in a horny condition, so as still to envelope the cham-
bered cone. In the last or largest chamber of the cone, distinct
remains of an ink-bag have been frequently met with ; from
which it has been argued, that, notwithstanding the strong
resemblance of the shell to that of many genera allied to the
true Nautilus and belonging to the Tetr -abranchiate group,
the animal must have been Dibranckiate, and must have
included the shell together with its massive sheath, in the same
manner as the Cuttle-fish included the pounce-bone. This argu-
ment was founded upon the fact, that the Nautilus — the only
Tetrabranchiate Cephalopod now living — possesses no ink-bag ;
its power of withdrawing the body completely into its shell,
rendering such a means of protection unnecessary : and its
justice is made evident by the recent discovery of specimens
of Belemnite, in which the soft parts of the animal are so well
preserved, as to enable their form and general structure to be
distinctly traced. From these it has been ascertained, that the
arms were furnished with hooks, as in the Onychoteuthis ; and
that the body had a pair of small lateral fins situated at about
the middle of its length. From the weight of its dense internal
shell, the Belemnite may be supposed to have commonly main-
tained a vertical position ; and, as its chambered portion was
provided with a siphuncle analogous to that which we find in
the Nautilus (§ 894), the animal probably had the power of
ascending and descending in the water with facility. It would
rise swiftly and stealthily to fix its claws in the belly of a fish
swimming at the surface above ; and then, perhaps, as swiftly
dart down and drag its prey to the bottom, and devour it. We
cannot doubt that, like the hooked Calamaries of the present
seas, the ancient Belemnites were the most formidable and
predaceous of their class.

352

ORDER II.— TETRABRANCHIATA.

894. From the remains preserved in a fossil state, the Cepha-
lopoda of this Order appear to have been formerly most abund-
ant in our seas ; as they present themselves throughout almost
all marine strata, from the very earliest of the Palaeozoic series,
to those of a comparatively recent epoch. Yet some causes, of
which we are at present ignorant, have produced the almost
entire extinction of the Order; the only existing representative
of it being the Nautilus pompilius, or Pearly Nautilus, so named

FIG. 548 — PEARLY NAUTILUS ; with the shell laid open ; t, tentacula ; e, funnel ; p,
foot ; m, portion of mantle ; o, eye ; g, siphon.

from the nacreous lining of its shell. The shell of this animal
is well known ; being found on most shores between the tropics.
Of the animal which constructs it, however, Naturalists had,
until recently, the most vague and incorrect ideas, — the Nautilus
being very rarely met with in the living state, owing to its being

ORDER TETRABRANCHIATA ; NAUTILUS. 353

an inhabitant of the open sea, and possessing the power of sinking
at the slightest alarm. The general structure of the shell, which
may be taken as a type of the whole group of chambered shells,
will be evident from the accompanying figure ; which represents
it laid open. Externally it presents nothing remarkable, being
a flattened spiral ; but when its interior is examined, it is found
to be divided into chambers, by a large number of transverse par-
titions of shelly matter. The outer chamber is by far the largest,
and to this the body of the animal is restricted ; but it maintains
a connection with the rest by means of a membranous tube, called
the siphuncle (g. Fig. 548), which passes down through a per-
foration near the centre of each partition, and thus penetrates
even to the innermost and smallest chamber. Although the
history of the growth of the Nautilus cannot (for want of a
sufficient number of specimens) be positively stated, there is
every reason to believe that, at the usual period for the enlarge-
ment of the shell, the animal adds to the edges of the outer
chambers, in such a manner as at the same time to prolong and
widen it ; and that it then throws a new partition across its
lower or inner part, so as to form an additional chamber. Hence
the number of chambers would vary in different specimens,
according to their respective ages, and the consequent number of
additions they have made to their shells ; and this is found to be
the fact.

895. The general structure of the animal is intermediate
between that of the Dibranchiate Cephalopods, and that of the
Gasteropods. The arms are very numerous, amounting to nearly a
hundred ; they are unprovided with suckers, and they are short
and slender, closely resembling the tentacula of many Gastero-
pods. The head supports a large fleshy disc ; upon which it is
believed that the animal can crawl over the bottom or shores of
the ocean, as a Snail upon its foot. The power which the
Nautilus possesses, of rising and sinking in water at will, has
been attributed to the chambered structure of its shell ; and to a
power which it has been supposed to possess, of diminishing its
bulk, by forcing water from the sac which surrounds the heart
into the siphuncle, — or allowing it to be expelled from that tube

354 NAUTILUS; — NAUTILITE ;— ORTHOCERATITE.

by the elasticity of the air in the chambers, when it desires to
increase the bulk of the soft parts of its body. If such increase
and decrease in bulk could be effected without any change in
the weight of the whole mass, it would be caused (according to
well-known principles of Hydrostatics) to ascend or descend in
water ; the animal with its shell being altogether of so nearly
the same specific gravity with that fluid, that a very slight
difference in this respect may produce either effect. But this
theory, however ingenious, is inconsistent with the fact that, in
some of the fossil chambered shells of this group, which we only
know from their fossil remains, the siphuncle was evidently con-
tinued as a shelly tube throughout, and therefore could not have
been distended with fluid ; and even in the recent Nautilus, it
does not appear to have been possessed of sufficient elasticity, to
admit the action thus assigned to it. The use of the chambered
structure, and of the siphuncle, therefore, still remains unknown.

896. The numbers of Fossil chambered shells formed on the
same plan, and therefore probably to be regarded as the remains
of Cephalopods of similar organisation, is very great. Thus we
find in almost all marine strata, from the oldest limestones and
sandstones of the Silurian system, down to those covering the
chalk, large numbers of shells, very nearly resembling the exist-
ing Nautilus, and therefore called Nautilites. Another fossil
genus, the Ortkoceratite, had a chambered shell, formed upon
the same plan with the Nautilus, but straight instead of being
spirally curved. In these two genera, — as in some others allied
to them, and forming the family NAUTILID^E, the partitions or
septa between the chambers are smooth or simple ; — that is,
although they are rather concave on the surface which looks
towards the outer chamber, and similarly convex on the other or
inner side, they have no inequality or irregularity of surface.
Moreover, in both instances, they are usually perforated by the
siphuncle nearly in their middle.

897. In the spiral and straight shells which form the family
AMMONITHXE, on the contrary, the partitions are very sinuous
or wavy, sometimes even forming sharply-bent or zig-zag lines
(Fig. 549) ; and the siphuncle usually runs along the outer edge,

AMMONITES. 355

and may be seen projecting from the surface. The Ammonites,
commonly called Snake-stones, are among the most abundant
of all fossils ; especially in the Lias,
Chalk, and Oolite formations. Their
size is sometimes very considerable ;
Ammonites being occasionally met
with of as much as four feet in dia-
meter ; and a diameter of three feet
being by no means uncommon. In
some places they are so numerous,
that the rocks seem (as it were)
composed of them alone. Above two

hundred species of these shells have been already described ; and
it appears that many of these were very widely distributed.
Thus two species of Ammonites found in the Himalaya moun-
tains, at a height of 16,000 feet above the sea, are identical with
species which are common near Lyme in Dorsetshire. These
animals must have evidently been very important agents, — their
carnivorous habits being duly considered, — in keeping the balance
among the other tenants of the seas, by preventing the excessive
multiplication of Crustacea, as well as (in all probability) of
other Mollusks, and of Fishes. That their mouth was armed
in the same manner as that of the existing Cephalopods, is
evident from the fact, that Rhyncolites, or fossilized beaks, are
found in large numbers, associated with the shells of the Ammo-
nites, in the beds in which they occur. It has been suspected
by some Naturalists, that the Ammonite might have been, like
the existing Spirula (§ 892), an internal, not an external shell.
This idea, however, is inconsistent with the size of the outer
chamber, which is quite large enough to receive the animal,
usually forming two-thirds of an entire 'whorl or turn of the
shell ; and also with the fact that the mouth of the shell, in
specimens in which it has been found perfect, is so constructed
as to have been evidently connected with the external parts of
the animal, and not to have furnished attachment to internal
organs. The shells of the Ammonites seeming to have been
thinner than those of the Nautilites ; and as their form was less

356 AMMONITES.

arched, they would have been less capable of resisting pressure
if they had not been furnished with ribs and bosses., variously
disposed in the different species, for the purpose of strengthening
them. In the species represented in the accompanying figure,
these ribs are very prominent.

FIG. 550. — AMMONITES.

898. Several kinds of chambered shells, with sinuous parti-
tions, are met with in various strata. These seem to have borne
the same relation to the Ammonite, as the Orthoceratite to the
Nautilus ; and they have been arranged, according to their
minuter diversities of structure. Some of them are spirally
curved, but the several whorls or turns of the spire are not in
contact with each other ; this is the case with the Crioceratite.
Others are straight, or but slightly curved ; such as the Baculite.
The Turrilite, again, has more of a corkscrew curve, resembling
that of many Gasteropod shells. — There is good reason to believe
that this group, which most abounded at the period when the
Ichthyosaurus and Plesiosaurus were the principal inhabitants of
the sea and shores, was preyed on by those marine tyrants ; the
remains of the beaks, and even of the horny rings surrounding
the suckers, of Cephalopods, having been found in the fossilized
excrement of those Reptiles.

CHAPTER XVI.

OF THE CLASSES OF PTEROPODA AND HETEROPODA.

899. NOTWITHSTANDING the small size of the class PTEROPODA,
it is interesting in many particulars. It may be regarded as
representing ', in the sub-kingdom Mollusca, the Birds of the Ver-
tebrated sub-kingdoms, and the Insects of the Articulated series;
and the inconsiderable number of distinct forms which it pre-
sents, may probably be accounted for by reverting to the wide
departure from the usual Molluscous type, which the animals of
this class exhibit in their structure and habits. They are par-
ticularly distinguished by the possession of a pair of fin-like

FIG. 551 CLIO BOBEALIS.

organs, or wings, consisting of an expansion of the mantle on
each side of the neck, and furnished with muscular fibres ; by
the aid of which instruments, they can be rapidly propelled
through the water. The body is uniformly symmetrical ; that
is, its two sides precisely correspond, — a condition evidently
favourable for rapid movement. It is from the wing-like cha-
racter of these lateral appendages, that the name of the class,
which means wing-footed, is derived. Although the number of
species belonging to this Class is small, and their dimensions are

358 PTEROPODA. CLIO.

inconsiderable, yet the number of individuals which associate
together in shoals is often enormous, so that the sea appears
literally alive with them. Some of them
are possessed of a shell; whilst others
are unprovided with such a protection.
Where it exists, it is very light and deli-
cate; and it seldom covers more than
the posterior half of the body (Fig, 552).
In one beautiful little Mollusk, the Cym-
lulia, it has the form of a slipper ; from
the large opening of which, the wings or
fins are put forth. The head of these
animals is usually prominent, possess-

Fio. 552.— HYALJEA. ,

ing eyes and sensory tentacula; and
their internal organisation is of a very complex nature.

900. The Clio (Fig. 551) is one of the best-known genera of
this class ; and its general aspect conveys a good idea of that of
the whole group. One species of this genus, the Clio lorealis,
abounds in the Arctic seas ; presenting itself in such vast num-
bers, that, when the weather is calm, the surface appears covered
with them for miles together; and an analogous species, the
Clio australis, appears to be equally abundant in the polar
regions of the southern hemisphere. These animals are well
known to the whale-fishers and others, as whales'* food, being
among the chief articles on which that monster, — the largest
existing animal, — is supported. It has been asserted that the
sea is sometimes so glutted with the Clios, that the Whale can-
not open its mouth without ingulphing thousands of them. — The
chief point of special interest in the structure of the Clio, is the
conformation of its organs for the capture and mastication of its
food. The six tentacula, which are seen to project from the
head, and which appear at first sight to be merely fleshy append-
ages, are in reality instruments of prehension, most elaborately
constructed. Each of these six appendages, when examined
attentively, is seen to be of a reddish tint ; and this colour, under
the microscope, is found to be dependent upon the presence of
numerous minute isolated red points, distributed over its surface.

CLIO BOREALIS. — HETEROPODA. 359

"When still further magnified, these distinct points are evidently
peculiar organs, arranged with great regularity, so as to give a
speckled appearance to the whole of the conical appendage ; and
their number, at a rough guess, may be estimated to be about
3000 on each. When very minutely examined, every one of
these specks is seen to consist of a transparent cylinder, not
unlike the cell of a polype, and containing within its cavity
about twenty sucking- discs, mounted upon stalks, by which they
can be made to project beyond the edge of their sheath, so as to
apply themselves to their prey. Thus, therefore, the head of one
Clio will bear about (3000 x 20 x 6) 360,000 of these micro-
scopic suckers ; an apparatus for prehension, which is, perhaps,
unparalleled in the whole animal kingdom. In this manner,
these active little animals are enabled to seize and hold their
minute prey ; and their mouths are furnished with efficient
instruments for reducing it. The jaws, which are placed laterally^
as in the Articulata, are furnished with long sharp comb-like
projections or teeth ; and the tongue is beset with a vast number
of sharp spiny booklets, curved backwards. Besides the prehen-
sile appendages just mentioned, two sensory tentacula are capable
of being put forth, for the purpose of feeling for the food. The
Clio possesses eyes, which, though extremely minute, have a
very complete organisation ; and altogether its structure com-
pletely corresponds with what has been already remarked in
regard to the character of the Class, as the Molluscous represen-
tative of Birds and Insects.

OF THE CLASS OF HETEROPODA.

901. The Mollusks of this class (which has been generally
considered as an Order of the Gasteropoda, but of which late
researches appear to require the removal to its present position)
are distinguished from all others by the structure and position
of the foot. This, instead of forming a horizontal disc more or
less flattened, is compressed, so as to constitute a vertical mus-

360

IIETEROPODA. CARINARIA.

cular paddle, serving as a fin. The edge of this, in many species,
is somewhat dilated at one part ; forming a kind of sucker, by
which the animals can attach themselves, and which seems to be
a rudiment of the expanded foot of the Gasteropods. The gills
are external, and form plume-like tufts, situated at the hinder
part of the back. The body is gelatinous in its consistence, and
so transparent as to permit much of its interior organisation to
be seen. The mouth is furnished with a sort of muscular tube
or proboscis, which can be protruded or drawn in at will ; and
it contains a rasp-like tongue. — One of the most remarkable

-»---_.-.— !'

FIG. 553. — CARINARIA ; a, mouth ; b, tentacula ; c, eyes ; d, stomach ; «, gills ; /, anus ;
g, shell ; h, liver ; i, foot ; k, sucker.

genera of this group, is the Carinaria ; which possesses a thin
shell, not unlike that of the Argonaut in form (§ 890). This
shell protects the heart and liver ; the gills float around its edge,
and the intestinal canal terminates in its interior. — All the known
animals of this group are inhabitants of the warmer-temperate,
and tropical seas ; many of them are found in the Mediterranean.
Their general form and structure correspond very closely with
those of the Carinaria.

CHAPTER XVII.

OF THE CLASS OF GASTEROPODA.

902. GASTEROPODS are those Mollusca, which are provided
with a head, and which move from place to place by means of a
fleshy disc, or foot, placed under the abdomen. This Class,
represented by the Snail, is extremely numerous ; and is chiefly
composed of animals living in a univalve shell, which is usually
cone-shaped and rolled into a spiral. Some species, on the con-
trary, are perfectly naked, or destitute of shell : the Slug, for

example. The body is elongated,
and terminates in front by a head
more or less developed, bearing
the mouth, which is provided
with fleshy tentacula varying in
number from two to six ; the
back is enveloped in a mantle,
which is more or less prolonged
FIG. 554—CAssis. backwards, and which secretes

the shell; and the belly is covered

on its under side by the fleshy mass of the foot. The viscera,
lodged on the back, occupy the superior part of the buckler or
cone formed by the shell, and always remain inclosed there ; but
the head and foot project beyond it, when the animal unfolds
itself for the purpose of walking ; and re-enter the last turn of the
spiral, when it again contracts. Hence the size of this last part
of the shell, and the form of the opening, are in keeping with
the size of the foot. In most aquatic Gasteropods whose shell is
spiral, there is a horny or calcareous disc, called the operculum
(Fig. 555, o), which is attached to the posterior part of the foot,
and which closes the entrance of the shell when the animal with-
draws itself.

362 CIRCULATION AND RESPIRATION OP GASTEROPODS.

903. The heart is always systemic (ANIM. PHYSIOL. § 281),
and is composed almost invariably of a ventricle and an auricle
(Fig. 539) ; it is placed near the back of the animal, opposite
that side occupied by the reproductive organs. — The organs of
Respiration are formed in some instances for aerial, in others for
aquatic, respiration. In the first case they consist of a cavity,
on whose walls the blood-vessels form a complicated net-work ;
and into the interior of which the external air penetrates, through
an orifice in the outer border of the mantle. This pulmonic, or

vb ab b ov

FIG. 555. — ANATOMY OF TURBO PICA : p, foot , o, operculum ; t, proboscis ; ta, tentacula ;
•/, eyes ; m, mantle opened longitudinally, to show the disposition of the respiratory
cavity ; /, anterior border of the mantle, which, in its natural position, covers the back
of the animal, leaving a wide slit by which the water enters the branchial cavity ; b, the
gills ; vb, branchial vein, returning to the heart, c ; ab, branchial artery ; a, anus ;
t, intestine ; e, stomach and liver ; ov, oviduct. On the upper side of the neck are seen
the cephalic ganglion, and the salivary glands. And at d is shown a fringed membrane,
which forms the lower border of the left side of the opening that leads to the respiratory
cavities.

lung-like cavity (Fig. 564), is situated on the back of the
animal, and is lodged in the last turn of the spiral shell, when
the Mollusk is provided with an envelope of this kind. Among
those Gasteropods destined to breathe in water, the arrangement
of the gills varies considerably ; in many, these organs are lodged

RESPIRATORY AND DIGESTIVE APPARATUS.

363

br p

FIG. 556. — PLBUROBRANCHUS : m, the mantle
turned back to show the gills, br : a, the
anus ; 6, mouth and proboscis ; v, hood ;
t, tentacula ; p, foot.

in a cavity analogous to that which constitutes the lung of the
preceding (Fig. 555) ; but in others, they are placed between
the mantle and the foot, or even on the back of the animal, so as
to float freely in the surrounding liquid. As examples of the
pulmonic Gasteropods, we may mention the Snail, and the Slug,
which live on land ; and the
Lymnaea, the Planorbis, and
others, which live in stagnant
waters, and come to the sur-
face to take in the air neces-
sary for their respiration.
Among Gasteropods provided
with gills inclosed in a dorsal
cavity we find the Volutes,
Whelks, Cowries, Olives, and

many others. The Limpets and Pleurobranchi (Fig. 556) have
these organs in the furrow which separates the foot from the

mantle ; a nd in
the Doris (Fig.
568), the Eolis
(Fig. 557), and
others, they con-
sist of folds or
tufts, sometimes
very numerous, fixed to the dorsal surface of the body.

904. The mouth of Gasteropods is surrounded with con-
tractile lips, and is sometimes armed with horny teeth, which
occupy the palate. In several other animals of this class, the
anterior part of the palate is very fleshy, and can be made to
project outwards, so as to form a proboscis. In some cases, the
stomach also is provided with cartilaginous, or even calcareous,
projections or teeth, fitted to divide the food. The intestine is
bent upon itself, and is lodged between the lobes of the liver and
ovary : lastly, the anus is situated nearly always on the right
side of the body, at but a little distance from the head.

905. In this Class, the organs of sensation are less developed
than in the Cephalopods ; the tentacula, which most Gasteropods

FIG. 557.— EOLIS.

364 GENERAL CHARACTERS OF GASTEROPODA.

carry in front, serve but for touch or smell. Their apparatus
for hearing, which has been only recently discovered, is very
simple ; consisting of a little sac on each side, which is almost
imbedded in the cephalic ganglion. The eyes, which are some-
times wanting, are very small, and of a very simple structure ;
sometimes they are situated on the head, and sometimes carried
at the base, the side, or the point of the tentacula. The Nervous
System is less developed than in the preceding Classes ; and is
chiefly composed of a cephalic ganglion, which is connected with
others, either placed immediately beneath the oesophagus, or
scattered in distant parts of the body, according to the position
of the organs they respectively supply, which varies considerably
in this group. (See ANIM. PHYSIOL. § 438).

906. Of these animals, some are terrestrial, some inhabit
fresh waters, but most live in the sea. In general they are
formed for crawling, as the Snail, the Whelk, the Limpet, &c. ;
but sometimes they are rather adapted for swimming, as is the
case with many of the naked Gasteropods. A few of this class
attach themselves to the surface of rocks, and pass a great part
of their lives with little variation in place. This is the case
with the Limpet for example ; which is frequently found par-
tially imbedded in a hollow exactly fitting to its shell, and
therefore evidently formed by its own action. But the attach-
ment of such is not a solid union like that of the Oyster and
some other Conchifera ; being only produced by the adhesion of
the muscular disc, or foot, which, acting like a sucker, can be
detached at any time by the will of the animal.

907. As already remarked, the Shells of Gasteropoda, where
they exist, are usually formed in one piece, or are univalve.
There is no instance of a Gasteropod forming a bivalve shell,
unless we consider the large calcareous operculum of some of
these Mollusks in the light of a second valve, with which it
cannot be rightly compared. But there is a group, nearly allied
to the Limpets, which is distinguished by the possession of a
multivalve shell (Fig. 584); the valves being disposed like the
segments of Articulated animals, and being connected by a
complex muscular apparatus, which strongly reminds us of that

FORM AND STRUCTURE OP SHELL. 365

which binds together and moves the several segments in that
sub-kingdom. The material of which the shell is composed,
varies considerably in regard to the relative quantities of animal
and of calcareous matter which it includes. In the Cones, Cow-
ries, Olives, and others known as porcellanous shells, the quantity
of animal matter is so small, that it can with difficulty be
detected; but in others, as the Limpet, there is considerably
more ; and in some instances there is an almost entire absence
of calcareous matter, the shell having merely the consistence of
horn. — It is remarkable that, notwithstanding so many of this
group are destitute of shell in their perfect condition, all the
species belonging to it possess the rudiments of a shell when
they come forth from the egg ; and this has nearly the same
form in every case, being usually a simple cone, with the point
slightly turned over. In most Gasteropods this shell is retained,
and is enlarged by successive additions ; but it soon falls off in
those cases, in which it is not to be permanent. The additions
which are made to the shell, for the purpose of deepening its
cavity and widening its mouth, sometimes appear to be confined
to the edge only ; whilst in other instances a new layer is thrown
out as a lining to the whole interior of the shell. In the former
case the line of junction between the old and the new parts is often
marked externally by a prominent rib ; but the internal surface
is beautifully smoothed off.

908. The forms of the shell in this Class are subject to great
variations ; but those which appear most widely separated, may
be shown to be connected by intermediate links ; as well as to
have a common origin. The simplest of all shells in point of
form, is that of the common Limpet, which is merely a cone,
more or less expanded at the base ; and in which the successive
additions are all made in the same direction. In an allied genus,
the Pileopsis, we find the point or apex of the cone somewhat
prolonged and turned over, so as to resemble a " fool's cap" in
its form ; and the increase of this tendency produces a regular
spiral shell, such as that of the Planorlis, in which all the whorls
or turns are upon the same plane, — as in a " Catherine's wheel."
But if the whorls do not continue in the same plane, but turn

366

FORM AND GROWTH OF SHELL.

round a central line in a corkscrew-like mode, a shell is formed
like that of the common Snail, or the Pleurotoma (Fig. 582).
From forms of this kind, we may return to the Dentalium, —

which has a long straight cone, like
that of the Limpet narrowed and
drawn out, — by the Scalaria or
Wentletrap, in which the coils of
the spire touch each other only by
their ribs ; and by the Magilus and
Vermetus (Fig. 583), in which the
commencement only of the shell possesses a spiral form, the
remainder being prolonged into a tube which nearly approaches
the straight direction. When the whorls revolve around a ver-
tical line, instead of remaining in the same plane, a sort of
central pillar is formed, which is termed the columella, (Fig.
558) ; this is usually grooved at its lower part, for the passage
of water. to the respiratory organs.

909. The margin of the shell is not unfrequently fringed with
spines, as in the Murex ; these are formed (as are similar ap-

FIG. 558. — SECTION OF ACHATINA
COLUMNAUIS.

FIG. 559.— MUREX TENUISPINA.

pendages in the Conchifera,) by prolongations of the Mantle ;
and the dissimilar number of them in different specimens has
caused the establishment of many species, which, now that the
habits of the animal are better known, prove to be but varying
forms of the same. For it has been ascertained that the animal
has not only the power of forming new spines, but of removing

CHANGES OF SHELL WITH AGE.

367

old ones, especially such as would interfere with the continued
growth of the shell. The edge of the Mantle is applied against
their bases, and a kind of absorption of shelly matter seems to
take place, a notch being formed, which causes them to be easily
broken off. Various analogous changes are produced by a similar
action in other shells, the portions first formed being wholly or
partially removed. Sometimes the walls of the older portions
are thinned for the purpose of lightening the shell ; and in other
cases the top of the cone is altogether removed, a groove having
been formed around its interior, which renders it so weak as to
be easily broken off; in these last cases, the animal previously
withdraws itself from the part that is thus to be separated, and
throws a new partition across, by which the top of the shell
remains closed after the division. A shell thus deprived of its
apex is said to be decollated.

910. It is not only by such removals, that the form of uni-
valve shells undergoes a great change. Sometimes additions are

FIG. 560.— PTEROCBRAS SCORPIO : a and 6. back and front viexvs of the young shell ;
c and d, the same of the adult.

made to them, which completely alter their figure, so that two
individuals of different ages would be scarcely supposed at first

cc2

368 CHANGES OF SHELL WITH AGE.

sight to belong to the same tribe. But in all these cases, the
form of the young shell may be traced in that of the adult. The
accompanying figures of the Pteroceras show this change in a
moderate degree ; in other genera it is much more remarkable.
In another group of shells, of which the common Cowry is an
example, a still more curious alteration takes place. In the
young shell the edge is sharp, and the mouth an opening of con-
siderable breadth. This state continues as long as the shell is
increasing in size ; but when it has arrived at adult age, the outer

FIG. 561— CYPRVEA EXANTHEMA : a, young shell ; b and c, back and front views
of adult shell.

lip is thickened, and brought so near the other as to leave but a
narrow chink between them. At the same time, a prolongation
of the mantle on each side deposits a new layer of shelly matter
on the outside of the previous one ; and as the two prolonga-
tions meet along the back, (the line of their junction being
usually evident on the shell), this additional coat, which is very
hard and porcellanous in its texture, incloses the whole previous
shell. — The operculum is principally confined to the aquatic
Gasteropoda. It is sometimes of the same texture as the shell
itself, and sometimes horny. It does not always close the entire

SUBDIVISIONS OP GASTEROPODA. 369

mouth of the shell ; but it is sometimes made to fit it, at all
stages of growth, with the most beautiful accuracy. Some of the
land species also possess an operculum ; but in general they are
destitute of it, and they form during hybernation a temporary
closure to the mouth of the shell, by a viscid secretion, which
hardens into a thin plate, and includes within it a bubble of air.
Behind this, a second and even a third similar partition is occa-
sionally found, as in the common Snail.

911. The subdivision of this extensive Class into Orders,
may be best effected by arranging the different tribes according
to the character and position of the respiratory organs. The
following are those adopted by Cuvier : —

I. PULMONEA. These are for the most part terrestrial species,
adapted to breathe the air by means of a pulmonary sac, or air
cavity, the orifice of which they can open or close at will. Many
have no shell.

II. NUDIBRANCHIATA. These, as well as all the succeeding
Orders, are aquatic, being adapted to respire water by gills, like
other Mollusca. The animals of this Order have no shell ; and
they carry their branchiae, which present various forms, on some
part of the back.

III. INFEROBRANCHIATA. These are similar in many respects
to the preceding, but the branchiae are situated under the margins
of the mantle.

IV. TECTIBRANCHIATA. In the greater part of the animals
contained in this Order, the branchiae are situated upon the back
or on the side, and are covered in by a fold of the mantle, and this
fold usually includes a shell more or less developed.

V. PECTINIBRANCHIATA. The animals of this Order, to which
belong all the spiral-shells, except those of the Pulmonea, are so
named from the comb-like form of the gills, which are usually
situated in a cavity behind the head ; corresponding with the
respiratory sac of the Pulmonea. This is by far the most
numerous Order of the whole.

VI. TUBULIBRANCHIATA. These have many affinities with
the last Order, but the shell is spiral only at its apex, where it
is commonly fixed to (or rather inclosed by) other bodies, and is
prolonged in the shape of a tube more or less regular.

370 PULMONEA; — SLUGS.

VII. SCUTIBRANCHIATA. In these, also, there la a consider-
able resemblance to the Pectinibranchiata in the form and
position of the gills ; but the shells are very open, scarcely in
any degree spiral, and cover the body and gills like a shield ;
and they also differ essentially in their mode of reproduction.

VIII. CYCLOBRANCHIATA. These Mollusks have their gills
disposed in little tufts under the margins of the mantle, much as
in the Inferobranchiata ; but they have shells, which are spread
out over the body, and differ from that Order in their mode of
reproduction.

ORDER I.— PULMONEA.

912. Although the greater part of the Mollusks of this
Order live on land, some are aquatic ; but these, like the aquatic

FIG. 562. — LIMAX

air-breathing Insects and Vertebrate, are obliged to come occa-
sionally to the surface to breathe. They all feed upon vegetables,
and many of them do so exclusively ; but some are extremely
voracious, and will devour almost any organised matter that
falls in their way. They are diffused through all climates,
particular species being restricted to eaeh. Those without a
shell, commonly known as slugs, constitute the family LIMA-
CINJE. In the common Slugs^ as in most of the terrestrial species
of this Order, we observe a prominent head, with four tentacula ;
and at the end of the longer pair the eyes are situated. These
tentacula can be drawn inwards, by a process resembling the
inversion of the finger of a glove. On the back there is a kind
of shield or disk, formed by the mantle, which sometimes incloses
a small shell. This shield covers the pulmonary sac, the opening
of which is on its right side, and the head can be withdrawn

PULMONEA ; SLUGS, SNAILS.

371

beneath it. The Testacella is a kind of slug which has the disc
of the mantle at the posterior extremity, and this always con-

ap p

FIG. 563.— TESTACBLLA.

tains a small shell. This animal, which feeds largely on earth-
worms, is abundant in the south of France, and has lately been
introduced into the gardens of this country, where it is multi-
plying rapidly.

913. The Snails and their allies, constituting the family
HELICIN^E, are closely allied to the Slugs in organisation ; differ-
ing in but little else than the possession of a shell, into which the
body may be withdrawn. The Common Garden-Snail of this
country, and the Helix pomatia, or Edible Snail of France and

Italy, are well-
known examples
» of this family.
More striking ones
are to be found,
however, in tro-
pical climates.
Among the mem-
bers of this group,
we may especially
notice the genus
Anastoma, which

FIG. 564— ANATOMY OF SNAIL; /, foot; t, tentacula half IS distinguished by
contracted ; d, a sort of diaphragm, separating the respira- ,1 y f

tory cavity from the other viscera ; *, portion of the sto- l

mach; I, liver; o, ovary; i, intestine; r, rectum, or last and position oftlie
part of the intestine ; a, anus ; h, heart ; ap, pulmonary

artery, distributed over the walls of the pulmonary cavity, mouth of the shell
P-, ar, aorta; v, secreting gland for the mucus which Jntheadult Dur-
covers the hody ; cv, its excretory duct, opening near the "

anus. ing its early life,

its mouth is in the same position as that of other snails;

372 PULMONEA; — ANASTOMA; BULIMUS; ACHATINA.

and thus it continues until the shell is increased for the last
time. The direction of the curve is then entirely changed ;
a mouth with thickened lips and projecting teeth is formed, so
as to be on the same plane with the spire ; and from henceforth
it must crawl with the spire downwards, unlike all other snails.

FIG. 565 — ANASTOMA GLOBOSA.

Some species of the genus Bulimus attain to great size, the eggs
being as large as those of a pigeon. In certain species of the latter
genus, the direction of the coils of the shell is opposite to what it

a
FIG. 566.— a, ACHATINA ZEBRA ; b, ACHATINA VIRGINBA, (a reversed species).

is in other spiral shells ; such are said to be reversed. A European

PLANORBIS ; LYMN^EA. - NUDIBRANCHIATA. 373

species is one of those most remarkable for the decollation of its
shell. Another large snail of tropical climates, as Achatina,
which feeds on trees and shrubs, chiefly on the western coast of
Africa, and in the West Indies ; several of its species are dis-
tinguished by the beauty of their colours ; and some of them
are reversed.

914. The aquatic Pulmonea have only two tentacula. From the
necessity of coming to the surface to breathe, they can only live
in water of inconsiderable depth ; and they chiefly inhabit ponds
and shallow streams, or the banks of rivers. Some, however, live

on the sea-shore.
The PlanorUs, the
shell of which is
quite flat, having
all its coils upon the
same level, is a very
common genus in
this country ; as is
also the Lymn&a,
which feeds upon

FIG. 567.-LVMN.*:,

softer parts of the
plants, and the stomach of which has a very muscular gizzard.

ORDER II.— NUDIBRANCHIATA.

915. The animals of this Order, which might be designated
Sea- Slugs, are all marine ; and being adapted to breathe
water at any depths, and also (in many instances) to swim with
facility, they are often found at a great distance from land.
When they swim, it is usually in a reversed position, the foot
being turned upwards ; this is made concave by muscular action,
so as to serve as a kind of boat, the buoyancy of which keeps
the animal at the surface without effort. This Order is a very
numerous one ; and some of its species attain considerable size.
The number of those existing on our own shores is much greater
than has been usually supposed ; a large number of species

374 NUDIBRANCHIATA ; — DORIS, TRITONIA, GLAUCUS.

having been discovered by late researches. The position of the
gills varies in different genera. Thus in the Doris (Fig. 568),

FIG. 568.— DORIS CORNUTA.

FIG. 569. — TRITONIJ

they are arranged in a circular form around the termination of
the intestine. In the Tritonia (Fig. 569) they are placed in

FIG. 570. — THETYS LEPORINA, UPPER AND UNDER SIDE.

tufts on each side of the back. In the Thetys (Fig. 570), also,
they are arranged in two rows
along the back ; this animal is
remarkable for the large mem-
branous fringed hood, which
covers the head. In the Glaucus
(Fig. 571) they form two or
three large tufts on each side,
which give assistance in swim-
ming. These beautiful little
Mollusks are inhabitants of the
Mediterranean and Indian
Oceans; their hues are azure blue
and silver ; and they swim with great rapidity on their backs.

FIG. 571. — GLAUCUS FORSTERI.

DORIS. INFEROBRANCHIATA.— TECTIBRANCHIATA. 375

In the Eolis (Fig. 557), the act of respiration appears to be per-
formed by means of numerous finger-like processes, with which
the back is covered. — Most of these animals deposit their eggs
on the shore in gelatinous masses ; the eggs being very regularly
arranged in rows or bands. Of the immense number of eggs
which some of these contain, an idea may be derived from the
following fact, which is mentioned by Mr. Darwin, in regard to
the mass deposited by a large white species about 3J inches long,
on the shores of the Falkland Islands. From two to five eggs
(each of them 3-lOOOths of an inch in diameter) were contained
in a little spherical case. These cases were arranged two deep
in rows ; and these rows adhered to each other in such a manner
as to form a ribbon, — running across it from one edge to the
other. One of these ribbons measured twenty inches in length,
and half an inch in breadth ; and by counting the number of
the spherical cases contained in one-tenth of an inch of each
row, and the number of rows in an equal length of the ribbon,
Mr. D. ascertained that there must have been, in the whole
mass, at least six hundred thousand eggs.

ORDER III.— INFEROBRANCHIATA.

916. The small number of Mollusks contained in this Order
differ but little from the last, except in the position of their gills,
and their incapability of swimming. They are, therefore, con-
fined to the sea-shore; where they subsist (as do also the
Nudibranchiata) upon sea-weeds and other aquatic plants.

ORDER IV.— TECTIBRANCHIATA.

917. This Order begins to show an approach to that
arrangement of the gills, which characterises the great bulk of
the Class ; these organs being concealed beneath a fold of
the mantle, in which a small shell is usually contained. The
animals composing it are all marine ; and live chiefly on the

376

ORDER TECTIBRANCHIATA. APLYSIA, BULLA.

shore, or on floating sea-weeds. A very characteristic example
of the group is the Aplysia, commonly termed Sea-Hare, which

Fio. 572. — APLYSIA.

is abundant on many parts of our own coasts. Its common
name is probably derived from the peculiar form of the superior
pair of tentacula, which are flattened and hollowed like the ears
of a quadruped. The head has a very distinct neck. The gills
consist of leaflets arranged in a complex form, and situated on
the back beneath a fold of the mantle, which also incloses a flat
horny shell (Fig. 572). The digestive apparatus is very com-
plicated ; consisting of a membranous crop like that of Birds, a
gizzard having cartilaginous walls, and a third stomach beset
with sharp hooks in its interior. These animals feed on sea-
weed. They are very sluggish in their movements, but have a
peculiar means of defence, — consisting of a deep purple liquid
(said by some to have acrid properties), which they can dis-
charge from the edge of the mantle when alarmed, and by which
the surrounding water is discoloured, so that the animal cannot
be discerned. Nearly allied to the Aplysia are the Bulla and

FIG. 573.— BULLJEA APERTA. FIG. 574.— BULLA LIGNARIA (a) ; . BULLA AMPULLA (&).

Bullcea ; these have a small calcareous shell, in which the spiral

TECTIBRANCHIATA. BULL^IA ; BURSATELLA.

377

form begins to manifest itself. The Bullcea aperta (Fig. 573)
is found in almost every sea, living on oozy bottoms. The
Bulla lignaria (Fig. 574, a) is remarkable for the density of the
walls of the stomach ; amidst the tendinous fibres of which, a
large quantity of calcareous matter is deposited, forming plates

of bony firmness; these
are moved against each
other by powerful mus-
cles, so as to rub down
almost anysubstance that
is placed between them.
The Author has more
than once found a small
bivalve shell in this
situation. The shell of
the Bulla ampulla (Fig.
574, b) is interesting as
exhibiting, in its flat open
form, a transition to-
wards that of the Aply-
sia. — To this group is
FIG. 575.— BURSATELLA LEACHH. also referred the curious

Bursatella (Fig. 575),

which is an inhabitant of the Indian seas. Its gills project far
beyond the opening of the mantle.

ORDER V.— PECTINIBRANCHIATA.

918. This Order is not only by far the most numerous in
the whole class, but contains the animals which may be regarded
as its most characteristic examples. They have all two tenta-
cula, and two eyes ; the latter being sometimes mounted on a
footstalk, as in the Snail. The mouth is prolonged into a sort of
proboscis; and the tongue is furnished with little hooks, or
recurved spines, which enable it to wear down the hardest bodies
by slow and oft-repeated action. The cavity, in which the gills

378 ORDER PECTINIBRANCHIATA. TROCHOIDJE.

are fixed, occupies the last whorl, or turn, of the shell (§ 903) ;
and in some of the Order there is a tubular prolongation of the
fciantle, termed the siphon, for the purpose of conveying water into
this cavity, so that the animal can respire without putting forth
its body from its shelter. By the presence or absence of this
organ, and by the form of the shell (which here appears to bear
a sufficiently constant relation with that of the animal), this
large group may be arranged under the following families : —

I. TROCHOIDJE, or the Periwinkle tribe, in which there is no
siphon, and which have the mouth closed by an operculum,
usually calcareous.

II. CAPULOID^}, which have a wide open shell, very much
like that of the Limpets, without an operculum, and destitute of
a notch at the margin for the passage of the siphon.

III. BUCCINOID^E, or the Whelk tribe, which have a spiral
shell, and a canal at the end of the columella for the passage of

" f O

the siphon.

919. The family TROCHOID^ is a very extensive one, and
includes numerous species which are interesting on account of
their peculiar habits, as well as for the beauty of their shells.
In the genera Trochus and Turbo, which may be considered its
types, the interior of the shell is nacreous; and the exterior, when
cleaned, usually presents a very pleasing mixture of colours. The
shell, though spirally coiled, usually has a more or less regular
conical form (as is seen in the common Periwinkle) ; — the first,
or earliest whorl, forming the point of the cone, and each whorl
extending a little beyond the one above it, so as to increase the
diameter of the shell very regularly ; — and the mouth being
situated at the base of the cone, which in the Trochus is almost
flat. The Trochus is distributed all over the world ; and
at least seventy species of it are known, the largest being
restricted to tropical climates. Among these we may especially
notice the Trochus agglutinans, a native of the West Indies,
which derives its name from its singular habit of glueing to its
shell small pieces of stone, coral, shell, &c. This seems to answer
the purpose of strengthening its shell, which is thin and brittle.
A fresh-water species from Brazil has been described, in which

TROCHOID^E ; — PERIWINKLE; PALUDINA. 379

there did not appear to be any real shell at all ; the animal being
inclosed in cases made up of little stones and grains of sand,
agglutinated together with such exactness, as to form the fac-
simile of a real Trochoid shell. The Trochus longispina from
India has the circumference ornamented with a row of long
spines, of a silvery or gold colour, placed at regular distances.
In the Turbo, to which the common Periwinkle belongs,* the
mouth of the shell is quite round ; and it is in this genus that we
find the most massive and stony opercula. The Periwinkle is
very generally used as an article of food in the neighbourhoods
in which it abounds. It is considered in Sweden to afford a
sign of the coming weather ; the peasants having observed that,
whenever the Periwinkles ascend the rocks, it is a sure sign of a
storm being near, their instinct having taught them to place them-
selves out of the reach of the dashing of the waves ; when, on the
contrary, they make a descent upon the sand, it is an indication of
a calm. The number of known recent species is between thirty
and forty; and, as in the former case, those of temperate climates
are much surpassed in size by the inhabitants of tropical seas.
Allied to the Turbo is the Scalaria, in which the turns of the
spire come in contact with each other only by their ribs, and of
which the principal species — the Scalaria preciosa, or Wentle-
trap — was long famous on account of the high price given for it
by shell-collectors.

920. The preceding genera are all inhabitants of salt water
only ; and their shells, as well as their bodies, have a very cha-
racteristic and peculiar structure. We have now to advert to
some, in which there is a considerable resemblance, in one or
both of these particulars, to the Helices and their allies. First
among them may be mentioned the Paludina^ which nearly ap-
proaches the Turbo in the form of its shell, but is an inhabitant of
fresh water ; it possesses, however, the rudiments of a siphon, for
the introduction of water into the respiratory cavity. In the com-
mon species, Paludina mvipara (Fig. 576), the young are produced
alive, the eggs being hatched within the oviduct. The lanthina,
or Violet Snail, is a beautiful little Mollusk, having a delicate

* This is referred by most Naturalists to a new genus, Littorina.

380 TROCHOIDjE. IANTHINA ; NERITA ; AMPULLARIA.

fragile violet-coloured shell, which presents the general form
of that of the Helix, although differing from it in some
important particulars. This shell has no oper-
culum; but this appendage is replaced by a
curious apparatus, which serves as a float,
enabling it to swim at the surface of the sea
without any effort. To the foot are attached
a number of vesicles, full of air, and resem-
bling foam-bubbles ; and the animal seems to
have the power of compressing or emptying
these at will, so as cause itself to sink.
When irritated or alarmed, it pours out a violet-coloured
secretion, resembling its shell in colour, which darkens the
water around it, and thus serves for its concealment, in the
manner of the ink of the Cuttle-fish. The genus Nerita, which
is nearly allied to this, contains several species which inhabit
fresh water ; and some which even live out of the water alto-
gether,— by the aid, probably, of some provision analogous to
that which enables the Climbing Perch, or the' Land Crab, to
live at a distance from the water. The Am.pullaria (Fig. 577),

has a shell still more like that of the
Helices ; and although provided with
a branchial comb, like that of the
Trochoidae in general, it has also the
rudiment of a pulmonary sac, like
that of the Snails, which is said to
be filled with water, and thus to
keep the gills moist for a long time.
The animal inhabits the fresh or
brackish waters of warm climates,

FIG. 577 — AMPULLARIA KUGOSA.

and forms a calcareous opercu-

lum. It is remarkably tenacious of life, partly in consequence
of the curious provision just alluded to. Thus specimens have
been brought from Egypt to Paris alive, although packed up in
sawdust ; and in one instance, a box containing a large number
of river-shells from the Nile having been delayed four months
on the road, the Ampullarias were found to have remained alive

CAPULOID.E. BUCCINOID^E ; CONES.

381

in the midst of the mass of putrefaction caused by the death of
the other animals. The Helicina, which is nearly allied to this,
is, like the Helix, a terrestrial Mollusk.

921. The family CAPULOID^E is a small one, containing only a
few genera, which have shells more or less closely resembling that
of the Limpet, but which must be placed among the Pectini-
branchiata, on account of the structure and position of their
respiratory organs. There is nothing in their history sufficiently
remarkable to detain us.

922. The family BTJCCINOID^E is a very extensive one, and
contains a large proportion of the shells which make the greatest
display in Conchological museums. They are all distinguished
by the notch at the extremity of the columella for the passage
of the siphon ; and the greater or less length of this canal serves
to distinguish the different subdivisions. Thus in the Cones,
Cowries, &c. (Figs. 578, 579), it is very short ; in the Buc-
cinum^ or Whelk, (Fig. 580), however, the canal is longer;
whilst in the Murex (Fig. 559), and its allies, the canal is very
much prolonged. The Cones, which are so named from the
conical figure of their shells, are remarkable for the length and
narrowness of the mouth, and for the consequent thinness and

breadth of the head and neck
of the animal. The shells of
this genus are in general very
beautifully coloured; and their
markings possess a peculiar
clearness and definiteness.
Some of the species are so
highly valued by Collectors,
as to bring a higher price
than almost any other shell —
as much as three hundred
guineas having been given for
a single specimen. The Cones

are found abundantly on the shores of all tropical countries,
particularly of Asia ; but they become more rare as they approach
the northern hemisphere ; and a few species only are found in the

FIG. 578 — CONUS GENBRAI.IS.

3S2 BUCCINOID^E. — CYPRJEA ; BUCCINUM.

Mediterranean. The Cy preset, or Cowry, is also remarkable for
the brilliancy of its colours, and for the high polish of which it
is susceptible. The shells of this genus and its allies are pre-
eminently porcellanous ; that is to say, they have much of the
half glassy appearance of porcelain when they are polished ; and

they break with a
fracture similar to
that of earthen-
ware. This results
in part from the
very small quantity
of animal matter
they contain. The
form of the shell in

the young Cyprcea is not very unlike that of the Cone ; its edge
being thin and sharp ; but it subsequently undergoes a very
remarkable change, as already described (§ 910) ; and it is then
only that the full beauty is acquired by the shell, as it depends
on the deposit of the final layer of shelly matter over the whole
exterior. The genus Cyprcea, also, is almost restricted to warm
climates ; where its species are very abundant. The Cypr&a
moneta, or Money Cowry, is the current coin of the natives of
Siam, Bengal, and many parts of Africa ; it is collected in the
latter by the negro women, and is sent thence to distant countries.
In Bengal, 3200 of these shells are reckoned to be equivalent to
a rupee, or about two shillings of English money. In the
Friendly Islands, permission to wear the Cyprcea aurantia, or
Orange Cowrie, as an ornament, is only granted to persons of
the highest rank. The Cyprcea aurora^ which is considered the
most rare species of the entire genus, is suspended by the New
Zealanders to their dress as an ornament. — Nearly allied to the
Cone and Cyprasa, are the Ovula, Oliva, and many other genera.
923. The Buccinum and its allies have the columella some-
what prolonged, and exhibit a considerable notch or furrow for
the siphon, which is bent towards the left. The genus Buccinum
probably contains the largest number of species, and these the
most universally diffused, of any Pectinibranchiate Gastero-

BUCCINOID.E ; — BUCCINUM OR WHELK.

383

FIG. 580. — BUCCINUM UNDATUM.

pods. The shells are found in all parts of the world, from the
Polar circles to the Equator ; and the animals of many species

are used as food, — those
of the Buccinum undatum
of our own shores being
known as Whelks. The
shells are not remark-
able for brilliant colours ;
but they present many
interesting varieties of
form and marking. The
animals never attain a
large size; and the greater
number of them frequent
the shore. Their habits
are analogous to those of a large proportion of this group, to
which, therefore, a similar description will apply. They obtain
their food by means of a long proboscis, inclosing a tongue that
is furnished with sharp teeth at its extremity; by means of
which they bore into other shells, and extract the animal from
the interior. This proboscis is not merely adapted, like that of
the Elephant, to bend itself in all directions ; but it may be
entirely retracted into the body, by means of a complex mus-
cular apparatus, which completely draws back the point, and the
half of the proboscis nearest to it, into the half attached to the
head ; — just as when the finger of a glove is pushed back into
the part that incloses the palm. "When the proboscis is extended,
the tongue is protruded, and by the file-like action of its teeth,
even the hardest shells are -worn away. These carnivorous
Mollusks are not restricted in their destructive operations by
any ties of kindred ; for\the shell of the Whelk itself is not
unfrequently ^ found perforated, just as if by one of its own
species.

924. Nearly allied to the Buccinum is the Cassis, or Helmet-
shell, which is one of the largest of the whole Class. Most of
the species rare inhabitants of tropical shores ; but a few are

D» 2

384

BUCCINOIDJE. — CASSIS ; PURPURA.

FIG. 581. — CASSIS TUBEROSA.

found on the coast of the Mediterranean. They live at some

distance from the
shore, on the sand,
into which they
occasionally bur-
row, so as to hide
themselves. The
shells of the Cassis
rufa and other
species are beauti-
fully sculptured
by Italian artists,
in imitation of
antique cameos ; the different layers of colouring matter which
they contain, strongly resembling in hue those of the onyx and
other precious stones formerly used for this purpose. Of these,
a great variety of ornaments are made ; and of late years a con-
siderable trade has been carried on in them on the Continent.
— Numerous other genera may be associated in the same group ;
but it will be sufficient here to notice the Purpura, a shell of
comparatively small size, but which is very abundant in some
situations on our own coast and elsewhere. The total number
of known species exceeds fifty ; the largest among them are
inhabitants of tropical seas. It was from the animals of this
genus that the Roman purple dye was obtained ; and a small
quantity of this may be found in the Purpura lapillus of the
British coasts. — All the Mollusks of this group, so far as is at
present known, have the habit of depositing their eggs in egg-
cases, or nidamenta; which are of various forms in the different
species, and are attached in different modes. That of the
Buccinum is often to be met with on our shores, in the form of .
a large irregular ball, composed of a number of little vesicles
attached together, each containing several eggs. The Purpura
forms a large number of distinct cylindrical cases, which it
.attaches to the rocks it infests.

,925. The last group comprised in this extensive family is

BUCCINOHXE ; — FUSUS ; STROMBUS ; PLEDROTOMA. 385

that of the Murex and its allies, which are distinguished by the
great length of the siphon, as well as (in many instances) by
the remarkable prolongation of the shelly canal in which it is
protected along a part of its course. This is nowhere more
remarkable than in the Murex itself (Fig. 559). Frequently,
however, the shelly canal is not itself prolonged ; as is the case
in the Pteroceras (Fig. 560). To this group belong a consi-
derable number of large shells. The Fusus much resembles the
Murex ; but has none of those ridges or
varices, which mark, in the latter, the
lines of successive addition to the shell. —
In like manner, the Strombus is allied to
the Pteroceras ; being distinguished, like
it, by a great extension of the lip, when
adult age is reached ; but this lip is desti-
tute of the long finger-like processes, which
are so remarkable in that shell. The
accompanying figure of the Pleurotoma,
another genus belonging to the same group,
is here introduced for the purpose of
explaining the names which are given by
Conchologists to different parts of a shell,
and which are made use of in the scien-
tific description of it. At a is seen the
canal for the passage of the siphon ; b,
a hollow, here nearly closed up, termed
the umbilicus; c, the internal edge or
left lip, which is partly formed by the
columella ; d, the external or right lip,
the edge of which is free; e, the notch
or slit, which is peculiar to this genus ; /,
the sinus ; g, part of the last turn of the
spire, which is called the venter or belly ;
k, h, the turns or whorls of the spire ; », the sutures, or lines of
union between these.

FIG. 582. — PLEUROTOMA
BABYJ-ONICA.

386

ORDER VI.— TUBULIBRANCHIATA.

926. The Mollusks of this Order construct an irregularly
tubular shell ; which so much resembles that formed by certain
Annelida, as to be scarcely distinguishable from it. They are
very few in number. The Vermetus (Fig. 583) is the principal
genus of the group. This is remarkable for the close resemblance

FIG. 583 — VERMETUS.

of its shell to that of the Serpula (Fig. 528) ; but, when perfect,
it may be generally distinguished by the regularly-spiral twist-
ing of its first-formed portion. Some species associate together
in large masses, so as even to form reefs ; whilst others attach
themselves to Coral, and lengthen their shells in proportion as
the Coral grows up around them. When the animal has quitted
the lower part of its tube, that it may keep itself at the surface,
it usually throws a partition across, in the manner of the
Nautilus ; and a tolerably regular series of such partitions is not
unfrequently found. In the Magilus, an allied genus of similar
habits, whose tube is sometimes lengthened in this manner to as
much as three feet, the first-formed part of the shell, instead of
being cut off, is sometimes completely filled up by the exudation
of solid matter.

ORDER VII.— SCUTIBRANCHIATA.

927. This Order is also a small one, containing but two prin-
cipal genera, which do not differ widely from the Limpets, except
in the disposition of the gills. The shells are very open, without
an operculum, and the greater number are not in any degree

HALIOTIS. CYCLOBRANCHIATA j LIMPETS; CHITONS. 387

spiral. In the Haliotis, the shell is slightly twisted ; and from
a faint resemblance it is thought to bear to the ear of a quadruped,
it has been called the Sea Ear. This animal, in its living state,
is one of the most beautiful of Gasteropods, on account of the
variety and richness of its colours. Its shell, when the surface is
polished, possesses a pearly lustre, with resplendent metallic
hues. It is consequently much sought for as an ornament. The
animal attaches itself to the rock, after the manner of a Limpet,
by a large muscular foot ; and the extent of the adhering surface
is so great, that a very considerable force is required to detach
it, when the animal is putting forth its strength. The best
mode of obtaining the shell, is to place the hand or some instru-
ment under its edge (which is usually a little separated from the
rock when the animal is undisturbed) ; and to endeavour to
remove it before the animal is alarmed. When this attempt is
not successful, the animal draws its shell down upon the rock
with such firmness, as to grasp most securely anything that is
under its edge ; and in this manner fatal accidents have occurred
to men, who have incautiously attempted to remove these shells,
when under water.

ORDER VIII.— CYCLOBRANCHIATA.

928. The general form of the Limpets, which principally
compose this Order, is well known ; and the peculiarity in the
position of their gills has already been mentioned. Closely allied
to the Limpets in general structure, but differing remarkably in
the formation of the shell, are the Chitons ; of which some small
species inhabit our shores, but which attain to much greater size
between the tropics. Their shell (Fig. 584) is composed of a num-
ber of plates arranged behind one another with great regularity, and
connected by a very complex series of ligaments and muscles,
which reminds the Naturalist of those which unite and move the
different segments in the Articulated animals. The Limpets
and Chitons fix themselves to the rock, in the same manner as
the Haliotis ; and it is stated that Crows and other birds,

388

LIMPETS. GEOLOGICAL DISTRIBUTION.

FIG. 584.— CHITON.

which endeavour to detach them for food, are sometimes caught
by the points of their bills, and are held there until they are
drowned by the advancing tide. The Limpets are herbi-
vorous, feeding upon sea-weeds, which
they reduce with their long riband-shaped
rasp-like tongues. Although we usually
see them attached quite motionless to
rocks, this is because exposure to the air
is unfavourable to their movement, since
too free an admission of it between their
gills would dry them up. It is when
covered with water, that their activity
manifests itself. — In many points of struc-
ture, the animals of this Order approach
those of Bivalve shells. The rock, in the
Limpet, may almost be regarded as a second
valve ; since the muscle takes a firm
attachment to its surface, and draws down the shell upon it, in
the same manner as the adductor muscle of the Bivalves enables
the animal to inclose itself by drawing the two valves of the shell
together (§ 932). Moreover the eyes are very imperfect or entirely
absent ; and many other points of internal structure prove the
inferiority of these animals to the Gasteropods in general.

929. To enter into any detailed account of the Fossil Remains
of this class, would be unsuitable to our present purpose ; and it
will be sufficient here to state some general facts in regard to
them. Remains of Univalve shells, of such a form and struc-
ture as evidently to have belonged to Gasteropod Mollusks, are
found in nearly every bed formed by the action of water, from
the very earliest of those containing fossils of any kind, down to
the present time. In many instances, the fossil shells, even of
the most ancient beds, may be referred to genera which still
exist ; — thus a species of Buccinum is found in the rocks of the
Silurian system ; — although they do not correspond with any
species now living, except in cases where there is reason to believe
that the deposit was formed at a comparatively recent period.

GEOLOGICAL DISTRIBUTION OP GASTEROPODA. 389

The Conchologist is generally able to determine, by an examina-
tion of the shell, whether it was formed by a marine or a fresh-
water Mollusk ; and in this manner he often receives important
guidance, in determining the circumstances under which a
particular deposit was formed. But he cannot be sure in regard
to this, from the examination of one or two shells only ; since
there are many genera, which contain species of both kinds. He
is guided, therefore, by the comparison of all the shells contained
in the deposit, with their nearest allies amongst those now
existing. Sometimes there is such a mixture of marine and
fresh-water shells, as to induce the belief, that the deposit was
formed in the estuary at the mouth of a river, of which both
might be inhabitants at once. In other cases, the shells are so
exclusively fresh-water, as to indicate that the deposit was
formed at the bottom of a river or lake ; and in this case, as
might have been expected, it is usually of no great extent.
"When the nature of the shells indicates a deposit from the
bottom of the sea, the same shells are frequently found in strata,
which differ greatly in their mineral materials, and which present
themselves at very different parts of the earth's surface ; and
they thus afford important assistance to the Geologist, in deter-
mining the real correspondence between these deposits. It is a
curious fact, that in all the earlier rocks, down to the chalk-
formation, the remains of the carnivorous Gasteropods bear a
very small proportion to those of the herbivorous group ; and their
place would seem to have been then supplied by the numerous
Cephalopods of predaceous habits, which then infested the seas
(§ 896). Nearly all of these disappeared after the Chalk was
formed; and the proportion of the carnivorous Gasteropods
exhibits a remarkable increase from that period.

CHAPTER XVIII.

OF THE LAMELLIBRANCHIATE CONCHIFERA.

r 930. THIS group is nearly synonymous with that of Bivalves
in the Linns3an arrangement, since all the animals which con-
struct bivalve shells belong to it ; but it also contains a few
species whose shells are Incottwalve ; and some others, in which
there appears at first sight an entire departure from the usual
form. The Mollusks belonging to this Class are, in common
with the Tunicata, destitute of a head ; that is, the mouth is
not situated upon a prominent part of the body, nor assisted in
its choice of food by organs of special sensation in its neighbour-
hood ; but the entrance to the stomach is buried between the
folds of the mantle.

931. The part of the structure of these animals which is best
known, is the shell. This is composed of particles of carbonate of
lime, exuded from the surface of the mantle, and contained in the
cavities of cells, or between layers of membrane (§ 870). If one of
the valves of an Oyster be examined, it will be seen to consist
of a number of layers, of which the external one is the smallest,
each inner one projecting beyond the one which covers it. This
is the case with other Bivalves ; but it is more evident in such
shells as that of the Oyster, in which the layers adhere loosely
together, than in others in which they are more compact. The
shelly matter is thrown out at intervals from the surface of the
mantle ; and as the animal enlarges at each interval, the new
layer extends beyond the old one. In this manner a constant
relation is preserved between the size of the animal and that of
its shell ; and the addition of the newly-formed portions, not to
the edge only, but to the interior of the whole previous shell,
strengthens the latter in proportion to its increase in size.

932. The valves are connected together in various ways.

BIVALVE SHELLS.

391

In the first place, they are jointed by a hinge, which is in some
instances so firm and complicated, that it holds them together

when all the soft
parts have been
removed. This
hinge is some-
times formed by
the locking of a
continuous ridge
on one valve into
a groove in the
other, and some-
times by a num-
ber of little pro-
jections or teeth,
which fit into cor-
responding hol-
lows in the op-
posite valve. In
the neighbour-
hood of the hinge
(sometimes out-
side, sometimes
inside, or both),
is fixed the liga-
ment ; which is
composed of an
elastic animal
substance ; this
answers the pur-
pose of binding
the valves to-
gether, and at

the same time of keeping them a little apart, which may be
regarded as their natural position. When the animal wishes to
draw the valves closely together, it does so by means of the
adductor muscle, which is fixed to the interior of both valves at

FIG. 585.— A, a, b, length of the shell ; c, d, height ; e, lunula,
above which is the summit ; d, the ventral or inferior edge.

B, the line across marks the thickness of bivalves.

c, a, anterior extremity ; 6, posterior ; c, d, muscular impres-
sions; e,f, palleal impression ; g, lower edge of the left valve.

392 GENERAL STRUCTURE OF LAMELLIBRANCHIATA.

some distance from the hinge, and of which the insertion can be
easily traced by a somewhat rough depression or pit, on the
interior surface of each valve. In some Conchifera, this muscle is
single, and in others it is double, the two parts being even at oppo-
site ends of the valve (Fig. 585, c). Upon this character it has been
proposed to found the primary division of the Class into Orders;
but the classification thus formed is not a natural one, inasmuch
as it brings together kinds which have little resemblance, and
widely separates others which are closely allied. — In Fig. 585
are shown the several parts of a Bivalve Shell, with the expla-
nation of the names by which they are described.

933. In order to describe the general structure of the Lamelli-
branchiata, it will be advantageous to select some particular
illustration ; and the Mactra (Fig. 586) is well adapted to this
purpose. On opening such a shell, it is seen that the two valves
are lined by a membrane, in which the animal is enclosed, like a
book between the boards of its cover. This membrane is divided
into two halves along a considerable part of the edge of the
valves ; but is united near the large end. In some Conchifera,
as will be presently noticed, the two valves of the mantle are
separated along their whole extent ; whilst in others they are
completely closed, with the exception of the two orifices for the
ingress and egress of water ; which are sometimes drawn out
into long tubes. In the Mactra, the water enters through one
of the short respiratory tubes, and passes out by the other ; but
the water thus introduced is principally for the supply of the
gills, — the mouth, or entrance to the stomach, being placed at the
other end of the shell, where the mantle is quite open ; and being
thus able to take in food from the surrounding water, which comes
into free contact with it. The gills in all Lamellibranchiata
consist of four riband-like fringes, fixed to the mantle along the
edge of the shell most distant from the hinge. Near the middle
of the shell is seen the stomach, with the short tube leading to it,
the orifice of which (or mouth) is furnished with four tentacula
or feelers. To the left of this is seen the long and complicated
intestinal tube, with the liver lying in separate masses amongst
its folds. Below this is seen the ovarium, in which the eggs are

STRUCTURE OF LAMELLIBRANCHIATA.

393

formed ; this occupies a large part of the cavity of the shell
during the breeding season. Close to this is the posterior adduc-
tor muscle ; by which, with the aid of the anterior muscle

.2 5

Foot —

Intestine . IJLt

Stomach

Gills ~Jfv*

Mantle

( Anterior
I Ganglia
Liver

Ovary
f Posterior
Ganglion

/ Posterior
\Muscle

Anus

Respiratory Tubes
FIG. 586 — ANATOMY OF AN ACEPHALOUS MOLLUSK.

situated near the mouth, the valves can be drawn together with
considerable force. The intestinal tube is seen to terminate near
the opening at the posterior extremity of the shell, in one of the
respiratory tubes, which discharges its contents, and serves for
the exit of the respiratory current.

394 GENERAL STRUCTURE OP LAMELLIBRANCHIATA.

934. The foregoing description will apply, with slight varia-
tions, to the structure of almost all Lamellibranchiata ; but we
have now to notice two organs, which are absent in some, and in
others more largely developed than in the present instance. At
the left side of the figure, projecting beyond the edge of the
mantle, is seen the foot; a fleshy muscular organ, somewhat
resembling the tongue of higher animals, and not containing any
hard support, or being protected by any envelope. This foot,
which is the only special locomotive organ possessed by the
Mollusca of this class, serves a great variety of purposes ; some-
times enabling the animal to leap with considerable agility along
a hard surface, sometimes being used to bore into the sand or
mud, and sometimes only serving to affix the animal to some
firm support. From the base of this foot there proceeds, in the
Mussel and its allies, a band of hair-like filaments, forming
what is called the byssus. These sometimes exist in great
abundance, and serve, by being fixed by their extremities to the
shore or bottom of the sea, to anchor the shell, and yet to allow
the animal considerable freedom of motion within certain limits.
Frequently the byssus is altogether absent.

935. The Lamellibranchiata have usually more power of locomo-
tion than the other Acephala. Some of them, however, are at-
tached to one spot during all but the earliest period of their lives.
Others adhere by the byssus, or by the foot, by which they obtain
a certain range; and others are free during the whole of their lives,
swimming and leaping with considerable agility. In these move-
ments some of them appear to be directed by powers of sight ;
and in these are perceived small red spots at the edges of the
mantle, which are believed to be eyes. They do not appear to
have much choice of food ; nor are they provided with any other
means of obtaining it, than the ciliary action, which introduces
constant currents of water into the mouth. In general they do
not attain any great size, but they are on the whole larger than
any Mollusks except the Cephalopoda ; and a few species attain
considerable dimensions, a Pinna having been known four feet
long, and a Tridacne (Giant Clamp shell) having been known
to weigh 600 Ibs. They are distributed over the whole globe,

CLASSIFICATION OF LAMELLIBRANCHIATA. 395

principally frequenting the shores or shallows. Each region has
certain species peculiar to it, or most abundant in it ; and there are
few which are not limited to one hemisphere. The temperate
zone appears as favourable to the development and multiplica-
tion of some species as the torrid zone to others ; but the largest
kinds are only found in warm latitudes.

936. In regard to the subdivision of the Lamellibranchiata into
Orders and Families, great difficulty is felt by those by whom
this group has been most studied. By some, the presence of a
single or double adductor muscle has been taken as the ground
of the primary division ; but for the reason already stated, this
is unsatisfactory (§ 932). By others, the degree in which the
two divisions, or lobes of the mantle, are united along their edge,
is adopted as the foundation of the arrangement; this also is
unsatisfactory for a similar reason, although it is probably a more
natural character than the other, because it seems to correspond
more with the general structure of the animal. Others, again,
have taken the degree of development of the foot as their guide ;
but this, too, if followed alone, would lead into many errors. —
The fact appears to be, that it is necessary to consider all these
characters together , in attempting to make a natural arrangement
of this family ; and the Author's recent inquiries regarding the
structure of the Shell, lead him to believe that this also will afford
a character of great importance, — frequently serving to deter-
mine the real position of genera, which would otherwise be
doubtful. For the present, however, it will be desirable to adopt
the following arrangement into ten primary divisions, which has
been proposed by M. De Blainville. The names of some of
these, however, have been changed ; to make them correspond
better with those adopted by other naturalists : —

I. The OSTRACE^E, including the Oysters and their 'allies.
These have the lobes of the mantle open along their whole length,
but the body is concealed by the adhesion of the laminae of the
gills ; the foot is altogether absent ; and there is but a single
adductor muscle.

II. The PECTINID.E, or Pectens (Scallop-shells) and their
allies, which have, like the last, the lobes of the mantle open ;

396 CLASSIFICATION OP LAMELLIBRANCHIATA.

but the branchial laminae are riot adherent ; there is but a single
adductor muscle ; and there is usually the rudiment of a foot.

III. The MARGARITACEJE, or Pearl-Oyster tribe ; these, also,
have the edges of the two halves of the mantle, and also of the
branchial laminas, free, or not adherent to each other ; and there
is but a single adductor muscle ; but the foot is larger, and
a byssus is usually present, by which the animals attach them-
selves to rocks, &c.

IV. The MYTILACE^, or Mussels, which have the lobes of the
mantle adherent posteriorly; the foot small, and provided with
a byssus ; and a double adductor muscle, of which the anterior is
small.

V. The UNIONIDJE, or Fresh-water Mussels, which have the
mantle non-adherent, but which have the branchial laminae
united posteriorly, so as to form a sort of siphon for the exit of
water. The foot is a large fleshy mass ; and there is no byssus.

In the preceding Orders, the hinge of the shell was very simple ;
it now becomes of increased complexity. In all the remaining
Orders, the adductor muscle is double.

VI. The ARCACE.E, or Arks, which have the mantle but
slightly adherent posteriorly, but adherent along the lower edge
of the shell : the foot is large ; and both adductor muscles are of
considerable size.

VII. The CAMACE.E, or Clamp-shells -, have the mantle still
more adherent, but always divided by a large opening at the
lower part for the passage of the foot, which is of great size. The
respiratory orifices are not prolonged into tubes, but are sur-
rounded by a circle of radiating tentacula.

VIII. The CARDIACE^E, or Cockle tribe, which have the lobes
of the mantle still partly open in front, but prolonged into tubes
at the posterior extremity ; these Mollusks have a large foot,
which they use for burying themselves in the mud.

IX. SOLENID^, or Solens, and their allies, in which the mantle
is quite closed in front, so as only to allow the foot to pass out,
and is prolonged behind into tubes of considerable length ; which
can, however, be withdrawn into the shell.

X. The INCLUSA, in which these characters are still further

ORDER OSTRACE^E ; — OYSTER. 397

manifested; the bivalve shell never covers the whole of the
body ; but frequently the respiratory tubes themselves secrete
shelly matter from their external surface, forming a tube with
which the valves are often blended (§ 963).

ORDER I.— OSTRACEJE.

937. The shell of these Mollusca is formed of two unequal
valves, connected together by a hinge on which there are no
teeth or ridges, and which is therefore of the simplest character.
The shell is attached by the most convex of its valves to rocks,
to pieces of wood, and even to others of its own kind. This
attachment is formed by the exact adaptation of each layer of
shell, prolonged beyond the margin of the former one, to the
inequalities of the surface upon which it lies ; and sometimes
the margin is actually made to re-curve backwards, to enter some

FIG. 587.— ANATOMY OF THE OYSTER : v, one of the valves of the shell ; v1, its hinge ;
m, one of the lobes of the mantle ; m', a portion of the other lobe folded back ; c, adduc-
tor muscle ; br, gills ; b, mouth ; t, tentacula, or prolonged lips ; /, liver ; i, intestine ;
a, anus ; co, heart.

furrow by which it may hold more firmly. The animal itself is
of very simple structure. No vestige of a foot can be seen ; and

398 OSTRACE.E ; — OYSTERS.

the ligament which unites the valves is of small size. On
separating the valves, the four rows of gills are observed, form-
ing what is called the beard, at a little distance from the fringed
edge of the mantle. The adductor muscle is situated at about
the centre of the body ; and the heart lies between it and the
mass of the viscera, and is easily to be distinguished by the
brown colour of its auricle. The mouth is to be found beneath
a kind of hood, formed by the union of the two edges of the
mantle near the hinge. The ovaries are of very large size at
breeding time ; and one individual produces, according to Poli,
1,200,000 eggs. These eggs appear to be generally developed
within the valves of the parent ; so that the young Oysters may
be often seen swimming slowly in the fluid surrounding the gills,
or attached to these organs. According to Leeuwenhoek, each of
these is about 1 -120th of an inch in length ; so that two millions
of them closely packed together would not occupy above a cubic
inch. He reckoned from 3000 to 4000 to exist in one Oyster at
the same time. The principal breeding time of the common
Oyster is in April and May, when they cast forth their young
in little masses like drops of grease, formed of several united
together by an adhesive fluid, upon rocks, stones, or other hard
substances that happen to be near ; and to these the spats,
as they are termed by fishermen, immediately adhere, soon
forming a thin shelly covering. Very commonly they adhere to
adult shells ; and thus are formed the large masses termed banks.
Their growth is very rapid. In three months they are larger
than a shilling ; and at the end of the first year they have a
diameter of two inches. When they are about a year and a half
old, they are reckoned fit for the table ; and they are then taken
by dredges, and stored in pits, where they undergo changes in
their condition, which render them more fit for the market.
When removed altogether from their native element, they very
commonly open their shells, and lose the water retained between
them, which occasions their speedy death ; but if placed in
situations which the tide occasionally reaches, they learn to keep
their shells closed in the intervals. Although no special organs
of sensation can be detected in them, except the tentacula around

OSTRACEJE ; OYSTERS. 399

the mouth, they are evidently very susceptible of the influence
of light, having been observed to close their shells when the
shadow of a boat passes over them.

938. The enormous number of Oysters which exist on our
shores, may be best judged of by considering the extent of the
banks which they form. These beds occupy portions of the sea, in
shallow parts, extending for miles in each direction; and in some
places, the depth of the stratum is very considerable. A remark-
able growth of them exists along the alluvial shores of Georgia, in
North America ; and their influence in preventing the encroach-
ments of the sea is very important. The marsh land extends
inwards for a space of from twelve to eighteen miles ; and it is so
soft, that an iron rod might be pushed into it without difficulty
to the depth of 18 or 20 feet. A great number of large creeks
and rivers are found meandering through these marshes ; and the
bends of these rivers would in a short time cut through the
adjoining land to such an extent, that the whole seaboard would
become a quagmire. But wherever the tide directs its destroying
force, its effects are counteracted by walls of living oysters, which
grow upon each other from the beds of the rivers to the very
verge of the banks. These hillocks are often found in bunches
among the long grass growing upon the surface of the soil. They
are in such abundance, that a vessel of a hundred tons might
load herself in three times her own length. These banks are
the favourite resort of fish and birds, as well as of the racoon
and some other quadrupeds. The neighbouring inhabitants will
sometimes light a fire upon the marsh-grass, roll a bunch of
oysters upon it, and then eat their contents. This barrier of
oysters, like rocks of coral, must offer the strongest resistance to
the force of the tide. Such immense collections of shells are
very interesting when viewed in relation to Geological pheno-
mena; since whole strata of rock are often found entirely
composed of shells thus aggregated ; which probably occupied,
on the shores of the land then upraised above the surface of the
ocean, a position similar to that in which we find the oyster-
beds at the present time.

939. Notwithstanding the enormous number of Oysters

E E 2

400 OSTRACE^E ;— OYSTER ; ANOMIA.

which thus accumulate, the race would speedily be extinguished
by the voracity with which Man preys upon them, were not the
destruction counterbalanced by the powers of multiplication
already noticed. But Man is by no means the only enemy to
the Oyster. Its body serves as food to many marine animals,
which have various methods of getting access to it, in spite of
its shelly defence ; from some of these it can secure itself by
closing its valves as soon as it is alarmed ; and against others
it has a more active means of defence, in the violent expulsion of
the water included between them, which (as it is itself fixed)
will frequently drive off its opponent. Various animals attack
it, also, by perforating its shell ; arid to these also it can offer a
passive resistance, by depositing new shelly matter within. So
that even this lowly-organised being, commonly regarded as one
of the most vegetative of animals, is provided by its Creator with
such means as are necessary for its preservation, and doubtless
also for its enjoyment.

940. Nearly allied to the Oyster, but having also some-
points of resemblance to the class of Palliobranchiata or Brachio-
poda, is the genus Anomia ; which is
remarkable for the perforation of one
of its valves by a large aperture ; through
which a great part of the adductor
muscle passes, to be inserted into a
third plate (sometimes calcareous and
sometimes horny), by which the animal
adheres to foreign bodies. The valves
are thin and of irregular form ; being
influenced by the surface on which they

FIG. 588. — ANOMIA EPHIPPUJAJ. mi n x- j i j

grow. Ihey are usually found attached
to the surface of other shells, especially those of Oysters.

401

FIG. 589. — PECTKN.

ORDER II.— PECTINID^.

941. The PectenS) or Clams, are known by the regular radi-
ation of the ribs *from the summit of each valve to the circum-
ference; and by the two angular
projections, or ears, that widen the
sides of the hinge. The shell is
often very vividly coloured ; and
a marked difference in hue is fre-
quently observable between the
two valves. The animal has a
small oval foot ; and some species
are attached by a byssus ; whilst
others are said to swim freely
through the water by the flap-
ping of their valves, and can

even regain the sea by a motion of this kind, when left upon
the shore. The large species upon our coast, Pecten maximus,
is the pilgrim's scallop shell, worn in front of the hat by those
who had visited the shrine of St. James at Compostella in Gal-
licia. Pectens are sometimes eaten ; but, as the animal is hard
and indigestible, few but the poor employ it as an article of food.
The hollow valve has been used as a dish ; and even as a culi-
nary vessel, being capable of bearing a considerable heat without
cracking. — Among other genera of this family, we may notice
the Spondylus ; in which the shell bears a general resemblance
to that of the Oyster ; but the hinge is provided with two teeth
in each valve, which enter into corresponding depressions in the
opposite valve. The shell adheres to solid bodies of all kinds ;
and its form is modified by the surface of the objects on which
it grows. The animal is eaten like the Oyster. The most
interesting peculiarity in this genus has been already noticed
(§ 870). Many of the species are of very vivid colours.

402

ORDER III.—MARGARITACE^E.

942. This group contains many genera of much interest ; all
of them agreeing in the structure of the shell, which is composed
internally of nacre, and externally of prismatic cellular substance.
The most important is the Amcula ; which receives its name
(meaning little bird) from the wing-like projections near the
hinge, which are very long in some species (Fig. 590),, One
species, the Amcula margaritifera, produces the most valued
Pearls, as well as the greatest quantity of Mother-of-Pearl (the
latter being simply the nacreous interior of the shell). The
former are separate formations of a similar substance, deposited
by the mantle at particular spots, in consequence of some irrita-
tion. Various causes will occasion this deposit. If grains of
sand find their way between the shell and the mantle, they are
generally incrusted by it ; one layer being thrown around
another, so that, if the calcareous matter be gradually dissolved

FIG. 590. — AVICULA MACROPTJERA. FIG. 591. — AVICULA MARGARITIFERA.

away by a weak acid, a series of concentric spheres of membrane
remain. Many pearls, however, inclose no such nucleus ; yet
still are produced by mechanical irritation of the mantle. It has
been observed that, if the shell be penetrated by boring-worms,
pearly matter is deposited at the spot perforated ; and an arti-
ficial expedient was thus suggested, which has been put "in
practice with a certain degree of success. This was, to obtain

MARGARITACE.E ; — PEARL-FISHERY. 403

the shells, with the animals alive, to make perforations in them,
and then to commit them to their native element. The expense
of this proceeding, however, has been found to exceed the profit
obtained by it ; especially as the pearls thus produced are seldom
possessed of that regularity of form, which is an important
element in their value. The best pearls are generally produced
at the point, where the attachment of the adductor muscle causes
a roughness in the shell. The gradual change which takes place
in the position of this muscle, in accordance with the growth of
the animal, causes the detachment of the pearl ; and it is gene-
rally found imbedded in the substance of the muscle, by the
motion of whose fibres its regularly spherical form seems chiefly
occasioned.

943. The formation of pearls is by no means confined to the
Amcula margaritifera. Any shell, univalve or bivalve, with a
nacreous interior, may produce them. They have been found in
Patellae (Limpets), Haliotides, and Pinnae ; and more especially
in the Unios, which are fresh water shells, abounding in most
rivers of the north.* It is the Pearl Oyster, or Mussel, as it
has been termed, which is most sought, as furnishing this com-
mercially-important article of luxury. The shell exists in con-
siderable banks in the Gulf of Manaar, on the shores of Ceylon,
the Persian Gulf, and other parts of the borders of the Indian
Ocean ; and also in the Gulf of Panama, and on the east shore
of California. It is attached by the byssus to submarine rocks,
usually at considerable depths. The most considerable bed is
said to occupy a space of twenty miles opposite Condatchy. To
prevent injurious destruction, the bank is divided as it were into
regular cuts ; one seventh part being worked every year, so as
not to exhaust the bed. The shells are brought up by divers,
who, by long practice, acquire the power of remaining under
water for four minutes, or even longer ; and in this time they
descend to the depth of from four to ten fathoms, pluck the shells
from their attachment, and accumulate about fifty in a net sus-

* The River Tay in Scotland affords pearls which are held in tolerable estima-
tion ; although they are much inferior in clearness and lustre to the * orient
pearl.'

404 MARGARITACE^E ; MALLEUS ; PERNA ; PINNA.

pended from the neck to receive them, and they are then drawn
up on giving signal to those above. Each diver can repeat
this operation about fifty times in one day ; but it is not uncom-
mon to see, after several descents, blood streaming from the nose
and ears. The shells are laid out that the animals may die ; and
when this has taken place (which is known by the opening of
the shell) the interior is searched for pearls, and the best shells are
set by to furnish mother-of-pearl. The produce of this operation
is very considerable. [In 1798, the pearl-fishery of Ceylon
yielded the sum of 200,OOOZ. ; but the banks seem to have been
too much exhausted, as the produce of the subsequent years
was much less, and it has not since risen to the same amount.

944. The Malleus, or Hammer-oyster, is another genus which
is chiefly worth notice on account of its singular form ; the two
sides of the hinge being extended so as to resemble in some
degree the head of a hammer, whilst the valves, elongated nearly
at right angles to these, represent the handle. In the Perna the
hinge has no teeth, but several parallel depressions opposite to
each other in the two valves, and lodging as many small elastic
ligaments. — Many fossil species of this character, some of them
of great size, exist in the Lias, Oolite, and other more recent
strata.

945. The Pinna, or Wing-shell, approaches the Mussels in
many respects. It has two equal wedge-shaped valves, united
by a ligament along one of their sides ; and is almost entirely
composed of the cellular substance formerly described (§ 869). It
sometimes attains a considerable size ; measuring as much as
three feet in length. The most interesting peculiarity of this
genus, is the byssus, which is remarkably long and silky. The
animal fixes itself by this to submarine rocks and other bodies ;
and lives in a vertical position, the point of the shell being under-
most, and the base or edge above. It even attaches its byssus
to a sandy or muddy bottom ; and in such situations large troops
of them are found at the depth of a few fathoms. The most
common species exist in the Mediterranean ; and the inhabitants
of Sicily and Calabria seek them, not merely for eating, but to
gather the byssus, of which a stuff may be formed that is

PINNA. — ORDER MYTILACEJ3 j MUSSELS. 405

remarkable for its suppleness and warmth. The filaments are
extremely fine, of perfect equality of diameter through their
whole extent, of great strength, and of a brilliant and unalterable
reddish-brown colour. The ancients were acquainted with this
sort of stuff; but, in consequence of the diminution in the
number of animals, it is becoming very scarce ; and, from its
expensiveness, it is little more than an object of curiosity.

ORDER IV.—MYTILACEjE.

946. In all the Mollusks of this order, there is a foot, which
some species employ for locomotion, whilst in others it serves
merely to draw out, direct, and fix the byssus. There are also
two adductor muscles, of which the anterior one is often very
small. The Mussels, properly so called, abound on the rocks of
our own coasts, to which they are fixed by their byssus ; and
they are often closely impacted together. Although in ordinary
circumstances they have no tendency to change of place, they
seem possessed of a certain degree of locomotive power. Reaumur
mentions, that in the saline marshes on the sea-coast, where the
fishermen throw the Mussels at hazard, they are found at the
end of some time united into packets. By putting them into
glass vessels, he observed that their mode of progression con-
sisted in thrusting their tongue-like foot out of the shell, curving
it, hooking it to some adjacent body, and thus drawing them-
selves forward to the point of attachment. Although Mussels
commonly afford a very wholesome supply of food, they some-
times acquire very poisonous properties. How this is to
be accounted for, is yet uncertain. Many instances have
occurred, in which a large number of persons have been suddenly
attacked with violent symptoms, after eating Mussels from a
particular bed ; and fatal cases have not been uncommon. Whilst
Mussels in general attach themselves to the surface of rocks,
&c., others appear to seek out hollows, and imbed themselves
there. Others form excavations for themselves in mud ; and
are found in spots which are occasionally left dry by the tide.

406 MYTILACE.E ; — LITHODOMI ; DREISSENA.

947. The Lithodomi are endowed with the power of per-
forating stone and masses of coral, as well as large shells of other
Mollusca. In the earlier stages of life, it is stated by Cuvier,
the Lithodomi suspend themselves by their byssus ; but when
they have pierced the bodies to which they are attached, and
introduced themselves into the cavity, the byssus disappears.
The excavation does not seem to be here produced by the
mechanical action of the shell, which is not adapted for such an
office. Nor is there any reason to believe that it is occasioned
by a solvent fluid secreted by the animal. It is attributed by
Mr. Garner principally to the currents of water constantly im-
pelled against the rock by the vibration of the cilia ; and in this
supposition there is much probability. — The lithodome Mussels,
as well as others, are used as food where they abound ; and
means have been taken on some parts of the coast, to cause them
to multiply. As with Oysters, it appears that the Mussels are
rendered more tender, and the quality of their flesh improved,
by putting them in places where the saltness of the sea- water
is tempered by rain or river- water. Accordingly, on the coasts of
France and Italy, regular breeding-places have been established,
where those which have been obtained from the sea are cast for
a time to improve their quality, and where also the spawn is
reared ; these are so arranged as to communicate with the sea,
but to #llow the intermixture of fresh water at pleasure. Like
all Mollusca which congregate upon the shores, Mussels serve as
an article of food to other animals besides Man. Many sea-birds
detach them from their situation by breaking the shell, and then
feeding on them. And there are Mollusca of higher Orders,
which are enabled to pierce their shells, and which then suck out
the soft parts by their proboscis.

948. A Mollusk allied to the Mussel, the Mytilus polymor-
phus, or Dreissena polymorpha, has been recently introduced into
this country ; and affords an interesting example of the complete
naturalisation and rapid multiplication of a foreign species. This
is evidently due to the variety of circumstances under which it
can exist. It is found abundantly in the Black Sea, the Baltic,
and other salt inland seas ; and it lives, like the Mussel, in

DREISSENA. — UNIONID^E.

407

aggregated masses, attached to the bottom by the byssus. But
it is also found in many of the large Continental rivers, such as
the Danube, the "Wolga, and the Rhine; and it thus seems
equally capable of living in fresh water. It was first discovered
in England a few years since in the Commercial Docks of London,
where it was probably conveyed with some timber ; and it has
since diffused itself through the rivers and canals of the whole
island. This may be partly accomplished by its adhesion to the
keels of boats.

ORDER V.— UNIONID^E.

949. The Mollusks of this Order, frequently called Fresh-
water Mussels, are for the most part included in the genera
Anodon and Unio. The former is named from the absence of
teeth in the hinge, which has merely a ligament along its entire

length. The ani-
mals are without
a byssus ; and
creep over the
sand or mud by
means of their
large foot, which
has three layers
of fibres disposed
in different direc-
tions, so that it
has considerable
power of altering
its form and di-
mensions. They
are most commonly found sunk in mud, however, with that
part of the aperture of the shell which corresponds to the mouth
directed upwards. It has been said that they have some power
of swimming, by striking the water with their valves. The
Anodon is viviparous, the eggs being hatched within the shell ;

FIG. 592. — ANODON DIPSAS.

408 UNIO. ARCACE^E.

and thousands of young ones may be seen in the winter, with a
microscope, dispersed among the gills, and opening and closing
their shells. — The Unio resembles the Anodon in the structure of
the shell, and the conformation of the animal ; except that the
hinge is more complicated. There is a short plate in the left
valve, received into a cavity in the right; and behind this a
longer plate closing between two others of the opposite side.
These, like the Anodontes, inhabit fresh-water, preferring run-
ning streams. Several are natives of this country; but they
especially abound in the rivers and lakes of North America.
The abundance of their nacreous lining causes it sometimes to be
employed for the purposes to which mother-of-pearl is applied ;
and pearls are occasionally obtained from them (§ 943). The
animal is of no value as food, from the insipidity of its taste.
— Some genera of marine shells have been approximated to the
Unio ; but as their animals are not known, there can at present
be no certainty on this point.

ORDER VI.— ARCACE^E.
950. The Area is distinguished by its equivalve shell, and by

FIG. 593.— ARCA BARBATA AND ARCA N<XE.

the long line formed by the hinge, which is studded with minute
teeth. The valves, which are covered with a velvety epidermis,
do not meet in the middle ; but a space is left for the passage of
a horny, apparently tendinous substance, which seems to replace

ARCA ; PECTUNCULUS. CHAMACE.E.

409

the foot, and by which the animals are affixed to submarine

bodies. They reside near the
shore in rocky places. There
are some species in the
Mediterranean at the pre-
sent time ; and others abound
in the older fossiliferous
strata of Italy. — In the
Pectunculus the hinge has
a similar elongated charac-
ter, but it is curved instead of being straight.

FJG. 594.— PECTUNCULVS.

ORDER VII.— CHAMACE^E.

951 . In this Order are included the largest, and some of the
most inert, of all the testaceous Mollusca. Nearly all of them
are attached to rocks or other
solid bodies, during the great-
est part of their lives ; some
by the adhesion of the shell
itself, and others by a tendi-
nous prolongation of the foot,
which serves as a byssus.
The shell is generally more or
less irregular in form, in con-
sequence of these adhesions ;
its hinge is very analogous
to that of Unio, the left valve
being provided with a tooth,
and further back with a pro-
jecting plate, which are re-
ceived into corresponding prominences in the right valve. The
foot is generally very small, and the adductor muscle is double,
the anterior one, however, being sometimes rudimentary. — The

Chama is one of those attached by the shell itself to rocksy
corals, and even to masses of similar shells, in the manner of

Oysters ; and the individuals are thus cemented so strongly to

FIG. 595 CHAMA, with the shell removed,

to show the arrangement of the mantle
and its orifice. The two lobes are adhe-
rent along their entire edges ; except at
the respiratory passages, r, and e, and to
give exit to the foot, /.

410

CHAMACE^E;— CHAMA, TRIDACNE.

each other, that they cannot be detached without breakino- the
shells. These are subject to changes not only of shape but of colour,
in accordance with the accidents of their position. The attached
valve is very irregular, and takes the form of the surface to which
it is applied ; and it is usually much less coloured than the other.
The valves have a series of foliations, or leaf-like projections, on
their surface; and the luxuriancy of these depends upon the
stillness of the medium in which the animal exists. If it inhabit
deep and placid water, the expansions will generally be of con-
siderable size ; whilst those of the individual that has borne the
buffetting of a comparatively shallow and turbulent sea, will be
poor and stunted. This genus is confined to the warmer seas ;
the Mediterranean being the locality of the lowest temperature
where any species have been hitherto found ; the shells have
been observed at various depths, ranging from points near the
surface to seventeen fathoms.

952. The Tridacne, of which one species is the largest known
Conchiferous Mollusk, is still more restricted to warm localities ;

the East Indian and
Australian seas alone
supplying specimens
of it. This is readily
distinguished from
the Chama by the
equality of the valves ;
since, instead of being
fixed by the adhe-
sion of one of these,
it is attached, during

part of its life at least, by a tendinous byssus that passes out
through a channel in the anterior part of the mantle, which forms
a well-marked groove in the shell. The Tridacne, or Giant
Clamp-shell, sometimes attains an enormous weight as well as
dimension. There is a pair in the Church of St. Sulpice at
Paris, which are used as " Benitiers" (receptacles for holy-
water), and weigh more than 500 pounds ; Lamarck mentions
a specimen in which each valve measured three feet by two ;
so that the story of an oyster which furnished a dinner to a

G, 596. — TRIDACNE.

TRIDACHE. — %CARDIACE.£. 411

whole regiment is scarcely an exaggeration, as the flesh of these
animals is commonly used as food where they abound, and is by
no means unpalatable. The remarkable difference of the shell
of this animal at different epochs of its growth, has given rise
to the formation of many species which have no real existence.
It is only when immature, and when the shell is comparatively
light, that the animal is attached by a byssus. This cord, how-
ever, seems rather to be a musculo-tendinous prolongation of the
foot itself, than a fibrous tissue secreted by it like the byssus of
the Pinna ; it is so tough as to require to be chopped with a hat-
chet, in order that the shell may be detached. As the animal
approaches adult age, however, and has by successive layers
very much increased the weight of the shell, the byssus, being
no longer required to secure it from injury, disappears, and the
groove in the shell is filled up with a solid deposit. When thus
free, it is said to be taken with a long pole, which is introduced
between the valves when open ; the animal immediately closes the
valves upon it, and does not quit its hold until it is landed.

ORDER VIII.— CARDIACE^E.

953. This Order, including the Cockles and their allies,
contains several genera, which, in the smallness and delicacy of
many of their shells, and in the comparative activity of the
animals that form and inhabit them, offer a remarkable con-
trast to those of the previous group. The shells are all equivalve,
or nearly so ; they are furnished with a regularly-toothed hinge,

often of great complexity and
beauty ; and there is always a
double adductor muscle. The
foot is here more largely de-
FIG. 597.— TBLINA. veloped than in any of the pre-

vious Orders, and it is a very

important organ to the animals, most of which use it in the exca-
vation of hollows in the sand or mud of the shores on which they
reside, as well as for progression. The respiratory orifices are

412 CARDIACE^E ; CARDIUM, OR COCKLE.

usually prolonged into tubes (Fig. 597) ; which can, however,
be drawn within the shell by means of a retractor muscle.

954. In the Cardium, or Cockle, the tubes or siphons are
shorter than in most of the other genera ; indeed they are some-
times reduced to mere openings ; and scarcely any vestige of a
retractor muscle exists. The foot is very large, and is capable of
being bent at an acute angle, and then suddenly straightened ; so as
to enable the animal to move from place to place by a succession
of leaps. But it is only occasionally, that it serves this purpose.
The chief use of the organ is as a boring instrument, by which
the animal may penetrate the sand or mud, below the surface of
which it is usually found. A very curious provision exists for
adapting it to this object. As usually seen, the foot, when
extended, tapers gradually to a point ; and, as its diameter is at
its largest point much less than the breadth of the shell, it is
not apparent by what means the hole that is excavated is made
sufficiently large for the reception of the latter. This is accom-
plished, however, by the distension of the foot with water,
through a tube which opens just within the mouth ; and thus
the size of the borer becomes so nearly equal to that of the
shell, that (its solid point first entering the sand) it is enabled,
by rotatory motions often repeated, to excavate a burrow large
enough to receive the animal with its shell. The Cardia are
found in all known seas; and in some they abound so much, that
they become very important articles of food to Man, as well as
to marine animals. Mr. Kirby mentions that, on the North
East coast of Norfolk, an alteration in the sands has taken place,
which has caused a great diminution of late years in the number
of boring bivalves ; and that the quantity of Soles and other
Flat Fish frequenting the coast, of which they form the principal
food, has consequently much decreased also.

955. Nearly allied to the Cardium are a considerable num-
ber of genera of great interest to the Conchologist ; many of
them being remarkable for the beauty of their shells, or for the
curious situations in which they live. The greater number of
them inhabit sand or mud ; but there are several which bore
into rocks ; and a few that burrow in masses of coral. The

CARDIACEJE. — SOLENIDJE ; RAZOR-SHELL. 413

means by which they make their excavations, are not understood.
The resemblance both in the shell and the animal, among these
numerous genera, is often so strong, as to produce a difficulty in
their classification, as well as to render it unnecessary to enter
here into details respecting them. It will be sufficient to name
the genera, Venus^ Mactra, Tellina, Donax, Lucina, Petricola,
and Fenerupis, as including the greatest proportion of the group ;
these being names with which even the ordinary Shell-Collector
must soon become familiar, on account of the large proportion
that the bivalves of this Order bear to others, on almost every
coast.

ORDER IX.— SOLENID^E.

956. The Mollusks of this Order are distinguished from those
of the preceding, by the wide gape of their shells at the poste-
rior extremity, and by the length of the respiratory tubes. Their
habit is to burrow much more deeply ; and their foot (which is
of small size) is made to project rather from the anterior
extremity, than from the middle of the body ; so that the form
of the whole is more cylindrical than we have yet seen it, though
not so much so as in the succeeding Order. The Solen, or Razor-
shell, is a well-known example of this group. It has an elongated
shell, of which the hinge is furnished with distinct teeth, and the
ligament is altogether externaL The animal burrows in the
sand, into which it sinks rapidly on the approach of danger. It
seldom or never quits its hole ; and its movements are nearly
limited, therefore, to an ascent or descent in it. This it
accomplishes by means of its foot, which it elongates and
attenuates into a point, when it wishes to bore ; contracting
it into a rounded form, so as to fix it by its enlargement within
the hole, when it desires to rise. The animal is sought for by
fishermen on some coasts, as a bait for certain fish. Its burrow
is often recognised by the little jet of water which the animal
throws out, when alarmed by the shaking of the sand occasioned
by the motion of the fisherman above. When the tide is low,

414 SOLEN; MYA; BYSSOMIA.

the holes are often seen in considerable numbers; and this is
also the time when the animal may be most easily procured.
The fisherman throws a little salt upon the hole, which induces
the animal to ascend, — according to some, by leading it to the
belief that the tide had returned, — and, according to others, by an
irritating effect of which it desires to get rid. To seize it when
it makes its appearance, some address and quickness are required;
for it speedily returns to its burrow; and, if entrapped, its
struggles are sufficiently powerful to cause injury by the sharp
edges of the shells. If it re-enter its hole, fresh pinches of salt
no longer produce the same effect; the animal having either
learned by experience that they do not indicate the return of the
sea above it, or deeming it better to submit to the irritation than
to expose itself to capture. The fisherman then has recourse to
a long iron crook, which he sinks pretty deeply ; and, drawing it
out obliquely, carries away the sand, and the Solen contained in
it. If he should fail in this attempt,he knows that to try again
would be useless; since the animal instantly burrows rapidly
down to such a distance, as to render pursuit of this kind useless.
957. This group is connected with the preceding by the
Mya, Lutraria^ and other genera, which are common on our
coasts ; and which burrow into sand or mud. In the Mya and
its allies, the two respiratory siphons are united into a single
tube, which is of fleshy consistence, and which is covered by an
epidermis prolonged over it from the shell. One genus, the
'Byssomia, is remarkable for possessing a byssus at the base of
its small foot. The shells of this Order are usually covered with
a thick epidermis, or horny skin.

ORDER X.— INCLUSA.

958. The last Order is one of the most interesting of the whole
group, as regards the habits of the animals composing it, and the
curious varieties of structure which they present. The peculiar
disposition of the mantle, which has been noticed as characterising
the group (§936), has an evident relation with the habits

INCLUSA. — PHOLAS. 415

of the animals composing it; which have the power of forming their
habitations, not only in sand and mud, but by excavating wood
and rock. No general description can be given of the shells of
this group ; for although they often bear some resemblance to
those of other bivalves, they frequently depart from them so
completely, as to leave their character in doubt, until the struc-
ture of the animal producing them has been examined. The
tubes cannot in any instance be drawn within the valves ; and
these frequently cover but a small part of the whole surface.
We then often find a kind of supplementary shell, formed by a
calcareous exudation, lining the hollow which the animal has
pierced ; and this sometimes involves the original shell, so that
the latter is entirely lost in it.

959. As connecting this Order with the preceding, and as
departing least widely from the general type of Bivalves, we
may first mention the P kolas ; this has a shell formed of two
principal valves, which leave a considerable space between them
at each end when they are closed j and of supernumerary
pieces, the number and position of which vary considerably.
The foot issues at the opening through the larger end ; and the
respiratory siphons, which are very long and extensible, pass out
by the other. Some Pholades form their cells in mud or clay ;
but many in rocks, and others in wood. It is evident that a
fleshy foot can be of little use in the excavation of a stony mass ;
and the organ here appears to serve a different purpose. The
boring operation seems to be performed (in many cases at least)
by the shell itself, which has a rasp-like surface, and which is
renewed by vital action as fast as it is worn down. In order to
make the valves rotate backwards and forwards (like a surgeon's
trephine), the foot is affixed to the bottom or end of the hole,
and becomes a fixed point from which the muscles can act.
They seem to commence this operation almost as soon as they
quit the egg ; the young beginning to bore the rock on which
they are cast, and enlarging their cell, which they never volun-
tarily quit, in accordance with their own increase in size. They
possess a very curious means of freeing the tube from the rasp-
ings of the rock produced by their penetration. The siphon

*FF2

416 INCLUSA; — PHOLAS, TEREDO.

being distended with water, the animal suddenly contracts it ;
and thus a jet is produced through the anterior orifice, which
washes out the part of the cavity occupied by the animal ; but,
as many of the particles expelled by it are deposited before they
reach the mouth of the hole, the passage is found to be lined
nearer its entrance with a soft mud.

960. The Pholades evidently prefer such beds, as are com-
posed of indurated clay, or soft lime-stones, to harder lime-stones ;
though they are occasionally found in the latter. Hence it might
be supposed that their action is always of the mechanical nature
just described ; but though it is certainly of this kind in many
instances (as is proved by the cylindrical form of the perforation,
as also by the rasp-marks on its interior), Pholades are some-
times found so imbedded, that they could not have turned in
their perforation. — In some countries they are much prized as
food; especially along the Mediterranean coast. They possess
one remarkable property, which is not, however, confined to
them, but which is manifested in a degree by other Mollusca ;
this is their phosphorescence. It is said to be so strong, that
persons who eat them raw, and in an obscure or dark place,
seem to be swallowing phosphorus. The Pholades are pretty
generally diffused over the globe. They usually multiply
around any spot which they have begun to frequent ; the young
produced from .the eggs probably boring near their parents.
Pholades are not very abundant in a fossil state ; but they are
occasionally found in tertiary strata, imbedded in the cavities
which they have themselves formed.

961, The Teredo is a genus which presents many points of
interest to the Naturalist, as well as to those who are practically
affected by its destructive operations. This animal bears a
general resemblance to the Pholas ; and it carries on its anterior
part a pair of valves, which it uses in the same manner, as
perforators of the wood into which it bores. When quite
young, it establishes its habitation in submerged timber, such as
ships' bottoms, piles, &c., which it perforates in every direction.
With its increasing, bulk, it enlarges its hole, advancing into the
wood ; but it does not draw the tubes of the mantle after it, for
they remain where they were, and deposit shelly matter, which

INCLUSA ; — TEREDO OR WOOD-WORM. 417

lines the cavity ; and thus a complete additional tube of shell is
formed, of a length proportional to the age of the animal.* At
the entrance of the tube, or the termination of the siphons, there
is a pair of pallettes, or small valves of shelly structure ; by the
motion of which the current of water is maintained, that is
necessary to bring a supply of food and oxygen to the animal thus
included. The highest point at which they commence to bore,
is always some feet below the lowest water-mark ; and they
usually work downwards. The orifice, being made when the
animal was young, is very small, and often difficult to perceive.
The beginning of the tube is usually horizontal or oblique ; and
afterwards it curves into a nearly vertical direction. The nature
of the wood has a great influence on the regularity and direction
of the canal which is hollowed in its interior ; but this is still
more affected by the neighbourhood of other Teredines, to avoid
whose tubes the animal will make sudden curves. It is difficult
to comprehend how it can become conscious of their proximity.
There can be no doubt that, in this instance, the excavation is
effected by the valves ; since it is always cylindrical, with very
smooth walls ; and the shell is adapted, both by its sides and
edges, for rasping and boring.

962. These animals are among the most formidable destroyers
of the works of Man. When it is considered that their instinct
prompts them to attack all the timber which he has, for various
objects, placed beneath the surface of the sea, it is seen that the
field of their operation is immense. The piles of bridges, piers,
and harbours, as well as shipping, are liable to their devastations ;
and Holland has been more than once threatened with an inun-
dation, by the destruction of the dykes which they have effected.
Many vessels have sprung leaks and foundered, owing to
the unsuspected demolition of the planking of their bottoms by
the same means. The most effectual protection against their
attacks, is a metallic sheathing ; but it is said that piles may be
secured by the previous charring of their surface to the depth of
a few lines. Different species of Teredo appear to exist in all

* The accessory pieces of the shell of the Pholas, may probably be considered
as a rudiment of the same structure ; they vary considerably in number and
arrangement ; and sometimes appear to form the commencement of a regular tube.

418 INCLUSA; — GASTROCHJENA, CLAVAGELLA, ASPERGILLUM.

parts of the world ; and on the coasts of the Atlantic they are
used as food, their flesh being reputed more delicate than that
of Oysters. According to Seba, who made his observations in
Holland, certain species of Nereis (§ 839) are mortal enemies to
the Teredines, penetrating into their tubes and devouring them.
As a British animal, the Teredo is now nearly or quite extinct ;
the precautions taken against it having prevented its multiplica-
tion ; and new importations being checked by the general use of
copper sheathing.

963. In the Gastrochcena, the valves bear but a still smaller
proportion to the shelly tube, which not only covers the part of
the excavation posterior to the animal, but lines the whole inte-
rior of the hollow, so as to include the valves. This tube js often
found in the perforations previously made by some other boring
Mollusk, and also in natural hollows in rocks, corals, &c. ; but
the animal has evidently the power of exca-
vating for itself, if it does not meet with a
hole adapted to it. — The Clavagella is an
animal of analogous structure ; but one of its
valves is incorporated, as it were, with the
shelly tube, the other remaining free. The
latter appears to perform by its movements
the same kind of function as the pallettes of
the Teredo. — The Aspergillum departs more
widely from the general type, than any of the
preceding ; so that, if viewed out of con-
nexion with them, its true place in the scale
would be doubtful. The shell, which derives
its name from its resemblance to the spout of
a watering-pot, has the form of an elongated
cone, terminating at the large end in a disk,
which is pierced with a number of tubular
orifices ; and the tubes of the outer row being
the longest, they form a sort of corolla
(a, Fig. 597) around the disk. At a little
distance above this, two small valves (#), in-
corporated in the substance of the tube, are easily distinguished.
The smaller end is open, and there is likewise a little fissure

FIG. 598->— ASPER-
GILLUM.

ASPERGILLUM. GEOLOGICAL DISTRIBUTION. 419

nearer the larger end ; by these apertures the water is freely
admitted to the interior of the shell. The animals of this genus
are borers. Some of them live in the sand, plunged down per-
pendicularly for about three-fourths of their length, and sup-
ported by the little tubular prolongations, which are supposed
to be filled by fleshy filaments of the mantle. Some, again,
burrow in stone, others in wood, and others in thick shells.

964. In regard to the Geological distribution of the Lamelli-
branchiata, it will be sufficient (as in the case of the Gasteropoda)
to say, that they make their appearance in the earliest fossili-
ferous strata ; and that, although there is always a difference
between the fossil and the existing species, until we compare
those of the comparatively recent geological periods, the same
genera are found to have existed in the ocean, from the most
ancient times to the present. It is interesting to remark, how-
ever, that the proportion which they bore to the Bivalves of the
succeeding class, was very small in the oldest fossiliferous rocks,
but has since been gradually reversed.

CHAPTER XIX.

OF THE CLASS OF PALLIOBRANCHIATA.

965. THIS Class, although at present very limited, — both as to
the number of existing species it includes, and the small number
of these which seem to be distributed through the ocean, — was
formerly of great importance ; since it included a very large
proportion of the Bivalve Mollusks of the older rocks. Although
an ordinary observer would not detect anything in the structure
of the shell, to justify the separation of this class as distinct from
the preceding, yet the necessity for this division becomes evident,
when the organisation of the animal is examined. The name of
the Class is derived from the peculiar conformation of the respira-
tory apparatus, which here consists of the mantle itself ; this is
traversed by blood-vessels, which ramify minutely over its surface ;
and is furnished, especially along its edge, with vibratile cilia,
which produce a continual current in the surrounding water, and
thus renew it for the aeration of the circulating fluid. In addi-
tion to this singularity of structure, the organs for procuring
food offer remarkable peculiarities. They consist of two long
spiral arms, one on each side of the mouth ; the existence of
which has given rise to the name BRACHIOPODA or Arm-footed,
by which the class is frequently designated. In many species,
these are capable of not only being unrolled, but extended beyond
the shell to a great distance in quest of food. They are usually
furnished with numerous vibratory filaments, for the more certain
capture of the prey, and probably also for assisting in the main-
tenance of the respiratory current — an extraordinary provision,
which is rendered necessary by the great depth at which these
animals live, and the consequent enormous pressure of the
water around. All the existing genera of this class are attached,
in some way or other, to solid bodies. In Terebratula and

BRACHIOPODA ; TEREBRATULA.

421

Lingula, this attachment is effected by means of a fleshy tubular
footstalk ; and this footstalk or peduncle passes out, in the
Terebratula and its allies, through an aperture or notch in the
beak of the shell (Fig. 600). In Orbicula, on the contrary, the

FIG. 599. — TEREBRATULA
PSITTACEA.

FIG. 600.— CONVEX VALVE OF
TEREBRATULA.

peduncle is wanting : and the lower valve of the shell itself becomes
the medium by which the attachment of the animal to the rock
is accomplished. There is thus the same kind of difference
between these genera, as there is between the pedunculated and
sessile Cirrhopods, — a Class, of which we are also strongly
reminded by the structure of the arms of the Brachiopoda.

966. The greater part of the existing Mollusks included in
this Class, belong to the genus Terebratula; of which about forty
species are at present known to exist, but of which several
hundred fossil species have been enumerated. These present
themselves in the very oldest rocks; and may be found, in
greater or less abundance, in almost all marine deposits, down to
the present time. The two valves in Terebratula are unequal,
one being nearly flat and the other convex ; it is in the latter,
that the opening is found for the transmission of the pedicle ;
but the former is still more remarkable for the curious internal
apparatus which is connected with it. This consists of a sort of
slender framework of shelly substance ; which projects consider-
ably into the cavity of the shell, and to which the arms just now
mentioned are attached. This framework is often found in
fossil shells, in a beautiful state of preservation. The arms of
the ordinary Terebratulae do not appear to be extensible beyond
the shell; but in the Terebratula psittacea (which is probably to

422 BRACHIOPODA ; — TEREBRATULA ; ORBICULA ; CRANIA.

be ranged under another genus) they are enormously developed ;
and being quite free except at their origin, they may be extended
far beyond the shell. When drawn in, they are disposed in six
or seven spiral turns. The mechanism by which these arms are
unfolded is very curious. The stem of each is tubular, and
contains a fluid ; which, being acted upon by a multitude of
muscles forming the walls of the canal, is forced onwards up the
tube, and thus causes the arm to project. We shall hereafter
meet with a very similar contrivance, in the numerous tubular
feet of the Echinodermata (§1007). The Terebratulse are
found in all seas, from the polar to the equinoctial, at a depth
of from ten to ninety fathoms, or even more.

967. The Orbicula may be noticed as the type of the sessile
group. Its two valves differ considerably in form and size ;
one being conical and rounded, like the shell of the Limpet
(with which it was formerly confounded), whilst the other is flat,
with a fissure in the centre for the passage of a ligament, by
means of which it is fixed to the rocks. The Mollusk has
ciliated arms, rolled up spirally when withdrawn. The recent
species of this genus are found attached to stones, shells, and
sunken wrecks, at various depths, down to seventeen fathoms.
They sometimes are found in vast numbers in particular spots. —
The Crania, another sessile genus, has been dredged up in 255
fathoms* water. These facts are of much interest, when taken in
connection with the circumstances, under which the fossil species
are found. It may be inferred, from the diminished numbers of
this class, that the ocean is at present less fit for their habitation
than it formerly was ; and perhaps a diminution of depth is one
of the circumstances which has given rise to this change.

CHAPTER XX.

OF THE CLASS OF TUNICATA.

968. ALTHOUGH the Mollusca are in general possessed of a
calcareous shell, sometimes enveloping the whole body, and
sometimes inclosing but a small portion of it, no appearance of
such a structure is presented among the animals of the lowest
group, — the Class TUNICATA. Feeble as are the powers of
sensation and locomotion in a great proportion of the Molluscous
tribes, they would seem almost extinct among the members of
this group. The greater number of them pass their whole lives
in one situation, agglutinated by their external tunic to submarine
rocks, or attached by a footstalk prolonged from it ; many species
associate together, like the Polypifera, to form a compound
structure, in which several individuals are united more or less
closely ; and those which have no fixed attachment enjoy little
independent locomotive power, but are driven about at the
mercy of the waves. No beings possessed of a complex internal
structure, a distinct stomach and alimentary tube, a pulsating
heart and ramifying vascular apparatus, with branchial append-
ages for aerating the blood, and highly-developed secretory and
reproductive organs, can be imagined to spend the period of
their existence in a mode more completely vegetative than these.

969. The animals of this Class are entirely enveloped in a
firm elastic tunic (whence their name), which is always provided
with two orifices. The general form of the body, as well as the
colour and consistence of this tunic, vary considerably in the
different species. Sometimes it is globular or egg-shaped ; some-
times narrow and prolonged. The tunic is often of leathery or
even cartilaginous firmness, and of a dark colour ; whilst we
occasionally find it soft, membranous, and transparent, and of a
light greenish tint, so that the clusters of animals look like

424 GENERAL STRUCTURE OF TCNICATA.

bunches of grapes. In the larger species, additional firmness is
often given to this tunic, by the agglutination of particles of sand,
bits of gravel or shell, or other substances with which it comes
in contact, to its exterior ; and a complete envelope is sometimes
formed in this manner, which might be compared to the shells
of the higher Mollusca, but that it is altogether derived from
external sources, — the glutinous matter which unites the par-
ticles together, being the only part furnished by the animal itself.

970. Within the external tunic is a muscular coat, repre-
senting the mantle^ consisting of fibres crossing one another in
various directions, by which compression may be exercised on
the contents of the cavity it surrounds. The openings which
have been mentioned as existing in the outer coat, penetrate this
one also ; and they are guarded by muscular fibres, arranged in
a circular manner around them ; by the action of which rings,
they may be entirely closed.

971. The cavity of the mantle is principally occupied by a
large bag, composed of a delicate membrane, over which the
blood-vessels are minutely distributed ; this evidently replaces
the gills of higher Mollusca, and it is accordingly termed the
branchial sac. It is closely adherent to the mantle around one
of the orifices, which leads directly into it, and which is there-
fore called the branchial orifice (a, Fig. 601). It also receives
support from it elsewhere ; but it by no means occupies the
whole of the cavity. There is a considerable space at the
bottom of it, which is occupied by the digestive and reproductive
viscera ; and there is also a space in the neighbourhood of the
second orifice (b), which serves for the discharge of several dif-
ferent egesta* and may thence be termed the funnel or vent. —
The branchial sac is probably to be regarded as formed by a
dilatation of the pharynx, or funnel-shaped commencement of
the oesophagus; and the branchial orifice as the real mouth.
We shall hereafter see, that a very near approach to this struc-
ture is presented by certain Polypes (Fig. 624).

972. The entrance to the digestive tube, lies at the bottom
of the branchial sac ; and the alimentary particles are derived

* Fluid or solid matter to be carried out of the system.

GENERAL STRUCTURE OF TUNICATA. 425

from the water introduced into it for the purpose of respiration.
The oesophagus is short, and leads to a capacious stomach,
surrounded by clusters of biliary follicles (ANIM. PHYS. § 356),
the rudimentary form of a liver. The intestine generally makes
one or two turns in the space between the branchial sac and the
mantle; and terminates in the neighbourhood of the funnel.
The ovaria are usually large, and lie amongst the viscera ; their
excretory duct also terminates in the same situation. The fun-
nel thus serves to carry out of the cavity of the mantle, not only
the fluid stream which has passed over the walls of the branchial
sac, and has served its purpose in aerating the blood, but also
the solid particles which are rejected from the alimentary canal,
and the ova which are discharged when mature from the ovaria.

973. Between the two orifices there is a nervous ganglion,
which sends filaments to each of them, and distributes its prin-
cipal branches over the general surface of the
mantle. No organs of special sensation,
however, are perceptible ; and the only indi-
cation of common sensibility shown by these
animals, is the contraction of the mantle
when they are touched, by which the water
contained in the branchial sac is spirted out,
sometimes to a considerable distance. Some-
times a number of them are so closely im-
pacted together on the rocks, that the
impression given to one causes it suddenly to

FIG. 601—NERvous SYS- retract, which acts also on the one next to

TEM OP ASCIDIA ; a, .

branchial orifice or it, and so on throughout several of them ;
ganglion ;V^Utie and each in contracting throws out a quan-
(the external coat be- tity of water. After the contracting force

ing removed). . * ,

has ceased to operate, the usual form is
restored by the elasticity of the tunic.

974. No regular movements of this kind, however, are com-
monly employed, either for the respiratory process, or for the
prehension of food. A continuous and equable current of water
enters the branchial orifice, and is propelled by the funnel, with-
out any other physical agency that can be perceived, than the

426 GENERAL CHARACTERS OP TUNIC AT A.

vibration of the cilia which cover the aerating surface. It is from
this constant action, that the unattached species appear to derive
the slight amount of independent locomotive power which they
possess.* In these, the two orifices are usually at the opposite
extremities of the body ; and the continual suction of water into
one end, and the discharge of it from the other, will of course
tend to propel the body forwards. This movement is most
evident when several are associated together, all having their
branchial orifices and funnels in the same direction. In the
Pyrosoma (§ 983), a number adhere together so as to form a
tube closed at one end, into the interior of which the funnels of
all the individuals open; whilst the branchial orifices project
from the outside as so many little papillae. The water drawn in
through these is discharged into the central canal ; from the end
of which a constant stream issues, with sufficient power to cause
the movement of the mass in the opposite direction, — a move-
ment which its brilliant phosphorescence allows to be watched
from some distance.

975. Although the Tunicata have been variously placed by
different Naturalists, the additions which have been recently made
to our knowledge of their organisation leave but little doubt, that
their true place is on the border of the Sub-Kingdom Mollusca,
connecting it with the Radiata. For, whilst its higher species
present many points of resemblance to the lower forms of the
Conchifera, its inferior tribes approach equally closely to the
Polypifera — not only through the structure of the individuals,
but in the examples they present of the union of a number of
independent beings to form a compound animal. So prevalent,
indeed, is the tendency to this association, that it may almost be
regarded as the peculiar character of the group ; and, when thus
viewed, it presents a very good illustration of the general principle
formerly laid down (§ 42, 43). We may regard the Tunicata,
then, as an aberrant group of Mollusca ; engrafting, as it were,
upon the general character of that Sub-Kingdom, the peculiar
tendency of the group of Radiata towards which it verges. The
tendency to aggregation exhibits itself among the Tunicata in
various ways. Sometimes we find a number of individuals

SUBDIVISIONS OF TUNlCATA. ASCIDLE. 427

simply adhering externally, but forming a mass of a certain
regular aspect. In other cases, we observe several individuals
included within a common envelope, — their own external coats
being absent. And in some instances, there is a continuous cir-
culation of blood among .several individuals, through vessels
passing along a stem, with which they are all connected by short
peduncles or foot-stalks.

976. The Tunicata may be better subdivided according to
the anatomical characters, and the mode of existence, of the
respective species, than by arranging them according to their
solitary or united condition. On this principle two Orders will
be formed ; one including the isolated and aggregated Ascidice ;
and the other, the isolated and aggregated Salpce. The promi-
nent differences in these two Orders are these. In the Asddice
the two orifices approach one another more or less closely (Figs.
601, 602). The body is either fixed immediately to some solid
mass, or attached to it by a peduncle. And the branchial ap-
paratus consists of a simple sac or bag, occupying the greater
part of the cavity of the mantle, and having the entrance to the
oesophagus at its lower part. In the Salpce (Fig. 603), on the
other hand, the two orifices are placed at the opposite extremi-
ties of the body, which is generally more elongated than in the
Ascidiae. They seldom attach themselves to any fixed basis,
but rather to floating bodies ; and many of them seek no support
from other masses, but trust themselves to the waters of the
ocean, in which they seem to have some power of spontaneous
motion. Instead of a capacious but simple branchial sac, we
find a long narrow tube, in which a riband-like fold of vascular
membrane stretches from end to end, and serves as the special
apparatus for the aeration of the blood.

977. It is among the solitary Ascidice , that the highest
organisation presents itself, which occurs in this family. The
two orifices are both evident on the upper part of the body ; but
the branchial aperture is the most prominent. "Within this may
be observed a fringe of tentacula, which are sometimes of con-
siderable length and minutely divided, sometimes short and
simple. Their office appears to be, to guard the entrance to the

428 TUNICATA. - ASCIDLE.

respiratory sac ; and it would seem probable that substances
unfit to enter it are kept out by the closure of the muscular
ring, excited through the nervous apparatus by irritation of the
tentacula (ANIM. PHYSIOL. § 436) ; beyond these, no organs of
sense can be detected. The solitary Ascidise are found in all
climates ; they generally frequent the shallow waters of the
shore, so as to be occasionally left uncovered by the tide. In
some localities they are so abundant, as to afford an important
source of nutriment to Fishes ; and some species are employed
as food even by Man. The power of ejecting the contents of the
branchial sac is their principal means of defence. Some of the
larger species are able to shoot the fluid to a height of three
feet ; and thus the person who places his hand upon one of them,
is very likely to receive a deluge of water in his face. We are
not justified, however, in attributing this action (as some have
done) to any intelligence on the part of the animal. It is the
only movement which these simple beings can perform ; and is
evidently a reflex action, which any bodily irritation, whether
internal or external, will excite. Some of the Ascidige have
the power of changing their hue; the Cynthia Momus, for
instance, is sometimes white, sometimes orange, and sometimes
of flesh colour.

978. The Ascidice are
not all, however, solitary
in their habits. The ac-
companying figure repre-
sents one of the compound
forms ; in which different
individuals are united toge-
ther by a common stem, in
the same manner as the

Pnlvnp« nf flip Rprtiilirin FlG> 602.— POHOPHORA, a compound Asci-

oiypes tne oertuiana dian. 6j branchial orifice, or mouth;

615). Each has its a,anal orifice; e, stomach ; i, intestinal

, canal ; t, common stem.

own heart, respiratory ap-

paratus, and digestive system; but each is fixed on a foot-
stalk that branches from a common creeping stem, through which
a circulation takes place that connects them all. The integu-

COMPOUND ASCIDIANS. 429

ment is so transparent, that the whole interior and its living
actions may be observed without difficulty. — As in other Ascidiae,
the branchial sac occupies a large part of the cavity of the mantle ;
at the sides and point, however, a vacant space exists between
these two membranes, which terminates in the funnel. The sac
is perforated with four rows of narrow oval openings, the edges
of which are thickened, and fringed with closely-set cilia. —
Through these openings, a part of the water which flows into
the sac by the branchial orifice, escapes into the space between
the sac and the mantle, and is thus discharged immediately by
the funnel. Whatever little substances, alive or inanimate, the
current of water brings, flow into the sac, unless stopped by the
tentacula at its entrance, which do not appear fastidious. The
particles which are admitted usually lodge somewhere on the
sides of the sac, and then travel horizontally (by some unseen
agency), until they arrive at the part of it, down which the cur-
rent proceeds into the entrance to the stomach, which is situated
at the bottom of the sac. Minute animals are often swallowed
alive, and have been observed darting about in the cavity, with-
out any apparent injury to themselves, or to the animal which
incloses them, for some days. In general, however, particles
which are unsuited for being received into the stomach, are
ejected by the sudden contraction of the mantle, — the funnel
being at the same time closed, so that they are forced out by a
powerful current through the branchial orifice.

979. It is in the Circulating apparatus, that the chief pecu-
liarities of these compound Ascidiae present themselves. The
creeping tube which unites the individuals of a group, contains
two distinct canals, which send off branches into each peduncle.
One of these branches terminates in the heart, which is nothing
more than a contractile dilatation of the principal trunk. This
trunk subdivides into vessels, of which some ramify over the
branchial sac, branching off at each of the passages between the
oval apertures ; whilst others are first distributed to the stomach
and intestines, and the soft surface of the mantle. All these
reunite, and form a trunk which enters the peduncle, and con-
stitutes the returning branch. The circulation through these

430 CIRCULATION IN COMPOUND ASCIDIANS.

tubes, however, does not take place constantly in the same
direction. At some periods the heart may be observed to con-
tract from behind forwards, so as to propel the blood in the
direction just mentioned. After a short time the pulsations
become fainter for a few beats, and the flow slower ; and sud-
denly, but with a slight pause, the whole current in all its
windings is reversed. The heart gives the opposite impulse ;
the channel in the peduncle that before poured in the blood now
carries it back ; and the other, the contrary. These changes
succeed each other alternately, the average time being the same
in both directions; but the period of each varying as much as from
thirty seconds to two minutes. By this circulation, all the
individuals in one group seem to be connected. As in the com-
pound Polypifera, increase takes place by sprouts or buds (of
which a small one is seen at the right hand of Fig. 602) ; and
the two streams of the stem run through the bud, before its organs
are developed. The circulation in each individual appears, how-
ever, to be independent of the rest ; for it continues when the
current through the stalk is interrupted. The stream which
returns from the branchial sac and the viscera, is then poured
into the posterior part of the heart, instead of entering the
peduncle. The circulating system then resembles that of the
isolated Ascidise ; and it is remarkable that the regular alterna-
tion of the flow may be observed in these also, in every instance
in which the integument is thin enough to allow the current of
blood to be distinguished.

980. A closer apparent union between the individuals may be
observed in the aggregated Ascidice ; though it may be doubted
whether the real connection is as intimate as in the species just
described. In these we find a large and variable number of
individuals, arranged with more or less regularity within a com-
mon envelope. Like the true Ascidiaa, they are all fixed ; some-
times forming a slimy crust upon Algae, or other submarine
bodies ; sometimes projecting in conical or globular masses ; and
not unfrequently spreading over the larger isolated species of
Tunicata. They agree with them, also, in the relative positions
of the branchial orifice and the funnel, and in the structure of the

AGGREGATED ASCIDIANS. SALPJE.

431

respiratory chamber. The individuals are occasionally connected
by a gelatinous flesh, like that which exists in many of the
compound Polypes ; and there is even sometimes found a calca-
reous deposition in this connecting substance, which would still
more closely establish their affinity with that group. It has been
recently shown, also, that all the individuals in these compound
masses originate by germination, or budding, from a single
one. — Both in the solitary and compound Ascidians, the young
animal, when it first issues from the egg, has active powers of
locomotion, being provided with a large tadpole-like tail, by the
stroke of which it is propelled through the water. Thus a pro-
vision is made for the general diffusion of these animals, which
would be otherwise crowded in particular spots.

981. The Salpce are animals of greater delicacy of organisa-
tion than the greater part of the Ascidians. They are usually
so transparent, that the interior structure may be examined
through their tunic with little difficulty. They consequently
seldom possess any decided colour, except when viewed in a
bright sun-light ; and then they present splendid iridescent hues.

FIG. 603.— BIPHORA, ONK OF THE SAL?.*: ; a, mouth ; p, posterior or anal orifice ; /, liver,
inclosing other viscera ; c, heart ; fir, branchial sac ; m, muscular bands ; n, nervous
ganglion.

They have all one dark spot, however ; generally of a brownish-
yellow colour. This, which has been termed the nucleus, is
occasioned by the opacity of the liver, and its coloured secretion.
The branchial orifice possesses no tentacula; but these are

GO 2

432 SALPJS. THEIR AGGREGATION AND LUMINOSITY.

replaced by a kind of valve, which permits the entrance of water
and prevents its return. By the constant action of the respi-
ratory apparatus, a considerable degree of locomotive power is
obtained for these animals, without any special apparatus for the
purpose. There do not appear, however, to be any sensory organs
by which the animals can be directed towards their food ; and
we can scarcely suppose, therefore, that their movements are
governed by an intelligent will.

982. The Salpee are most abundant in tropical climates.
Messrs. Quoy and Gaimard relate having seen on one occasion, not
far from the Cape of Good Hope, long zones of a reddish-brown
colour traversing the surface of the ocean, as far as the eye could
reach. These were found, on examination, to consist of minute
Salpae, each not more than two or three lines in length, aggre-
gated together in bands. The colour was given by their nuclei,
which did not exceed millet-seeds in size. These bands are
driven through the ocean by the action of the waves ; and they
seem to have a remarkable power of preserving their continuity,
even when a considerable force (for animals of such delicacy) is
applied to separate them. In fact, the connection is so strong in
some species, that it is easier to tear the animals themselves than
to part one from another ; although their union is accomplished
only by the adhesion of their surfaces, or of little suckers, adapted
to meet each other, and not by any structural connection. In
other species, the adhesion is less powerful ; so that when a mass
is placed in a vessel of water, and the sides of it are smartly
struck, the individuals fall asunder.

983. Nearly all of the SalpcR are phosphorescent, or self-
luminous ; and the small aggregate species are usually more so
than the large isolated ones. The bands which they form are,
consequently, among the most brilliant of those luminous tribes,
which occasionally give such a sparkling lustre to the waters of
the ocean. The Salpse, when thus chained together, produce the
effect of long ribands of fire, sometimes drawn straight in the
direction of the currents, sometimes twisted and almost doubled
by the action of the waves. One of the most brilliant combina-
tions of Salpse, however, is that which forms the Pyrosoma. This

AGGREGATED SALPJE. PYROSOMA. 433

is a hollow cylinder, from five or six to fourteen inches in length,
and composed entirely of minute animals of this form. These
are aggregated together in the following manner. A number
unite, like the radii of a star, so as to form a circle with a central
space, into which the vents of all the individuals open, — their
mouths being at the circumference. Several of these circular
clusters are piled one on another, the central aperture of all of
them corresponding so as to form a tube ; and through one end
of this tube (the other being closed) a constant current of water
is forced out by the united ciliary action of all the individuals, —
thus causing the mass to move through the ocean in an opposite
direction. The Pyrosoma is never met with but in the open
sea; and then it often occurs in troops composed of a great
number of these masses. " Nothing can be more brilliant,
sparkling, and lively, than the phosphoric light which these
animals emit. They often form long trains of fire, from the
manner in which the masses are disposed in cordons. But a
more singular phenomenon attached to this phosphorescence is,
that the colours vary instantaneously, passing rapidly from the
most lively red to the principal tints of the solar spectrum, to
the crimson of the morning, to orange, to greenish, to azure blue,
and finally to opaline yellow, when the mass is, to all appear-
ance, in a state of absolute repose."

984. None of the Salpae at present known are attached to
each other by continuous blood-vessels, like those of the com-
pound Ascidias (§ 979). It is remarkable, however, that the
same alternation in the direction of the circulating current takes
place in them, as that formerly described. In fact it may be
regarded as characteristic of the Tunicata ; since it has been
observed in every species, in which the current of blood has been
traced.

985. One of the most curious circumstances in the economy
of the compound Salpoe, is (if there be no error in the account
of it) that which has been described by Chamisso in regard to
their mode of multiplication. He states that most of the species
present themselves under a double form ; — a race of isolated
animals ; — and another of aggregate masses composed of nume-

434 REPRODUCTION OF SALP.E.

rous individuals. These last are so unlike the individuals of the
separate race, that they might be regarded as distinct species.
Nevertheless it is found that the associated individuals produce
eggs, from which the solitary Salpus are developed ; and that
these in their turn produce chains of eggs, from which the riband-
like groups originate ; — these last, again, giving birth to the
solitary race ; and so on alternately. Thus, a Salpa which
differs equally from its parent and its own progeny, resembles its
grand-parent, its grand -children, and its own brethren.

CHAPTER XXI.
GENERAL CHARACTERS OF RADIATA.

986. THE Radiated subdivision of the Animal Kingdom may
be regarded as, on the whole, a very natural group. It includes
all those animals, in which there is a regular disposition of similar
parts around a common centre, as in the Star-fish (Fig. 606), or
Sea- Anemone (Fig. 617)- In the most characteristic forms of
this group, these parts are but repetitions of each other ; and
one or more of them may be removed without injury to the
functions of the rest. It is by no means uncommon to meet
with Star-fish, which, by some accident, have been deprived of
a ray, and yet appear to have suffered but little inconvenience
from the loss. In most of the Radiata, the parts so lost are
replaced by a new growth ; and not unfrequently it would appear
that these parts may themselves reproduce the whole structure.
Here, then, is an important character, which evidently displays
an affinity with the Vegetable Kingdom. In Plants we observe
that the whole structure is made up of an assemblage of similar
parts — the leaf-buds — which may almost be regarded as distinct
individuals ; for though, whilst associated, they contribute to
form a structure which is common to all, and share alike in per-
forming the functions of that structure, yet they may be separated
from it and from each other without the loss of their vitality, if
placed in circumstances favourable to their growth under this
new condition. We shall presently observe that, in the POLY-
PIFERA, compound structures are produced by the association of
individuals, which have very nearly the same relation to each
other, and to the whole mass, as exists amongst the buds of a
tree, and between these and the woody trunk and branches.

987. But it is not only in this repetition of similar parts, that
we may trace an affinity between the RADIATA and Plants. The

436 GENERAL CHARACTERS OF RADIATA.

resemblance is manifested, also, in the regular disposition of these
parts around a common centre, which may be termed circular
symmetry. The tendency to this kind of symmetry exists through-
out the Vegetable Kingdom; being most obvious in the arrangement
of the parts of the flower (VEGET. PHYSIOL. § 463). That the
Radiata should preserve the mode of development, which is so
remarkably characteristic of the Vegetable Kingdom, is not sur-
prising, when we reflect upon the very small proportion which
their animal functions bear to those of organic life. None of
them possess any high degree of sensibility ; and whilst many
of them are fixed like plants during a part or the whole of their
existence, none possess any very active powers of locomotion.

988. Although the radiated form may be observed in certain
members of every class which has an undoubted claim to admis-
sion into this group, it by no means follows that it should exist
in each individual of those classes. Like every other natural
character, it is subject to modifications. The species which pre-
sent it in the most remarkable degree may be regarded as the
typical forms of their respective groups ; whilst others, in which
it is less evident or altogether absent, serve as connecting links
with those divisions of the Animal Kingdom which are formed
upon a different plan. Thus, among the POLYPTFERA, the Sea-
Anemone^ and many of the associated animals resembling it,
have a most regular arrangement of similar parts, both externally
and internally, around a common centre. On the other hand,
there is an important group of Polypes, which, with the same
circular arrangement of the tentacula or arms round the mouth,
presents, in its more complex digestive apparatus, an entire
departure from that regularity; and through this group we are led,
by almost imperceptible gradations, to the MOLLUSC A. — In like
manner we have, in the Star-fish^ a perfectly symmetrical dispo-
sition of all the organs of the body. The stomach, situated in
the centre, sends a prolongation into every arm ; the absorbent
vessels which arise from its walls are united in a central ring,
and are distributed on a uniform plan in each ray ; the nervous
system has a similar central ring, and sends equal branches in
every direction ; the locomotive organs are the same in each

GENERAL CHARACTERS OF RADIATA. 437

division of the body ; and at the extremity of each ray (in the
species possessed of visual organs) an eye of equal size exists.
But in the Echinus (Fig. 604), with an equally symmetrical
exterior, we have a somewhat irregular distribution of the con-
tained digestive viscera. And in the Holothuria (Fig. 608) we
observe that the general form of the body is approaching that of
an Articulated animal ; although the radiated disposition of parts
is still evident around the mouth. — Not ^infrequently it happens
that the Radiated form is so completely departed from in parti-
cular instances, that we should hesitate in referring the animals
to this group, if we were not able to trace the links which con-
nect them with forms unequivocally belonging to it.

989. In these remarkable aberrant forms we perceive indi-
cations of a presiding Unity of Design, even more remarkable
than those furnished by the beings whose regularity of structure
is more apparent. It would seem but a comparatively simple
matter to devise certain types of conformation, and to sketch out
a number of forms presenting slight deviations from these types.
But to combine forms essentially dissimilar, and to modify the
organs respectively peculiar to them, so that their functions may
go on with that perfect harmony which is essential to the con-
tinuance of their existence, — appears (to our human apprehension
at least) a more striking display of Creative power ; and the
regularity of the original design becomes still more wonderful,
when it is traced by the eye of the Philosophic Naturalist,
through the apparent irregularity of its results. In this respect
we may compare the Organised Creation with the Solar System ;
and we may fearlessly ask, whether the mind capable of enjoying
such contemplations, does not derive a far higher satisfaction from
considering the principle of mutual attraction as the cause, not
only of the regular movements of the planets round the sun, but
of those perturbations which are balanced against each other
with so astonishing a precision — than it would receive from the
mere view of any unconnected series of motions, perfectly regu-
lar in themselves, and destitute of influence on each other.

990. There is one very aberrant group, however, which, if
received into the Animal Kingdom at all, must be associated with
the Radiata, unless we create a new subdivision expressly for it.

438 GENERAL CHARACTERS OF RADIATA.

This is the Sponge tribe, which has been united by Blainville
with some others into a group, which he terms Amorphozoa^ or
form-less animals. It is through these curious beings, that the
connection between the Animal and Vegetable Kingdoms is most
completely established. These Kingdoms approach each other,
not through the most perfect forms of either, but by the most
simply- organised members of each. Among the lowest Plants,
the greatest indefiniteness of form prevails ; and we are prepared
to expect, therefore, a similar indefiniteness in the lowest groups
of Animals. This obviously results, in both cases, from the low
degree in which distinct or special organs are developed. In
proportion as each minute division of the structure performs all
the functions essential to its life, it will be independent of the
rest ; and the whole structure will thus approach the condition
of an inorganic mass, in which each particle exists by and for
itself, and of which the form is entirely determined by circum-
stances external to it. The Sponges have a much closer connec-
tion with the group of Radiata, than they have with any other
division of the Animal Kingdom ; for one of the divisions of the
Polypifera may almost be regarded as consisting of Sponges
advanced to a higher grade of organisation. We may, then,
place them on the border of this group ; in sueh a position as to
stand at that extreme edge, as it were, of the whole Animal
Kingdom, which approximates the Vegetable Creation.

991. There are certain other forms of this group which, on a
cursory view, would seem as little characterised by the Radiated
structure as the Sponges themselves. When we look at a mass
of branching Coral of any description (Fig. 623), we at once
perceive its resemblance in form to the productions of the Vege-
table Kingdom, and we are at a loss to detect any regular arrange-
ment of its parts, — still less that circular symmetry for which
we are seeking. But we must remember that this structure is
merely the frame-work, which connects a number of individuals
capable of existing separately ; and it is in these, that we must
seek for the radiated conformation. This we find very distinct
in the Polypes themselves ; and, in one group, it is marked in
the stony cells which they form (Fig. 619).

992. If we ascend from the lowest to the highest RADIATA,

GENERAL CHARACTERS OP RADIATA. 439

we may observe a progressive removal from the Plant-like con-
dition, in which the simplest of these beings exist. This
elevation is manifested in two ways ; — in the gradual complica-
tion of the nutritive system; and in the evolution of those
powers of sensation and independent motion, which differ from
any faculties exhibited by vegetables. We shall notice that,
whilst in Sponges the tissue is nourished simply by the intro-
duction of the surrounding fluid into the channels of its substance
— a mode differing but little from the absorption by the roots
and general surface of plants — the Polypes are furnished with a
regular stomach, and with prehensile appendages for conveying
into it solid nutriment, on which it exercises a most powerful
digestion. In the larger and more solid Echinodermata, this
complexity of organisation becomes more distinct ; the tissues,
instead of consisting of soft and nearly homogeneous membrane,
exhibit all the varieties of nerve and muscle, tendon and liga-
ment, distinct vessels and cartilaginous or even bony skeletons.
The stomach, instead of being a simple bag into which everything
is introduced that comes within the animal's reach, whether it
be digestible or not, is but the commencement of a regular ali-
mentary canal, furnished with a set of teeth at its entrance for
the reduction of the food, and with glandular appendages for the
secretion of the fluids required in the digestive process. And
we even find distinct organs appropriated to the aeration of the
blood, which sometimes present a very complex arrangement.
Now it is remarkable that, with so great an advance in the
organisation of the nutritive apparatus, we should find the
locomotive and sensorial powers very little developed even in
the highest ; so that in this respect they are far surpassed by
the simpler Articulata, whose general organisation is much
inferior. But it must be remembered that the perfection of the
locomotive apparatus is the distinguishing or typical character of
the Articulata, and that everything is made subservient to it ;
whilst conformity with the Plant-like condition seems to be
equally the typical character of the Radiata ; — being only de-
parted from in those higher forms, which conduct us towards
other groups.

440 CILIARY MOVEMENT.

993. In looking at the apparatus, by which the various
bodily movements are effected, that are concerned either in
obtaining food, or in changing the place of the entire body, we
observe a considerable diversity in the Radiated classes. In the
lowest, the whole tissue appears equally contractile ; whilst, in
the highest, a distinct muscular structure exists, in which this
contractility specially resides. There is another very remarkable
structure, however, which is widely diffused through the group ;
and which enables very active movements to be performed by
animals, in which no distinct muscular structure can be detected.
This is termed the ciliary apparatus; and, as its extensive
diffusion through almost the whole animal kingdom, and great
importance in the economy, have only of late been recognised, it
will be desirable that we should pause here for a short time, to
examine its nature in some detail.

994. The organs termed cilia are little hair-like filaments,
covering the surface and fringing the edges of various membranes
both external and internal, which are in contact with fluid ; and
in this fluid they produce, by their vibrations, currents which
may serve various important purposes in the economy of the
animal. In the active and free-moving Infusorial Animalcules,
the cilia on the exterior of the body are the principal, if not the
only organs of locomotion : in the Polypes, fixed to a particular
situation, and unable to go in search of food, the currents which
they produce in the surrounding element bring it within reach of
their tentacula or arms ; and in all animals modified for respira-
tion in water, from those simple structures in which no particular
division of the surface seems appropriated to this function, to
Fishes, and the larvae of Batrachia (§481), their movements
appear to have an important relation with it, in constantly
renewing the stratum of water in the neighbourhood of the
aerating surface. Cilia are even found on the mucous membrane
lining the trachea, and ramifying air-passages of the higher Verte-
brata; and their use appears there to be to convey the secretions
and foreign particles, if such should be present, along the surface.
They have also been observed in the upper part of the alimentary
canal of Reptiles, throughout its whole extent in the Mollusca,

CILIARY MOVEMENT. 441

and in the stomach and its appendages in the Asterias, as well
as in many other situations.

995. The presence of cilia, when they are moving with
rapidity, can frequently be inferred only from the eddies which
they produce in the neighbouring fluid. Sometimes the return-
stroke, which is made more slowly, can be seen when the direct-
stroke is too rapid to be followed. This is particularly the case
with the wheels of the Rotifera (§ 537), which appear to revolve
continuously in one direction, from the observer being only able
to trace one set of the vibratory movements of the rings of cilia
which compose them. In general, however, the cilia may be
best seen when their motion slackens; and their shape, size,
arrangement, and manner of moving, may then be distinguished
with tolerable accuracy. Their figure is that of slender filaments,
sometimes a little flattened, tapering gradually from the base to
the point. Their size is extremely variable, the largest being
about 1 -500th of an inch long, and the smallest being stated at
1 -13000th. They are generally arranged in regular order, some-
times in straight rows, sometimes spirally or in circles ; and they
are usually set pretty close together, so as even occasionally to
resemble continuous fan-like membranes. When in motion, each
cilium appears to bend from its root to its point, returning again
to its original state, like the stalks of corn when depressed by the
wind ; and when a number are affected in succession with this
motion, the appearance of progressive waves following one
another is produced, as when a corn-field is agitated by frequent
gusts. Mr. Lister has described the action of the cilia, which
surround the respiratory apertures in the branchial sac of a com-
pound Ascidia (§ 978), as resembling that of delicately-toothed
oval wheels revolving continually in the same direction ; the
movement ascending on one side, and descending on the other.
But the cilia are very much closer than the apparent teeth ; and
the illusion seems to be caused by the fanning motion which is
given to them in regular and quick succession. This will pro-
duce a series of short waves, of which every one corresponds to
an apparent tooth. The movement of the cilia is sometimes,
however, of a different kind. The point of each describes a circle,

442 CILIARY ACTION. CLASSIFICATION OF RADIATA.

the base remaining fixed ; so that the whole ciliura describes a
cone, of which the apex is at its point of attachment.

996. The movement of the cilia appears to be, in some
instances, completely under the control of the animal ; and in
other cases, to be quite independent of the will, being seen after
death, and proceeding with perfect regularity in parts separated
from the body. Its duration then varies according to the species
in which it is observed ; and it is influenced by many external
circumstances. It has been seen fifteen days after death in the
Tortoise, when putrefaction was far advanced ; and in the River-
Mussel it seems to endure with similar pertinacity.

997. The Classes which exhibit the Radiated disposition of
parts most distinctly, and which are, therefore, unquestionably
to be referred to this Sub-Kingdom, are the following : —

I. ECHINODERMATA, or prickle-skinned animals. This Class,
which includes the Echinus (sea-egg or sea-urchin), the Asterias
(star-fish), and many less known forms, displays the radiated
structure in its most characteristic form. The bodies of these
animals are covered with a firm integument, which is thickly
beset with spines ; and from this, the name of the Class is
derived. In many species this integument consists of calcareous
plates, regularly jointed together; and in all it possesses greater
toughness, than we elsewhere meet with in the Radiated Sub-
Kingdom. This is a character by which they are easily recog-
nised, and are well known. There are, however, a few species
in which it is less apparent, — the skin having no greater con-
sistence than that of thin leather ; but these are associated with
the more typical forms, on account of their similarity in internal
structure.

II. ACALEPH^E (sea-nettles), the Jelly-fish tribe. These
animals all live singly, and are well-known inhabitants of our
seas. They consist of an extremely soft gelatinous tissue ; and
this is rarely supported by any harder substance. They float
freely in the water ; and some of them have considerable locomo-
tive power. The common MeduscB exhibit the radiated cha-
racter with great distinctness. In others it is less apparent.

CLASSIFICATION OF R ADI AT A. 443

Nearly all of them possess both a stinging power and the pro-
perty of phosphorescence.

III. POLYPIFERA, or polype-bearing animals. This includes
the beings commonly termed Zoophytes, or Animal-Plants, on
account of the resemblance in their mode of growth to that of
Vegetables. Although the various forms of Corals, Madrepores,
&c., which belong to this group, are themselves of an irregular
form, the individual polypes (as already remarked § 991) possess
the regular radiated conformation. And, as many species of
polypes live separately, it is obvious that we should look to
these, and not to the structures which they form, for the cha-
racter of the Class; and to their varieties, for the characters of its
subdivisions.

998. In the higher species of all these groups, which possess
sufficient firmness and definiteness of structure to allow of a ner-
vous system being detected, its form is found to correspond with
the characteristic disposition of other organs. It consists of a
circular filament surrounding the mouth, on which are a number
of ganglia (or distinct centres of nervous action) usually equal to
that of the segments of the body, and disposed at regular inter-
vals. From these, diverging filaments are sent off, which are
distributed to the various organs with great regularity. From
this arrangement of the nervous system, the term Cyclo-neura
(circular-nerved) has been applied to this division of the Animal
kingdom, and is sufnciently characteristic of it.

999. Besides these classes, there are two others, in which
neither nervous system nor radiated structure can be detected -y
but which must, for the present at least, be referred to the same
group, although not possessing the radiated structure.

IV. PORIFERA, or animals whose surface is covered with
pores. This group comprehends the Sponge tribe, and may be
considered as intermediate between Polypifera and Plants.

V. POLYGASTRICA, or many-stomached animals. This name
has been given to the lower of the two groups into which, since
the researches of Ehrenberg, the Infusorial Animalcules have
been divided. It is believed by that Naturalist, that they pos-
sess a large mmvber of separate digestive cavities, with distinct

444 CLASSIFICATION OF RADIATA,

walls, opening from an intestinal tube which connects them all.
Much doubt yet exists on this subject, however ; and until their
real structure has been more fully determined, their place in the
Animal kingdom cannot be satisfactorily assigned. No traces of
a nervous system can be discovered even in the most highly-
organised among them, by which this question could be set at
rest. "We shall associate them with the Radiated classes, on
account of the general simplicity of their structure.

CHAPTER XXII.

OF THE CLASS OF ECHINODERMATA.

1000. THIS Class is unquestionably to be regarded as the
highest, in point of complexity of structure, among those which
constitute the Radiated division of the Animal Kingdom. It
is characterized by the very regular disposition of parts round a
common centre, which is found in nearly all the animals com-
posing it, and which is never departed from in any remarkable
degree ; but chiefly by the hard integument, beset with spines
or prickles, from which its name is derived, and which may be
regarded as its chief external mark. This character, however,
is not presented by all the species, which, on account of the
general similarity of their organisation, are associated in the
group ;* but it is decidedly absent only in those, which
evidently constitute links of transition towards other divisions
of the animal kingdom. In no being is the radiated form more
distinctly marked, than in the Asterias or Star-fish (Fig. 606),
which is one of the best known species of this Class. And it
exists not only in its external aspect, but in the arrangement of
its internal organs, which are all disposed with perfect regularity
around a common centre. In the Echinus or Sea-TJrchin
(Fig. 604), it is equally manifested in the arrangement of the
plates which form its nearly globular shell (commonly termed
sea-egg) ; but the more highly-organised condition of the diges-
tive apparatus prevents the radial symmetry from being equally
shown in the internal viscera. In the Holothuria (Fig. 608), it
is still preserved in the circular form of the body, and in the
disposition of the appendages around the mouth ; although the

* The tubular feet hereafter to be described (§ 1006) are more universally
present than the spines ; hence it has been proposed to designate the Class
Cirrhodermata.

446 GENERAL CHARACTERS OF ECHINODERMATA. ECHINIDA.

globular shape of the Echinus gives place to a more prolonged
form, which, in some species, even approaches to that of the
Vermiform tribes (Fig. 609.).

1001. The three genera just named may be taken as the
types of three Orders, into which this group may be conve-
niently divided. Between these orders, the links of transition
are so very gradual (being often afforded by fossil species when
no recent forms supply them), and the general similarity of
organisation with many important differences is so well marked,
that the whole group may be regarded as eminently natural.
These orders we shall now describe separately, commencing with
the one which may be regarded as most characteristic of the
class, — that, namely, which contains the Echinus and its allied
forms.

ORDER I.— ECHINIDA.

1002. In the order Echinida, the whole body is inclosed
within a hard shell, usually of globular form, which is made up
of a number of polygonal plates. The structure of the shell is
not analogous to that which is found among the Mollusca.
Instead of being solid, it is extremely porous ; and seems as if
it were made up of areolar tissue (ANIM. PHYSIOL. § 24),
consolidated by carbonate of lime. The same kind of structure
is met with in the hard parts of the entire group.— In order that
it may keep pace with the growth of the soft parts, it is neces-
sary that the shell should be capable of enlargement, or that it
should be periodically thrown off and renewed, like that of the
Crab. The former plan is here adopted ; and it is beautiful to
observe how perfectly the plan by which it is carried into effect
is adapted to the wants of this simply-organised animal. The
soft parts being, as it were, boxed up within the shell, it is
obvious that a mere addition to the edges which surround its
openings (such as takes place in the Mollusca), would rather com-
plete its inclosure than add to the interior space. But by the
regular addition of new matter to the edges of each plate, the

SHELL OP ECIIINIDA. 447

equable enlargement of the whole is provided for, and room is
also made for the addition of new plates around the superior
orifice. From the recent observations of Agassi/ it appears that
these new plates are developed according to a spiral arrange-
ment ; that is, a whole circle is not formed simultaneously ; but
the new plates at the top of the several rows are added in suc-
cession. This is an interesting fact, as showing a striking
analogy to the growth of the leaves, and parts of the flower, in
Plants. (See § 987, and VEGET. PHYSIOL. § 302.)

1003. The shell is covered in the living state by a membrane,
which is sometimes very delicate, sometimes thick and spongy.
This unites the bases of all the spines, and communicates with
the interior of the shell by delicate processes, which pass between
the adjacent edges of the plates ; it is by these processes that
the new material is secreted, which adds to the dimensions of
each, and thus increases the capacity of the shell. Upon looking
to the part of the shell which surrounds the superior orifice, it
is seen that the plates are there less fully developed than they
are below ; their edges are not in such firm contact ; and the
tubercles to which the spines are attached have often scarcely

FIG. 604 — SHKLL OF ECHINUS, on SEA-URCHIN ; on the right side, covered with spines ; on
the left the spines removed.

made their appearance. The enveloping membrane at this part,

II H2

448 SHELL AND SPINES OF ECHINIDA.

in the living state, is softer and more spongy than in the lower
portion ; and it is in its substance that the first deposition of
calcareous matter takes place, which constitutes the origin of a
new plate. A careful examination of a specimen in progress of
growth will show plates in all stages of development, from the
thin calcareous scale on which no rudiment of spines can be seen,
to the solid plate furnished with bold projections, to which are
attached spines several inches long. The structure and origin
of these spines will be presently described.

1004. The shell of the Echinida is covered in the living state
by spines, which are sometimes very short and delicate, in other
instances long and slender, and in many species of moderate
length and considerable massiveness. These spines are attached
to tubercles upon the surface of the shell, which are usually large
in proportion to the size of the organs they support. The tuber-
cles do not cover the whole surface, however ; but they are
disposed in regular rows from one opening of the shell to the
other ; and the plates from which they are developed are called
tubercular plates. Between the bands of tubercles there are
others almost destitute of these prominences ; and the pieces
of the shell composing them are termed ambulacral plates.
These plates are usually not altogether destitute of tubercles ;
but the tubercles, as well as the spines which they bear, are very
small in proportion to the same parts on the other series. The
ambulacral plates are perforated by a large number of very
minute orifices, through which delicate membranous tubes are
put forth ; these assist the animal in walking, or seizing its
prey, in the manner to be presently described.

1005. The spines are united to the shell by the general
enveloping membrane, which attaches itself round their bases ;
this membrane seems to have the power of contracting in all
directions, as if it were composed of muscular fibre ; and in this
manner the spines are caused to move towards any required
point, — their cup-like bases working upon the tubercles, in the
manner of a ball-and-socket joint. In the Cidarif, which may
be regarded as the most perfect of the Echinida, the spines are
also attached by a round ligament (exactly like that of the hip-

SPINES OF ECHINIDA. 449

joint in Man), which is inserted into a little depression at the
top of the tubercle, and also into a small hollow in the bottom
of the cup. In this manner great freedom of motion is pre-
served ; and that degree of strength is added, which is required
for the vigorous actions performed by the solid massive spines
of this animal. The general enveloping membrane serves not
only for the movement of the spines, but also for their nutrition.
During the formation of the plates, as just now described, they
shoot out from its surface like horns from the head of a stag.
They remain covered, however, by delicate prolongations of the
living membrane ; and by these new layers are deposited, one
around the other, so that the diameter and the length of the
spine are increased at the same time. The structure of the
spines corresponds with that of the shell ; and it is remarkable
for the exquisite beauty and regularity of its arrangement, as is
seen when a very thin transverse section is placed under the
Microscope. — The degree in which the spines are employed as
organs of locomotion, or for other purposes, will vary, of course,
with their size and strength. In the Cidaris, they seem to act
as so many legs ; and they are also used for excavating hollows
in the sand, upon which the animal lies. In many of the Echini,
they would appear too slender and fragile to support the weight
of the body ; but it is to be remembered that, when it is im-
mersed in water, the pressure upon them will be very small. In
some, however, they are broad and flat ; and enlarge towards
their extremities, instead of tapering to a point ; the animals
possessing these can move themselves in any direction by means
of them, even on land. In the Scutella^ the spines are extremely
minute, but, at the same time, vastly increased in number ; each
of them is as perfectly organised, and its motions as much
governed by the animal, as when they are fewer and larger ;
and by means of their combined action, the animal can speedily
bury itself in the sand, for the purpose either of procuring food
or of escaping from its enemies.

1006. In many of the Echinida, however, the chief locomo-
tive organs are of a character entirely different. From the
openings in the ambulacral plates, a number of very delicate

450 TUBULAR SUCKERS OF ECHINIDA.

membranous tubes, each of them furnished with a sucker at its
extremity, are capable of being projected. These tubes consist
of two layers of muscular fibre, the outer one of which is circular,
whilst the inner one is longitudinal. Each tube is connected
with a little vesicle containing fluid, which is found within the
shell, just behind the minute orifice through which the tube
is projected. The several vesicles, which form five double rows
(//, Fig. 605), are connected by a set of vessels adapted to
distend them with fluid ; but every one seems to have a perfect
command over its own tubular foot. When the vesicle propels
fluid into it, the tube is projected to a considerable length ; and
the bands of muscular fibre which it possesses enable it to be
turned in any direction, and to apply its sucker in the most
advantageous manner. When the distension is withdrawn, by
the relaxation of the walls of the vesicle, the longitudinal fibres
contract, and the tube is shortened with considerable force ; the
water which it contained flowing back through the aperture of
the shell into the vesicle behind. In many species this apparatus
appears to afford the principal means both of locomotion and of
the prehension of food. When several tubes are projected in any
particular direction, and their suckers are attached to a fixed
point beyond, it is obvious that, if the tubes then contract, the
whole body will be drawn towards that point. Appearing, as
it will then do, to turn upon the spines, it is not remarkable that
many observers should have regarded the spines as the real
instruments of locomotion ; since the transparency of the tubes
will prevent their being observed, unless they are carefully
looked for.

1007. The action of these tubular suckers may be well seen
in the common Asterias or Star-fish ; from the under side of
whose arms they project in great numbers. If one of these
animals be placed in a glass vessel of sea- water, it may be seen
to climb up its sides by the use of this apparatus. One set of
suckers is fixed, and the animal is drawn towards them by the
contraction of their tubes ; it then takes a fresh attachment by
a set which were previously free ; and thus the numerous feet
are all employed, fixing and detaching themselves alternately,

PREHENSILE ORGANS OF ECHINIDA. 45 1

so that the animal gradually ascends the smooth surface, as it
would the face of a submarine rock. In the animals of this
form, too, we have abundant evidence of the use of the tubular
feet in conveying food to the mouth. If the Asterias were
entirely dependent on the slight hold which it can take by
bending its rays, many animals upon which it preys would
easily escape ; but in this beautiful apparatus of suckers at the
extremities of the feet, is a provision for retaining with great
force whatever has been once entrapped, and for carrying it
towards the central mouth. In the Echinus these tubes are
much longer, and would seem to act like the tentacula of the
Polypes, — floating loosely in the water, ready to attach their
suckers to any animal that in its active movements may cross the
field which they command. When a single foot has gained an
attachment, others are speedily brought to its assistance ; and
the unlucky victim is soon secured. That the Echini use their
tubular feet for progression also, is evident from the fact that, if
placed in a basin of water, they are not unfrequently found
within a short time perambulating its margin.

1008. Besides these tubular feet, there exists another series
of appendages, so remarkable in their character, that they have
been supposed to be separate animals parasitic upon the Star-
fish and Echinus, and have been described as such under the
name of Pedicellaria. Each consists of a stem, bearing at its
summit a sort of forceps of calcareous matter, not unlike a crab's
claw; except that the two (sometimes three) blades are equal and
similar. When the point of a fine needle is introduced between
the blades, which are for the most part open in a fresh and
vigorous specimen, they instantly close and grasp it with con-
siderable force. The particular use of these prehensile organs is
not evident. They are not confined to the neighbourhood of the
mouth ; but, where they exist at all (for it is not in every
species that they are found), they are disposed over the greater
part of the surface, often forming dense groups around the
spines.

1009. In all the Echinida the alimentary canal forms a long
tube, possessing two orifices. We shall presently find that the

452

INTERNAL STRUCTURE OF ECHINIDA.

relative position of these orifices undergoes important variations
in the different species. The intestinal tube usually makes about

FIG. 605. — ANATOMY OF ECHINUS : a, mouth, surrounded by the teeth and jaws, c, c ;
b, oesophagus ; *, stomach, or first portion of the intestine ; d, intestinal tube ; e, ovary ;
f, f, ambulacral vesicles ; g, g, shell.

two turns within the shell ; and it is attached to its walls by a
fold of the membrane that lines the general cavity. This mem-
branous fold contains distinct blood-vessels, by which the nutri-
tive matter seems to be absorbed from the digestive cavity ;
and these blood-vessels form part of a complex system, by which
the absorbed fluid is distributed over the whole body. We have
in these animals, too, a distinct provision for the aeration of their
fluid, by its exposure to a constantly-renewed layer of water.
The whole cavity of the shell, except the portion occupied by
the intestinal tube and its appendages, seems to be one great
respiratory chamber. Water is admitted to it from without ;
and its lining membrane, on which the blood-vessels are minutely
distributed, is covered with cilia, by the vibrations of which
the fluid covering its surface is continually renewed, and
the blood thus obtains a constant supply of oxygen from the

INTERNAL STRUCTURE OF ECHINIDA. 453

atmospheric air diffused through the waters of the ocean. The
fluid is introduced into the cavity by ten respiratory tubes,
which are placed around the mouth, and which bear a strong
resemblance to the tentacula of the Sea- Anemone (Fig. 617). In
the neighbourhood of the other termination of the alimentary
tube are situated the ovaries, which open by separate orifices
around the vent, just as do those of the Medusa around the single
aperture of its stomach. These ovaries periodically enlarge to
a considerable size ; and in some species they are used as food,
being termed the roe of the Sea-egg. In ancient Rome these
parts of the Echini constituted a favourite dish at the tables of
the great. It is not yet satisfactorily known, what degree of
development the germs acquire, before quitting the parent.

1010. Many of the animals of this group are provided with
a very complex masticating apparatus, consisting of five hard
and sharp teeth, which are put in motion by a powerful set of
muscles ; these take their origin chiefly from five plates which
project around the mouth into the cavity of the shell. The
teeth work in bony sockets or jaws, which, when fixed together
in their natural positions, form a five-sided conical mass (Fig.
605, c, c), aptly enough compared by Aristotle to a lantern, and
frequently described by modern writers under the name of the
"lantern of Aristotle." This complex machine consists of
twenty-five pieces, moved by thirty-five muscles. It would
seem to constitute a very powerful mill, in which the food is
speedily reduced to fragments. Regarding, the nature of their
aliment, however, there is still some uncertainty; but there seems
reason to believe, that small Crustacea and Mollusca constitute
their chief food ; but it is not improbable that, like others of the
class, they are omnivorous, and can digest almost any organic
matter that comes within their reach.

1011. The two most important genera of this Order are the
Cidaris and the Echinus. The former is usually regarded as
the most highly organised of the entire class ; its spines being
proportionally few and powerful, and being connected with their
tubercles by a mode of attachment superadded to those which
we find elsewhere (§ 1005). The Echinus, however, is the best

454 CLYPEASTER ; SCTJTELLA ; SPATANGUS.

known of these genera, in consequence of its more extensive
geographical distribution, and its abundance in the places it
frequents. One species, found on the coast of Ireland, has the
power of excavating for itself hollows in the limestone rock on
which it lies ; but by what means it does so is uncertain. — In
the Clypeaster and Scutella, the shell is more or less flattened ;
and is sometimes divided by vertical partitions, so as in some
degree to resemble a Star-fish. At the same time, the vent
leaves its central position on the upper surface, and approaches
the mouth, which still retains its central position below. In
the Spatangus, or Heart-Urchin, common on many of our sandy
shores, the radiated form is considerably departed from. — The
shell, instead of being round, is oval ; and it is often much pro-
longed in one direction, so that the radial disposition of its parts
gives place to a bi -lateral symmetry. We here find neither the
mouth nor the vent occupying a central position. Of the habits
of the Spatangi little is known. They are almost always found
buried in the sand ; and their alimentary canal is filled with the
same substance, in which they seem to find enough nutriment,
composed probably of the minute animals mingled with it. As
they are entirely destitute of teeth, and seem unable to bring
their suckers into proximity with the mouth, they must derive
their nourishment from the chance-supplies, which the substances
in contact with their mouths may furnish. But their whole
organisation is adapted to this mode of existence; as much as
the more complex structure of the Cidarites is to the life, which
they are intended to lead. Yet it is difficult to imagine how,
with so little power either of locomotion or prehension, they can
obtain the necessary amount of aliment.

ORDER II.— STELLERIDA.

1012. In this Order, of which the common Asterias, or Star-
fish, may be taken as the type, we approach in a certain degree
to the inferior forms of Radiata, Instead of the complete diges-
tive apparatus, with two orifices, which we have seen in the

GENERAL STRUCTURE OF STELLERIDA. 455

Echinida, we find a stomach only, with a single aperture, like
that of the Actinia (§ 1057). This stomach has a distinctly radi-

FlG. GOG.— ASTERJAS, OR STAR-FISH.

ated form. In the Asterias it occupies the centre of the body,
and prolongations of it extend into the rays. The side of the
body on which the mouth is situated, is always termed the lower
surface ; as the Star-fish and its allies generally live in this appa-
rently-inverted position. The body and rays of the Stellerida
are composed, like the spheroidal shell of the Echinida, of calca-
reous plates joined together. — The upper surface is usually
covered with short spines, moving upon small tubercles, and
connected by the general integument, as in the Echinus. It is
on the lower surface only, and in the central line of each ray,
that we find the ambulacral plates. The tubular feet are very
numerous, though short, in the Star -fish; but much fewer in
some other forms belonging to the Order. They are connected,
as in the Echinus, with a tubular apparatus, which enables the
animal to project them either together or separately ; and this

456 GENERAL CHARACTERS OF STAR-FISH.

apparatus (by which water is introduced into the body from
without) seems to be the principal means of respiration enjoyed
by the animal. The ovaria are disposed in a radiated form
around the mouth; and they are found to be turgid in the spring
and the commencement of the summer. Their spawn is thrown
out upon sandy shores, where it is exposed to the action of the
sun. It has not, however, been properly examined ; nor has the
mode of development of the young Star-fish been studied.

1013. The mouth of the Asterice opens at once into the
stomach ; it is unprovided with teeth ; and the digestive secre-
tions appear to constitute the only means possessed by the
animal of reducing its food. There is considerable variety in
this group, as to the number of rays, the proportion which they
bear to the central disk, and the degree in which the stomach
is continued into them. Some are so little divided at the
edges, that in external form they approach the Clypeasters
(§ 1011) ; whilst in others the disk seems almost absent, the
animal being, as it were, all rays. In general organisation,
however, there is a pretty close correspondence throughout. —
The Asterice appear to enjoy a considerable amount of loco-
motive power. Their rays are very flexible, so that they
can be drawn up towards the mouth, or moved from side to side
towards each other, so as to give the animal the power of insi-
nuating itself through narrow apertures. The rays appear to be
principally moved by the general integument, which is thick and
contractile. Small red points have been observed at their
extremities in some species, which, from their connection with
the nervous cord of each ray, and from their analogy with the
eyes of other Invertebrata, are believed to be visual organs.
This belief is strengthened by the observation of Professor
Forbes, that the spines are disposed around them in a peculiar
circular mode, so that they may be closed over these organs
for their protection, or may diverge for their most extended
employment. The same gentleman has remarked that these
animals appear to take cognisance of objects of food placed at a
little distance from them ; and that, in their movements from
place to place, they seem to be aware of obstacles in their direct

GENERAL CHARACTERS OP STAR-FISH. 457

path, and to go out of their way to avoid them. It has been
remarked also that, when all their feet are protruded, they will
suddenly retract them, if any substance be brought in close
proximity to them, but without touching them.

1014. Notwithstanding their possession of this amount of
perceptive power, however, they do not seem to be very
susceptible to painful impressions. If severe mutilations be
performed whilst the animal is in a state of activity, it does not
appear conscious of them, but continues its movements as before.
The suckers in the neighbourhood of the injured part are
retracted ; but the others, even in the same ray, continue their
actions, as if unaffected by the sense of injury. Of the extent to
which reproduction of parts may take place after such mutila-
tions, details have already been given. — The Asterice are animals
of great voracity. Like the Actiniae, they seem to be always
gaping, as it were, for food ; and to swallow whatever falls in
their way. The mouth is extremely dilatable, so that it can
admit large shell-fish and Crustacea, as well as small fishes, and
fragments of larger bodies which may be cast upon the shore.
Like the Sea- Anemone, they disgorge the undigestible parts by
the same orifice ; and they seem also possessed of the power of
partially everting their stomachs, or turning them inside-out, so
that the lining membrane projects through the mouth. Indeed
it is in this condition that they frequently lie in wait for their
prey ; the protruded portion being wrapped round the object,
and then drawn in. It seems to be by some means of this kind,
that the Asteriaa are able to destroy and digest Oysters and
Mussels, without drawing their bodies from the shell.

1015. In the Ophiurce we find a more distinct central disk
than in the Asteriaa; and to this the viscera are confined. It is
furnished with arms, which are sometimes simple or undivided
from one extremity to the other, and of a rounded tapering form,
like a serpent's tail, as in the genus Ophiurce ; whilst in other
genera, as the Euryale, they ramify minutely, dividing regularly
into branches which again subdivide, so as to form a most com-
plex series of appendages. These arms are all composed of
jointed plates, like those of the Asterice ; and they are possessed

458 CRIN01DEA. COMATULA.

of spines or scales. The Ophiurce are much more active in their
habits than are the Asterias. Their rays seem very flexible ; and
by the contraction of their envelope, they may be moved in all
directions. Thus they are able to swim and to walk with con-
siderable facility ; as well as to exercise considerable power in
obtaining their prey.

1016. To the Order Stellerida, also, belong the very interest-
ing family of Crinoidea ; in which we find some important
differences in organisation. This family, which was formerly
much more abundant than at present, receives its name from the
lily-like form which several of its members present (Fig. 607).
The greater part of them, instead of moving freely where they
will, are attached, during a portion or the whole of their lives,
by a peduncle, or footstalk, to some solid body. And all of them
seem to possess two orifices to the digestive cavity. Of this
family the Comatula is the most abundant example ; and as its
organisation is better understood than that of any other genus,
our notion of the character of the group is principally derived from
it. In general form, the Comatula does not depart widely from
some of the animals just described. The star-like aspect is still
regularly preserved ; and the mouth is in the centre of what
must yet be regarded as the under surface of the body. The
viscera are contained in the central disk, which is composed of
numerous polygonal plates. The arms arising from this disk are
five in number; but they speedily subdivide, each usually
separating into four. These are composed of a number of calca-
reous pieces, solid and nearly cylindrical, which are inclosed in
a living flesh of greater thickness than the integuments of the
Asterice. Thus we have seen the rays, which in the Asterias
contained the principal part of the animal, first deprived of the
prolongation of the stomach, and then losing their cavity alto-
gether, so as to become mere locomotive appendages to the
central disk. To the skeleton of the arms, we find that jointed
lateral appendages, of a similar structure, are attached ; and these
also are clothed with the fleshy integument which secretes them.
Between these lateral appendages is a slight furrow, occupied by
papillse, which are furnished with vibratile cilia ; and it appears

CRINOIDEA; — COMATULA; PENTACRINUS. 459

to be principally by the action of these cilia, that food is brought
towards the mouth. Although the digestive cavity has two
orifices, it is not constructed upon the plan of that of the
Echinida. There is no separate alimentary canal ; but only a
stomach like that of the Asterice, with a short tubular prolonga-
tion, of which the orifice projects between the mouth and the
side of the disk. (This projecting orifice, which is very evident
in the Encrinites, has been commonly mistaken for the mouth,
which is much less apparent.) The Comatula often attaches
itself to sea- weeds, or other floating bodies ; and, bending its
long arms in various directions, it presents a very elegant appear-
ance. Sometimes it swims freely through the sea, by an undu-
lating movement of these appendages ; and sometimes it employs
a part of them for seizing its prey, whilst with the remainder it
clings to rocks, corals, or other firm supports.

1017. Now if we imagine a Comatula turned with its mouth
upwards, and the opposite surface of the disk prolonged into a
five-sided stalk, the root of which should be attached to some
solid body, we shall have the form of the Pentacrinus. With
the animals of this tribe we are chiefly acquainted by their skele-
tons alone. Only two species are known to exist at the present
time. One of these, the Pentacrinus Europceus, is found in the
Bay of Cork ; the other, the Pentacrinus caput Medusae^ in the
neighbourhood of the West India Islands. The former only has
been observed in its living state ; and it is so minute, that the
anatomical investigation of its structure is a matter of some
difficulty. It appears, however, to correspond in every particular,
except the attachment by a stem, with the Comatula ; and there
appears good reason to regard it as, in fact, the young state of
that animal. When arrived at its full growth, the disk and arms
quit the stem, and pass the remaining term of their existence in
a state of freedom. The Pentacrinus caput Medusce is a much
larger animal, and its skeleton presents a most beautiful and
regular structure. The disk and arms are formed like those of
the Comatula; the latter are very numerous, and thickly set
with the jointed lateral appendages. The stem is more than a
foot long, and is composed of a large number of pieces similar to

460 CRIN01DEA ; PENTACRINUS.

those of the arms. From this stem there arise, at regular inter-
vals, several verticils, or whorls, of secondary arms ; which do
not subdivide, and are destitute of lateral appendages. From
what is known of the animal in its living condition, there can
be no doubt that all these parts are covered with a fleshy integu-
ment, by which they are produced, and to which they owe their
power of movement. This integument seems to dip down
between each joint, and to form the connecting medium between
the different pieces. As the base of the stem of the recent species
has never been obtained, the mode by which the Pentacrinus
attaches itself to solid bodies has never been clearly made out ;
but there is reason to believe, from the circumstances under
which fossil remains are sometimes met with, that the animals
of this genus are not permanently adherent to solid masses, but
have the power of occasionally detaching themselves.

1018. In some of the fossil species, the subdivision and
ramification of the arms is carried to a much greater extent, than
in either of the recent forms of this tribe. The number of pieces
in the skeleton thus becomes very large. In the Pentacrinus
Briareus, it has been calculated that at least 100,000 exist,
exclusively of the joints of the lateral appendages, which are
probably more than 50,000 additional. As each joint was fur-
nished with at least two bundles of muscular fibre, one for its
contraction, the other for its extension, we have 300,000 such in
the body of a single Pentacrinus — an amount of muscular appa-
ratus far exceeding any that has been elsewhere observed in the
Animal Creation. But it will be remarked that these parts are
but repetitions of one another in structure, and that consequently
their variety of actions must be very small ; and, accordingly
we find that the movements of this complex piece of mechanism
are far less capable of being combined and adapted to a specific
purpose, than those of a prehensile structure of higher organi-
sation,— the hand of Man — with its twenty-seven bones and
thirty-nine muscles. A repetition of similar parts always
implies a low degree of organisation, as it indicates a very
small amount of variety in the functions to be performed ;
and the approach towards a higher character is marked

PENTACRINUS ; ENCRINITES.

461

by the modification of some of these for particular purposes —
a specialisation, or setting-apart, for some object of a more im-
portant nature, than those general functions to which they all
contribute. But the simple actions, which alone can be performed
by the arms of the Pentacrinus, are all that it needs for the
grasp of its food.

1019. The general "structure of the Encrinus, of which no
recent species exists, bears a close affinity with that of the
Pentacrinus. The body and jointed stein exhibit rather a rounded
than a pentagonal form ; the latter is often des-
titute of secondary arms ; and the principal
branches do not ramify witli the same minute-
ness as those of many Pentacrini, but rather
resemble in their distribution those of the
Comatula. The stalk is attached by a sort of
spreading root, like that of many Corals ; and
we must therefore believe this tribe of Crinoi'dea
to havebeen entirely fixed. — Besides the Encrinus
and Pentacrinus, there are many other extinct
genera of Crinoi'dea, which present a very
beautiful series of forms, all referable to the
same general type ; but on these our limits
forbid us to dwell. — In the recent species of
Crinoi'dea, one or two of the arms may occa-
sionally be found, of much smaller size than the
rest, and apparently in process of replacing others which have
been accidentally lost. Among the fossil Crinoi'dea, such instances
are by no means rare.

FIG. 607. — ENCRINUS.

ORDER III.— FISTULIDA.

1020. This Order may be regarded as connecting the
Echinida^ which may be considered as the types of the Class,
with the Articulated series. In some respects it may be con-
sidered to present a higher grade of organisation than we else-
where meet with among the Echinodermata ; but this does not

462 FISTULIDA ; HOLOTHURIA.

entitle it to rank as the typical order of the class ; since its more
elevated character is only obtained by its approach towards a
very different type of organisation. This Order, which consists
of the Holothuria and its allies, is known by the absence, except
in a few instances, of the calcareous plates and spines of the
Echinida and Stellerida. The skin is soft, and very distensible
and contractile ; so that the size and form of the body are
capable of great variation. The tubular feet, however, still exist.

F(G. 608. — HOJ-OTHURIA.

They are sometimes arranged in distinct rows, stretching from
one end of the body to the other ; and sometimes scattered
irregularly over the surface. The general form of the body
varies considerably in the different species. In some it is of a
nearly globular shape, as in the Echinus ; not flattened at the
poles, however, but prolonged at these points. In others it is
still more lengthened, and presents slight transverse markings.
And in the most aberrant species, the body exhibits an almost
worm-like form ; being greatly prolonged, and contracted at
intervals into distinct articulations. Nevertheless, in all these,
the radiated type is evident in the conformation of the parts
around the mouth. This is situated at the anterior extremity of
the body, and is surrounded by appendages more or less ramified
and fringed ; so that, on looking down upon these parts only, we
might almost suppose them to belong to one of the Stellerida.

FISTULIDA ; — HOLOTHURIA ; SIPUNCULUS. 463

1021. Although the body is not furnished with any complete
calcareous skeleton, we occasionally find a circle of plates around
the mouth. These afford attachment to the muscles, which
stretch along the entire surface of the body, and which are con-
cerned in its alterations of form. The mouth does not lead to a
distinct stomach ; but it is the commencement of a long alimentary
tube, of nearly uniform diameter throughout ; which, after many
convolutions, terminates at or near the opposite extremity of the
body. — The Holothuria has the power of drawing inwards its
tentacula, and of closing its mouth around them ; so that no
appearance of them can be seen. It improbably by a movement
of this kind that it swallows its food, which seems to consist of
almost any kind of organised matter that falls in the way of the
animal ; for the intestine is generally found distended with sand,
in which may be detected the remains of corals, sea-weeds, and
other marine substances. — There are some interesting points in
the internal organisation of this group, which tend to show its
relationship to the Articulata ; and their analogy to that group
is further shown in their power of comparatively active locomo-
tion. By the flexibility of their integument, and the muscular
fibres with which it is furnished, they are able to swim and crawl
with facility. Some of them frequent deep waters ; whilst others
are found among rocks and floating sea- weeds, at no great distance
from the shore.

1022. Near the Holothuria, we are probably to place the
Sipunculus and its allies ; although the worm-like aspect of

their bodies, and the entire ab-
sence of either prickles or tubular
feet from the skin, would lead us
to suppose them entirely different

FIG. 609.-SIPUNCULUS. in character. In fact they consti-

tute an extremely aberrant group

—just such as the philosophic Naturalist might expect to find
between classes formed upon types so different as the Radiated
and Articulated. The mouth is not surrounded by radiating
arms, as in the Holothuria, but it is armed, in many species,
with a set of teeth arranged in a pentagonal form, like those of

n2

464 SIPUNCULUS. — GEOGRAPHICAL DISTRIBUTION.

the Echinus. In some, however, this is replaced by a sort of
proboscis, which may be protruded or retracted like that of many
Annelida (§ 835). So great a resemblance, in fact, do such
animals bear to certain species which we find in this Class, that,
until their structure has been more fully investigated, and the
arrangement of their nervous system ascertained, it may be
doubted whether their true place is not in it, rather than among
the Echinodermata. Nothing can be imagined that is wanting
to complete the connection between these two classes, which is
established by means of this group. The Sipunculi are seldom
found but on sandy shores. They excavate holes in the sand,
in which they conceal themselves, occasionally protruding their
heads from the orifice. They are much sought after by fisher-
men, who use them, like the common lob-worm (Arenicola pisca-
torum) whose habits are so similar, as baits for their hooks.
Some of them attach stony particles to their skin, by a glutinous
exudation, so as to cover it with a hard crust, resembling that
formed by some Annelida (§ 840).

1023. In regard to the Geographical distribution of the
Echinodermata, it may be stated generally, that all the families
of this Class are represented in nearly every portion of the globe.
As among other classes, however, so in this, it would appear that
the largest species (especially of the Comatula and Pentacrinus)
are found in tropical regions ; but Echini, Asteriae, and
Holothurice, occur in plenty on our own coasts. Star-fish occa-
sionally abound so much on the shores of France, as to be used
for a profitable manure. We have no certain knowledge as to
the animals which find in the Echinodermata their regular food.
Of the Stellerida, Man makes no other use than that just stated ;
and of none of the Echinida does he eat any other part than the
roe (§ 1009). The large use made of the Holothurice by Man, as
a source of nutriment, is not generally understood. One species
is collected and eaten by the poor inhabitants of the Neapolitan
coast; but there is another which constitutes an important
article, not only of consumption, but of regular traffic. Captain
Flinders (1803) fell in with a fleet of Malay proas, near the
Gulf of Carpentaria, on the north coast of New Holland ; and

HOLOTHURIA; TREPANG. — GEOLOGICAL DISTRIBUTION. 465

was informed that sixty proas, carrying one thousand men, had
left Macassar two months before on an expedition to that coast,
the object of which was the collection of trepangs for the Chinese
market. The trepang, leche de mer, or sea-cucumber, is no
other than a Holothuria^ which is extremely abundant on that
coast ; in shallow water, the animal may be taken up by the
hand; in deeper water it is obtained either by diving or
spearing. In order to preserve the edible portion of it, the
body is split down one side, boiled, and pressed with a weight of
stones, then dried in the sun and stowed away in bags. About
a thousand of them make a,picol} which is equivalent to 1331bs. ;
and 100 picols are a cargo for a proa. It is carried to Timor
and sold to the Chinese, who meet them there ; and when all
the proas are assembled, the fleet returns to Macassar. It
would seem that European traders have now become alive to
the value of this traffic ; for there are regular establishments in
different parts of the Dangerous Archipelago, for those who go
leche-de-mer-ing, as the employment is commonly termed. After
exhausting the supplies furnished by one island, they pass on to
another, and usually complete their cargo within a few weeks.
The quantity annually sent to China from Macassar, which is
the principal market of the trepang, is usually about 7000 picols,
or 416 tons ; the price usually varying from 8 dollars a picol to
115, according to the quality. There is also a considerable
export of trepang from Manilla to Canton. The Sipunculus,
also, is used as an article of food in China and Japan.

1024. The Geological position of the different families of
Echinodermata presents us with many points of great interest.
No remains of any of them can be traced in the very oldest
fossiliferous rocks ; but, judging by the abundance of the skele-
tons of Crino'idea in the limestones of the Transition series, the
animals of that group must have been among the most numerous
of the larger inhabitants of the ocean, at the time these strata
were deposited. So abundant are they, indeed, that they may
be almost said to constitute those thick and extensive beds of
Transition limestone, which, from the wheel-like form of the
separate joints of the Encrinite stems, is termed Entrochal

466 GEOLOGICAL DISTRIBUTION OF ECHINODERMATA.

Marble. " The substance of this marble," says Dr. Buckland,
" is often almost as entirely made up of the petrified bones of
Encrinites, as a corn-rick is composed of straws. Man applies
it to construct his palace, and adorn his sepulchre ; but there are
few who know, and fewer still who duly appreciate, the sur-
prising fact, that much of this marble is composed of the skeletons
of millions of organised beings, once endowed with life and sus-
ceptible of enjoyment, which, after performing the part that was
for a while assigned to them in living nature, have contributed
their remains towards the composition of the mountain masses
of the earth." It cannot be deemed improbable that, of those
forests of Encrini to which these depositions are principally
owing, some grew on the sides of the Coral reefs from which
other beds of limestone seem to have originated ; and that the
debris (or separate particles) of the reefs furnished the calcareous
matter, by which their skeletons are held together. Fragments
of Encrinites are also dispersed irregularly throughout all the
deposits of the Transition period, intermixed with the remains
of other contemporary marine animals. No other species of
Echinodermata, however, as yet present themselves ; and it is
interesting to remark, that the Crino'idea which so abound in
the Transition epoch (more than thirty species being known)
belonged, with one exception, to the Encrinus and other round-
stemmed genera, and were therefore more unlike the existing
forms of that family, than were those which we find at a later
period. All these Crino'idea, which continue to abound in the
Mountain Limestone and other of the more ancient secondary
rocks, become extinct when we arrive at the Lias ; and are then
replaced by the Pentacrinus. The stems of Encrinites compose
extensive beds in the Carboniferous, as in the Transition series ;
and these are often found in the neighbourhood of those of a
distinctly Coralline nature, so that the animals probably grew
on the banks of such reefs as are now being elevated in the
Southern Ocean, and which, if properly examined, might be
found to support their living analogues. The joints of the
Encrinite-stems often fall asunder when the connecting rock is
not firm enough to hold them, — the animal membrane which

GEOLOGICAL DISTRIBUTION OF ECHINODERMATA. 467

united them in the living state having long since decayed away.
Their flat round form, and central perforation, have occasioned
them to receive the name of Entrochi, or wheel-stones. They
were formerly strung as beads for rosaries ; and in the northern
parts of Britain they still retain the appellation of St. Cuthbert's
beads.

" On a rock by Lindisfarn
Saint Cuthbert sits, and toils to frame
The sea-born beads that bear his name."

1025. The Pentacrinus first began to abound at the com-
mencement of the Lias ; and its remains present themselves in
great numbers in that formation, and in the Oolite which
succeeds it. From that period they diminish, and we gradually
lose sight of this interesting group, — the few existing species
serving, as it were, but to indicate the structure of those, which
formerly occupied so important a rank among the inhabitants
of the ocean. — As the Crinoidea disappeared, the other Stellerida
and Echinida took their place ; and remains of these are met
with in almost all marine strata, down to the present time.—
being particularly abundant in the Chalk and Oolite.

CHAPTER XXIII.

OF THE CLASS OF ACALEPH^).

1026. THE animals composing the class ACALEPH^: differ
widely in external form, and frequently, also, in the arrange-
ment of their organs ; so that it is difficult to assign any
character which shall be
applicable to them all.
Perhaps their most gene-
ral point of agreement is
the extreme softness of
their tissues, and their
free unattached condition :
by the former they are
distinguished from the
Echinodermata ; by the
latter from the Polypifera.
Although the radiated
structure is well marked
in the forms which we
may regard as typical of
this group (Fig. 610),
yet it is so entirely ob-
scured in others (Fig.
614), that, if they be re-
garded out of connection
with the rest, their claim

to a place in this division of the Animal Kingdom would be
very doubtful. In general, however, it is not difficult to find
links of transition, by which the radiated forms pass into those
that are constructed apparently upon a different type ; and,
when this is the case, we should have no hesitation in uniting

FIG. 610. — PELAGIA.

GENERAL CHARACTERS OP ACALEPHJE. 469

the latter under the same general denomination, since they agree
in the peculiar character of the group as stated above, and cannot
be received into others.

1027. The Acalephse derive their name (which means
nettles), from the stinging power which nearly all of them pos-
sess ; and some of their common names, as " Sea-nettles/' or
" Stang-fishes," have the same origin. This stinging power
appears due to a peculiar acrid secretion from the surface, which
remains after the death of the animal, and may be communicated
to substances which are placed in contact with it. They are
also commonly denominated "jelly-fish," " sea-blubber," &c. ;
partly from their uncouth appearance when cast upon the shore ;
and partly from the extreme softness of their tissues, which melt
away (as it were) when removed from the water. This delicacy
of structure is common to the whole group. In the greater
part, there is no hard support whatever; and the animals,
when taken out of water, lose their form completely. In a few
species, however, there is a very thin cartilaginous plate, which
retains its form when dry. The substance of these animals consists
of a tissue somewhat resembling cartilage (ANIM.PHYSIOL. § 45);
but containing so little solid matter, that a Medusa, weighing
several pounds when alive, is reduced almost to as many grains
when dried. The fluid gradually drains away, leaving but a
thin pellicle incrusting the surface on which the mass was placed.

1028. In most of all the Acalephse, which possess a distinctly
radiated form, the stomach or digestive cavity is central (Fig.
611). It usually opens by a single orifice, placed in the centre,
and surrounded by tentacula ; but there are several curious
species (Fig. 612), in which there is no regular mouth ;
the food being taken in by a number of suckers, having minute
orifices at their extremities. In all, however, it is remarkable,
that the number 4 and its multiples may be almost constantly
observed to govern the distribution of the organs. Although
possessed of a certain degree of locomotive power, the movements
of the Acalephse are very feeble ; they are carried about by the
ocean currents, almost at their mercy ; and many of them have
the means of making the gentle breezes subservient to their

470 GENERAL CHARACTERS OF ACALEPHJE. LUMINOSITY.

change of place in search of food. None of them, however, can
endure a rough sea. Although in calm weather they float in
countless myriads upon the surface, they sink, on the slightest
disturbance of it, into the depths of the ocean. For the same
reason, they prefer the open sea to the neighbourhood of the
coast ; and in fact to approach the land is almost fatal to them.
They are often driven by the winds and currents which they
cannot resist, against the hard shore, and there they are soon
beaten to pieces by the waves ; or they are left dry by the tide,
which they have not the power of following, and speedily melt
like the spangled hoar-frost beneath the sun-beam.

1029. The voyager in the open sea, however, often encoun-
ters whole fleets of these animals, extending, as far as the eye
can reach, basking as it were in the sunshine that illumines the
surface, and reflecting its rays with all the gorgeousness of the
most brilliant iridescent hues. Most of the Acalephae seem
inclined thus to associate ; and in tropical regions, where they
exist in the greatest abundance, the voyager, after passing through
a fleet of one species, will in a short time encounter an equally
extensive collection of another kind. It is not by day only,
however, that these animals delight the eye of the mariner. It
is chiefly to them that the phosphorescence of the sea is due, which
is occasionally observed on our own coasts, but only in a degree
which affords a faint idea of the extraordinary nature of this
phenomenon as it presents itself in warmer latitudes. The whole
surface of the ocean displays a diffused luminosity, like that of the
Milky- way on a clear night. The path of the ship is marked by
a brilliant line of glowing light. The waves, as they gently curl
over one another (this phenomenon is never seen with a rough
sea), break into brilliant spangles. The oars of a boat rowing
over them, seem dripping with pearls when raised from the
water; and every stroke is marked with anew line of brightness.
And amidst this general splendour, varied forms of more glowing
lustre are seen to move — some like ribands of flame — some
like globes of living fire — some gently gliding through the still
ocean, others more rapidly moving just beneath its surface.
Now, although other marine animals — such as the Pennatula

PHOSPHORESCENCE OF THE SEA. 471

(Fig. 622) and other Polypifera, the Pyrosoma (§ 983) and other
Tunicata — contribute to produce this dazzling effect, it is prin-
cipally due to the various species belonging to the group we are
now considering.

1030. The diffused luminosity is given by minute species ;
and on our own coasts it is principally due to the Noctiluca, a
little animal much resembling a grain of boiled sago in size and
appearance. The anatomy of this animal has not yet been satis-
factorily investigated, notwithstanding its occasional abundance ;
and its true place in the Class has not been ascertained. It
seems like a little granule of jelly, with a long stalk. This stalk
appears to be a trunk or sucking-tube, by which the food is taken
in ; and it is capable of being extended, or drawn in, to a con-
siderable degree. The luminous secretion appears in all instances
to become more vivid, when the animal is alarmed or stimulated
in any way. Hence the disturbance of the water, by the gentle
curling of the waves over each other, or by their ripple on the
shore, is marked by lines of increased brilliancy. The movement
of a boat, and the stroke of the oars, will have the same effect.
If the animals be washed over the sands, they continue to display
their luminosity in a fainter degree for some time ; but every
footstep of a person who walks over them is studded with bril-
liant points. And if the hands be dipped in the water thus
phosphorescent, and then rubbed together, they will be covered
with luminous spots ; which, when examined, are found to be
occasioned by the phosphorescent glow of these delicately-formed
little animals. There are few parts of the British coasts, where this
phenomenon is not occasionally witnessed. It generally follows
a continuance of some particular wind ; but the direction required
varies in different parts of our island. It is thus that we obtain
a more accurate idea of the vast amount of animals composing
this tribe, than we derive from any observations that can be made
during the day. Their bodies are often so transparent, that they
can scarcely be distinguished from the water through which they
are diffused, except when displaying their phosphorescence. But
when the whole surface of the ocean, as far as the eye can reach,
is seen to exhibit a uniform luminosity, and this is ascertained to

472 ACALEPELE ; MEDUSA.

be due to animals not larger that the head of a pin, in close
apposition to each other, — the vast amount of organic life which
ordinarily escapes our notice, can scarcely fail to strike us with
astonishment, not unmingled with pleasure at the thought, that
each of these little beings is passing a life of enjoyment, and is
performing an allotted function in the great economy of Nature.
1031. The structure of a large proportion of the Acalephse
is not yet sufficiently understood to permit a very satisfactory
arrangement of the Class ; and we must be satisfied with a
description of some of the principal forms which it includes.—
The Medusa (Fig. 611) presents to the eye, when it is floating

A

FIG. 611.— MEDUSA; A, under surface, showing the mouth in the centre, surrounded by
the tentacula, and the ovarial chambers exterior to the origins of these ; B, side
view, showing the tentacula hanging down in their natural position.

in its native element, an umbrella-shaped disk, from beneath
which hang down four tentacula or arms. The central part of
the concave side of this disk is occupied by the stomach, in the
middle of which is the mouth, opening downwards, and sur-
rounded by four leaf-like tentacula. Around the stomach are
four ovarial chambers, with separate orifices. These organs
occupy the space inclosed, as it were, within the frame- work of
the umbrella; but the delicate membranous disk projects con-
siderably beyond them, and floats freely in the water. It
appears to have some muscular power ; for it is by its gentle
undulations, which are performed with great regularity, that
these animals are propelled through the ocean. This free por-
tion of the disk is traversed by numerous canals, which are to be
regarded as prolongations of the digestive cavity. Eight of these
pass directly outwards, and terminate in a corresponding number

MEDUSA ; — EHIZOSTOMA.

473

of orifices at the edge of the disk. But another set of eight sub-
divide and ramify, so as to form a sort of net- work of vessels, which
appear to serve for the nutrition of the portion of the structure
at a distance from the stomach, and also to expose the nutritive
fluid to the aerating action of the surrounding water. The
Medusce often attain considerable size. It is said that their disks
have been seen three or four feet in diameter; and that the
animals have weighed as much as 60 Ibs. It might be inferred
from the extreme delicacy of their structure, that they are sup-
ported only on food most easily obtained; but this is by no
means the case ; for in their stomachs are found small Crustacea,
Mollusca, and even Fishes. It would seem that their tentacula,
like those of the Hydra, possess considerable muscular power ;
and that they are capable of drawing towards the mouth almost
anything which comes within their reach. Even large Fishes
are occasionally found entangled amongst them. Very probably
their stinging power is of use in weakening the resistance of
thei rprey.

1032. There are several Acalephee, which resemble the Medusce
in general form, and especially
in the possession of this um-
brella-shaped disk, by the un-
dulations of which they move
through the water ; but which
yet differ from them in many
important and curious points
of organisation. Sometimes
the mouth is prolonged into a
sort of proboscis, formed, as it
were, by the union of the bases
of the tentacula, so as much to
resemble the stalk of a mush-
room. Sometimes the tentacula

are of much smaller proportional size, and then we usually find
a series of filaments hanging from the free margin of the mantle
(Fig. 610). Occasionally the tentacula almost disappear, and
then these filaments are largely and abundantly developed, and

FIG. 612 — RHIZOSTOMA.

474 ACALEPH.E ; — MEDUSA.

probably replace them in function. The most curious modifica-
tion, however, is that which is displayed to us in the Rhizostoma
(Fig. 612), an animal bearing a close external resemblance to
the Medusa. Here the central mouth is entirely absent ; but the
tentacula are channelled through their whole length, and their
tubes open at their base into the stomach. At the free
extremity, the tube of each subdivides and ramifies like the
roots of a plant; terminating in a number of small suckers,
in the centre of each of which there is a small pore. It has been
shown, by placing one of these animals in a coloured fluid, that
solid particles, if sufficiently minute, may enter these pores ; but
this species must either be nourished by extremely minute
animalcules, or by imbibing the juices of other animals, upon
which it fixes its suckers.

1033. According to Ehrenberg, a nervous circle may be
detected surrounding the mouth in some animals of this group ;
and another, connected with the first, running round the margin
of the disk. From the latter he states that filaments may be
seen to pass to certain red spots upon the edge of the disk, which
he imagines to be eyes. Upon this point, however, there is yet
considerable doubt. The animals of this group appear very
little sensitive to injurious impressions. They give no signs of
feeling the deepest and most extensive wounds of their surface ;
and the movements of contraction and dilatation have been seen
in parts of the disk almost separated from the rest, as well as in
the entire animals when nearly two-thirds of their bulk had been
lost by the draining of their fluids. In such instances, the move-
ments may be re-excited after they have ceased, by friction and
by punctures of the fibrous substance, just like those of the heart
and alimentary canal in the higher animals; and they would
seem to be of an equally involuntary character.

1034. Some very curious discoveries have been recently
made, in regard to the development of the embryo in the Medusa
and its allies. The esrsfs are transferred, when they leave the

O« *

ovarial chambers, into certain marsupial sacs or pouches, on the
under side of the arms. There they undergo the early stages
of their development, and then issue forth in the condition of

ACALEPHvE; CYDIPPE. 475

Animalcules, freely moving by the cilia with which they are pro-
vided at their edges. — After a time they fix themselves at one
extremity; and gradually become converted into Polype-like
animals. In this state they remain several months, obtaining
their food by means of long slender tentacula ; and each of these
polype-like bodies then separates, by transverse division, into
from ten to fifteen young Medusae, which gradually acquire the
form of the parent.

1035. Another most interesting form is the little Cydippe
(formerly called Beroe\ which is often abundant on our own
coasts. This animal is of a nearly globu-
lar form, sometimes a little elongated at
the two extremities, and about three-
fourths of an inch in length. It is com-
posed of a delicate jelly-like substance,
strengthened by eight bands of somewhat
firmer texture, which run like meridian
lines from pole to pole. These bands are
covered with rows of large cilia, arranged
side by side, so as to form narrow plates
?£±S±i toS£ of a fin-like character. There are, in the most
common species, from three to seven cilia
in each row ; and about twenty rows on each ridge. The whole
ridge is not unlike the paddle-wheel of a steam-boat ; but the
motion is given by the vibration of the separate floats, and not
by the revolution of the whole. Over these floats the animal
has evidently complete control ; it can retard or stop their move-
ments at pleasure ; and arrest the play of one, two, or more rows
whilst the remainder continue in rapid vibration. By these
means it is capable of swimming through the water with consi-
derable activity, and of changing its course at will. The animals
themselves are of a bright faintly-blue aspect; and the cilia
present vivid iridescent hues when in motion. The mouth
is situated at one of the poles of the globe, and it is always
directed forward when the animal is in motion. It is a wide
entrance to the short oesophagus, which terminates in the sto-
mach ; it can be closed by the animal when irritated ; but when

476 ACALEPHJE ; — CYDIPPE.

freely swimming through the water, it is always widely dilated.
From the stomach, there passes a narrow straight intestine, which
terminates at the opposite extremity of the body. When the
animal is in active movement, therefore, a continual stream of
fluid will enter its mouth, and will pass out again behind ; and
from the minute particles contained in this fluid, its nourishment
is probably in part derived.

1036. These apparently powerless little animals feed, however,
like other Acalephas, upon species of much higher organisation
and firmer texture ; and they are provided with similar means
of obtaining them. From the posterior part of the body arise
two filaments, which are many times its own length. These are
provided with lateral filaments, which arise at regular intervals
from one side along their whole course, and are spirally coiled
like the tendrils of a pea. The principal filaments do not arise
from the surface of the body, however, but from the bottom of
two deep cavities extending into its interior. Into these cavities
the main filaments with their appendages can be entirely retracted.
The lateral fibrils seem to contract spirally towards the longitudinal
filaments ; and the latter are drawn by irregular contractions
into the cavity, so as to be entirely concealed. When the animal
wishes to put them forth, it seems to contract the cavity, and the
filaments are jerked forth, as it were, not simultaneously, but
first on one side and then on the other. When the main fila-
ments have been ejected from the body, the little tendrils begin
to uncoil. When one of these beautiful little animals is placed
in a vessel of sea- water, it sometimes remains at the bottom,
projecting its long filaments upwards. At other times it darts
upwards with great velocity, drawing its long filaments after it,
retracting and extending them alternately. Not unfrequently it
remains for some time at the top of the water ; and, when it
wishes to descend, it turns over, drawing up its filaments sud-
denly, and then swims, mouth-downwards, to the bottom of the

1037. The Cesium Vmeris, or Girdle of Venus, an Acalepha
belonging to the same group with the preceding, is a flat riband-
shaped animal, which sometimes attains the length of five or six

CESTUM VENERIS. HYDROSTATIC ACALEPH^E. 477

feet, whilst its breadth is not more than as many inches. At first
sight, the form of this species might forbid us from ranking it
near the Cydippe. "When we examine its structure, however,
we find that there is a much greater real correspondence than
would have been suspected. The mouth is placed, not at one
extremity, but at the centre of one of the sides. The alimentary
tube passes straight across the body,6 and terminates on the
opposite side ; the digestive organs closely resembling those of the
Cydippe. The uniformly gelatinous consistence of the whole
animal, as well as this peculiar conformation of its alimentary
canal, forbid our ranking it in the Articulated series ; to which its
prolonged form might have led us to refer it, if the mouth had
been placed at one extremity, and the alimentary tube had
traversed its length. The edges of both sides are fringed with
cilia from one end to the other ; and it appears to be by the
vibrations of these cilia, rather than by any movement of the
body itself, that it is propelled through the water. As in the
Cydippe, a system of vessels absorbs the nutritious fluid produced
by the actions of the digestive apparatus, and conveys it to the
remainder of the structure, here so remote. And here, also, we
find a part of these vessels running under the ridges bearing the
cilia, as if to expose the fluid they convey to a stratum of water
continually renewed by the ciliary action. We might then regard
this animal as a Cydippe, flattened and extended in a lateral
direction ; and many very interesting forms of transition have
been discovered, which show that this view of its structure is
the true one.

1038. The group of Hydrostatic Acalephee, is characterised
by the presence of one or more large air- sacs, by which great
buoyancy is given to these beautiful animals. It would appear
that they have considerable power over these organs ; either
forcing out the air contained in them, or compressing it into a
much smaller compass, when they wish to sink ; and distending
the sac by some unknown means when they desire to rise.
"We seldom meet with anything like radial symmetry in this
group. The forms of the species are extremely variable and
irregular ; but there is usually a correspondence between the two

478 HYDROSTATIC ACALEPH^. PHYSALUS.

sides of each individual. A well-known example of this group
is the Physalus utriculus, commonly j,,

termed the Portuguese Man-of-war. This
possesses a single large air-sac, beneath
which the digestive apparatus is disposed ;
and the sac is surmounted by a sort of
crest (£>), which possesses a greater degree
of firmness than the rest of the structure,
and is elevated entirely above the water,
when the animal is floating at the sur-
face ; so that when exposed to the in-
fluence of the gentle breeze, the animal
is wafted by its means from place to place. FIG. ei 4.— PHYSALUS.
The air-sac itself possesses considerable muscular power. It is
provided with two orifices (0, c), one at each extremity, through
both of which air is forced out when the bag is compressed by
the hand ; each of these orifices is provided with a little circular
muscle, which usually keeps them closed, but which allows of
their dilatation during the continuance of the outward flow of air.
It is not improbable that the alteration in the specific gravity
of this animal required for its sinking in water, is effected partly
by the expulsion of air in this manner, and partly by the com-
pression of the remainder. No definite stomach can be found
beneath. There is a mass of short flask-shaped appendages,
which hang down from the under side of the air-sac, and are
terminated by suckers, with an orifice in each. Whilst the
lower surface of the air-sac is not itself above six inches from one
end to the other, the tentacula sometimes hang down like fishing
lines, to an extent of sixteen or even eighteen feet. They
generally possess an active stinging power, and are also very
contractile, so that they are able to draw the prey which they
have attacked towards their point of origin. It would seem that
the short suckers are attached to the bodies of animals thus
entrapped ; and that the Physalus derives its nourishment by
imbibing their juices through the pores of these numerous
cirrhi. This animal is one of those most commonly observed by
voyagers, sailing in fleets upon the calm surface of the ocean, and

ACALEPH.E. GENERAL SUMMARY. 479

disappearing with great rapidity when alarmed by the roughness
of the waves.

1039. Our account of the Acalephse cannot be better
summed up than in the words of M. Peron : — " Among the
animals of this family," he observes, " we find the most import-
ant functions of life performed in bodies which offer to the eye
little more than a mass of jelly. They grow frequently to a
large size, so as to measure several feet in diameter ; and yet we
cannot always determine what are their organs of nutrition. They
move with rapidity, and continue their motions for a long time ;
and yet we cannot always satisfactorily demonstrate their mus-
cular system. Their secretions are frequently very abundant,
and yet the secreting organs remain to be discovered. They
seem to be too weak to seize any vigorous animal, and yet fishes
are sometimes their prey. Their delicate stomachs appear to
be wholly incapable of acting upon such food ; and yet it is
digested within a very short time. Most of them shine at night
with great brilliancy, and yet we know little or nothing of the
nature of the agent which produces so remarkable an effect, or
of the organs by which it is elaborated. And, lastly, many of
them sting the hand which touches them ; but how, or by what
means, they do so, remains a mystery."

KK2

CHAPTER XXIV.

OF THE CLASS OF POLYPIFERA.

1040. No doubt can now exist of the Animal character of
the beings composing this class ; although the Plant-like form
which many of them present, deceived the Naturalists of former
days, as it does the uninformed observer at the present time,
into the belief of their Vegetable nature. In the works of the
older Botanists, the zoophytes (a term which may be advan-
tageously restricted to this class), whether hard and stony, or
flexible and horny, were arranged and described with Sea- weeds
and Mosses, without any misgivings as to to the propriety of
doing so. So far was this theory carried, that the Sea-Anemone
was described as a veritable flower ; and Count Marsigli, who
detected the existence of analogous beings in coral and madre-
pore, spoke of them as the blossoms of these stony plants. It is
now just a century since the doctrine of their Animal character,
now universally admitted, was received with any degree of favour
by the learned.

1041. It is only of late, however, that this class has been
carefully investigated and, well understood. A large proportion
of those compound structures, which are known as Coral^
Madrepore, &c., come under the inspection of Naturalists only
in their dry state, stripped of all that characterises the living
animal. Hence their classification has, until recently, been
founded solely upon the characters presented by these structures.
Some of them are massive and stony ; others of more delicate
conformation, and of horny consistence. Some of them serve as
a central axis or stem, which is clothed with the living flesh ;
others form a tube, which sheaths the softer tissues, and this
variety is found to exist among both the stony corals or litho-
phytes, and the horny flexible corals or keratophytes. Moreover

GENERAL CHARACTERS OF POLYPIPERA. 481

there are some polypes which do not form associations, and
which deposit no hard skeleton, but which are closely allied in
general structure to those that do ; such are the Hydra or fresh-
water Polype (Fig. 615), and the Actinia or Sea- Anemone (Fig.
617). In the classification founded only upon the characters of
the compound masses, therefore, the naked Polypes (as they were
termed) were associated into a separate order. By this method
— as by any which depend upon a single set of characters, and
are therefore artificial — beings the most dissimilar were asso-
ciated together ; and those which were really allied in the
structure of the individuals, were separated, because there was a
dissimilarity in the form of the compound masses.

1042. Bearing in mind the resemblance formerly pointed
out, between one of the compound Polypifera and a Vegetable
structure, in regard to the aggregation of distinct individuals into
one common life (§ 986), we shall at once perceive the necessity
of looking for the characters which are to serve for the classifi-
cation of this group, not in the degree of density of the stem, or
in the arrangement of its branches, but in the structure of the
separate Polypes. The Botanist well knows that in the leaves
and flowers he must find the materials for his classification ; and
not in the degree of firmness of the wood, or the mode of growth
exhibited by the whole structure, which are liable to vary so
much with age and circumstances, and to differ so completely in
species which are really in close alliance. In this manner, the
class of POLYPIFERA may be divided into four Orders, character-
ised by four distinct kinds of structure. Each of these Orders
contains Polypes in various degrees of association ; — some living
solitarily ; — some existing in societies ; — some united by a con-
necting flesh ; — and some having a common circulation of fluid
amongst them. Each, therefore, contains some which form a
solid structure, and others which are destitute of it. — The differ-
ences between these Orders are such, that it will be desirable to
give a detailed account of each separately.

482

ORDER I.— HYDROIDA.

1043. The Hydra, to which reference has been made as the
type of one of the divisions of the Polypifera, is a minute animal,
common in stagnant pools of water,
where numbers are often found
clustering upon aquatic plants, or
other floating bodies. Although
most of the species prefer fresh
water, some are occasionally found
at sea. These curious little crea-
tures possess an organisation which
appears very simple, and so it has
long been considered; but recent
improvements in the power of the
microscope have enabled its struc-
ture to be more fully analysed, and
have revealed (in this as in every
other instance) details that were
previously unsuspected. The Hydra
viridis, or Green Polype, and the

Hydra fusca, or Brown Polype, are the two best known species ;
and to these our description will chiefly apply. The body of
the Hydra consists of a simple bag, or sac, constituting the
stomach of the animal, and capable of varying its form and
dimensions to a very remarkable extent. In the largest species
it sometimes attains the length of an inch, when stretched out in
a cylindrical form ; whilst it will appear, in its contracted state,
as a small globe of scarcely perceptible dimensions. At the
upper end of this digestive sac is an opening, which may be
regarded as the mouth of the animal ; and round this are arranged
a certain number of tentacula^ or long flexible arms, which diverge
from each other like the spokes of a wheel. If we look at the
mouth of the Hydra from above, therefore, we shall at once
perceive the claim of this animal to a place among the Radiated
Sub-Kingdom, The arms vary in number ; being usually from six

FIG. 615.— HYDRA.

HYDRA; ITS ACTIONS. 483

to ten. They vary also in dimension ; not exceeding in the for-
mer species the length of the body; whilst in the latter they often
extend themselves to as much as seven or eight inches, still heing
able to contract themselves down to minute tubercles or knobs
projecting around the mouth. The animal, in its general aspect,
is thus seen to bear a close resemblance to the Cuttle-fish ;* and in
the peculiar organisation of its arms for the seizure of prey, this
resemblance, as we shall presently see, is extremely remarkable.
In fact, this little Polype may be regarded as one of those
sketches or fore-shadowings of higher forms, which we occasionally
meet with in the lowest groups.

1044. The arms are destitute of cilia ; and this is an import-
ant character, by which all the Polypes of the Hydra-form kind
may be at once distinguished from those of a higher group
(§ 1095). They are thickly set, however, with minute bristles ;
besides which, a number of little wart-like processes may be
observed, from whose summit sharp and firm spines are occa-
sionally protruded, by which a very firm hold is taken of what-
ever substance is embraced by the animal. The mechanism by
which these are pushed out of their sheath is very curious.
Each spine is mounted upon the summit of a small vesicle,
which is capable of expanding and contracting within an
envelope, that embraces the whole apparatus. When at rest,
this vesicle lies at the bottom of the including sac, and the spine
is drawn entirely within it ; but, when the animal lays hold of
any object with one or more of its arms, the vesicle is distended
by some unseen means, and protrudes the spine which is seated
upon it.

1045. When in search of prey, the Hydra permits its arms to
float loosely through the water. It is rather curious that so
inactive a creature as this should principally depend for its food
on the minute Crustacea and aquatic Worms, whose rapid move-
ments would seem to place them beyond its reach. By lying in
wait, however, with its arms thus disposed, the Polype soon

* It was this resemblance which caused Reaumur to give to the Hydra the
name of Polypi; the polypi of the ancients being the animals now included in the
genus Octopus of the Cephalopoda.

484 HABITS OF HYDRA.

succeeds in obtaining its supply ; for if, in their active course-
any of these animals should but touch one of the tentacula, its
doom is sealed ; — it is immediately seized by it ; — other arms are
soon coiled round it ; — and the unfortunate victim is speedily
conveyed to the mouth. It has been noticed that, if held for a
little time in the arms without being swallowed, soft-bodied
animals (such as worms) always die, even when released alive ;
whence it has been inferred, with some plausibility, that the
spines are the means of conveying into the prey some poisonous
secretion, in the same manner as the poison-fang of the Serpent,
or the sting of the Bee. Upon minute Crustacea and other hard-
shelled animals, however, this secretion appears to have no power.
Such animals are often swallowed alive, and their movements
within the stomach may often be perceived for some little time ;
but, their life being at last destroyed, the process of digestion
goes on very rapidly. The transparency of the membrane
which composes the stomach, at first permits the outline of the
animal to be clearly seen. The film over it gradually becomes
turbid, however, and the outline of the animal indistinct ; until,
at last, its form is wholly lost. The soft parts are completely
dissolved; and the harder indigestible portions are rejected
through the mouth. This is, at least, the case with regard to
the larger masses; the more finely-divided parts seem to be
expelled through a small orifice at the opposite extremity of the
cavity, evidently corresponding with that which, in the com-
pound Hydraform Polype, opens into the tube that connects all
the individuals by a common circulation (§ J 056). It would
seem that Animal matter is more readily dissolved than par-
ticles of Vegetable structure.

1046. It not unfrequently happens that, in the process of
swallowing, the Hydra draws in its own arms, which are coiled
round its prey. The digestive process never seems to affect
them, however, in the slightest degree ; even though they remain
thus inclosed during the whole period of the solution of the
food. Trembley, the first discoverer of these Hydras, to whose
accurate description of their habits scarcely anything has been
added by subsequent observations, once witnessed a very curious

HABITS OF HYDRA. 485

circumstance. " Two Polypes had seized upon the same animal ;
both had partially succeeded in swallowing it; when the largest put
an end to the dispute, by swallowing its opponent, as well as the
subject of contention. Trembley naturally regarded so tragical
a termination of the affray as the end of the swallowed Polyp's
existence ; but he was mistaken ; for, after the devourer and his
captive had digested the prey between them, the latter was
regurgitated safe and sound, and apparently no worse for the
imprisonment." It has been noticed that, when the Hydra is
gorged with food, its tentacula may be touched with impunity
by the animals, whose contact would at other times arouse it
into active movement. This scarcely proves, however, an exer-
cise of the will, to which some have referred it. We may easily
understand that the distention of the whole of the tissues with
fluid may be unfavourable to their contractility ; and we have a
parallel case in the Human being, for every one can perceive the
difference in the facility of swallowing, at the commencement and
termination of a full meal. It will scarcely be asserted that this
variation is an effect of the will ; in fact, it is often opposed to
it, being one of those beautiful adaptations, by which the welfare
of the economy is provided for, but which the indulgence of the
sensual appetites opposes.

1047. When the difference between the external integument
and the lining of the stomach is considered, it seems not a little
wonderful that the two should be mutually convertible. Yet
such is the fact. Amongst the many curious experiments per-
formed on these animals by Trembley, was the following : — By
means of a fine wire, he actually succeeded in turning the Hydra
inside-out, as we might the finger of a glove ; and this violent
disturbance did not seem to interfere with the comfort of the
animal, for all its functions soon went on as before. What was
previously the lining membrane of the stomach now becomes the
external integument, and from it the buds are produced, which
will be presently described ; whilst the tegumentary membrane
seems to be capable of speedily doing all that is necessary, towards
the digestion of the food. The remarkable power with which
these Polypes are endowed of adapting themselves to circum-

486 NUTRITION AND REPRODUCTION OF HYDRA.

stances, seems to be given to them as a compensation for their
low degree of organisation. While the want of cilia on their
tentacula prevents the creation of currents for the purpose of
bringing a constant supply of food to the mouth, and thus affords
less choice to the animal, the body is so constructed as to be
capable of accommodating itself to a prey of extremely variable
size ; and the digestive secretion can act upon almost any kind of
organised substance, so as to convert it into alimentary materials.
And, in like manner, the absence of any special means of aerat-
ing the fluids is compensated by the exposure of every part of
the tissue, both by its internal and external surface, to the
surrounding element.

1048. The reproduction of the Hydra usually takes place by
means of buds developed from its external surface. At first these
appear as slight protuberances from the body ; they gradually
increase in size, and present somewhat of the form of the parent ;
an aperture is then seen at the unattached extremity, and tenta-
cula sprout around it. During the whole of this period, the
interior of the young Polype communicates with the general
cavity of the parent. At first its nutriment is supplied entirely
by the latter ; but when the tentacula are developed, it catches
prey for itself with much eagerness. It is not an unusual thing
to see the young one and its parent struggling for the same
worm, and gorging opposite ends of it together. There is still a
communication between the stomachs of the two, as appears from
the distention of either when the other is fed. As the young
Polype advances towards maturity, however, this aperture con-
tracts, and is at last obliterated. The stalk, by which the bud
is attached, gradually becomes more slender ; and at last it is
broken by any slight effort on the part of either animal, and the
young one swims off. Not unfrequently, however, it has begun
to produce buds from itself, before its separation from its parent ;
and thus three generations may be seen united together. During
warm weather, this multiplication goes on with great rapidity,
if the animals are well supplied with food. From one parent,
six or seven buds have been seen to sprout at one time ; and,
several of these bearing another generation, as many as eighteen

REPRODUCTION OF HYDRA. 487

have been observed united in one group. Sometimes the whole
process is concluded within twenty- four hours ; so that, at this
rate of production, above a million would be formed in a month
from a single Hydra.

1049. It is not only in this manner, however, that the Hydra
propagates itself. The process just described is evidently analo-
gous to the extension by buds, which is so characteristic of
Plants. But there is another mode of reproduction in the
Vegetable kingdom — that by seeds or spores ; and this, also, the
Hydra possesses, in common with all the higher tribes of Animals.
Towards autumn, some little gelatinous globules are seen to be
liberated from the tissue of the Polype. These fall to the bottom
of the water, and remain undeveloped until spring ; when they
produce a new generation of Hydras, which are said to be smaller
than those which have sprung immediately from the parent.

1050. Perhaps the most remarkable feature in the history of
the Hydra, is its capability of reproducing the whole structure
from separate portions of it. Not only will the body send forth
new tentacula, to replace any which have been accidentally lost
or artificially removed, but the arm thus separated has the power
of developing the whole body. If the body is divided trans-
versely, each segment will become a new animal ; the upper one
closing the aperture at its base, and the lower one speedily
developing tentacula around the newly-formed mouth. If divided
longitudinally, each half will form a separate tube in an hour, by
the folding-in of its edges, and will soon begin to ply its ten-
tacula. Even if divided into several longitudinal strips, each
becomes a new tube ; not as before, however, by the folding in
of its edges, but by the formation of a cavity in its substance.
If cut transversely into several segments, each will in time
become a perfect animal, so that thirty or forty Hydra may thus
be produced by the section of one. Further, by slitting the
tube at one end only, two heads or two tails may be formed —
each division soon becoming perfect in itself. These may be again
divided, and any amount of multiplication may thus be effected,
thus realising in Nature the Hydra of ancient fable. The animal
does not appear to suffer from these experiments, for it is

488 SENSIBILITY AND MOVEMENTS OF HYDRA.

observed that, as if excited by the injury, young Polypes sprout
more abundantly from the wounds thus made, than from un-
scarred parts. But even this is not all ; for two Polypes may
be grafted together by any parts ; and not only two of the
same species, but a green and a brown one may be thus
united.

1051 . The Polype does not seem to possess any special organs
of sensation, or to have any kind of feeling but that of touch.
It may be doubted, indeed, how far the greater part of its ac-
tions necessarily involve true .sensation ; that is, how far it is con-
scious of the impressions which are made upon it, and to which
its organs respond. Many of its movements present considerable
analogy with those of Plants ; especially those of the Dioncea
(VEGET. PHYSIOL. § 422). The Hydra generally seek the
light ; and, if a number of them be placed in a glass vessel, they
will cluster at the side on which it strikes. We have no reason
to suppose, however, that they are conscious of its presence as
light, since no rudiments of visual organs can be detected. It
would rather seem that it exercises an influence on their bodies,
which causes them to seek it, very much in the same manner
that Plants direct themselves towards it. The locomotive powers
of the Hydras are more exercised for this purpose than for the
search after food. When seeking their prey, they generally fix
themselves, by a kind of sucker at the lower end of the stomach,
to some solid body ; and their food is obtained by the tentacula
alone. When they desire to change their place altogether, they
do it in the manner of the geometrical Caterpillars (§ 702), and
of some Leeches. If the foot or sucker be attached, the body is
bent until the head touches the surface, along which it intends
to move. It then adheres by the mouth, or by one or two of
the tentacula ; and, detaching the foot, draws it up into close
proximity with the head. The foot then takes a fresh attach-
ment ; and the head is projected forwards, fixes itself, and is
followed by the foot in the same manner as before. This mode
of progression is, from the minute size of the animal, necessarily
slow. A march of two inches occupies several hours for its per-
formance ; and seven or eight inches may be regarded as a very

HYDRA. — HYDRAFORM POLYPES. 489

good day's journey even in summer. But sometimes a more
expeditious mode of travelling is adopted. The head being
brought down and fixed as before, the foot is made to describe a
semicircle over it, and .takes its new attachment at an equal
distance on the other side ; the foot being then fixed, a similar
movement is performed by the head ; and thus the animal ad-
vances by a succession of somersets.

1052. By these and similar means, the Hydrce are enabled
to move along solid surfaces, such as the bottom or sides of the
vessel in which they are contained, and the leaves or stems of
aquatic plants. There is another very curious position, to which
it frequently has recourse. By projecting the flat surface of the
foot above the water for a short time, it soon becomes dry, and
in this state serves, by its repulsive action on the water around,-
as a kind of float, from which the animal suspends itself. In
this state it can move itself, by means of its tentacula, with
great facility ; and it is also acted on by the wind, so that it
can travel a considerable distance without effort. If, whilst
thus floating, a drop of water be made to fall upon the foot so
as to wet it, the hydrostatic power of the organ will be
destroyed, and the animal will immediately sink to the bottom.

1053. The first subdivision of the Polypifera, — termed
Hydroida or Hydra-form^ or Sertularian Polypes, from the
name of one of its most characteristic genera, — includes, with the
simple genus just described, all those compound structures, in
which a number of Polypes similar to it are associated together.
In all these, the polypidom, or solid frame-work which gives
support to the softer portions of the structure, is external to the
living animal matter, and incloses it as in a tube. It is of a
texture varying from that of membrane to that of horn ; it
never contains stony matter to any amount ; and it is always
flexible. This horny sheath is formed by the consolidation of
the living animal membrane, which originally acts as the
envelope of the soft and almost fluid texture within ; and it is
continuous with the external layer of that, which forms the
Polypes themselves. This horny tube is enlarged at certain
points into sheaths or cells for the protection of the Polypes ;

490 HYDRAFORM, OR SERTULARIAN POLYPES.

within these the individuals can retract themselves, although,
when in search of prey, they extend beyond it. Each single
Polype resembles a Hydra in every important respect but this; —
the stomach, instead of being nearly closed at the bottom, com-
municates freely with the interior of the stem and branches ; and
the membrane lining its sac may be regarded as a prolongation
of that which surrounds their cavity. The pulp contained in
the hollow stem, rather than the Polype itself, appears to be the
essential part of the animal ; for the latter is not only formed
subsequently to it in the first instance, but frequently dies, and
is reproduced by it.

1054. Of all Zoophytic productions, these structures are the

most graceful in their ap-
pearance, and delicate in
their conformation. They
are very abundant on our
own shores, seeming to prefer
temperate to tropical cli-
mates ; and they constitute
a large proportion of what
are commonly, but incor-
rectly, denominated Coral-
lines* They have generally
a plant-like aspect ; consist-
ing of a stem, attached at
its base (where it sometimes
diverges into root-like pro-
longations) to some larger
mass, and sending off its
branches above with extreme
and mostbeautifulregularity.
The cells are arranged upon
the sides of these, like the
FIG. Gia-SERTULARrAN POLYPES, minute leaflets of Mosses ;

and it is not surprising,

* The real Corallines are a much smaller group, probably of Vegetable charac-
ter. In general aspect, their stems have some resemblance to those of the Sertu-

HYDRAFORM OR SERTULARIAN POLYPES. 491

therefore, that by the older Naturalists, who were ignorant of the
existence of the Polypes, these productions were regarded as of
a vegetable nature, and were termed Sea-Mosses. The resem-
blance is still more striking when the mode of propagation in
the two groups is contrasted.

1055. Although the reproductive gemmules are in some
instances produced from the Polypes themselves, as in the
Hydra, a more special apparatus is usually evolved for the
purpose. At certain periods, there are formed from particular
spots upon the stem of the Sertularia and its allies, expansions of
its horny structure, somewhat resembling those which encase
the Polypes, but usually larger. These ovarial vesicles, which
so much resemble the urns of Mosses ( VEGET. PHYSIOL. § 429),
are like them provided with a lid, which falls off when the con-
tained gemmules are mature, so as to permit their escape ; and
after their purpose is thus completed, the vesicles fall off, like
the seed-capsules of all plants. The gemmules are usually
clustered around a central column (analogous to the columella of
Mosses) ; and when mature they swim forth by the action of
the cilia with which they are provided, being detached from the
central column at the same period that the lid of the vesicle falls
off. The gemmules move to and fro by the vibration of their
cilia, during a period which varies from a few hours to two or
three days. When they have fallen upon a site fit for their
development, they attach themselves to it by a root-like fibre,
and then begin the formation of the polypidom. The real
nature of this gemmule has been elsewhere explained (ANIM.
PHYSIOL. § 745).

1056. All the compound Hydroida are inhabitants of the
ocean. Some of them seem to attach themselves indiscriminately
to any solid mass ; whilst others seem to have a preference for
some particular kind of support. Thus one is found only on
rocks which are constantly beneath the surface ; others on those
which are occasionally uncovered by the sea ; and others attach

larian Polypes ; and hence they are associated together in the minds of those
ignorant of this department of Natural History. The real Corallines may be
distinguished by the absence of any trace of cells upon their surface.

492 HYDRAFORM POLYPES. HELIANTHOIDA.

themselves to the fronds of Sea- Weeds, which are exposed by the
reflux of every tide. The deserted shells of Mollusca are the
favourite bases of many species ; and a few attach themselves
even to these tenants of the deep whilst yet alive. The duration
of these structures is various. Many of them do not exist above
a year, especially such as are parasitic upon Algae ; but others,
particularly those which attach themselves to rocks, probably
attain a much greater age. It would seem, however, that the
age of the Polypes cannot be measured by that of their cells.
In some instances all the Polypes disappear during the winter,
dying off like the leaves of a tree ; and they are all renewed
with the light and warmth of spring, whilst at the same time
fresh branches are produced. In other species, a constant death
and regeneration of the Polypes seem to take place.

1057. One of the most curious phenomena exhibited by the
Polypes of this group, is the circulation which may be seen to
take place in the stem and branches, and which seems to con-
nect the different individuals together. This circulation much
resembles that which has been described in the compound Asci-
dians (§ 979), and is, like it, reversed in its direction at intervals;
but only a single current can be seen at a time ; and it is not
maintained by any visible movement of the walls of the cavities
or tubes in which it takes place. The flow is sometimes very
rapid ; it then slackens, and at last stops ; and recommences,
sometimes immediately, sometimes after an interval, in the oppo-
site direction. Five ebbs and flows have been observed to occupy
about fifteen minutes.

ORDER II.— HELIANTHOIDA.

1058. No very evident links of transition exist between the
different subdivisions of the class Polypifera ; and we accordingly
pass at once to the next group, of which the common Actinia
(Sea- Anemone) may be regarded as the type. Although so
different in size and general appearance from the Hydra, this is,
like it, a Polype; and the difference will be found, on close

ACTINIA OR SEA-ANEMONE. 493

examination, to consist more in the relative development of the
different parts, than in any fundamental change in their arrange-
ment. The animal still consists principally of a stomach ; this
is provided with but one orifice, the mouth, which is fringed with
numerous tentacula. Instead, however, of the delicate membrane
composing the walls of the stomach in the Hydra, we have a
dense fleshy sac, possessed of considerable firmness, but still very
extensible. And, instead of the few long filamentous tentacula,
we have a large number of short fleshy arms, arranged in several
circles round the mouth. Further, instead of the prolonged
pedicle or foot, with the minute sucker at its extremity, which
has been described in the Hydra, we observe in the Actinia an
expanded fleshy disk, which forms the whole base of the animal,
and which is of size sufficient to take a very firm attachment to
the rocks upon which it is fixed. The whole body may be
likened to that of the Hydra in its most contracted state. When
the Actinia closes its mouth, folds in its tentacula, and draws
together the upper part of its body, it presents an almost hemi-
spherical form — the flat side being attached to the rock, and the
mouth being just visible at its summit ; but when the animal
expands itself, the body represents a short cylinder, the mouth
becomes as wide as the base, and the fringes of tentacula display
their brilliant colours to the light of day. The arrangement arid
appearance of these so much correspond with that of the petals
of double flowers, still more with that of the flowerets of the
Composite tribe, that it is by no means surprising that the
uninformed observer should almost always regard this being as
a member of the Vegetable Kingdom. The movements it exhi-
bits are not, when superficially considered, very different from
those which take place in certain Plants ; and there is nothing
ridiculous, therefore, in the appellation given to it by Hughes,
who, in his Natural History of Barbadoes (a work published
before the distinctions between the Animal and Vegetable King-
doms were properly understood), denominates it a sensitive plant
having animal properties.

1059. The Actinias, are found on the shores of every sea. As
in other tribes, each species has its peculiar haunt. In general,

494 ACTINIA OR SEA-ANEMONE.

we find them attached to rocks, which are alternately left dry
and submerged by the tide. Sometimes, however, the portions
which are constantly under water, are selected as their habita-
tion ; and they may be observed suspending themselves from the
vaults of submarine reefs, or covering the sides of rocks as with
a tapestry of flowers. Brilliant as are the colours exhibited by
the species common on our own shores, when these are illumined
by the direct rays of the sun, they are far surpassed by the
glowing hues of the tropical Actiniae ; and the relative abund-
ance of the two is nearly the same. Many voyagers have
spoken with enthusiasm of the gorgeous spectacle presented by
groups of these animals ; and Le Sueur describes himself as with
difficulty withdrawing from the contemplation of it, to collect
specimens for examination.

1060. Here it may be thought, that the pursuits of the
scientific investigator of Mature are inconsistent with that simple
admiration of her beauties, which is capable of affording so high
and pure a gratification to the most uninstructed mind. But it
may be questioned whether the two are really incompatible, or
whether, if rightly directed and cultivated, they do not strengthen
each other. Need an acquaintance with the wondrous structure
and curious habits of beings like those we are considering,
diminish our pleasure in the contemplation of the beauty of their
forms and the arrangement of their colours ? And does it not
become a source of still higher gratification, a pleasure more
purely intellectual because less dependent upon the senses, when
we regard these graceful forms and glowing hues, not only as
beautiful in themselves, but as forming a part of that great
scheme, in which Infinite Benevolence is so wondrously displayed
in conjunction with Infinite Wisdom and Infinite Power. There
are some who arrogate to themselves the title of " lovers of
Nature," and affect to despise the minute acquaintance with
detail, which the Man of Science aims at obtaining. They deem
such knowledge injurious to that taste for her beauties, which, in
their minds, is paramount to every other consideration. And
there are others who run to the opposite extreme, overlooking, in
their eagerness for scientific research into her more concealed

ACTINIA OB SEA-ANEMONE. 495

wonders, those beauties which are bountifully scattered over her
surface, as if to invite us to further acquaintance. As an expres-
sive countenance displays the workings of the mind within,
combined with the beauty which itself possesses, and attracts us
to the study of the mind which animates it, so should the varied
beauties which abound on the face of Nature, lead us to the
contemplation of that Mind which at first formed and which is
continually acting through all. It is only when either of the
tendencies above alluded to is indulged in its exclusiveness, that
it can interfere with the other. Much will depend upon early
education and habits ; much upon subsequent self-training. For
ourselves, we admire the feeling of Le Sueur, who walked for
some time on the shore of the calm ocean, indulging his admira-
tion of the beauties which it exhibited, before he could prevail
upon himself to make even a slight interruption in the brilliant
spectacle, of which he was" the sole witness.

1061. The Actinice which attach themselves to rocks, some-
times adhere so firmly, that they cannot be removed without the
laceration of their base. This fleshy disk adapts itself perfectly
to the inequalities of the surface ; and even sends down little
prolongations into any pits or fissures that may exist in it.
There is an interesting species inhabiting the British seas, the
Actinia maculata, which attaches itself to dead shells, forming
from its base a kind of horny expansion, that partly extends over
their aperture. It has been remarked by Dr. Coldstream that
in all the specimens which came under his notice, a Hermit-Crab
had taken up its abode in the shell. It would seem, therefore,
as if the addition made by the Actinia rendered the shell pecu-
liarly suitable for the habitation of this tenant. Some species of
Actiniae confine themselves to the smooth sands, on the surface of
which they spread out their tentacula, and beneath which they
withdraw when danger threatens. Although the body has, in
general, no further covering than the leathery envelope already
mentioned, there are a few species (such as the Actinia verrucosa
of the British seas) which, by means of a glutinous exudation
from the body, form a kind of case by attaching together bits of
shell, grains of sand, and other small substances. This casing

LL2

496 ACTINIA OR SEA-ANEMONE.

would seem to have for its purpose the concealment of the animal,
as much as its direct protection. Individuals of the same species,
inhabiting deep water, as if aware that they do not require such
a mode of concealment, form no extraneous covering, but leave
the surface clean ; and this then acquires more vivid and varied
tints, whilst the glandular warts by which the glutinous secre-
tion is formed, become smaller, or disappear,
: 1062. The essential difference between the Hydra and the
Actinia consists in this ; — that in the former the stomach occu-
pies the whole volume of the body, the membrane which lines it
being the same with that which serves as the general envelope ;
whilst, in the latter, the stomach has walls of its own, being
suspended (as it were) in the middle of the body, and leaving a
considerable space between its exterior surface and the general
envelope. This cavity is divided by vertical partitions, which

FIG. 617.— A, SEA-ANEMONK seen from above. B, SECTION OF SKA-ANEMONE ; a cavity
of stomach, b surrounding chambers.

pass in a radiating direction from one membrane to the other, so
as to form a considerable number of chambers arranged round
the central digestive sac. In these chambers the germs of young
Actiniae are evolved. There is not any regular communication
between the chambers and the stomach ; although it would seem
that an opening must be occasionally formed, as young polypes
are often sent forth by the mouth (§ 1067). The partitions all have
openings, however, by which the chambers communicate with
each other ; and there is also a free entrance from them into the
tubes of the hollow tentacula, which are formed of a membrane
like the envelope of the body, and are provided with an orifice
at their extremity, which the animal has the power of closing.

ACTINIA OR SEA-ANEMONE. 497

1063. The muscular structure of the fleshy base of the inner
part of the general envelope of the radiating partitions, and of
the circle round the mouth, is very distinct in the larger species
of Actinia^ and confers upon the animal considerable power in the
prehension of food. Dr. Grant mentions that he has caused the
common Actinia crassicornis to lift a basin of sea-water, weighing
more than six pounds, by making it swallow the perforated shell
of a Purpura, through the aperture of which a cord had been
passed. By this cord the basin was lifted, without the Actinia
quitting its hold — either of the shell in its contracted stomach, or
of the basin to which its foot was attached. It is not surprising,
therefore, that these polypes should be able to master not only
shell-fish and other animals that have little means of active
resistance, but even crabs, prawns, and other Crustacea of con-
siderable size. These, indeed, seem to constitute its ordinary
food. The luckless individual which walks over one of these
stomachs gaping for its prey, is immediately secured by its ten-
tacula, and in spite of its struggles is drawn into the mouth,
which seems capable of distention to an almost unlimited degree.
Sometimes the tail of a shrimp, or some other hard projecting
appendage, will occasion a little trouble, and may be seen in
active movement outside the mouth, when the mass of the body
has been swallowed ; but this is soon restrained by the tenta-
cula, which entwine themselves round it, and gradually convey
it into the stomach. These tentacula possess a remarkably
tenacious power, which has been attributed to a glutinous
exudation from them ; but nothing of this kind can be seen on
surfaces to which they have firmly attached themselves, and
their adhesion is more probably due to the temporary conversion
of a part of the arm into a sort of sucker.

1064. The digestive powers appear very considerable ; for
when Mollusca or Crustacea have been swallowed, the shells are
subsequently rejected by the mouth, with not only their soft
contents, but even their tendinous and ligamentous portions, dis-
solved away. It has been said that the Actinia sometimes
swallows a shell, of which it cannot get rid in the usual manner,
owing to its broad diameter being turned to the mouth ; and

498 ACTINIA OR SEA-ANEMONE.

that the troublesome substance works its way out through the
sides of the body, the artificial aperture soon closing, and the
animal appearing to suffer but little inconvenience. In rejecting
through its mouth the indigestible substances remaining within,
the Actinia seems to draw up the stomach towards the orifice,
so as the more completely to expel its contents. Sometimes
this muscular action, which is assisted by the compression exer-
cised by the general envelope, is carried so far, that the stomach
is everted — completely turned inside-out — through the mouth.
This fact is familiar to all, who have watched the habits of these
animals on the sea-shore.

1065. The Sea- Anemone never seems to decline any article
of food presented to it, on account of its bulk, but makes the
most laudable attempts to swallow it, though occasionally com-
pelled to relinquish its vain endeavours, and even to disgorge
what it had partially swallowed. Sometimes the process of
digestion is going on in the lower part of a mass which has been
included in the stomach, whilst the remainder is projecting
above the mouth, being gradually drawn inwards. It will hence
be seen, that few animals surpass the Actinia in voracity. Never-
theless it is capable of fasting for a considerable period ; or, at
any rate, of subsisting upon no other nutriment, than the small
quantity of animal matter that may be diffused through the sea-
water, in which it is kept. It is after such a fast, that the efforts
to swallow are most vigorous ; and sometimes an amusing
spectacle is presented by the contest of two for the same prey.

1066. Sea-Anemonies do not seem to exercise any choice in
regard to food ; but will swallow whatever is placed within the
grasp of their mouth, — not even their own kind being exempt.
They contract their tentacula and close the mouth, not only
when mechanically irritated, but even when any change takes
place in the amount of light to which they are exposed. When
fully expanded, and displaying their glowing colours to the mid-
day sun, a passing cloud will cause them to fold in their flower-
like summits ; and even the shadow of the hand will produce
the same effect. The following interesting account of those
inhabiting a rock-basin on the shore of Barbadoes, is given by

ACTINIA OR SEA-ANEMONE. 499

Hughes in his Natural History of the Island. " In the middle
of the basin, there is a fixed stone, or rock, which is always
under water. Bound its side, at different depths, seldom
exceeding 18 inches, are seen at all times of the year, issuing
out of little holes, certain substances that have the appearance
of fine radiated flowers, of a pale yellow, or a bright straw
colour, slightly tinged with green, having a circular border of
thick-set petals, about the size of, and much resembling, those
of a single garden marigold. I have attempted to pluck one of
these from the rock, to which they are always fixed, but never
could effect it : as soon as my fingers came within two or three
inches of it, it would immediately contract close together its
yellow border, and shrink back into the hole of the rock ; but
if left undisturbed for about four minutes, it would come
gradually in sight, expanding, though at first very cautiously,
its seeming leaves, till at last it appeared in its former bloom.
However, it would again recoil, with a surprising quickness,
when I came within a little distance of it. Having tried the
same experiment by attempting to touch it with my cane and
a slender rod, the effect was the same." This last statement
shows a high degree of sensibility to light ; since there is no
reason to believe that any special organs of vision are possessed
by these animals, which can enable them to see objects in their
neighbourhood. They appear also to be, like some plants, very
easily influenced by atmospheric changes ; and this, even when
kept for some time within-doors. The Abbe Dicquemare, who
watched their indications for many years, considered them a
most valuable marine barometer ; fine weather being indicated
by their expansion, bad weather by their closure, and very
boisterous weather by their extreme contraction.

1067. These movements are not the only ones, however,
unconnected with the prehension of food, exhibited by this
interesting animal. It is observed frequently to distend itself
with water, so as to attain many times its usual size, — the
membranes of its body becoming proportionally thinner.
This water is not taken in by the mouth alone ; indeed it is
doubtful if any enters there under these circumstances ; at any
rate, the chief part is introduced through the orifices at the

500 SEA-ANEMONE; ITS REPRODUCTIVE POWERS.

extremity of the tentacula, and the distension exists in the
radiating chambers and arms rather than in the stomach. The
water is afterwards expelled in jets through the same orifices
with considerable force ; so as to rise to the height of a foot or
more. There is reason to believe that this process is chiefly one
of respiration. The whole interior of the chambers, into which
the water is received, is covered with vibratile cilia ; and it has
been observed that, if Actiniae are kept in a limited quantity of
water, from which the air is soon exhausted, the distension
of the body is enormously increased, so that its appearance
•almost resembles that of an inflated bladder. Sometimes
this distending process appears to be performed for the purpose
of facilitating locomotion. The animal is then almost of the
same specific gravity with water ; and, if it withdraws its foot
from its attachment, it is carried away by the least agitation of
the water, and may thus go in search of a new abode without
exertion of its own. When it is cast upon a surface adapted to
its wants, it forms a new attachment ; and there remains, until
deficiency of food or some other cause again excites it to removal.
It would appear that, when thus supported by the water, it can
use its tentacula for assisting in its movements ; and can even
walk upon these, turning its mouth downwards. It can, how-
ever, glide along the surface of a rock, by the alternate contrac-
tion and expansion of the fleshy foot in one particular direction,
—in just the same manner that the Snail, or other Gasteropod
Mollusca, perform their movements.

1068. The power enjoyed by the Actinia of reproducing
parts of which it has been deprived, is almost equal to that pos-
sessed by the Hydra (§ 1050). Our knowledge of it is principally
due to the experiments of Dicquemare. He found, that if the
tentacula be cut off, they are soon replaced. If the body be
divided transversely, — so that the upper portion possesses a
•mouth and tentacula but no base, and the lower one has the
base and open stomach without a regular mouth or tentacula, —
both parts will continue to live, the one gradually closing its
under side,* and forming a new disk, the other after some

* This is not always the case, however. In one instance, a new set of tentacula
were sent forth, and a complete new mouth formed, at the lower orifice ; so that
the animal could take food bv either.

SEA-ANEMONE; ITS REPRODUCTIVE POWERS. 501

months acquiring a complete new set of tentacula and a perfectly,-
forrned^mouth. The upper part did not seem conscious of the
loss of its base ; but, like Baron Munchausen's celebrated horse,
took food presented to it, even though it passed out almost
immediately by the orifice newly-created below. If the body
be divided vertically, each half becomes in time a perfect
animal, capable of performing all its functions ; and it would
appear that such a division occasionally takes place sponta-
neously. The following very curious instance of the power,
which the structure of this animal has, of adapting itself to
circumstances, is related by Dr. Johnston. "Iliad once brought
me a specimen of Actinia gemmacea, that might have been
originally two inches in diameter, and that had somehow con-
trived to swallow a valve of Pecten maximus of the size of an
ordinary saucer. The shell, fixed within the stomach, was so
placed as to divide it completely into two halves, so that the
body, stretched tensely over it, had become thin and flattened
like a pancake. All communication between the inferior portion
of the stomach and the mouth was of course prevented ; yet,
instead of emaciating and dying of an atrophy, the animal had
availed itself of what undoubtedly had been a very untoward
accident, to increase its enjoyments and its chances of double
fare. A new mouth, furnished with two rows of numerous
tentacula, was opened upon what had. been the base, and led to
the under stomach : the individual had indeed become a sort of
Siamese twin, but with greater intimacy and extent in the union."
—It sometimes happens that, in tearing away an Actinia from the
rock, some portions of the disk are left behind ; and even these
are said to be capable of developing perfect individuals. The
following circumstance is mentioned by Hughes, in the account
already quoted. " Many people coming to see these strange
creatures, and occasioning some inconvenience to a person through
whose grounds they were obliged to pass, he resolved to destroy
the objects of their curiosity; and, that he might do so effec-
tually, caused all the holes out of which they appeared to be
carefully bored and drilled with an iron instrument, so that we
cannot suppose but their bodies must have been entirely crushed

502 REPRODUCTION OF SEA-ANEMONE.

to a pulp ; nevertheless they appeared in a few weeks from the
very same places." The Actiniae have not only the power of
repairing injuries of this description, but seem to resist the effects
of other agents in a very remarkable manner. They are not
killed by being frozen in a mass of ice, but return to activity
when thawed ; and they withstand the action of water heated to
140°. They may be placed with impunity in the exhausted
receiver of an air-pump ; and yet their life is destroyed in a few
minutes by immersion in fresh water.

1069. We do not find in the Actiniae anything exactly resem-
bling the reproduction by buds, which is so remarkable in the
Hydra. The spontaneous division of the body just alluded to, —
which is said to take place occasionally, not into two parts only,
but into several — constitutes an approach to it. The special
reproductive apparatus, by which distinct germs are formed, is
here very highly developed ; consisting, as already described,
of a series of chambers, surrounding the stomach, within
which they are developed. They sometimes pass out by the
tentacular orifices, in the state of simple gemmules furnished
with cilia, like those of other polypes. Sometimes, however,
they are retained for a longer period, and their development goes
on within the body of the parent, so that when liberated they
already present something of the form of the adult animal,
having a mouth, stomachx and tentacula, — the latter being at
first few, but gradually increasing in number. In this state they
generally find their way out by the mouth of the parent ; and
Dicquemare says that he has had eight or ten born in his hand
at once. In the course of six years, an Actinia, kept by Sir
J. Dalyell, produced above 276 young. If all these had been
preserved, and their progeny reckoned, the amount would have
been enormous. The young are frequently disgorged along
with the half-digested food ; thirty-eight appearing thus, in
various states of development, at a single litter. Monstrosities
are not uncommon among the young. One is mentioned by
Sir J. D., which had two perfect bodies springing from a single
base. When one body was gorged with food, the other con-
tinued ravenous. — The process of respiration already described,

SEA-ANEMONE. CARYOPHYLLIA. 503

appears to have an important connexion with the development
of the progeny ; and the introduction of water into the ovarial
chambers may not improbably furnish them with supplies of food
as well as of air.

1070. The Actinia have been stated to feed upon small
Crustacea, Fish, &c. In their turn, they become the prey of
the larger species of these tribes. They constitute by no means
an unpalatable article of food, even for Man. Particular species
are highly prized as delicacies in some tropical countries ; and
others are commonly employed by the inhabitants of northern
shores. Along our own coasts, there is a remarkable neglect of
these and of many other marine productions, to which, if not
constantly employed, recourse might be advantageously had in
times of scarcity. They seem to have been a favourite dish at
the Abbe Dicquemare's table. " Being boiled some time in sea-
water,"" he tells us, " they acquire a firm and palatable consis-
tence, and may then be eaten with any kind of sauce. They
are of an inviting appearance, of a light shivering texture, and
of a soft white and reddish hue. Their smell is not unlike that
of a warm crab or lobster." A few species have the power of
stinging, like the Acalephse with which they were associated
by former naturalists.

1071. The Actinia are by no means the only Polypes be-
longing to this Order. Several other genera exist, of which
some are, like it, unpossessed of any calcareous deposit, whilst
others form a hard skeleton more or less complete. Between
these, however, there are links of close connection ; for some
among the first have a portion of the base and of the lower part
of the cylindrical body hardened into a kind of horny cell,
within which the animal can retract the upper portion that re-
mains soft. In those species which construct a stony basis, the
calcareous matter is deposited in the same situation. Such a
deposit is formed by the Caryopliyllia, a solitary Polype much
resembling the Sea- Anemone, which is to be met with on the
southern shores of England ; and thus a stony cell is formed,
in the bottom of which are to be seen a number of thin vertical
plates or lamella?, formed in the partitions between the ovarial

504 STONY CORALS; — CARYOPHYLLIA, DENDROPHYLLIA.

chambers, and, like them, radiating from the centre towards the
circumference of the cell. These radiating lamellae are, in fact,
characteristic of all the Coral structures formed by the group of
Helianthoid Polypes ; being present, more or less evidently, in
every one known to be the work of these animals, and not
occurring in any, of which the animal is known to resemble either
of the other groups. The cells are not by any means constantly
circular; but still the laminated plates project inwards from their
circumference, so as to occupy a corresponding position. The
Madrepores and their allies have thence been designated lamelli-
form corals ; a term which is very expressive of their character,
and has the advantage of relating to the structure of the animals
which produce them.

1072. Some species of Caryophyllia build up their cells in a
cylindrical form, to a considerable height (Fig. 618). As the
upper edge is extended by the gra-
dual consolidation of the soft structure,
which is the continuation of it, the
lower part is strengthened by new de-
posits, which are added to the bottom of
the cell ; so that a stony column is thus
formed, which may almost be described
as solid through nearly its whole extent.
It is not uncommon to meet with several
of these, clustered in one mass ; and
thus we can understand the production
FIG. 6i8.-CAHvoPH.LUA. of thoge.arborescent (tree-like) forms,

to which the name Dendrophyllia has been given. In these,
the stem sends out branches, instead of remaining simply
columnar ; and these branches again subdivide ; in all instances,
however, the cells terminate the branches, which increase in
length by the progressive*fconsolidation of their basis, just as in
the solitary species. The whole structure is covered with a
gelatinous flesh of some consistence, which seems to be continuous
with the outer membrane of the Polypes inhabiting the cells.
This flesh appears to have the same functions with the pith of
the Sertularian Polypes. It seems, in fact, to constitute the

STONY CORALS; — DENDROPIIYLLIA. 505

animal, of which the Polypes are only subordinate parts. It
has no direct communication with their stomachs, however ; nor
does it appear to connect the different Polypes very intimately
together. But it is largely concerned in the deposition of the
calcareous matter of the polypidom, especially in those forms of
it in which the cells are connected together by a solid mass
(Fig. 619), instead of being seated, as in the Dendrophyllia, upon
the extremities of diverging branches. Even here it may be
observed, however, that a new twig or ramification is at first
produced, not by a Polype, but by a projection of the flesh, of
which the centre becomes consolidated, forming a cell in which
the Polype subsequently appears. The same takes place in the
early development of the gemmules. Moreover, if a piece of
this flesh be stripped from the surface and placed in sea- water,
it will begin to form a cell, by the deposition of calcareous mat-
ter, upon the spot where it happens to rest ; and this cell is soon
tenanted by a Polype like an Actinia. Many other arborescent
forms of lamelliform corals might be enumerated, which are of
great beauty to the common observer, and highly interesting to
the Naturalist on account of their affinity with the extinct species
so abundant in limestone rocks.* Amongst these are the true
Madrepores, in which the whole surface of the stem and branches
is covered with minute cells. In all these, as in the plant-like
Sertularidce, the living flesh is withdrawn from the lower part, in
proportion to the extent of growth above ; and, if attached to a
limestone rock, the root can scarcely be distinguished from the
basis on which it has been implanted.

1073. We now pass to another series of forms presented by
the lithophyte corals ; — those in which the Polype-cells, instead
of being placed on the ends or sides of branches, are distributed
over a continued surface, sometimes in close apposition with each t
other, sometimes widely separated, but united by a solid calcareous
mass which fills up the interspaces. Of the first of these kinds,
the common Astrcea affords an excellent example. We might

* It may be desirable to remark tbat the Red Coral and its allies do not belong
to this group, being destitute of laminated cells. They will be described among
the Alcyonian Polypes (§ 1093).

506

STONY CORALS ; FUNGIA.

imagine it composed of a number of Fungice packed closely
together. Here the same gradual consolidation of the lower part
of the cells takes place, as in the Caryophyllia; so that the mass
acquires considerable thickness. The cells of these Polypes do
not always, however, preserve their regular rounded form ; being

sometimes oval, and in many
instances forming a long fur-
row, as in the Meandrina.
Each of the furrows, however,
is occupied by several Polypes
arranged side by side ; and
their point of junction is
usually indicated, either by a
slight transverse partition in
the furrow, or by a change in
the direction of the laminae
arising from its sides. In
the Meandrina cerebriformis
(brain-stone coral), the whole
mass, whether young or old,
is nearly hemispherical. It is
at first small, but extends in all directions by a process of growth
and consolidation analogous to that already described ; so that,
whilst its surface is always covered with a living flesh, and
studded with vast numbers of polypes, the interior is a mass of
solid limestone, the particles of which remain cemented together
by the animal matter in which they were at first deposited.
On breaking this hemispherical mass, the ridges which bound
the furrows may be traced inwards through its substance, even
to the central nucleus from which they commenced ; the deposit
in the interstices of these being of a softer character, and possibly
more of the nature of an exudation from the under surface of the
flesh. These Meandrince sometimes attain a considerable size.
Ehrenberg noticed single masses, in the Red Sea, from six to
nine feet in diameter. Their rate of growth, however, appears
to be slow.

1074. It is principally by the animals of this group, that

Fie.61 9. — MASS OF ASTRJEA VIRIDIS ; a, a,
expanded Polypes .- b, b, Polypes with-
drawn into their cells ; c, stony mass
uncovered by flesh.

RATE OF GROWTH OF CORAL. 507

the formation of coral reefs and islands is effected. Many
errors have prevailed upon this subject, both as to the rapidity
of their extension, and the depth from which they are built up
to the surface of the ocean. It has been commonly stated that
many channels and harbours in the Red Sea have been closed
up, within the memory of man, by the rapid increase of coral
limestone. But Ehrenberg, who carefully examined these
localities, attributes the obstruction rather, in some instances, to
the quantities of coral sand which have been washed into the
harbours, and in others to the accumulation of ballast (generally
composed of pieces of coral rock) thrown out from vessels. In
Captain Beechey's late Expedition to the Pacific, no positive
information could be obtained of any channel having been filled
up within a given period ; and he states, as an indisputable fact,
that several reefs had remained, for more than half a century, at
about the same depth from the surface. On the other hand, there
is evidence of the occasionally rapid growth OA these structures.
In the Museum of the Bristol Institution is a mass of Agaricia^
weighing 2 Ibs. 9 oz., surrounding a species of Oyster, whose age
cannot be more than two years. Pieces of coral, detached from
a reef, and thrown into some other situation, soon become fixed
by the deposition of new stony matter, if the animal flesh have
not been too much destroyed ; and in this manner a sort of arti-
ficial reef may be formed in any spot desired, provided the depth
of water be suitable. The natives of the Polynesian Islands
have long employed this method for building their piers, wharfs,
fish-preserves, &c. Mr. Stutchbury mentions that he saw, at the
Island of Taapoto, in about seven fathoms water, the anchor of
a large ship, wrecked there not more than fifty years previously ;
this was completely incrusted by coral, though it preserved its
original form. One of the most interesting proofs of the occa-
sionally rapid growth of Coral, is afforded by the alteration in
form which is seen in two kinds of shells that inhabit the reefs —
the Vermetus and Magilus (§ 926).

1075. There can be no doubt that, whether the growth of
Coral takes place as rapidly as some maintain, or as slowly as
it is believed to do by others, it is among the most important of

508 FORMATION OF CORAL ISLANDS.

the progressive changes, which have been altering the surface of
the Globe since it has been tenanted by Man. To it is due the
existence of a large proportion of the Islands of the Polynesian
Archipelago, as well as many of those in the Indian Ocean ; and
the extent of these islands is far less than that of the reefs, which
are not yet raised above the level of the sea, — some presenting
themselves at a distance from any upraised land, others fringing
the shores of continents and islands, composed of other formations.
It is not correct, however, to affirm (as has been frequently done)
that these islands and reefs have been upreared by the Coral-
polypes from the depths of the ocean. It is now satisfactorily
ascertained that no known species can build from a greater depth
than twenty fathoms ; and a large proportion seem to prefer a
depth of from twenty to thirty feet. As very deep water is
found in the immediate neighbourhood of many of these reefs,
the question arises, upon what basis they are constructed ; and
to solve this, it is necessary to look at the forms which these
massive structures present.

1076. A large proportion of the Coral Islands of the Poly-
nesian Archipelago are shaped like a crescent, sometimes like a
complete ring ; and these islands never rise many feet above the
surface of the ocean. The highest part is always on the windward
side,* against which the waves are almost constantly dashing.
Within the crescent or ring is a basin, termed a lagoon ; and
this usually communicates with the open sea, by a channel,
sometimes of considerable width, on the leeward side of the
island. Occasionally this channel is completely filled up by the
growth of the Coral ; and the lake, thus inclosed, only commu-
nicates with the sea by filtration through the Coral rock. The
Coral-polypes never build above low-water mark ; and they are
not, therefore, immediately concerned in the elevation of the surface
from beneath the waves. This is principally accomplished by the
action of the sea itself. Large masses are often detached, by the
violence of the waves, from the lower part of the structure ; and

* The prevalence of easterly winds in the tropical regions, causes this name to
be given to the eastern side of islands situated there ; the western shore being
known as the leeward.

FORMATION OP CORAL ISLANDS. 509

these (sometimes measuring six feet by four) are washed up on
the windward side of the reef. Shells, coral-sand, and various
other debris, accumulate upon it in like manner, until it is at
last changed into an island, upon which there is a calcareous soil
capable of supporting various kinds of vegetation. When these
have once established themselves, the elevation of the surface
continues with greater rapidity — successive layers of vegetable
mould being deposited by the rapid and luxuriant vegetation of
these tropical islands, which are soon tenanted by various forms
of animals, and at some subsequent period afford a habitation to
Man. It is not usually, however, until after the windward
coast has attained considerable elevation, that the leeward side
is perfectly closed in. Two causes may be assigned for this.
There seems to be a natural instinct on the part of the animals,
which impels them to build with greater rapidity on the most
exposed side ; and the leeward side is therefore the part last
completed. Moreover the closure of this passage is impeded by
the current almost constantly passing out of it, which is caused
by the dashing of the waves over the windward side into the
lagoon ; and until this ceases, there will always be a free exit in
the opposite direction. After the wall has been sufficiently
upraised, however, the lagoon is often completely enclosed. In
the centre of this lagoon, deep water is often found, and no living
animals can be seen upon its bottom ; but the shelving edges of
the shallower portion are clothed with luxuriant growths of the
more delicate species of coral, and its waters abound in marine
animals of all descriptions.

1077. These lagoon-islands vary in diameter from one to fifty
miles ; the breadth of the elevated ring which encloses the lagoon,
is from 400 or 500 yards to about a mile, though seldom above
half a mile ; and its height above the water is not often more
than four or five feet in any part. The annular (ring-like) cha-
racter of these islands naturally suggests the idea, that they may
have been built upon the edges of submarine volcanoes, or upon
circular elevated ridges, forming basins, resembling those which
abound in the parts of the globe at present upraised, and which
may reasonably be supposed to exist in those still submerged.

510 FORMATION OF CORAL ISLANDS AND REEFS.

In support of this doctrine, it has been stated that fragments
of volcanic rocks have been found in the water of a lagoon.
That there is nothing in the essential nature of coral structures
which impels them to assume this form, is evident from the fact
mentioned by Ehrenberg, that in the Red Sea the islands are
oblong or square without lagoons ; as well as from the variety
which we meet with even in the Polynesian Archipelago. In fact,
they always appear to correspond with the form of the base on
which they are erected ; and the evidence that some lagoon islands
(at least) are founded upon the tops of submarine volcanoes,
or upon the edges of large basins, seems therefore satisfactory.
But it is difficult to conceive that there should exist beneath the
ocean so large a number of summits, all so nearly approaching
its surface, as these must do in order to form a basis for coral
islands., — not to mention the other ridges on which the reefs are
built, which will next be noticed. This difficulty appears to be
solved by the very ingenious hypothesis lately put forth by Mr.
Darwin, which will be presently explained.

1078. Almost all the shelving shores of tropical seas are
fringed more or less closely by ridges of Coral. These are not
built immediately upon the edge of the land, but at some little
distance from it. If the wall of coral were upraised close in-shore,
the fresh water draining down from the land, and entering the
basin thus formed, would render it unfit for the habitation of
the Polypes. They are, therefore, endowed with a power of
choosing a situation more advantageous to their growth ; and we
accordingly find these skirting reefs upraising themselves at some
distance from the shore, but not so far off as to have a base of
greater depth, than is suitable to the constitution of the Polypes.
Very often such reefs run from point to point of a bay, so as
completely to enclose it.* But beyond these skirting reefs are

* In the little island of Cariacou (one of the chain of Grenadines, between
Grenada and St. Vincent) the whole coast is a succession of such bays, and each
of these is shut in by such a reef ; a narrow passage into one of them being the
only means of access, when the Author visited it a few years since. From a hill in
the centre of the island, nearly every part of the coast can be seen ; and the white
lines of surf, connecting the dark rocky points, present a very striking appearance.
The Society Islands are generally skirted by similar reefs, which are generally 400

FORMATION OF CORAL REEFS. 511

sometimes other ridges, often at a considerable distance from the
shore, but still preserving a direction parallel to it. These are
termed barrier reefs ; and the most remarkable of them is the
one, which stretches along the north-eastern coast of New Hol-
land. The total length of this is above 1000 miles ; along 350
miles there is no break or passage whatever ; and for 700 miles
northwards towards New Guinea, there are no intervals exceed-
ing thirty miles in length. When we endeavour to account for
such a structure upon the commonly received opinions alone, we
are met by the same difficulty as that, which opposes itself to
the supposition of a rocky base to all the coral islands, at a depth
of less than 120 feet. There is no mountain range, extending to
anything like the length of this reef, of which the summits are so
nearly equal in height ; — still less any one presenting a continu-
ous ridge, such as would be required for the base of the uninter-
rupted portion of the reef. We have, therefore, no right to
suppose that such a ridge should arise from the depths of the
ocean ; and yet without it, our knowledge of the habits of the
Coral Polypes does not enable us to account for the remarkable
structure under consideration.

1079. This difficulty, however, appears to be satisfactorily
solved by Mr. Darwin's hypothesis. He has adduced several
reasons for the belief, that the bottom of the whole Pacific Ocean is
changing its level, in some parts slowly subsiding, whilst in
others it is undergoing gradual elevation. Now if we imagine
the whole of New Holland to have been at a former time con-
siderably more elevated than at present, its area would of course
have been greater, and it might have extended to the line of the
present reef. This reef might have then been formed as a
skirting reef in the usual manner ; stretching at the distance of
a few hundred yards along the whole coast in shallow water. If
a slow subsidence then took place, the coral would be kept up to
the surface of the water, by the labours of the Polypes, in an
almost unbroken ridge ; whilst the water would gradually gain

or 500 yards off-shore, with a deep channel, into which ships can enter hy nume-
rous passages. — These passages are generally opposite the mouths of fresh-water
rivulets.

M M2

512 EFFECTS OF SLOW SUBSIDENCE.

upon the land, and increase the distance of its shore from the
reef. In this manner the skirting reef, upraised from a depth of
ten or fifteen fathoms, and at a distance of five hundred yards from
the shore, may be gradually converted into a barrier reef, with
water one hundred and fifty feet deep on each side of it, and the
shore one hundred miles off. Let us imagine the gradual sub-
sidence to continue, until the whole of New Holland should be
submerged, with the exception of its loftiest hills. These would
then remain as rocky islands rising out of the ocean ; but the
barrier reef would continue in its present aspect, since it would
be still maintained on a level with the surface, by the labours of
its innumerable builders, although the depth of its base would be
constantly increasing. If a rapid subsidence were to take place,
however, the summit would be submerged to a depth inconsistent
with the vitality of the Polypes ; and all increase must then
cease.

1080. It is evident that this hypothesis will be equally appli-
cable to the case of the lagoon-islands. If the area over which
they occur were formerly more elevated, some of its volcanic
peaks and circular ridges might have lifted themselves high
above the ocean ; others would have been nearer its level ; and
others might have been just submerged. Upon the latter,
the formation of coral would have begun; and circular reefs
would have been built up to the surface. If a slow subsidence
then took place, these reefs would still retain their surface-level
by addition, whilst a new set of hills would be submerged, and
would serve as bases for new coral islets. In this manner
all the summits, however different their original elevation,
would be rendered of an uniform height ; each, as it was sub-
merged, becoming the basis of a coral growth, which keeps pace
with the progressive lowering of the whole mass ; — and so on
until all are thus submerged, and no land but coral islets remains
above the surface.

1081. This very ingenious hypothesis corresponds well with
the fact that, over certain large areas of the Pacific, we find
lagoon islands and barrier reefs abundant, whilst skirting reefs
are scarcely ever met with. Moreover, actual proof of a slow

EFFECTS OF ELEVATING FORCES. 513

subsidence is not wanting. Thus in the Keeling or Cocos Islands,
situated in Lat. 11° 50' S., and Long. 96° 51' E., the old cocoa-
nut trees surrounding the lagoon, in which the water is as
tranquil as in the most sheltered lake, are undermined and
falling. The foundation posts of a store-house, which, according
to the inhabitants, had stood seven years before just above high-
water mark, were, at the time of Mr. Darwin's visit, washed by
the tide. The islands are occasionally shaken by earthquakes.
Such changes are by no means unfrequent in many parts of the
Pacific ; and, if the accounts of the natives are to be relied on.
many instances of the submergence of whole islands have occurred,
within the period of recent tradition.

1082. The evidence in regard to the areas of elevation is still
more satisfactory. It is by no means uncommon to find beds of
recent Coral, at a considerable height above the sea level. Some-
times whole coral islets are thus upraised. Among these,
Elizabeth or Henderson's Island, examined by Captain Beechey,
is one of the most remarkable. This is about five miles in length
and one in breadth. It has a nearly flat surface ; and on all
sides, except the north, is bounded by perpendicular cliffs about
fifty feet high, composed entirely of dead coral. In some parts,
the height of the surface was nearly eighty feet above the water
level. The face of the cliffs presented a smooth surface, and was
destitute of any ridges or other indication of the action of the
sea at different levels ; so that it may be reasonably inferred, that
it was upraised by one convulsion. At a distance of a few
hundred yards of this island, no bottom could be gained with
200 fathoms of line. — The most remarkable instance of this kind
on record is the one observed by Mr. S. Stutchbury in the island
of Tahiti. This island is composed of volcanic rocks ; and there is
in it a lofty mountain ridge with two summits, of which the
lower one is evidently the crater of a volcano, perhaps not very
long extinct. The principal peak rises to the height of about
10,000 feet ; and near its summit is a distinct and regular
stratum of coral-limestone, which cannot be distinguished from
that, which is being at present formed in enormous quantity
around the shores of the island. As there is no other deposit of

514 GENERAL EFFECTS OF CORAL-GROWTHS.

coral, either on the sides of this mountain, or on the summit of
the volcanic crater, it is a reasonable inference that the island
must have been upraised, to the whole amount of the elevation
of the ancient ridge of coral above the reefs at present in course
of formation, at one movement. — In the bands of the Pacific
Ocean, regarded by Mr. Darwin as areas of elevation, no lagoon
islands or barrier reefs are met with ; but the shores are fringed
by skirting reefs ; and active volcanic changes are notofunfre-
quent occurrence.

1083. The following remarks by Mr. Darwin form a very
appropriate conclusion to this part of our subject : — " It is not
that the ocean spares the rock of coral ; the great fragments
scattered over the reef, and accumulated on the beach, whence
the tall cocoa-nut springs, plainly bespeak the unrelenting power
of its waves. Nor are there any periods of repose granted. The
long swell, caused by the gentle but steady action of the trade-
wind always blowing in one direction over a wide area, causes
breakers, which even exceed in violence those of our temperate
regions, and which never cease to rage. It is impossible to
behold these waves, without feeling a conviction that an island,
though built of the hardest rock, let it be porphyry, granite, or
quartz, would ultimately yield and be demolished by such irre-
sistible forces. Yet these low insignificant coral islets stand and
are victorious ; for here another power, as antagonist to the
former, takes part in the contest. The organic forces separate
the atoms of carbonate of lime one by one from the foaming
breakers, and rear them up into a symmetrical structure. Let
the hurricane tear up its thousand huge fragments ; yet what
will thus tell against the accumulated labour of myriads of archi-
tects at work day and night, month after month. Thus do we
see the soft and gelatinous body of a polypus, through the agency
of the vital laws, conquering the great mechanical power of the
waves of an ocean, which neither the art of man nor the inani-
mate works of nature could successfully resist."*

1084. Much discussion has taken place in regard to the
sources, from which the Coral-polypes obtain the enormous quan-

* Darwin's Journal, p. 548.

SOURCES OP LIME IN CORAL. 515

tity of lime deposited by them ; and this question affects not
only those of the present epoch, but those of former ages, to whose
labours, in conjunction with those of the testaceous Mollusks, the
greater part of the Calcareous strata of the secondary and sub-
sequent periods are immediately or remotely due. Some have gone
so far as to imagine, that the lime is produced by some organic pro-
cess in the animals themselves. No positive evidence of such a
production can, however, be obtained from any source ; and the
hypothesis is quite unnecessary in the present instance. We
have reason to believe that lime existed in large quantities on
the surface of the earth, before any organised beings were placed
upon it ; and there is also ground for supposing, that a larger
quantity of carbonic acid existed in a free state at that epoch,
than at the present time. It is not improbable, therefore, that
the waters of the ocean contained a much larger quantity of lime
than they now do — this ingredient being held in solution by the
free carbonic acid; and the enormous beds of calcareous rock,
separated by the action of Coral-polypes, are therefore easily
accounted for. Moreover, in volcanic countries at the present
time, springs charged with carbonate of lime thus held in solution
are very abundant ; and it is not unfair to suppose that, — as the
part of the globe in which the coral-formations increase most
rapidly (the Pacific Ocean), is also one of the chief areas of
submarine volcanic action, — such springs may occur with similar
frequency, and may greatly assist in the growth of these masses.
In illustration of this doctrine, it is remarked by Mr. Lyell that,
in lakes which have no unusual supply of carbonate of lime,
there is no accumulation of shell-marl — the thin shells of one
generation of Mollusks decomposing, so that their elements supply
the requisite materials to succeeding races. But, if springs or
streams charged with carbonate of lime enter such a lake, the
shells accumulate and form marl. There are many plants and
animals, in whose economy lime appears to be an important agent;
and the quantity introduced bears a strict relation (within a
certain limit) to that with which they are supplied.

516

ORDER III.— ASTEROIDA.

1085. Having thus considered the two Orders, in which
the structure of the single and associated Polypes is most cha-
racteristically presented, we may pass on to the two others ;
which exhihit such modifications of this structure, as connect the
Polypifera with the classes below and ahove them.

1086. We shall first consider (as being most nearly allied to
the preceding) the Order, which, from one of its principal genera,
we may term that of Alcyonian Polypes. In many of these,
the polypidom, or solid framework, so closely resembles Sponge,
that, in the dry state, the former can only be distinguished by
the regular disposition of cells upon its surface ; and, in the
immature condition, the resemblance is still more close, — the
young branches of the polypidom, on which the polypes have
not yet appeared, presenting all the characters of sponge, as will
be presently shown (§ 1088). There is a greater apparent
diversity in the character of the members of this Order, Whilst
one family approaches the Sponges so closely, that it may be al-
most regarded as formed of Sponges provided with polype-mouths,
another has a dense horny, or even calcareous, arborescent stem ;
whilst in another, the soft parts of the body are entirely inclosed
in a firm tubular sheath. But, however different in the cha-
racter of their aggregated masses, they all bear a general
resemblance, as to the structure of the individual polypes ; and to
these we shall first, therefore, direct our attention.

1087. None of the Alcyonian Polypes live so entirely isolated
as the Hydra or Actinia. The closeness of the connection
between the individuals, differs extremely in the various groups ;
for whilst, in the lower forms which assimilate with the Sponges,
the Polypes seem quite subordinate to the general mass, from
which they are developed, and to the support of which they
minister in common, — there is another group, in which each
seems to live for itself alone, although united externally with its
fellows. In all, however, the essential characters of the Polypes

STRUCTURE OF ALCYONIAN POLYPES.

517

FIG. 620. — ALCYONIAN POLYPE.

remain the same. On comparing the external appearance of one
of them with that of a Hydra or Sea-Anemone, we perceive that,
whilst the mouth is surrounded by tentacula as in them, there is
a marked difference in the form and number of these prolonga-
tions. Instead of long delicate filaments like those of the Hydra-
form Polypes, or short cylindrical tubes like those of most of
the Actinice, we find six or eight
broad leaf-like expansions, dis-
posed with great regularity
around the mouth, so as very
much to resemble a Star-fish
(Asterias). Hence the term
Asteroida has been proposed as a
designation for the group ; and
it represents sufficiently well its
chief external character. These
tentacula are unprovided with
cilia ; but a number of little pro-
jections may be seen along their

margins, which probably increase their prehensile power.
The mouth leads into a stomach, which resembles that of the
Actinia^ in being suspended in the midst of the general cavity of
the body, by partitions radiating from its walls. Instead of
being closed at its lower extremity, however, it opens like that of
the Sertularians, into the canals which ramify through the fleshy
mass, and which thus connect all the Polypes into one system.
This opening is surrounded by a circular muscle, or sphincter, by
the action of which it may be expanded or entirely closed. The
chambers which surround the stomach correspond in number
with the tentacula ; and these are hollow, opening below into the
chambers (as in the Actinia), whilst they have a small orifice
at their extremity. The chambers are continuous at their lower
part with the ramifying canals just mentioned ; and the mem-
branous folds which support the stomach do not cease at its
lower extremity, but are prolonged downwards as plaits of the
lining of these canals, until they gradually disappear.

518 GENERAL STRUCTURE OF ALCYONIAN POLYPES.

1088. The ova or germs are developed in the substance of
the membranous folds, or from the lining of the canal. They
grow like seeds in a seed-vessel ; at first appearing as little pro-
tuberances from the plane surface ; then acquiring a distinct
globular form, and remaining attached by a little stalk ; and
finally, being liberated by the separation of this pedicle. They
then make their way outwards, by passing into the stomach
through its lower aperture ; and finally escape by the mouth .
Like the gemmules of other Polypes, they consist in this state
of a membranous bag including fluid; and they are covered with
cilia, by the action of which they move freely through the water
for some time before fixing themselves, though not with the same
rapidity as the ova of some other Polypes. They are usually
coloured with great vividness ; and, during their motions, they
often contract themselves and alter their form.

1089. Very little is known of the general habits of these
Polypes ; but they probably differ but little from those of the
groups already described. We may pass on, therefore, to con-
sider the chief subdivisions of this Order, which includes many
very interesting and well-known forms. These subdivisions are
principally founded upon the nature of the polypidom ; and it is
desirable, before proceeding to describe them, that the relation
of the parts of which the animals are composed should be clearly
understood. Delicate as is the membrane of the Polypes them-
selves, it may be distinguished, like that of the Sertularians
(§ 1052) into two layers. — Of these, the outer one is continuous
with the general envelope of the whole mass ; whilst the inner
one lines the canals which ramify through it. But instead of
these two membranes being in contact, as are the horny sheath
and the lining of the tubes in the Sertularians, a thick mass
of flesh is interposed between them ; and it is usually in this
flesh, and not in either of the membranes, that the hard deposit
takes place, which gives firmness and support to the general
structure.

1090. The family we shall first consider, includes those
species which have a spongy polypidom, — of which the Alcyo-

ALCYONIUM.

519

nium is a characteristic example. Here the general form and

aspect closely re-
semble those of the
Sponges; but, in the
living state, it will
be evident that the
projecting orifices are
tenanted by Polypes ;
and, even in the dry
skeleton, it may ge-
nerally be observed
that the openings of
the large canals are
not simple, like those

FIG. 621.— ALCYONIUM : A, portion enlarged, «r+l,«, ^ *«^f«2

showing the Polypes. of the vents of Sponges,

but present some in-
dications of the radiating partitions already mentioned. Between
the large canals, into which the Polype-stomachs open, there is
a network of minute tubular ramifications, which connect them
very intimately. In the interstices of these ramifications, which
are occupied by the gelatinous flesh of the animal, spicula, or
long needle-shaped crystals, of earthy matter are deposited ;
which, as in Sponges, give a general support to the whole mass,
though not consolidated in any one point. The general vitality
of the polypidom, however, would seem to be greater than that
of Sponge. If a single Polype be irritated, it withdraw^
itself within its tube ; and the edges of the cell, which were at
first prominent, become nearly flat. If the irritation be more
severe, several of the neighbouring Polypes also withdraw them-
selves ; and if it be sufficiently prolonged, a collapse and con-
traction of the whole polypidom is evident. The analogy is
very striking between this phenomenon, and that exhibited by
the Sensitive Plant, in which the effects of the irritation are
manifested at a greater or less distance, according to its intensity
(VEGET. PHYSIOL. § 422). If, instead of the Polypes being
irritated, a portion of the general surface be touched, a curious
series of changes will take place. After some little time the
part touched becomes opaque, more dense, and depressed ; and,

520 ALCYONIUM.

if the stroke be severe, this contraction will extend through the
whole mass, and the Polypes also will shrink. This is pecu-
liarly evident if the vessel containing the animal be smartly
struck ; since the shock will then be simultaneously felt through
the whole structure. Even the complete division of the poly-
pidom with a sharp knife, does not produce so evident an effect
as a slight shock, of which the effect is thus diffused. On the
other hand, when at rest and undisturbed, the Polypes protrude
their bodies, and unfold their beautifully-formed tentacula, and
take in a large amount of water. This is transmitted through
the whole interior of the polypidom by its anastomosing canals,
and the mass becomes distended to twice or thrice its original
size ; and from being firm and opaque, it becomes soft and
pellucid.

1091. The general integument of this spongy mass has a
firm leathery texture, and sometimes contains a distinct calcare-
ous deposit ; as does also that continuation of it, which forms the
external coating of the Polypes themselves. From the integu-
ment the buds are produced, which originate in the spongy
structure itself, and are, in fact, prolongations of it. These are
traversed by canals, that branch off from those of the parent
mass ; and resemble pieces of Sponge in every important par-
ticular. It is not until the Polypes are developed at the ter-
minations of these canals, that the real character of the mass can
be positively stated. This is another example, in addition to
the number we have already seen, of the progressive development
of the higher forms of organised beings ; and of the correspon-
dence between its several phases, and the forms which remain
permanent in the lower parts of the scale.

1092. The form and dimensions of the various species of
Alcyonia differ as much, as do those of the Sponges, to which they
bear so great an external resemblance. The Alcyonium digita-
tum creeps along the surface of loose stones and shells, forming a
thin fleshy crust, which rises up in irregular lobes or projections.
This small species is so abundant on some parts of our own
coasts, that scarcely a stone or shell can be dredged up from deep
water, whicli does not serve as a support to one or more specimens
of it. The particular form it presents, varies according to the

ALCYONIUM. PENNATULA. 521

nature of the surface on which it grows. Sometimes it spreads
out into finger-like projections ; and hence has received from the
fishermen the name of Dead-man s-hand. Other species attach
themselves to rocks, and grow, like sponges, hanging down from
the upper surface of submarine hollows in the face of overhanging
cliffs. Others of still firmer texture stand erect beneath the
shallow waters of the shore. Of this kind one of the most
remarkable species, probably the largest Alcyonium at present
existing, is the A.poculum, or Neptune's cup, which was disco-
vered by Sir Stamford Raffles upon the Coral reefs that sur-
round the Island of Sumatra. Many specimens, brought from
the neighbourhood of Singapore, now exist in the Museums of
this country ; and among these, some have attained the dimen-
sions of nearly three feet in height, and eighteen inches in
diameter. Their affinity with the Sponges is drawn yet closer,
by the siliceous character of the crystalline deposits, to which
they owe their firmness ; and, by some Naturalists, this species
has actually been referred to the class Porifera.

1093. In the one family of this Order, the polypidom is
unattached ; and the animals are carried about by the action of
the waves, having but little power even of directing their move-
ments. Of this group, the Pennatula, or Sea-pen, is a charac-

Fio. 622.— PENNATULA.

teristic example. It consists of an axis which is stony for a
considerable part of its length, but is flexible at its two extre-
mities. This is clothed with a flesh, which extends along the
sides into pen-like prolongations, arranged like the barbs of a
feather ; and one edge of each of these is fringed by Polypes.
The skin contains a large amount of calcareous spicula, and is

522 PENNATULA. ASTEROID POLYPES.

often deeply coloured ; being, in the British species Pennatula
phosphorea, purplish-red along the stalk, and orange at its
extremities. It is not often that the Pennatulae rise to the
surface. They are usually brought up from considerable depths
by fishing-lines ; and the fishermen believe that they are gene-
rally fixed in the bottom, with their ends immersed in the mud.
Some of the Pennatulce are very brilliantly phosphorescent ; and
the appearance of the larger species, when displaying their
luminosity in the dark ocean, is very striking. The disengage-
ment of light is, however, by no means constant ; but, as in all
other instances of phosphorescence, depends upon the condition
of the animal. When it is irritated or alarmed, a vivid emission
takes place ; but this soon dies away. When frequently struck
by the waves, it is possible that they may continue the display
with little interruption ; but observation proves that, when
preserved in calm water, they do not voluntarily disengage light,

although they readily show it if disturbed. The accompanying
figure represents a genus of Alcyonian Polypes, nearly allied to
the Pennatula.

1094. The next group of Asteroid Polypes includes many
well-known species, — such as the Red Coral, the Gorgonia or
Sea-fan, the Antipathes or Black Coral. In all of them the
structure of the Polypes is nearly the same ; and the differences
of the polypidom chiefly relate to the portion, in which the
solidification of the structure has taken place to the greatest
extent. It will be recollected that, in the true Alcyonia, the
calcareous or siliceous spicula are deposited, as in the Sponges,
through the whole mass ; and that, with the exception of the
fibrous bands which interlace between the canals, no one portion

GORGONIA, OR SEA-FAN. 523

is harder than another. Now in the group at present under
consideration, a solidification takes place in the centre or axis
of the polypidom, and often in the integument also. Almost all
the species included in it have an arborescent form ; and so much
does the flexible axis of many kinds resemble the stem of a plant,
that, even so late as the year 1825, the celebrated Blumenbach
writes — '* The stems appear to be really vegetables (the woody
nature of which in the larger ones cannot be mistaken) incrusted
with corals."

1095. Among the Gorgonice, or Sea-Fans, there are some
species which very closely resemble the Alcyonia, in the uniform
distribution of the firm texture through their whole substance.
In others, however, a firm horny skeleton is found, which is
commonly known as the Sea-fan ; and, in the living state, the
flesh which clothes this is covered by a dense integument, con-
taining an abundant deposition of calcareous particles. If the
flesh be allowed to dry upon the stem, the integument remains
as a friable crust, which may easily be peeled or rubbed off,
disclosing the horny stem within. No mark of the habitation
of the Polypes is ever found upon the internal axis ; but the
remains of the cells may often be observed in the integument,
when dried over it. The dry form in which the skeleton of the
GorgonicB is commonly known, does not give a correct idea
of its real character ; since, in the living state, there is by no
means a complete isolation between the hard axis and the soft
living flesh, but the one passes gradually into the other. On
cutting across the stem, it is observed that it is formed by
concentric layers, like those of a dicotyledonous tree ; and it is
probable that these are formed by the successive consolidation of
the flesh in contact with its surface. Beyond this general
analogy, however, no resemblance can be made out ; since nothing
like the intricate arrangement of dissimilar parts in a woody
stem, can be found in these simply-organised but beautifully-
formed structures. Whilst the axis of the Gorgonia is usually
brown or black, its crust often exhibits colours of great brilliancy,
especially in the living state ; in some species it is of a deep red,
in others of a bright yellow, and in others of a crimson hue.

524

ANTIPATHES, OR BLACK CORAL. RED CORAL.

1096. The structure of the Antipathes is by no means unlike
that of the Gorgonia. The axis is still more firm, presenting
when dry a smooth polished surface, which, joined to its dark
colour, has caused it to receive the designation of Black Coral.
The calcareous deposition in the integument, also, is still more
abundant ; so that the crust, when dry, is sometimes even thicker
than the stem. The solidifying matter having thus entirely left
the flesh, we find it extremely soft ; — so soft, indeed, that when
brought up from the depths of the sea, this substance runs off
almost entirely, leaving the integument adhering to the axis. —
In the Corallium rubrum, or Red Coral, the solidification of the
axis has proceeded still further ; for it contains not only horny
animal matter, but a large quantity of calcareous particles, so
closely deposited in every part, as to give great solidity to the
stem, and to enable it to receive a fine polish when cut into
fragments. This is a
valuable article of com-
merce, and is principally
obtained from the Medi-
terranean, where it is
brought up from consi-
derable depths. No ves-
tige of polype-cells can
be detected upon the
surface of the axis.
These are confined to
the flesh and its integu-
ment, which are both
very soft ; the latter
does not contain enough
calcareous matter to
make it perceptible as
a crust when dried upon
the axis. The density
of the Red Coral renders
it very brittle ; and, did
it not grow in a somewhat stunted form, it would be liable to

FIG. 623.— RFC CORAL.

ASTEROIDA. ISIS HIPPURIS ; TUBIPORA MTJSICA. 525

injury from the violent motion of the water in which it grows.
—There is a very interesting species of this group, which con-
nects in a remarkable manner the stony Corallium with the
horny Antipathes. This is the Isis Hippuris^ in which the stem
is composed of both these substances alternately, so as to give it
a jointed appearance. It is formed by the deposition of calca-
reous matter at intervals along the horny stem ; and in this man-
ner it is endowed with a considerable degree of flexibility. If
the axis be submitted to the action of an acid, the calcareous
deposit is removed ; and its structure appears uniform throughout.
Although its aspect is jointed, therefore, no real articulations exist;
the flexible substance, of which the intervals are alone composed,
being really continued through the whole. We may perhaps
regard this as a kind of sketch of the Vertebrated structure.

1097. The last group of the Asteroid Polypes differs from
those we have hitherto considered, in several important respects.
In the Tuliporidce, each polype is inclosed in a distinct cylin-
drical tube, which is formed by a continuation of its external
membrane ; and there is no communication among the individual
members, nor anything like the gelatinous flesh or central axis of
other Alcyonians. In some genera the tube is membranous, or
somewhat horny ; but in the Tubipora, the genus from which
the order takes its name, it is of firm calcareous structure. Of
this genus only one species, the Tubipora musica, inhabiting the
Indian Ocean, is known. It takes its name from the regular
arrangement of its cylindrical tubes by each others' side j whence
it is commonly termed " Organ- pipe Coral/' These tubes are
of a dark and rich crimson ; whilst the Polypes themselves have
a bright green colour when alive ; so that the contrast is very
striking. The Polypes resemble those already described, in all
the leading particulars ; except that the living membrane, which
lines their interior, does not seem to extend far down the calca-
reous tube ; and the ova are developed, not from its folds, but
from filaments prolonged from the base of the stomach, which
hang down into the cavity. The calcareous tube is formed by
the solidification of the membrane, which envelopes the Polype ;
and this is reflected in a funnel-shape, so as to close the mouth of

526 TTTBIPORA MUSICA. — CILIOBRACHIATA.

the tube, within which the Polype can be entirely withdrawn.
The tube is gradually prolonged by the deposition of stony mat-
ter in this membrane, which is continuous with its upper edge ;
and the Polype always maintains its position at its extremity.
At intervals, however, a sort of collar is formed around each
tube ; and as a number of Polypes usually grow in close proxi-
mity with each other, and form this collar at about the same
time, an almost continuous horizontal partition or floor is thus
constructed, which gives great additional strength to these
delicate polypidoms. This collar is produced in the following
manner. The membranous continuation of the tube, instead of
growing straight upwards, makes a turn outwards, as if it were
flattened-down all round. A double fold is thus occasioned, in
which calcareous matter is deposited, and the collar is thus com-
pleted. From this point the membrane is prolonged in a straight
direction as before, until the new impulse arises, which causes
another floor to be constructed ; and thus a succession of stories
is built up. — The ova, when they issue from the parent, have
little or nothing of their perfect form. They seem to fall upon
a neighbouring portion of the floor, and there to begin the deve-
lopment of a tube, which grows up among the older ones. Thus
it happens that, between every two floors, there are more tubes
than in the division below ; and the whole mass assumes some-
what of the form of an inverted pyramid.

ORDER IV.— CILIOBRACHIATA.

1098. The last order of POLYPIFERA differs so greatly from
all the rest in its internal organisation, that it almost deserves to
rank as a separate class. As the Asteroida connect the Polypes
with the Sponges, so does this group form the transition to classes
of much higher organisation. In general aspect and delicacy of
structure, the Polypes of this order bear no inconsiderable re-
semblance to the compound Hydraform groups (§ 1052) ; and
especially to the SertularidcK^ under which family many of them
have until recently been classed. They are not known to occur

CILIOBRACHIATE POLYPES; — BOWERBANKIA. 527

singly, but they sometimes present themselves in an almost
isolated form ; their cells arising separately from a creeping stalk.
In other instances they are closely aggregated, as in the common
Flustra, where thoy are spread out into an expanded surface ;
but they never seem to exhibit the same degree of structural
connection, as that which exists in the inferior groups. In a
large proportion of instances, the cells are of a delicate horny
structure ; and in those which are calcareous, the animal mem-
brane remains as a much more definite tissue, when the stony
matter has been removed by an acid, than in lithophyte corals
of the other groups, As in the Tubipora, the wall of the cell
is distinctly continuous with the membrane which closes the
mouth of it ; as this is with the external integument of the Polype
itself. Moreover, the mouth of the cell generally possesses some
flexibility, and is drawn inwards, so as to form a kind of oper-
culum or lid to the cavity, when the Polype retracts itself within.
The cells undergo remarkable modifications in form at different
periods of age, even in the calcareous polypidoms. The poly-
pidoms of this group never attain any considerable size ; and
they are almost always parasitic upon other marine formations,
such as corallines, sea- weeds, shells, or even different species of
their own tribe.

1 100. The species, which has been most carefully studied and
minutely described, belongs to that group in which the isolation
of the Polypes is most complete ; and it will, therefore, be con-
venient to enter first upon the consideration of its structure. The
Polypes of the Bowerbankia densa are, when fully expanded,
about half of an inch in length ; when retracted, they are com-
pletely inclosed in delicate horny cells, so transparent as to admit
of the whole structure being seen through their walls. These
cells, which, when the edges are turned in by the retraction of
the animal, are not above half the length of the expanded body,
arise separately from creeping stems, which attach themselves
to the Flustra in aggregated masses, of from half an inch to one
inch in diameter. The animal possesses ten tentacula, arranged
in the usual manner around the mouth ; and each of these is
thickly set with cilia on both sides. The mouth does not lead

NN 2

528

CILTOBRACHIATE POLYPES ; — BO WERE AN KI A,

at once, as in the inferior Polypes, into the stomach ; but it
forms the entrance to a wide funnel-shaped tube, which may be
termed the pharynx. This soon contracts
into a narrower canal, the oesophagus, which
terminates at its lower end in the digestive
cavities. The first of these is an organ
which seems closely to resemble a gizzard.
It is of a globular form, and has two dark
spots upon its sides, from which radiating
lines are seen. These are probably composed
of muscular fibres, the office of which is to
effect the trituration of the food, by means
of the teeth that project from the inner wall
of the cavity. The gizzard opens at its
lower end into a larger bag, which seems to
be the true digestive stomach. Its walls
are thickly studded with spots of a rich
brown colour ; these appear to be caused by
minute follicles or sacs opening from its
cavity, in which bile is secreted for assisting
the digestive process. A fluid is poured out
from them which tinges the whole stomach, as
well as its contents, with the characteristic hue of that secretion; and
we may therefore regard these follicles as constituting the simplest
form of hepatic gland or liver, which we meet with in the animal
kingdom. It is easy for the comparative anatomist to trace the
gradual concentration of these scattered elements, up to the con-
solidated form in which they present themselves in the highest
grades of organisation (ANIM. PHYSIOL. § 356). From the
upper part of the stomach, and by the side of the entrance from
the gizzard, arises the intestine ; the orifice of which is surrounded
by vibrating cilia. This passes up as a straight tube by the
side of the ossophagus, and terminates by a distinct orifice outside
the circle of tentacula.

1100. The whole of this complex digestive apparatus floats
freely in the general cavity, formed by the integument of the
animal ; the space between being occupied by a clear fluid, and

FIG. 624. — BOWER -
BANKIA. a, oesophagus j
b, gizzard ; c, stomach ;
d, orifice of intestine.

CILIOBRACHIATE POLYPES; — BOWEBBANKIA. 529

by the muscles which change the place of the animal in its cell.
The cell is formed by the outside of this integument ; of which
the lower part is -so consolidated by horny matter, as to be nearly
unyielding; whilst the upper third remains flexible. This
flexible part consists of two portions ; the lower half being a
simple continuation of the rest of the cell ; whilst the upper
consists of a row of delicate bristle-shaped processes, or setce,
which are arranged parallel with each other round the walls of
the cell, and are prevented from separating beyond a certain
distance, by a membrane of excessive tenuity, which surrounds
and connects the whole. This mode of termination is very
common in the cells of the Ciliobrachiate Polypes; and it is
evidently a provision for allowing the freest possible motion of
the upper part of the body in its expanded state, to which it
affords at the same time support and protection ; whilst it com-
pletely defends it when retracted or withdrawn into the cell, as
will presently appear.

1101. For the purpose of retraction, two distinct sets of
muscles are provided; one acting upon the animal, and the
other upon the cell. The first set arises from the bottom of the
cell, and is attached to different parts of the digestive tube.
The second set arises from the upper part of the firm portion
of the cell, and is attached to the flexible continuation of it.
When the animal wishes to withdraw itself, the tentacula are
first closed together into a straight line ; and immediately the
whole digestive tube begins to descend, its different parts being
folded upon one another, and drawn back within the integument,
which is inverted over them so as to form a close sheath around
the tentacula. When the animal is completely retracted, the
oesophagus is bent upon itself like the letter S ; and the tentacula
lie straight in its axis, inclosed in the inverted tube of integument,
their extremities being on a level with the top of the unyield-
ing portion of the cell. By the time that the end of the arms
are on a level with the base of the setce, the retraction of the
latter commences. This is performed exactly in the same
manner as that of the tentacula ; and the flexible portion of the
cell is inverted over them, so as to form a complete envelope. —

530 CILIOBRACHIATE POLYPES; BOWERBANKIA.

The protrusion of the body takes place by a contrary series
of processes. The bundle of setce first makes its appearance
out of the apex of the cell, and is followed by the flexible portion
on which it is set. The tentacula next pass up between the setae
and thrust them asunder ; while the integument is seen gradually
rolling onwards from around the tentacula. These latter con-
tinue to emerge, and the integument to be inverted from around
them, until the base of the tentacula has risen above the top of
the expanded setae ; when the act of protrusion is completed, the
tentacula separate and expand, and the cilia commence vibrating.
These actions are generally performed with an extraordinary
rapidity ; and it is only when they are executed with unusual
slowness, that the several movements concerned in them can be
distinguished.

1102. Upon reviewing the complex organisation of this
minute Polype, it must be admitted that its mechanical functions
are executed with a degree of perfection, which cannot but excite
our surprise and admiration ; and not less interesting is it to
observe the other vital operations exhibited by it, which the
transparency of the whole structure enables us to watch with no
interruption. The little animal, when in full vigour, is seen
projecting from its cell with the arms extended and the cilia in
active operation ; the upper part of the body being frequently
turned from side to side over the edge of the cell, the extremity
of which, from its peculiar flexibility, moves along with it.
The action of the cilia forms a kind of whirlpool, by which the
particles contained in the surrounding water are carried into the
funnel-like pharynx. By the contraction of its walls, they are
carried rapidly down the oesophagus into the gizzard, which
expands to receive them. Here they are submitted to a sort of
crushing operation ; the movement of its walls very much resem-
bling that, which is seen in the dental apparatus of the Wheel-
Animalcules (§ 857). Their residence in this cavity, however,
is only momentary ; and they are immediately propelled into
the true stomach below, where they become mixed up with its
contents, which, during digestion, are always of a dark rich
brown colour, being tinged by the secretion of the biliary follicles

CILIOBRACHIATE POLYPES; — BOWERBANKIA. 531

surrounding it. The food appears to be retained for a consider-
able time in the stomach, and may frequently be seen to pass
back into the gizzard, for the purpose of being again submitted to
its operations. After being subjected to the digestive process in
the stomach, the particles which remain are transmitted into the
intestine ; but previously to their entering it, they are seen to
rotate for some time about its orifice, the movement being pro-
duced by the action of the cilia that fringe it. The granular
matter accumulates in little pellets in the intestine; and when
these pass out from its extremity, they are immediately whirled
off to a distance, by the same action of the cilia upon the arms,
as that which produces a current towards the mouth.

1103. Considerable power of selection appears to be enjoyed
by these Polypes in regard to their food. The movements of
the cilia which fringe the tentacula, seem entirely under the con-
trol of the individual ; and by their vibrations currents of water
are produced, which bring particles of various kinds of living
and dead matter to the entrance of the alimentary canal. It
has been sometimes noticed that animalcules, which have thus
been drawn into the pharynx, escape during the act of swallow-
ing ; but they are usually met by one of the tentacula, which
bends inwards, and by means of a sharp blow drives them back
into the mouth. They do not immediately perish in the stomach,
but may sometimes be seen to continue their movements for a
considerable period within its cavity. Of the vortex which is
drawn by the cilia towards the mouth, a considerable amount
passes out between the bases of the arms; and this usually
contains the finer particles, which thus escape. Of those which
remain within the cone, those of fitting size are received into the
pharynx ; and, when they have passed downwards to its termi-
nation, a more perfect selection appears to take place, by which
some are admitted into the stomach, whilst others are rejected.
Besides this regular flow of water into the pharynx, the fluid is
occasionally introduced in larger quantity, by the sudden dilata-
tion of the tube, which quickly returns to its former diameter,
and expels a large part of what it had thus taken in. This
movement is not improbably connected with the function of

532 CILIOBRACHIATE POLYPES; — BOWERBANKIA ; FLUSTRA.

respiration. That a part of the alimentary canal should be
specially modified for this purpose, is by no means surprising ;
for such a modification, in a somewhat different form, is not at
all uncommon in various divisions of the animal kingdom.
Thus, in the lowest group of Mollusca, to which these Polypes
bear considerable affinity, we have seen that the entrance to the
stomach lies at the bottom of a large cavity lined by the respira-
tory membrane, over the walls of which currents of water are
constantly passing, which supply the digestive organs with
alimentary materials, besides effecting the aeration of the blood
(§ 974).

1104. As in the two preceding Orders, we meet with species
among the Ciliobrachiate polypes, which have the power of
forming stony cells, by a deposit of lime in their soft tissues.
The cells of some of these polypes are covered-in, when the
animal is withdrawn, by a sort of lid or flap, which is provided
with muscles for drawing it down upon the mouth of the cell.
In others of the compound polypidoms, however, the cells over-
lap one another obliquely ; and the orifice is not at their extre-
mity but rather on one side, so that the operculum has only to
be slightly upraised, to allow of the protrusion of the animal.
This is the case in the common Flustra of our own coasts, which
presents a flat expanded surface, so thickly set with these
apertures, as to appear like a delicate network. These Sea-mats,
as they have been fancifully termed, so much resemble common
seaweeds in their general aspect, that they are often mistaken
for them by ignorant collectors. They may readily be distin-
guished, however, by the crispness of their feel, when contrasted
with the flabbiness of the Algas, as well as by the polype-cells so
beautifully arranged on their surface. The extension of these
compound structures takes place by buds which are developed
from the outer surface of the cells. From one original cell of
the Flustra, five such buds may be sent off, which develope
themselves into new cells around it ; and these, in their turn,
produce buds from their unattached margins, so as rapidly to
increase the number of cells to a very large amount. This
extension may go on almost without limit ; and it often happens

CILIOBRACHIATE POLYPES ; — FLUSTRA. 533

that the cells in the centre of a leaf-like expansion of the Flustra
are devoid of polypes, and have lost their vitality, whilst the
edges are in a state of active growth. Although this mode of
multiplication appears to be the one most characteristic of the
group, the production of gemmules or ova occasionally takes
place, as in other Polypifera. These are developed from the
lining membrane of the cell, and gradually increase so as to fill
up its cavity, and to cause the death of the contained polype.
When mature, they escape from the cell, and swim about for
some time, after which they fix themselves, and lay the founda-
tion of new structures.

1105. The polypes forming these compound structures are
usually packed closely together ; and are of very minute size ;

c b a

Fro. 625.— PLUMATKLLA : a, natural size ; b, a group enlarged ; c, anal orifice.

so that a single polypidom of very moderate dimensions must
contain an enormous multitude of individuals. Dr. Grant has
reckoned that, on an ordinary specimen of Flustra carbasea, there
are about ten square inches of surface ; in each square inch there
may be about 1800 polype-cells, thus making altogether 18,000
within this small space. Each of these polypes has 22 teuta-
cula ; so that there will be about 396,000 of these minute arms

534 CILIOBRACHIATE POLYPES. FOSSIL CORALS.

upon this little specimen. If each of these tentacula has only
100 cilia upon its edges (and there are probably many more),
the whole polypidom will have 39,600,000 of these minute but
important organs. Other species certainly contain more than
ten times these numbers. Dr. Grant has computed about
400,000,000 cilia to exist on a single Flustra foliacea. In the
Alcyonella, a fresh- water species composed of long membranous
cells arranged side by side so as to form a spongy mass, the
number of tentacula on a moderate-sized specimen may be com-
puted at nearly five millions and a half ; and the cilia are cer-
tainly not less than a hundred times that number. The figure in
the preceding page represents another very beautiful fresh- water
polype of this Order, which is by no means uncommon. It is
found upon the surface of leaves, &c., of aquatic plants.

1106. From the very imperfect degree in which the greater
part of the polypes of this group have been yet examined, the
subdivisions of it are at present necessarily founded only upon
the arrangement of the cells in regard to one another. Such an
arrangement is liable to this great objection, that the mode in which
they are disposed will vary extremely with the surface upon
which they grow. Hence it is not advisable for us to enter more
particularly into the classification of this group ; but the study
of it may be especially recommended to those who have oppor-
tunities at their command, as a most interesting pursuit, which,
with but a moderate amount of previous information, and of skill
in observation, is sure to be productive of much that will be
alike interesting, novel, and important.

1107. The most extended survey we can take of the opera-
tions of the Polypifera upon the surface of the globe at the
present time, will give us but a very inadequate idea of the
important part which they performed, in the remoter epochs of
the history of the earth. Our wonder is excited when we hear
of a continuous reef of coral more than a thousand miles in
length; yet what is this to the formation of limestone strata,
covering superficial areas, not only of thousands, but of tens of
thousands, of square miles, to a thickness, in many instances, of

METAMORPHOSES OP CORAL. 535

3000 feet ? Yet the Geologist of the present day has little hesi-
tation in regarding these formations, as having taken their origin
from the labours of these apparently-insignificant and simply-
organised beings. As at the present time, the greater proportion
of these structures appears composed of the Lamelliform corals
(§ 1069) ; but the remains of Alcyonian polypes are by no
means unfrequent in the limestone rocks, and are especially abun-
dant in particular strata ; and some of the harder forms of the
Ciliobrackiate group are occasionally found.

1108. There are many instances in which the Coral struc-
tures of comparatively recent origin have undergone a metamor-
phosis, which causes them to lose, in greater or less degree, their
original aspect. Large masses, when long exposed to the ah*,
become changed into a solid, often somewhat crystalline, rock ;
in which the traces of organic structure are very indistinct, and
with which the Mountain or Secondary Limestone closely cor-
responds. This is observed in the Bermudas, — a group of
islands, which seems to have been for the most part formed by
Coral Polypes of the same species with those now existing in the
seas around. — Moreover, the Coral Sand, formed by the action
of the waves upon the living structure, often becomes consoli-
dated into a hard stone by the filtering of water through it ;
a small quantity of the carbonate of lime being probably dissolved
at the surface (where the carbonic acid of the air increases the
solvent power of the water), and set free again below, so as to
glue together the separate particles. It is in such a mass, that
the human skeleton is imbedded, which was found on the shore
at Guadaloupe, and is now placed in the British Museum.
This stone, when minutely examined, is found to consist of a
number of rounded grains, cemented, as it were, together ; and
it closely resembles the rock known to the Geologist as Oolite. —
Further, where shallow water exists around Coral islands, the
bottom is found to be covered with a layer of white mud, which
is formed by the decay of the animal matter that held together
the particles of carbonate of lime in the stony corals ; and these,
being thus set free in a finely-divided state, fall to the bottom in
a form which, if dry, would constitute Chalk. Thus we may

536 ANCIENT CORAL- FORMATIONS.

trace very distinctly the mode in which three principal kinds of
limestone rocks may have taken their origin from Coral
formations.

1109. Now, the Mountain, or Carboniferous Limestone, — a
rock very abundant in Britain, extending over large areas
beneath the coal-fields, and sometimes exhibiting a thickness of
nearly 3000 feet, — though in some parts evidently composed
of accumulations of Shells, Encrinite stems, &c., exhibits the Coral
structure very distinctly in many situations ; and these parts are
so blended with the neighbouring rock, as to make it appear
probable that the latter also was once in the state of coral, but
was gradually changed by the process just described. Further,
the collections of other animal remains are such, as we should
expect to find on the margin of a coral reef or island existing at
that epoch ; and a similar process of fossilization is taking place
at this very time, on the shores of the islands now being built up, —
the species of animals imbedded being, however, not the same. The
great thickness of the beds of this rock may be very well accounted
for, in the same manner as the depth of the coralline masses of
recent formation (§ 1077)« The Oolite had its origin in the
wearing-down of the older limestone beds, with additional matter
derived from the skeletons of the races of animals, which existed
during the period of its formation. And there can be little doubt
that the CW&-formation owes a considerable part of its substance
to the same sources ; though part was doubtless derived from the
decomposition of shells, and a large proportion in some situations
from the remains of animals of extreme minuteness, presently to
be described (§ 1107). — There are observed, in rocks of more
recent formation,. appearances which still more clearly indicate,
that they too were originally formed by Coral-polypes. These
are often found within narrow limits, as if they had been reefs
or islands of small size. Thus we find a stone, called Coral-
rag, in Oxfordshire ; and very distinct Coral- beds in the Crag
of the eastern coast of England. It is interesting to remark,
that the remains of Coral, which are found in the older limestones,
all correspond with those at present abounding near the equator,
and exhibit the Lamelliform structure (§ 1069) ; whilst they are

FORAMINIFERA. 537

gradually replaced in the newer strata, by species more allied to
those at present existing in temperate climates. This is one of the
many facts, which tend to prove that this part of the earth had,
at some former period, a much higher temperature than at present.
1110. Under the class Polypifera, we are probably to include
a large and very important group of minute calcareous structures,
which, from their strong resemblance to the spiral-chambered
shells of some Cephalopoda (§ 894), have been supposed to be
formed by animals of that class. Many kinds of them exist on
almost every sandy shore ; but their extreme minuteness causes
them to be usually overlooked, and is also an obstacle to the
satisfactory determination of the character of the animals which
construct them. By D'Orbigny, who first attracted the atten-
tion of Naturalists to the details of this curious group, it was
regarded as an order of Cephalopoda; and he gave to it the
name of Foraminifera, on account of the communication
between the chambers not being established by one principal
tubular aperture, the siphuncle, but by numerous minute
foramina or porous orifices. The species which exist on the
shores of Northern Europe are so minute, as not to be easily
examined, even with the microscope ; but those which are found
in the Adriatic Sea, are sufficiently large to be recognised with the
naked eye. From an examination of recent specimens, it has
been ascertained that the animals by which these shells are con-
structed resemble polypes more than any other group, although
allied also to the Polygastric Animalcules ; and that we are
thus to regard these little isolated masses as coralline structures,
each being formed by the continual growth of one individual.
The character of the animal appears very simple. No part of it
is seen externally, except when it is preparing to add a new
chamber to its shell. It seems to consist of a series of mem-
branous bags, united together like a string of beads, in the outer
layer of which is deposited the calcareous matter that gives the
shell-like character. If this latter be removed by a weak acid,
the animal membrane will be left ; and the spiral may then be
unrolled. Whether any of the species possess a regular mouth
and tentacula, is yet uncertain.

538 FORAMINIFERA ; — NUMMULITE ; MILIOLA.

1111. If we merely consider this group as it presents itself
to our notice in the existing epoch, we should have but a very
imperfect idea of its importance. The forms under which it
once existed in much greater abundance, have been preserved to
us ; and recent inquiries have added to our knowledge of these
in a most astonishing degree. The fossils termed Nummulites
have long been observed to bear a large share in the formation
of extensive beds of limestone rock. They were remarked by
Strabo in the stones of the Pyramids ; and he informs us that
they were commonly reputed to be the petrified impressions of
the lentils, which had been used as daily food by the workmen
engaged in building them, and takes some pains to refute this
idea. By subsequent authors, these Nummulites have been
supposed to be the opercula (§ 902) of the Ammonite (§ 897),
which, it was imagined, might probably form a new one, eArery
time that it added a chamber to its shell. The discovery, how-
ever, of minute shells of a similar character at present existing,
and evidently belonging to distinct animals, established their
claim to a similar position. Nummulites are probably the
largest forms of this group, of which D'Orbigny has described
fifty-two genera, and above 600 species ; some of them measure
about an inch and a half in diameter, whilst a great proportion
of the rest are microscopic. Many limestone strata of the tertiary
period, are almost entirely composed of the larger Nummulites ;
and these strata constitute the principal part of several mountain
ranges in Southern Europe, such as the Alps, Carpathians, and
Pyrenees. The Sphinx, as well as the Pyramids, are composed
of a limestone loaded with Nummulites. — A more minute shell,
the Miliola, of the same description, but no larger than a millet-
seed, bears an equal proportion in the mass of limestone strata
which are quarried near Paris. " We scarcely condescend,"
observes Lamarck in reference to this fact, " to examine micro-
scopjc shells, from their insignificant size ; but we cease to think
them insignificant when we reflect, that it is by means of the
smallest objects that Nature everywhere produces her most
remarkable and astonishing phenomena. Whatever she may
seem to lose in point of volume in the production of living bodies,

FORAMINIFEBA OF CHALK. 539

is amply made up by the number of the individuals, which she
multiplies with admirable promptitude to infinity. The remains
of such minute animals have added much more to the mass of
materials which compose the exterior crust of the globe, than
the bones of Elephants, Hippopotami, and Whales."

1112. But these facts sink into insignificance, when compared
with those lately revealed by the researches of Ehrenberg, in
regard to the existence of a race still more minute, and its multi-
plication to a still more inconceivable extent. In examining,
with a high magnifying power, Chalk or Whiting in a state of
extremely minute division, two sets of particles may be distinctly
seen; one set having a crystalline structure, and the other
presenting some indications of an organic aspect. If these be
rendered more transparent by the use of Canada balsam, it is
seen that they are polythalamous (many-chambered) shells of
great minuteness ; some of them in fragments, and others nearly
or quite perfect. The size of these varies from -fa to -^^ of
a line ; and when, as in the Chalk of Southern Europe, they
constitute nearly the whole mass, there must usually be above a
million in every cubic inch. In the fourth part of a cubic line,
or T^ of a grain, from 150 to 200 can be ascertained to exist ;
and thus there would be from 1800 to 2400 in each grain, and
far above ten millions in every pound of chalk. In the chalk of
this country, and of other parts of the north of Europe, there is
a predominance of particles of a somewhat crystalline character ;
but even these have in all probability once been combined in
organic structures. In pursuing his researches on this subject,
it occurred to Ehrenberg to examine the finer particles of calca-
reous matter, which have been artificially separated from chalk,
and are employed for various purposes. Of such, the glazing of
the papers with which the walls of apartments are sometimes
covered, and that of visiting cards, are partly composed ; and on
scraping a little of this, and subjecting it to microscopic exami-
nation, he was delighted to find the organic structure almost
everywhere apparent.

CHAPTER XXV.

OF THE CLASS OF POLYGASTRICA.

1113. THE next class we shall consider is that of Polygas-
trica ; which includes the simpler kinds of Infusorial Animalcules.
Its true place in the Animal scale cannot be satisfactorily assigned,
until the internal organisation of the beings composing it has
been more thoroughly examined. At present, the general sim-
plicity of their character, and the absence of any other decided
type, leads us to rank them among the Eadiata ; although few
of them present any distinct indications of the radiated confor-
mation. This class was formerly supposed to contain the sim-
plest members of the Animal Kingdom ; many tribes belonging
to it having been imagined to obtain their nutriment, by direct
absorption from the surrounding fluid. It is now known, how-
ever, through the researches of Ehrenberg and others, that most
of these possess an organisation of much greater complexity,
having a distinct mouth (usually surrounded by a fringe of cilia),
and internal cavities for the reception of food.

1114. Wherever any decaying organised matter exists in a
fluid state, and is exposed to air and warmth, it will speedily be
found peopled with minute inhabitants, of the most varied forms
and diversified movements, possessed of considerable activity,
and evidently endowed with an energetic system of nutrition.
They are, therefore, by no means so nearly allied to Vegetables,
as are those inactive and simple creatures — the Sponges and their
allies. The cause of the spontaneous appearance of these Ani-
malcules, where no germs were previously suspected to exist, and
where it was not easy to suppose that they had been conveyed,
has been a matter of much speculation. Many have had recourse
to the supposition that the germs formed part, in a latent state,
of the living tissues of the animal and vegetable structures, from

POLYGASTRIC ANIMALCULES.

541

the decomposition of which they were evolved ; and others have
even supposed them to have arisen from accidental combinations
of inorganic elements. As yet, however, somewhat of the same
obscurity hangs over their origin, as envelopes the propagation
of the Fungi ; since there is some reason to believe that amongst
the Polygastrica, also, the same germ may be developed into
different forms, according to the character of the infusion from
which it derives its support. But these Animalcules are not
confined to infusions of organised matter ; they are found in the
stagnant waters around our cities ; in the waters of rivers, har-
bours, and lakes ; and even, it is believed, in every fluid drop of
the ocean. From their minute size and almost universal distri-
bution, therefore, we cannot doubt that they are by far the most
numerous living beings, which exist on the face of the globe.
Indeed, from the calculations which will be hereafter given
(§ 1132), it would appear that a single cup of water may easily
hold a number of the smallest known species, far surpassing that
of the whole human population of the earth. And the ideas
we form of their present amount seem mean and insignificant,
when we contrast them with those, to which we are led by the
contemplation of the fossil remains of those of former epochs
(§ H30).

1115. The forms presented by these Animalcules are ex-
tremely various. In some we can scarcely detect any definite

VARIOUS FORMS OF ANIMALCULES.

shape ; their bodies appear composed of a mass of gelatinous
matter without any solid support, which may project itself into

542 POLYGASTRIC ANIMALCULES.

almost any figure. In others there is still considerable variety
in the forms assumed by the same individual under different cir-
cumstances (Fig. 626, d) ; but still a prevailing shape can be
recognised. In others, again, the body, although still unprotected
by any firm envelope, appears to undergo little change in figure,
except when affected by some temporary pressure. But there are
many species which cannot be influenced even by this ; their soft
bodies being enclosed in a delicate but firm integument, strength-
ened by a deposit of siliceous matter. These are termed loricated
Infusoria ; and these envelopes, which are often preserved after
the death of the animals, are termed the shields or sheaths.

1116. Although most of the Polygastrica have the power
of freely moving through their native element, some occasionally
attach themselves to a solid base, like Polypes ; but many, like
the Hydra and Sea-Anemone, have the power of occasionally
detaching themselves, and go in search of a new field for the
supply of their voracious appetites. The analogy to the Poly-
pifera is very strongly marked in some species, however ; in
which we not only observe the Animalcules attached during
nearly the whole of life, but find a large number associated into
one plant-like structure. In almost all the Polygastrica, we
find the body furnished more or less abundantly with cilia, which
serve various important purposes. Sometimes they are only
disposed around the mouth, towards which they produce a vortex
of fluid, that brings a supply of alimentary particles. Where the
digestive cavity has a separate termination, this also is usually
fringed with cilia, by the action of which the particles rejected
are thrown off to a distance. And, in many of the higher species
not enclosed in a siliceous envelope, the whole body is beset with
rows of these little filaments ; by the action of which every pos-
sible variety of movement seems to be produced.

1117. The name Polygastrica has been applied to these
Animalcules by Ehrenberg, in consequence of his belief that
they possess a large number of distinct stomachs, or cavities for
the reception and digestion of aliment. This belief is founded
on the appearance which many of them present, when they have
been allowed to remain for a short time in water, in which finely

POLYGASTRIC ANIMALCULES. 543

divided particles of colouring matter are suspended. The par-
ticles are observed to be drawn towards the mouth, by the action
of the cilia with which most of them are provided ; and before
long, the whole of the transparent body is seen to be studded
with coloured globules of an uniform size, many times larger
than the separate particles themselves. Sometimes these globules
are very numerous, amounting to more than one hundred. If
two kinds of colouring matter be put into the water, as for
instance carmine and indigo, separate pink and blue globules will
be seen in the bodies of some of the Animalcules. In many
species, there is evidently a second orifice communicating with
the interior of the body ; by which a part of the colouring matter,
and other substances taken in by the mouth, is afterwards
rejected.

1118. From these facts it has been inferred by Ehrenberg,
that a large number of globular cavities exist in the substance of
the body, into which the food is received. He considers that
sometimes these communicate only with the mouth, as in the
Monas ; but that in general they are arranged along an intestinal
tube, into which they open by a short neck. The course of this
tube he infers from the disposition of the coloured globules, rather
than from any more distinct indication of its presence. Thus
in the Vorticella., he thinks that it returns to the neighbourhood
of the mouth ; whilst in Euchelys and Leucophrys it terminates
at the opposite extremity t>f the body, — running straight in the
first from one end to the other, and in the second making two
spiral turns in its passage. He does not affirm that he has ever
distinctly seen food passing along this narrow intestine ; or that
he has been able to trace the walls of the globular stomachs, any
more than of this alimentary tube, when they are not filled out
with colouring particles. And his account of them, therefore,
can scarcely be regarded as free from doubt.

1119. The views of Ehrenberg have not been by any means
universally received amongst Naturalists ; and many of those
who have paid most attention to the structure and habits of
these Infusoria, are of opinion that they are very erroneous. A
kind of circulation has been seen to be performed by the globular

oo2

544 POLYGASTRIC ANIMALCULES.

masses already mentioned, as if they floated loosely in the cavity
of the Animalcule, and did not form part of the supposed
alimentary canal. And it has been found that, when a small
quantity of an alkaline solution is allowed to touch their bodies,
they burst, and discharge these globules, which seem to have
been imbedded in a soft gelatinous substance. Some of the
globules appear as if entirely composed of the particles on which
the animal has been feeding ; and they have probably derived
their globular form, from being moulded (as it were) in a little
cavity behind the mouth. They are, for the most part, of very
uniform size in the same species of Animalcule. But others
have all the character of Cells; and it may be questioned
whether they do not perform, in the economy of the Animalcule,
the same purposes as the cells which float in the nutritious fluids
of higher animals. — The whole subject of the nature of the
organisation and life of these Animalcules, is still enveloped in
great mystery, notwithstanding the extraordinary discoveries of
the last few years. Some Physiologists doubt whether the
greater number of them are to be regarded in any higher light
than as single cells, not possessed of any consciousness or will,
and having the same kind of power of movement as that which
is possessed by those Epithelium cells which are furnished with
cilia, — these, when detached from the surface on which they
lay, being often seen to move in fluid for many hours. The
Author does not at present feel himself able to express a decided
opinion upon this interesting question.

1120. Putting aside the undetermined question of the
interior organisation of the digestive apparatus, we may pass
to the consideration of other phenomena presented by this
remarkable class. Food is usually conveyed to the mouth by
the vibration of the cilia which surround it ; in this manner a
vortex is produced in the fluid, which brings the particles float-
ing in it, or other Animalcules swimming in its neighbourhood,
within the grasp of the lips of that aperture. Sometimes even
very large substances (in proportion to the size of the individual)
are entrapped and swallowed in this manner; many species
having much of the voracious character of the Sea- Anemone,

POLYGASTRIC ANIMALCULES; THEIR MOVEMENTS. 545

and swallowing entire the bodies of the Animalcules not very dis-
similar to themselves, — to receive which the entrance to the
digestive cavity has to undergo a distention, that very much
alters their general form. In one genus, Nassula, there is a
very curious dental apparatus, for the prehension and reduction
of food. This consists of a sort of cone, formed by a large
number of diverging flexible bristle-like organs, at the apex of
which the mouth is placed, whilst the base can be projected and
expanded so as to inclose the prey, over which it then contracts
by the approximation of these curious teeth ; these, although
flexible, appear to possess considerable firmness.

1121. It is to the cilia, also, that the movements of the
greater part of the Animalcules, which freely swim through the
water, appear due. These movements are extremely various in
their character in different species ; and when a number of dis-
similar forms are assembled in one drop of water, the spectacle
is most entertaining. Some propel themselves directly for-
wards, with a velocity which appears (when thus highly magni-
fied) like that of an arrow, so that the eye can scarcely follow
their movement ; whilst others drag their bodies slowly along,
like the leech. Some make a fixed point of some portion of the
body, and revolve around it with great rapidity ; whilst others
scarcely present any appearance of animal motion. Some move
forwards by an uniform series of gentle undulations or vibra-
tions; whilst others seem to perform consecutive leaps, of no
small extent compared with the size of their bodies. In short,
there is no kind of movement, which is not practised by these
Animalcules. They have evidently the power of steering clear
of obstacles in their course, and of avoiding each other when
swimming in close proximity. By what kind of sensibility the
wonderful precision and accuracy of their movements is guided,
is yet very doubtful. The general surface, in those whose
bodies are not inclosed in a firm envelope", appears very sus-
ceptible of impressions. No organs of special sensation, however,
can be detected ; except certain red spots observable in the
bodies of many species, which are believed by Ehrenberg to be
eyes. This belief rests only upon an analogy which may very

546 INFLUENCE OF LIGHT AND HEAT ON ANIMALCULES.

possibly be unfounded. There can be little doubt, from their
position and their similarity to the undoubted visual organs in
the class nearest allied to them, that the red spots on the neck
of the Rotifera (§ 857) niay be fairly regarded as eyes. But
the same arguments by no means hold good in regard to the
Polygastrica.

1122. Light has certainly, however, a considerable influence
on these Infusoria, both in regard to their first production,
and their subsequent movements. It has been found that they
will appear much more speedily in an infusion exposed to light,
than in one secluded from it. But there are some species which
can exist in almost total darkness ; being found in the recesses of
the deepest mines. And it is further observed, tha,t a very
powerful light is injurious to them, and that they seek to avoid
it ; this may be due, however, to the heat which accompanies it,
of the influence of which they are very susceptible. The greater
number are instantaneously killed by a moderate heat, which
acts equally upon both ova and adults ; but they can support it
better if the temperature be raised gradually. There are a few
species which can support a temperature of 120°. On the other
hand, cold is very injurious to these Animalcules ; but it affects
the adult more than the germ. If the water in which they
exist be suddenly congealed, they are usually killed within two
hours ; but they are at first able to develope heat enough to
prevent the freezing of their own bodies, as appears from the
small quantity of water which remains fluid around them. If
the congelation be gradual, however, they retreat beneath the
surface, so as not to be included in the coating of ice ; and in the
winter, therefore, we meet with them just below the frozen
covering of the waters which they inhabit. Even if they are
entirely inclosed, and the greater part of them destroyed, it is
seldom that one or two individuals do not remain, — the eggs
being preserved where the parents have perished ; and from these
a new population, as great as the previous one, will speedily,
originate (§ 1123) at the return of the genial warmth which
calls them into active life.

1123. The presence of Oxygen in the atmosphere, with

POLYGASTRIC ANIMALCULES. 547

which the Water they inhabit is in contact, is necessary to the
continued life of Animalcules. But this may be in very small
amount. Many species will live in water placed under the
receiver of an air-pump, from which the greater part of the air
has been removed. Others are not killed for a long time, by the
interposition of a stratum of oil between the water and the air
above. The microscopic observer well knows that he can keep
most kinds of Animalcules for several days in a drop of water,
flattened between two pieces of glass, so that it is only in con-
tact with the air at its edges. But if some other gas be substi-
tuted for atmospheric air, a positively injurious effect results ;
when a vessel was three-parts filled with water containing
Animalcules, and the remaining fourth was filled with hydrogen,
they died within seventeen hours.

1 1 24. Animalcules are very susceptible of the influence of
Electricity. A spark drawn through water inhabited by them,
usually destroys all those that happen to be in its current ; and
this is the case whether the Electricity be generated by an
electric machine, by a galvanic pile, or by a magnetic appara-
tus, provided that the current be of sufficient intensity to decom-
pose water. These beings are also readily acted upon by various
substances, which are soluble in water, or which can otherwise
act upon them in a fluid form ; but the susceptibility to such
influences varies with the species. Thus Animalcules inhabiting
fresh- water are killed by a single drop of sea- water, which may
nevertheless be full of other species peculiar to it. Alcohol
usually destroys the inhabitants of fluids to which it is added even
in small quantities ; sugar has the same effect on many species ;
and strychnine on all. On the other hand, substances which are
only mechanically suspended, or but slightly soluble in water,
such as arsenic, appear to have little or no influence, even when
their particles are swallowed ; and calomel, corrosive sublimate,
and camphor, are not fatal until some hours have elapsed.

1125. The universal presence of Animalcules in fluids con-
taining organic matter, and exposed to the air, joined to the
suddenness of their appearance under particular circumstances,
has led to the belief that they are generated by the decomposition

548 REPRODUCTION OF POLYGASTRIC ANIMALCULES.

of the animal or vegetable particles, which thus consisted, as it
were, of their latent germs. But this hypothesis is unnecessary
to account for the phenomena ordinarily observed ; and it is
inconsistent with ascertained facts. It does not appear that
the Polygastric Animalcules are usually capable of retaining
their vitality when dried up, as some of the Rotifera are known
to do (§ 859). But it is unquestionable that their ova or germs
are susceptible of this treatment without injury ; and in this
manner they are probably carried about, in the form of minute
particles of dust, ready to develope themselves in any spot which
may afford them the requisite moisture and nutriment. In this
respect they probably resemble the Fungi, whose germs are
known to be thus diffused (VEGET. PHYSIOL. § 50 — 64).

1126. The extraordinary powers of reproduction possessed
by these Animalcules, will fully account for their rapid multi-
plication, when once they have obtained the means of develop-
ment. Several modes of propagation are observed among them.
Not unfrequently we observe, as in the Vorticella (§ 1128), a
reproduction by buds developed from the side of the body, as in
the Hydra. In other species, again, the process of generation
is accomplished by the separation of the body into two parts :
the division, which may be observed in several stages of its pro-
gress, is sometimes^trans verse (Fig. 626, £>), sometimes longitu-
dinal (c), sometimes oblique. In other tribes propagation takes
place by ova or germs evolved within the body of the parent, the
greater part of whose bulk is often made up by them. By these
methods, sometimes employed singly, occasionally in combina-
tion, a single individual may soon become the parent of an
immense population. Thus the Paramecium aurelia, if well
supplied by food, has been observed to divide itself every twenty-
four hours ; so that in a fortnight, allowing the product of each
division to multiply at the same rate, 16,384 animalcules would be
produced from the same stock ; and in four weeks, 268,435,456
new beings would result from a continued repetition of the pro-
cess. But this animalcule has occasionally been observed to
increase with much greater rapidity ; the first million being pro-
duced (according to calculation based on fair data) within seven

POLYGASTRIC ANIMALCULES ; MONADS. 549

days. But even this is as nothing to the more recent state-
ment of Ehrenberg, that some species are sufficiently fertile to
produce in four days 140,000,000 from a single germ ; a number
sufficient to compose, by the aggregation of their minute siliceous
shields, two cubic feet of solid rock like the Polierschiefer of
Bilin (§ 1132). -

1127. The classification of the Polygastrica proposed by
Ehrenberg is principally founded on his views in regard to the
alimentary canal ; and, until these shall have been established, it
cannot be regarded as valid. For this reason it seems undesir-
able to introduce its details in this place ; but a few of the more
important groups, which are separated from one another by
evident characters, may be here noticed. It is interesting to
remark, however, that nearly every one of the subdivisions
founded upon the arrangement of the digestive organs, may be
further divided into two groups ; one characterised by the pre-
sence, and the other by the absence, of a firm envelope or sheath,
the existence of which becomes evident when the animalcule is
compressed between two pieces of glass.

1128. The Monads constitute the smallest, and perhaps the
simplest, of the Polygastric Infusoria. They usually present
a spherical form ; and seem like moving points of gelatinous
matter. They swim freely and with activity, apparently by the
vibrations of a sort of filament, which is said to be tubular. The
number of coloured particles seen in their bodies, when the fluid
in which they live has been tinged for the purpose, is usually
small ; in many species never above four or six. They only seem
to possess one orifice to the digestive cavity ; and from their
extreme minuteness no cilia can be detected in its neighbourhood,
though it is probable that such exist there. Of the Animalcules
included in this family, some have a tendency to aggregate
themselves in clusters ; and it is probable that those which thus
unite pass the earlier part of their lives in a separate condition.
It is often very difficult to distinguish the Monads from the
young of other species, which they much resemble. Where a
number of minute gelatinous points are seen in the neighbour-
hood of clusters of larger forms, they are probably to be regarded

550 POLYGASTRIC ANIMALCULES ; — VOLVOX.

as their germs in a state of development. The Monads propa-
gate both by subdivision, and by the production of ova. The
former takes place either into two parts, by a transverse line of
separation ; or into four by a crossed division.

1129. The next family to be noticed is that which contains
the Volwx and its allies. The nature of these beings was, until
recently, quite misunderstood. The Volwx globator, commonly
found in ponds, has a spherical form ; and its diameter is as much
as -TjL- of an inch, so that it is easily discovered by the unassisted
vision. This sphere, when examined with a high magnifying
power, is seen to consist of a thin transparent pellicle, studded at
regular intervals with minute green spots. Further examina-
tion makes it evident, that each of these spots is an individual
animalcule of the nature of a Monad. From every one of these,
two filaments proceed, which pass through the general envelope,
and vibrate in the surrounding fluid ; so that, the whole surface
of the sphere being beset by them, it is made to perform very
active movements. It is usually seen rolling over and over like
a ball ; sometimes spinning in the same place, like a top ; or
gliding along smoothly, without turning itself. Sometimes its
motions are slow ; at others rapid. The general envelope is
traversed by canals, which seem to connect the different indivi-
duals together ; in the same manner as the Polypes of a Sertu-
laria (§ 1056) are united by their common circulation. Within
the parent sphere may generally be seen other globes of darker
colour, and varying in number from one or two to twenty.
These are young formations of a similarly-compound nature.
They appear to have taken their origin from the subdivision of
one of the Monad-like beings, which enter into the composition
of its parent ; and for some time they remain attached to its
inner wall. They afterwards detach themselves, however, and
may be observed revolving in its cavity, by the action of their
own ciliary filaments. After a time the parent globe bursts,
and the young ones swim forth, and speedily undergo the same
changes. Their dark colour appears due to the closer approxi-
mation of these component Monads ; the transparent polypidom,
for so it may almost be termed, being developed between them at

POLYGASTRIC ANIMALCULES; BACILLARLE. 551

a subsequent time. Not unfrequently a second generation may be
observed within the globes still contained in the parent structure;
and, with a good light, a third generation within these again.
The animals of this family do not always form, by their aggrega-
tion, a globular structure ; but are sometimes united in flat-
tened clusters of various forms.

1130. The family of Bacillariae is a very interesting one,
since it includes nearly all the Animalcules, whose fossil remains
(Fig. 627) have yet been discovered. A large number of the
species composing it were formerly regarded as belonging to the
vegetable kingdom ; and, even now, considerable doubt may be
entertained as to the claim of all to be regarded as Animals.
This claim seems to rest more upon their general organisation,
than upon the movements they exhibit ; for the latter are very
slight, and not distinctly referable to spontaneous action. In
the greater number of species of this order, we find the body
inclosed in a siliceous sheath of considerable firmness ; some-
times, however, the envelopes are simply membranous : but no
other mineral matter than silex has ever been detected in them.
Their forms are extremely various. Most of them are elongated,
like the Navicula, whose siliceous sheath has somewhat of a
prismatic form. It has six openings, two at each end, and two
in the centre, the latter being the largest. Through the latter
it would appear that food enters the body. That there is an
internal digestive cavity, is made apparent by the accumulation
of colouring particles, which the transparency of the siliceous
shield allows to be distinctly seen. Along the sides of the body
are seen dark masses, which appear to be the organs for the
evolution of ova ; and the germs are said to escape from these,
through the apertures at the extremities. There is much uncer-
tainty, however, as to the vital actions of these beings. Many of
them have a tendency to aggregation ; and thus very curious
forms result.

1131. The Vorticellince are a very interesting family to the
Microscopic observer, from the variety of their forms and actions,
and from their great abundance in most pools in which vegeta-
tion is going on. The ciliary action is here very distinct and

552 POLYGASTRIC ANIMALCULES; — VORTICELLIN-E.

powerful ; and the Animalcules show by their movements a
great susceptibility to external impressions. Thus, the common
Vorticella (Fig. 626, a), which clusters round the stalks of duck-
weed, is usually attached by a long peduncle, which, when the
animal is seeking for its prey by the vibration of its cilia, seems
fully extended, and almost put on the stretch. But if the stage of
the miscroscope be smartly tapped, the Animalcule is seen to
contract its peduncle suddenly ; and it afterwards slowly extends
it when free from alarm. In the Stentor (Trumpet Vorticella),
which is one of the largest of the Polygastrica, the body is itself
prolonged, and attached at its basis. In general these Animal-
cules have the power of separating themselves from their attach-
ment, retracting the foot into the body, so that no appearance
of a peduncle is seen, and then swimming freely in search of a new
point to which to fix themselves. Some of them produce buds
from their sides, like the Hydra ; and others multiply by sub-
division. Both these processes take place, if the temperature be
genial, and the animals be well supplied with food, with great
rapidity. By the older observers, those which were seen
during their change, and whose form was thus very different
from the one usually observed, as also those that were seen in their
unattached condition, were regarded as distinct species. Errors
of this kind have been by no means uncommon in Natural
History, and will always be committed whilst observers are
content with the cursory inspection of external forms, and do
not make the changes, which these forms may undergo in the
progress of life, an object of special study. In some genera
belonging to this group, we observe the stalks of a number of
individuals proceeding from one common stem ; and sometimes
this ramifies and subdivides, so as to exhibit a completely
arborescent form, analogous to that of the Polypifera. The
circular arrangement of the cilia around the mouth, and the
mode in which these organs are employed in obtaining food, has
occasioned the Vorticellce and the "Wheel- Animalcules to be con-
founded together.

1 132. The almost universal diffusion of this class of Animal-
cules is not the least astonishing part of their history. There is

POLYGASTRIC ANIMALCULES. METEORIC PAPER. 553

scarcely any situation, in which we cannot find some traces of
their existence. Although they may be found, with the most
certainty, in infusions of decomposing organised matter (whence
their name Infusoria is derived), they are, as already stated,
diffused in greater or less degree, through almost all the fluid
masses upon the earth's surface ; and thus the animalcules found
in such infusions, may be regarded as but a minute specimen of
those at present existing in the waters, which cover so large a por-
tion of our globe. But they are not confined to a fluid medium.
There are many species whose natural habitation is mud ; and
others which aggregate together in masses, so as themselves to
form a kind of earth, which only requires a moderate amount of
moisture to preserve them alive. The extraordinary discoveries
of Ehrenberg, presently to be mentioned, in regard to the exist-
ence of the remains of Polygastrica in a fossil state, led him to
make a series of experiments upon their production in this
curious condition ; and he has fully succeeded in manufacturing
living earth, in large quantities. This corresponds precisely with
the Tripoli which occurs as a mineral in large beds, and which
is important to Man from its use in the arts ; and, according to
Ehrenberg, a small rise in the price of Tripoli would make it worth
while to manufacture it from the living animals, as an article of
commerce. There are many species which are capable of main-
taining a torpid existence, in earth dried up by the summer sun ;
and they are thus raised into the air, in countless myriads, in
the form of the most finely-divided dust. Perhaps if received
into a moist atmosphere, they may even revive and grow under
these circumstances ; for they are sometimes deposited again in
large masses. In 1687? a great quantity of a black paper-like
substance fell, with a violent snow-storm, from the atmosphere
in Courland. A portion of this substance, preserved in the
Berlin Museum, has been microscopically examined by Ehren-
berg ; and has found it to consist entirely of an organic mass of
Conferva^ matted together, and including twenty-nine species
of Infusoria, all of which occur in the neighbourhood of Berlin.
It is not unlikely, however, that this mass was originally formed
at the surface of a marsh, and was raised altogether by a storm ;

554 MEADOW LEATHER. — FOSSIL ANIMALCULES.

since others of similar character have been found in such situa-
tions. One of these, formed as a green slime on the surface of
stagnant water covering a meadow, deposited itself when the
water was slowly let off; and it then became quite colourless,
resembling white dressed glove-leather, whence it received the
name of " Meadow Leather." When examined with the
microscope it was found to consist, like the Meteoric Paper, of
Conferva, intermixed with the siliceous remains of Infusoria
of various kinds. A similar mass of greater extent and thick-
ness, was recently found covering the ground after an inundation,
near Sabor in Siberia. This extended over a surface of several
hundred square feet, and was of a consistence resembling flannel.
It consisted, like the Meteoric Paper, and Meadow Leather, of a
matted mass of Conferva, interwoven with fifteen species of
Infusoria, and some shells of the Daphnia (water-flea).

1 133. It is in considering the accumulations of these remains,
however, which have taken place in successive ages, and which
have come down to us, sometimes in the form of large distinct
beds, sometimes as constituents of others, that we are the most
impressed with the vast amount of animal life, to which they owed
their origin. Even the accumulations of this nature which are
at present in progress of formation, startle us by their magnitude,
when we consider the extreme minuteness of the organised structures
of which they are composed. Ehrenberg states that, in the Public
Garden at Berlin, workmen vrere employed for several days in
removing in wheelbarrows masses of earth, which, on examina-
tion, were found to consist entirely of Infusoria already becoming
fossilized. These had probably lived and increased, much in the
condition in which their remains were found. In other instances,
a deposit of mud is taking place at the bottom of lakes and
marshes containing the living animals ; and thus an accumulation
is going on, which will possess something of the laminated struc-
ture exhibited in all masses slowly deposited in water. Of this
fact, abundant instances are related by Ehrenberg as occurring in
various parts of Europe. Such a deposit has also been found by
Professor Bailey at West Point, New York, at about a foot
below the surface of a peat bog ; it was eight or ten inches thick,

FOSSIL ANIMALCULES. 555

and probably several hundred square yards in extent ; and it
was wholly made up of the siliceous shields of Bacillarice. A
similar deposit has been recently discovered by Dr. Drummond
in Ireland. The author has seen water, brought from a lake in
the island of St. Vincent, crowded with the shields of races of
Naviculce at present inhabiting it ; and a thick layer of mud,
which is being deposited at the bottom of the lake, is almost
entirely composed of them.

1134. Some species of these Animalcules especially prefer
waters impregnated with iron ; and have the power of separating
the metal from its solvent, and incorporating it into their own
structures. Hence originates a soft yellow ochreous substance,
called Marsh Ochre or Meadow Earth, which is found in large
quantities every spring in the marshy neighbourhood of Berlin,
covering the bottom of ditches, and the hollows left by the foot-
steps of animals. The iron may be separated from the siliceous
shields of these Animalcules, which retain their form after it has
been extracted ; and, after the death of the Animalcules, the
iron forms a nucleus, to which more is attracted from the solution
in which they have lived. Similar ferruginous and siliceous
remains of Infusoria, have been found in ochreous substances
brought from the Ural mountains and from New- York ; and
also in a yellow earthy substance formed on the surface of the
mineral water of the salt works at Colberg, which is used for
iron-colour in house-painting. These discoveries, therefore,
open an immense field for inquiry, into the constitution of the
larger beds of ferruginous matter, deposited at former periods,
going back from those which are known as bog-iron-ore.

1 135. Of the more recent among such deposits of these Infu-
sorial exuviae, as may be regarded as fossil, are those of the
Beryhmehl) which is found in small masses in various parts of
Europe, and consists of a kind of siliceous earth mixed with
animal matter. On account of its nutritious qualities, this has
been employed as an article of food, especially in Sweden, where
it is very abundant in some localities. When microscopically
examined, it is found to be entirely composed of the remains
of animalcules, the siliceous shields of which inclose the origi-

556

FOSSIL ANIMALCULES.

FIG. 627- — FOSSIL REMAINS OF ANIMAL-
CULES, FORMING TRIPOLI.

nally soft tissue of the body in a dry state. By exposing this
substance to a white-heat, the animal matter is driven off, and
the delicate siliceous shields are obtained in a perfectly unaltered
state. By this process it is found that about 25 per cent, of dry
animal matter is contained in the earth. In some of these col-
lections, the animalcules are of large size, their siliceous shields
measuring as much as ToVo" °^ an m°k m length. la the older

strata of the tertiary formation
more extensive deposits are
found. One of the most re-
markable of these, is that which
is termed the Polierschiefer
(polishing slate) of Bilin ; this
supplies the tripoli used by arti-
sans in metal for polishing their
work, and also the fine sand
employed to form moulds for

casting small articles of Berlin iron. For these purposes, Ehren-
berg estimates its consumption in Berlin only, at from 50 to 60
cwt. yearly. This deposit occupies a surface of great extent,
probably the site of an ancient lake, and forms slaty or laminated
strata of fourteen feet in thickness. It is almost entirely com-
posed of an aggregation of the siliceous shields of one of the
minute forms of fossil Infusoria, the Gaillonella distans. The
length of one of these is about g-|T of a line, which is about £ of
the thickness of a human hair. About 23 millions of animalcules
are contained in a cubic line of the Polierschiefer, and 41,000
millions in a cubic inch. A cubic inch of the Polierschiefer
weighs 220 grains ; and thus 187 millions go to a grain ; or the
siliceous shield of each animalcule may be regarded as weighing
about the 1 87 ooo"o~o"o °f a grain. The minuteness of these is
surpassed by that of the Animalcules of the Marsh Ochre, which
are only ToVo~ °f a ^me m diameter, -j^- part of the thickness of
the human hair, ^ of the diameter of a globule of the human
blood. A cubic line of such animal iron-ochre would thus, in
the same proportion, contain 1000 millions, and a cubic inch
upwards of 1,000,000,000,000 of living beings

FOSSIL ANIMALCULES. 557

1136. In the Polierschiefer are found hard nodules of an
Opaline character, which are pretty obviously composed of the
siliceous shields of Gaillonellce, united together by an inorganic
cement, formed by the partial solution of some portions of the
mass,— just in the same manner as compact limestones may be
formed by the solidification of coral-sand (§ 1105). By the simi-
larity in the character of these nodules to the Semi-opal of older
formations, Ehrenberg was led to examine various specimens of
this mineral ; and he has succeeded in obtaining distinct organic
remains of animalcules from their interior : so that it is probable
that its nodules have been entirely composed, like those of the
Polierschiefer, of the siliceous remains of Animalcules, which have
subsequently undergone a partial metamorphosis. In the white
and opaque bands of Chalk Flints, he has also found spherical
bodies, which he considers to be of organic origin ; these are
especially abundant in the white siliceous crust which forms the
exterior of the flints, and in the mealy siliceous powder some-
times found within their cavities. As the same flints often
exhibit remains of the structure of Sponges, it would not seem
improbable, that the Animalcules may have been drawn into the
canals of the Sponge whilst alive, and may have thus been im-
bedded within it. It is not a little interesting to remark that,
whilst the microscopic contents of more recent strata are all fresh-
water Infusoria, those of the chalk are species which must, or at
least can. live in the waters of the ocean. It is also a curious
and important fact, that, of about eighty species of fossil Infu-
soria, discovered in various strata, almost half are species which
still exist in the waters ; and thus these forms of life, so long
overlooked as invisible specks of brute matter, have a constancy
and durability through the revolutions of the earth's surface,
which is denied to animals of more conspicuous size and higher
organisation, the continuance of whose existence depends upon
a greater variety of favourable conditions.

CHAPTER XXVI.

OF THE CLASS OF PORIFERA.

1137. THE lowest of the classes usually comprehended under
the Radiated type, is one whose claim to a place in the Animal
Kingdom must be regarded as very doubtful. Not only is the
radiated disposition of parts altogether wanting, but even that
definiteness of form is absent, which so peculiarly distinguishes
the higher groups of Animals from the members of the Vegetable
Kingdom. The absence of charac-
teristic structure does not extend to

external form alone ; it is equally
remarkable in the internal arrange-
ment of the parts, of which these beings
are composed. There is no stomach
or digestive cavity for the reception of

,. FIG. 628.— SPONGE.

food, — no nervous system or organs for

sensation or locomotion, — and nothing beyond the very simplest
apparatus for reproduction. In the vital actions performed by
these beings, there is nothing distinctly characteristic of an
Animal nature. No movements can be observed, either in the
whole structure, or in portions of it ; neither is there any indica-
tion of the possession of sensibility. In fact, the only obvious
vital action which can be observed in their ordinary state, is a
movement of fluid through their channels ; and this does not
differ, except in rapidity, from what may be seen in Plants.

1138. There can be little question, then, that if the Class
PORIFERA, consisting of the Sponges and their allies, is to be
ranked in the Animal creation, the lowest place in the scale is
justly assigned to it; since the beings which it contains exhibit
so few indications of any but organic life, that it has been,
and perhaps still may be, doubted, whether they should not

PORIFERA, OB SPONGE TRIBE. 559

rather be assigned to the Vegetable Kingdom. Perhaps the
strongest argument for their Animal nature, is to be found in the
resemblance of their structure to a part of that, which constitutes
beings whose animal character is undoubted. The group of
Alcyonla (§ 1087) consists of Sponges with Polype-mouths; and
in the growth of these structures, the spongy mass is first formed,
the polypes not appearing until a subsequent period. The
substance commonly known as Sponge is in reality but the frame-
work or skeleton of the being in its living state. When growing
beneath the waters it inhabits, this framework is covered by a
living flesh, which not only envelopes its exterior, but lines all
the canals that ramify through its substance. This enveloping
flesh is so extremely soft, as to drain away when the mass
is removed from the water, like the white of an egg, or the
vitreous humour of the eye ; hence its existence was for a long
time overlooked, and the mode in which the harder texture
grows was not at all understood. It is principally to the obser-
vations of Dr. Grant (which have been confirmed by other
naturalists), that we owe the elucidation of the real character of
the spongy structure, and of its concern in the actions performed
in the living state.

1139. When we examine the exterior of a piece of common
Sponge, we observe that it is covered with minute orifices or
pores (whence the name which has been given to the class),
thickly set together ; and that larger openings are disposed at
intervals amongst these. If these larger orifices, or vents, be
traced into the substance, it will appear that they are the
mouths of canals or vessels which ramify through it ; these have
definite walls formed by the firm tissue of the sponge, but per-
forated with a large number of orifices, connecting them with
the spaces that lie between their net-work of branches. The
pores, on the other hand, open into a less regular arrangement of
small tubes and cells, of which the spongy mass is principally
composed. These spaces are produced by the interlacement of
the fibres that form the solid framework ; they communicate
with one another throughout the mass ; and the canals seem to
take their origin from the midst of them, arising by small tubes

pp2

560 STRUCTURE AND ACTIONS OF SPONGE.

which unite into larger ones, and these again meeting to form
the wide channels which terminate in the vents. If, after making
such an examination of the structure of the Sponge, we tear a
small portion of it into fragments, its fibrous nature becomes
very apparent. If we submit these fragments to a low magnify-
ing power, it is perceived that they form a complete network,
inosculating with each other in every direction. By applying a
higher power, it is^ ascertained that they are of tubular structure.
In the Common Sponge, the whole framework is composed of
these tubular fibres, which in some parts are set very closely
together, whilst in others they are loosely arranged. They con-
sist entirely of an organic texture, rather approaching the horny
substance of Animals (as is made evident by the smell emitted
on burning it), than anything which we meet with in the
Vegetable Kingdom; and it is to their elasticity, that the Sponge
owes those properties, which make it so useful to Man.

1140. In other forms of the group, however, spicula of earthy
matter are disposed amongst these ; which add to the firmness of
the structure, and diminish its elasticity, according to the amount
in which they are present. These spicula are in some instances
composed of carbonate of lime; in others they consist of pure silex;
and their form varies according to the material. The earthy
spicula are disposed at intervals through the whole mass ; but
they are especially abundant in the neighbourhood of the canals,
and around the external orifices, both of these and of the pores.
In fact each of these orifices is strengthened by a regular frame-
work of spicula disposed around it ; and a high magnifying
power enables us to see, that across the entrance to the pores,
there is also a very delicate membranous network, which acts as
a filter or sieve, preventing the entrance of improper particles
along with the fluid which is drawn in through them. In many
instances, the sharp ends of the spicula project from the surface
of the Sponge, as if for its defence.

1141. When Sponges are examined in their living state and
natural condition, a constant and rapid stream of water is seen
to issue from the larger orifices or vents. This stream is made
apparent by the movement of the minute particles contained in

NUTRITION AND GROWTH OF SPONGE. 561

it, and by the disturbance of those which may be floating in the
surrounding fluid. On the other hand it is easily made apparent,

FIG. 629. — SECTION OF LIVING SPONGE.

that water is as constantly being imbibed through the minute
pores ; and that, after traversing the smaller cavities of the
spongy structure, it finds its way into the canals through which
it is expelled. Some such absorption must take place, to supply
the fluid incessantly discharged through the vents. It is im-
possible to assign a cause for this movement ; no cilia have been
discovered in any part of the adult animal ; and the tissues are
altogether possessed of so little contractility, that it is difficult to
suppose the fluid propelled through the tubes by any mechanical
influence on their part.

1142. The nutrition and growth of the Sponges appear to
depend entirely, then, on the water which enters the* pores, on
the substances which it holds in solution, and on the minute
particles suspended in it. The entrance of any but the smallest
solid substances is prevented by the network, which has been
described as stretching over the pores. From these, and from
the water itself, the animal tissue appears to derive the materials
of its nourishment ; and the siliceous and calcareous substances
must be separated by it, from the state of solution in which they
exist in the surrounding fluid. When the large quantity of this
fluid, which passes through the canals of the Sponge in a short
time, is taken into consideration, it is not difficult to account for
the derivation of these ingredients from it ; although they often

562 NUTRITION AND GROWTH OF SPONGE.

exist in such minute proportion, as scarcely to be recognised by
the chemist. Not only does this circulation of fluid answer the
purposes of nutrition, but it is subservient also to the process of
excretion. On watching the currents of water that issue from
the vents, it is observed that minute flocculent particles are
incessantly detached and carried out by them ; these appear as
if they were the residue of digestion, or pellicles excreted from
the body and thrown off from the surface of the internal canals.
Sometimes the vents are all on one side, whilst the absorbent
pores are on the other; and in one interesting species of a
bottle-like form, the Leuconia compressa, the pores are entirely
situated on the outside, and the vents on the interior, so that a
single constant and rapid current of fluid proceeds from the
mouth, which is contracted into rather a narrow orifice.

1143. This movement of fluid through their tissue seems
to be almost the only action, that proves the existence of life in
these simple beings. No obvious contraction can be perceived
when they are touched or irritated. They may be punctured or cut
with sharp instruments, pierced with red-hot wires, or torn into
fragments; and yet no change of form, or other evidence of sensi-
bility, can be perceived in them. The parts which are unimpaired
will continue to present the same phenomena as before ; and no
injury seems to have any influence, beyond the portion imme-
diately affected by it. Nevertheless some observers maintain that
a shock, affecting the whole mass alike, does produce an evident
effect upon it. This has been particularly noticed in the
Spongilla, or River-sponge. When allowed to fall into water
from the height of a few inches, or when the stage of the
miscroscope is struck, the tubular prolongations on which the
vents are situated contract very sensibly, until the orifice is
nearly closed, and projects but slightly. It has also been
noticed that these projecting orifices vary considerably in their
form at different times, even within short intervals, and when
no external cause has influenced them. Some Naturalists state,
moreover, that, although no sensible contractions and dilatations
can be seen in the whole mass, a peculiar sensation is felt when
the hand is placed upon a specimen still under water. This
sensation is of a tingling character, and appears due to some

REPRODUCTION OF SPONGES. 563

movement in the individual particles, of which the flesh of the
Sponge is composed.

1144. The Sponges may be multiplied by artificial division ;
each portion then becoming a new individual, like the sepa-
rated buds of Plants. But no such division appears to occur
in their natural state ; and they are reproduced by the separa-
tion of minute spore-like bodies from the gelatinous portion of
their tissue. This process takes place, in the species of our own
coast, at the earlier part of winter. At that period, the little
reproductive bodies, or gemmules., first appear as minute opaque
yellow points, irregularly distributed in the substance of the
body, and usually at a distance from the surface. As their
development proceeds, they become larger and more opaque, and
present a regular oval form. They then protrude from the
gelatinous lining of the canals, into their cavity ; and it is seen
that the protruding portion is covered with cilia, which are in
active operation. After a further period, they become altogether
detached from the parent structure, and swim forth, by means
of the cilia, through the large orifices in which the canals termi-
nate. In this condition they appear as egg-shaped particles of
gelatinous matter, the greater part of whose surface is covered
with cilia ; but the smaller end, by which they were previously
attached, is left bare. By the vibration of these cilia they swim
about for some time, very much in the manner of Animalcules.
Their motions are equal, smooth, and gliding ; and they appear
to be influenced by each others' proximity. When they
approach near to each other, as is sometimes observed, they often
arrest their course, and swim for a short time round each other.
They appear by these movements to seek a place adapted to
their development ; and to this they seem partly guided by the
influence of light, which they seek to avoid. The nature of the
site chosen varies with the species. Some incrust the surfaces
of loose stones or shells ; others stand erect upon a solid base ;
and others hang from the under surfaces of projecting rocks.
Sometimes earthy spicula may be observed in the gemmules,
before they have attached themselves ; and in those species which
possess them in the perfect form, they always appear within a
short time after they are fixed. No trace of internal canals, how-

564 DEVELOPMENT OF SPONGES.

ever, can be discovered at this period; and the formation of
these does not begin, until after the gemmule has completely
changed its condition.

1145. When it attaches itself to any surface, the gemmule
adheres by its small extremity, and the cilia continue their action
for some little time afterwards, as if to clear a proper site for the
extension which is immediately to take place. The gemmule
then spreads itself out into a flat transparent film ; and the
earthy or horny fibres soon begin to appear in them. They
then exhibit minute depressions on their surface, which gradually
become deeper, so as to form canals penetrating into it ; these
unite with each other, and send out ramifications through the
whole structure as it extends ; and thus the spongy mass is at
last fully formed. The spicula and fibres, which at first ap-
peared to be confusedly developed in the gelatinous growing
membrane, then manifest great symmetry and method in their
distribution, with relation to the pores, canals, and vents. The
existence of this locomotive power in the gemmules of Sponges,
cannot of itself be regarded as an unequivocal proof of their
Animal nature ; since, as it has elsewhere been shown ( VEGET.
PHYSIOL. § 424), the sporules or reproductive granules of the
ALGM are equally active before fixing themselves. But in their
possession of cilia, which are not known to exist in the Vegetable
kingdom, and in the parallelism between their subsequent
development and that of the gemmules of the Polypifera, there
exist reasons in support of their Animal character, though this
is very feebly manifested.

1146. The Geographical distribution of the Porifera is
very extensive ; indeed it may be said to be almost universal.
Every coast, from the Equator to the highest Polar regions,
furnishes some kinds of Sponge ; but they exist in much greater
abundance in warm latitudes than in cold, and they attain also a
much greater size. They are all, of course, inhabitants of the
water only, and if long removed from it they lose their vitality ;
but there are many species, which seem able to bear exposure to the
air between the intervals of the tide, appearing to flourish equally
well in deep water, or at a level which is occasionally left dry.

FOSSIL REMAINS OP SPONGES. 565

] 14 7 x There is some difficulty and uncertainty in regard to
the Fossil remains of Sponges ; but it is probable that these have
come down to us from a very remote period of the earth's
history, and it may be reasonably supposed that Sponges were
among the earliest inhabitants of the ocean. These remains are
found in two states. Sometimes the whole tissue has been per-
meated by siliceous or calcareous matter ; so that, on the mass
being broken, its internal structure is very evident. In other
instances we have only the casts, which have been formed by the
subsequent filling-up, with stony matter, of the cavities left by
their deeay. There is reason to believe that, in the Sponges of
ancient date, the siliceous epicula must have predominated ; for
we find their fossil remains almost always silicified, even in
calcareous rocks. Thus, in the Chalk (in which they greatly
abound) all the remains of Sponges present the character of flints.
Some of these flints, when broken, exhibit very beautifully the
structure of the Sponge ; and others possess only its external
form. Now, many of the Chalk fossils are infiltrated with car-
bonate of lime, and not with flint ; and this even when associated
with Sponges. In the same flint-nodules which envelope
Sponges, the shells of the Echinus (§ 1002) are found converted
into crystallized carbonate of lime, and dense shells of Mollusca
are scarcely at all changed. It is evident, then, that some
peculiar attraction for siliceous matter exists in the Sponges ;
and this is readily explained upon well-known chemical prin-
ciples. If in a saturated solution of two salts, a crystal of one
of those salts be placed, it will be increased by a crystalline
deposit of its own composition ; whilst the other salt will not
form any deposit around it. If two organic structures, there-
fore,— one containing siliceous spicula, and the other calcareous
crystals, be exposed to a fluid holding both these substances in
solution, they will attract from it their own ingredient.

" O LORD, HOW MANIFOLD ARE THY WORKS ; IN WISDOM HAST
THOU MADE THEM ALL."

APPENDIX.

ON THE INSTINCTS OF SOCIAL INSECTS.

A GENERAL account has been elsewhere given (ANIM. PHYSIOL.,
Chap. XIV.) of the habits and instincts of the Hive Bee ; and a
similar sketch will be here given of the History of the Termites
or White Ants, and of that of the Common Ants.

The Termites, or White Ants, belong to the Order Neuroptera
(§ 675) ; and are the only true social insects contained in that
group. Next to the Locusts, they may be reckoned the most
destructive Insects known to Man ; since not only articles of
food, but clothing, fences, trees, and even houses, fall before their
devouring jaws. As they are confined, with scarcely any
exception, to tropical climates, we are only acquainted with
their ravages by the reports of travellers who have visited those
regions ; but these reports are such, as we may fully trust to. —
The Termites live in immense communities, consisting of kings
and queens, soldiers and labourers. The kings and queens are
perfect insects, male and female; and their office is solely to
increase their kind. The soldiers appear to be the pupce, stopped
in their development, so as never to possess wings or to acquire
the reproductive organs ; it is their office to attack every object
or living thing, that in any way injures or endangers the safety of
the nest ; and this duty they perform with the most reckless
bravery, the labourers retiring within the nest during the time of
danger. The labourers are probably to be regarded as the larvce,
alike checked in their development ; their offices are manifold, —
their duty being to take the eggs from the queen as fast as she
lays them, to convey them to the nurseries and to tend them
until hatched, and to feed the young, store provisions, build the
nest, repair damages, and perform every kind of labour requisite
for the good of the community,

The nests of the Termites are so numerous all over the island of
Bananas and the adjacent Continent of Africa, that it is scarcely

568

INSTINCTS OF TERMITES, OR WHITE ANTS.

possible to stand upon any open place, such as a rice-plantation
or other clear spot, where one or more of these buildings is not to
be seen within fifty paces. In some parts near Senegal, as men-
tioned by Adanson, their number, magnitude, and closeness of
situation, make them appear like the villages of the natives.
These buildings are usually termed " hills" from their outward
appearance, which is that of little hills, generally pretty much
in the form of sugar-loaves, and about ten or twelve feet in height.
These hills continue quite bare until they are six or eight feet
high ; but in time become, like the rest of the earth, almost
covered with grass and other plants ; and in the dry season, when
the herbage is burnt up by the rays of the sun, they somewhat
resemble very large hay-cocks. The exterior of the building
consists of one large shell or domed wall; which is large and

NESTS OF TERMITES The large nests, of which one is cut open vertically to show the
interior, are those of the Termes bellicosus. The small nest (a) in the tree, is that
of the Termes arborum ,- and at 6 is seen the arched gallery, by which it communicates
with the ground.

strong enough to shelter the interior from the weather, and to
protect the inhabitants from the attacks of most of their enemies.
It also serves to collect and preserve a regular degree of genial
warmth and moisture ; which seems very necessary for hatching
the eggs and cherishing the young ones. The interior is divided,
with great regularity and contrivance, into a great number of

INSTINCTS OF TERMITES, OR WHITE ANTS. 569

apartments ; some of which are intended for the residence of the
kings and queens, and for the rearing of their numerous progeny;
whilst others serve as magazines, and are always found well filled
with stores and provisions.

These hills make their first appearance above ground, by a little
turret or two, in the shape of sugar-loaves ; which only rise to the
height of a foot, or a little more. Soon afterwards, at some little
distance, while the former are increasing in height and size, the
Termites raise others ; and so go on increasing the number, and
widening them at the base, till their works below are covered with
these turrets, which they always raise the highest and largest in
the middle ; they then, by filling-up the intervals between each
turret, collect them, as it were, into one dome. They are not
very curious or exact about these turrets, except in making them
very solid and strong ; and when, by the junction of them, the
dome is completed (for which purpose the turrets answer as
scaffolds), they take away the middle ones entirely, except the
tops, which, joined together, form the crown of the cupola ; and
they apply the clay to the building of the works within, or to
the erection of fresh turrets for the purpose of raising the hillock
still higher.

The royal chamber, so called on account of its being adapted
for, and occupied by, the king and queen, is situated near the
centre of the hillock. It resembles the shape of an egg cut in
half lengthways, and is at first not above an inch in length ; it
is afterwards increased, however, to six or eight inches, or even
more, in proportion to the size of the queen (§ 675). The floor
and roof of this chamber are very solid, and are composed of
hardened clay. Its walls are pierced by several entrances, which
will admit the soldiers and labourers, but which are not large
enough to allow the king and queen (who is, at full size, a
thousand times the weight of a king) to pass out. It is sur-
rounded on all sides by a series of chambers, which may be called
the royal apartments, and which are occupied by the soldiers and
labourers that guard thte pair, on whose safety depends the hap-
piness, and probably even the existence, of the whole community.
These apartments, being connected together by openings and
passages, form an intricate labyrinth, which extends a foot or
more in diameter from the royal chamber on every side ; and
they are surrounded by the magazines and nurseries. The former
are chambers of clay ; and are always well filled with a kind of
provisions, which appear to consist of the gums or other thick
juices of plants. The nurseries, which are so called because they

570 INSTINCTS OF TERMITES, OR WHITE ANTS.

always are found to contain eggs and young ones, are entirely
composed of wooden materials, seemingly joined together with
gums. These are placed as near as possible to the royal apart-
ments. When the nest is in the infant state, they are close to
the royal chamber ; but as, in process of time, the queen enlarges,
it becomes necessary to enlarge this chamber for her accommo-
dation ; and as she then lays a greater number of eggs, and
requires a greater number of attendants, so is it necessary to
enlarge and increase the number of the adjacent apartments ; for
which purpose, the small nurseries that were at first built are
taken to pieces, and are rebuilt a little farther off. The nurseries
are inclosed in chambers of clay, like those which contain the
provisions, but much larger. In the early state of the nest they
are not larger than a hazel-nut ; but in old hills, they are often
as large as the head of a child a year old. Under the dome is a
large open space, which is surrounded by three or four large
arches of a somewhat gothic form ; this space may perhaps be
intended to equalise the temperature of the chambers below, by
preventing either the sun or the cold air from at once affecting
the latter.

Beneath the lowest apartments are found a set of large passages,
which communicate with all the chambers of the interior, and
also with the galleries that diverge from the nest in various
directions. These passages, which are thickly lined with the
same kind of clay as that of which the hill is composed, ascend
the inside of the shell in a spiral manner ; winding round the
whole building up to the top, and intersecting each other at
different heights, and communicating with the various chambers
by galleries branching out from them. From the bottom of
these are several large galleries, which lead downwards into the
ground below, sometimes to the depth of three or four feet ; these
are mines or quarries, whence the Termites obtain the fine gravel
and clay, which they work up in their mouths to the consistence
of mortar ; and then use in the construction of their buildings.
Other galleries extend horizontally beneath the ground, at a
small depth below its surface, to a great distance. Sometimes
these passages cannot be continued under ground in the required
direction ; and the Termites then make pipes or covered- ways
along its surface, composed of the same materials with the nests.
These they continue, with many windings and ramifications, for
great lengths ; and they construct, where it is possible, subter-
ranean pipes running parallel with them, into which they may
sink and save themselves, if their galleries above ground are

INSTINCTS OF TERMITES, OR WHITE ANTS. 571

destroyed by violence, or the tread of men or animals alarm them.
When a person accidentally enters any solitary grove, where the
ground is pretty well covered with their arched galleries, they
give the alarm by loud hissings, which may be distinctly heard
at every step ; soon after this, their galleries may be searched
in vain for the insects; but little holes are found, just large
enough to admit of their escape into the subterraneous roads.
These galleries are of sufficient size to allow the Termites to pass
and repass without stopping each other (though there are always
numerous passengers), and to shelter them equally from light
and air, as well as from their enemies, — of which the Ants, being
the most numerous, are the most formidable. If the Termites
are dislodged from their covered ways, the various species of
Ants (which are probably as numerous above ground as the
Termites are in their subterranean passages) instantly seize and
drag them away to their nests, to feed their young brood. The
Termites are, therefore, exceedingly solicitous about preserving
their covered ways in good repair ; and if one of these be de-
molished for a few inches in length, it is wonderful how soon
they will rebuild it. At first, in their hurry, they run into the
open part an inch or two, but stop so suddenly that it is evident
they are surprised ; for though some will run straight on, and
get under the further part of the arch as speedily as possible,
most of them run back as fast, and very few will venture through
that part of the gallery which is left uncovered. In a few
minutes they may be seen engaged in rebuilding the arch ; and
even if three or four yards of their gallery have been destroyed,
it will be restored by the next morning, and will be found to
contain numerous Termites passing along in both directions. If
the gallery be several times destroyed, they will at length seem
to give up the point, and build another in a different direction ;
but if the old one led to some favourite plunder, they will
rebuild it again in a few days ; and unless the nest be destroyed,
they will never totally abandon their gallery.

The galleries of the Termites are often carried beneath the
foundations of houses and store-houses, at several feet below the
surface ; sometimes they rise through the floors ; but they are
frequently continued in the interior of the posts of which the
sides of the buildings are composed, following the course of
the fibres to the top, and having lateral perforations or cavities
here and there. While some of the Termites are employed in
gutting the posts, others ascend from them, entering a rafter or
some other part of the roof, in search (as it would seem) of thatch,

572 INSTINCTS OP TERMITES, AND OF ANTS.

which is their favourite food. If they find it, they bring up wet
clay, and build galleries through the roof in various directions, as
long as it will support them. In this manner a wooden house is
speedily destroyed ; and all that it contains is, at the same time,
subjected to the ravages of these destructive insects. In carrying
on this business, they sometimes appear to find, by some means
or other, that the post has a certain weight to support, and then,
if it is a convenient track to the roof, or is itself a kind of wood
agreeable to them, they bring their mortar ; and, as fast as they
take away the wood, replace the vacancy with that material,
which they work together more closely and compactly than
human strength or art could ram it. Hence, when the house is
pulled to pieces, the posts formed of the softer kinds of wood are
often found reduced almost to a shell ; and almost all of them
are transformed from wood to clay, as solid and hard as many
kinds of free-stone used for building in England.

Of the true Ants, which belong to the Order Hymenoptera, a
general description has been already given (§ 694) ; but it re-
mains to notice some of the chief points in the structure of their
habitation, and in their social economy. As among the Termites,
there are four orders in the community, — the perfect males and
females, the workers, and the soldiers ; the workers and soldiers,
however, cannot be regarded as either larvae or pupae, since they
undergo the regular metamorphoses ; but they have neither the
wings nor the reproductive organs developed. As among the
other social Hymenoptera, they are neuters, that is, of no sex ;
but they most nearly approach the female. The soldiers of the
Red Ants of this country are nearly three times the size of
the workers, and their heads are larger in proportion ; those
of the Yellow Ant are about twice the size of the workers. In
describing the habitations of this race, it will be best to confine
ourselves to the latter of these species, which is very abundant in
our own country. Their hillocks are apparently made in a much
less elaborate manner than the dwellings of the Termites ; but
they are not less perfectly adapted to their required object. They
are composed of bits of stubble, fragments of leaves, small stones,
splinters of wood, &c., which are collected by the Ants, and laid
(as it might appear) promiscuously together ; but although
apparently a careless heap, the hillock is really a most ingenious
device for evading the eflects of wind and the attacks of enemies,
and yet more especially for receiving and husbanding the heat of
the sun. Its exterior always presents the appearance of a dome ;

HABITATIONS OF ANTS. 573

»

and from its summit a number of avenues, carefully excavated
like tunnels, lead downwards into the interior, — the number of
them depending on the population and extent of the nest. Their
external apertures are of varied size ; there is sometimes a prin-
cipal one at the top ; but there are usually several, of unequal
size, which are surrounded by passages arranged with great
regularity. In the habitations of many species of Ants, we never
find an aperture of sufficient size to allow the entrance of enemies
or the passage of rain-water ; the dome being closed on every
side, and having only one aperture near the base, which is not
unfrequently continued into a serpentine gallery many feet in
extent. With the Yellow Ants, however, it is quite different.
They stand in crowds on their nests during the day, and seem
quite fearless of any disturbance to the interior ; and at night,
before retiring to the bottom of their habitation, they close all
the apertures with the greatest care. This curious fact was first
discovered by Huber, to whom we owe so much of our knowledge
of the economy of Bees and Ants. On closely watching the
appearance of one of these nests, he found it undergoing an hourly
change ; so that the apertures, so spacious in the middle of the
day, gradually diminished in size towards the evening, and at
night entirely disappeared ; the dome being then closed in every
part, and all the Ants being concealed within. In order to
accomplish this, the Ants draw little bits of wood into the
openings, placing them across the entrance, and sinking the ends
in the covering of the hill ; they then fetch others, laying them
across the first, and so continue selecting other pieces, smaller
and smaller as the work advances towards its accomplishment ;
and finally close the opening with bits of dried leaves, and similar
materials. — In the morning, a few Ants may be seen wandering
about the exterior of the nest, — the numbers gradually increasing,
as others emerge from the interior under the little roofs formed
at the entrance of each avenue ; and these soon set to work, and
begin to clear away the barricades. This employment continues
for hours, until at length the apertures are sufficiently extended;
and the materials used in closing them are distributed over the
exterior of the nest. This is a daily labour, unless it rains, or
the morning threatens rain ; and if rain come on after it has been
performed, they hasten to close the apertures as at night.

The dome contains a number of spacious chambers, communi-
cating with each other by galleries ; these chambers, however,
are low, irregular in figure, and carelessly constructed ; but they
are convenient, nevertheless, for the purpose for which they are

Q Q

574 INSTINCTS OF ANTS.

constructed, — that of containing the larvae and pupae at certain
hours of the day. The eggs, when deposited by the female or
queen ant (who drops them at random in her progress through
the nest), are taken charge of by the workers ; who immediately
seize them and carry them in their mouths, in small parcels,
and lay them in heaps in separate apartments. They constantly
tend them until they are hatched, incessantly turning them back-
wards and forwards with their tongues for the purpose of mois-
tening them, without which they would come to nothing ; and
it must be to the moisture thus imparted to them, that the great
enlargement of the eggs is due, which has been constantly noticed
previously to the hatching of the larvae. The workers frequently
remove the eggs from one quarter of the nest to another, as they
require a warmer or a cooler, a moister or a drier atmosphere ;
and at intervals they brood over them, as if to impart to them
a genial warmth. When the larvae come forth, the workers are
almost constantly engaged in supplying their wants and forward-
ing their growth. Every evening, an hour before sunset, they
regularly remove the whole brood (as well as the eggs and pupae)
to cells situated lower down in the earth, where they will be safe
from cold ; and in the morning they as constantly remove them
again towards the surface of the nest, — unless there is a prospect
of cold or wet weather, in which case they do not remove them.
When the rays of the sun first strike upon the nest, a most ani-
mated scene takes place. The Ants on the exterior are the first
to feel the influence of the warmth ; they enter the nest, run
along the avenues and galleries to the various chambers, and
communicate the intelligence to every ant they meet, — tapping
their fellows gently with their antennae, or, if this be not attended
to, biting them severely with their mandibles. At last the whole
colony seems to partake of the excitement, and each labourer
then carefully takes a larva or a pupa in his mouth, conveys it
through all the winding passages to the outside, and places it in
such a position as to receive the rays of the sun. The larvae and
pupae are seldom exposed to the full rays of the sun for a longer
period than fifteen or twenty minutes ; they are then conveyed
into little cells constructed on the exterior of the nest purposely to
receive them, and are protected from the too great heat of the
sun's rays, by a slight covering of chaff, stubble, or other light
matter. As the heat of the sun decreases in the afternoon, the
larvae and pupae are again fully exposed to it for a short season
as before, and are then carefully returned one by one, through the
almost interminable passages, each into the identical chamber

INSTINCTS OF ANTS. 575

from which it was brought in the morning; and after this they are
carefully fed by the workers, who nourish them with the food
they have collected during the day.

When the larvae have attained their full growth, they spin a
cocoon, in which they remain as pupae until the time of their
final change. In this state they are commonly, but erroneously,
known under the name of " eggs ;" and being a favourite article
of food with pheasants and partridges, they are eagerly sought
after by persons who rear these birds from the egg. The cocoons
containing the pupae are of a long cylindrical form, and of a dirty
white colour ; and the contained animals are perfectly motionless.
When ready to come forth as perfect Ants, they cannot, like most
other Insects, set themselves free from their envelope ; but they
are dependent upon the assistance of the workers, who moisten it
and cut it with their mandibles, and then gently draw forth the
contained body. The greatest care is bestowed upon the winged
Ants, — the perfect males and females, — on which the continuance
of the race depends ; these are most assiduously tended by the
workers, who cleanse their bodies, extend their wings, supply
them with food, and accompany them in their wanderings
through the hive. A large number of the winged Ants are
produced every season in each community ', and they may be
frequently seen in the autumn, covering almost the whole surface
of the hillock. The greater number of these, however, perish in
various ways ; and only a small number remain, either to found
new colonies, or to keep up the population of the parental resi-
dence. Sometimes the new colony is commenced by the queen
alone: who excavates her future dwelling-place, and lays the
eggs, feeds the larvae, and tends the pupae, without any assist-
ance; but the workers that are first produced, then aid her in
the requisite attentions to the subsequent progeny. In other
instances, the queen falls in with a few workers, that have wan-
dered, at this period of excitement, to an unusual distance from
the nest ; and if so, they unite their labours with hers.

The most remarkable fact connected with the history of Ants,
is the propensity possessed by certain species to kidnap the
workers of other species, and to compel them to labour for the
benefit of the community, thus using them completely as slaves ;
and, as far as we yet know, the kidnappers are red or pale-
coloured Ants, whilst the slaves are of a jet black. The time for
capturing slaves extends over a period of about ten weeks, and
never commences until the male and female Ants are about
coming forth from the pupa state ; and thus the marauders never

Q Q2

576 INSTINCTS OF ANTS,

interfere with the continuation of the species. This appears to
be a special adaptation of their peculiar instinct ; for if the attacks
were made on the nests of the Negro Ants, before those by whom
the race is propagated are ready to issue forth, it must speedily
become extinct. — When the Red Ants are about to sally forth on
a marauding expedition, they send scouts to ascertain the exact
position in which a colony of Negro Ants may be found ; these
scouts, having discovered the object of their search, return to
their nest and report their success. Shortly afterwards, the
army of Red Ants marches forth, headed by a vanguard, con-
sisting of eight or ten Ants only, which is perpetually being
changed, — the individuals which constitute it, halting, when they
have advanced a little before the main body, falling to the rear,
and being replaced by others. When they have arrived near the
Negro colony, they disperse, wandering through the herbage, and
hunting about, as if aware of the neighbourhood of the object of
their search, yet ignorant of its exact position. At last they
discover the settlement ; and the foremost of the invaders rush-
ing impetuously to the attack, are met, grappled with, and
frequently killed by the Negroes on guard. The alarm is
quickly communicated to the interior of the nest; the Negroes
sally forth by thousands; and the Red Ants rushing to the
rescue, a desperate conflict ensues, which, however, always
terminates in the defeat of the Negroes, who retire to the
innermost recesses of their habitation. Now follows the scene of
pillage. The Red Ants, with their powerful mandibles, tear
open the sides of the Negro Ant-hill, and rush into the heart of
the citadel. In a few minutes each of the invaders emerges,
carrying in its mouth the pupa of a worker Negro ; which it has
obtained in spite of the vigilance and valour of its natural
guardians. The Red Ants return in perfect order to their nest,
bearing with them their living burthens. On reaching the nest,
the pupae appear to be treated precisely as their own ; and the
workers, when they emerge, perform the various duties of the
community with the greatest energy and apparent good-will ;
they repair the nest, excavate passages, collect food, feed the
larvae, take the pupaa into the sunshine, and perform every office
which the welfare of the colony seems to require ; in fact, they
conduct themselves entirely as if fulfilling their original des-
tination.*

* The details of this Appendix have been chiefly taken from Mr. Newman's
very excellent " Familiar Introduction to the History of Insects."

INDEX.

N.B.—The numbers refer to the paragraphs.

A.

Amphioxus, 585

Argonauta, 890

AARD-WOLF, 198

Amphipoda, 794

Argulus, 813

Aard-vark, 249

Amphitrite, 841

Armadillo, 246

Aberdevine, 387

Ampullaria, 920

Armadillo pustulatus, 799

ACALEPHJE, 1026

Anabas, 561

Arnee, 271

Acanthocinus, 657

Anabasidee, 561

Artemia, 803

Acanthopterygii, 551

Anableps, 567

ARTICULATA, 593

Acarida, 75}, 765

Anarrhicas, 563

Arvicolce, 228

Acarus domesticus, 766

Anastoma, 913

Asaphus, 800

Acarus scabiei, 766

Anatidae, 453

Ascaris, a39

Accentor, 400

Anchovy, 571

Aspergillum, 963

Achatidce, 668

Andreenidce, 697

Asp, 510

Achatina, 914

Anglers, 564

Ass, .501

Acherontia, 707

Angora Goat, 272

Asterias, 976

Acipenseridce, 581

Anguine Lizards, 501

Asteroida, 1082

Acrochordus, 507

Anilocra, 799

Astraea, 1071

Actinice, 1058

ANNELIDA, 599, 834

Athalia, 687

Actinia gemmacea, 1066

Anobium, 647

Athericera, 726

Aculeata, 606

Anodon, 949

Auk, 457

Acontias, 502

Anolis, 494

Aurelia, 706

Aculeata entomophaga, 68

Anomia, 940

Aurochs, 279

Aculeata praedones, 692

Anomoura, 784

Australian bower-bird, 395

Addax, 268

Anoploura, 637, 736

Avicula, 942

Adder, 510

Anoplotherium, 298

Avocet, 451

Adjutant-Stork, 449

Ant, 694, App.

Axolotl, 514

^Eolis, 915

Ant-eaters, 239, 246

Aye-aye, 164

Agamidce, 490, 497

Antelopidce, 264

Agrion virgo, 673

Agaricia, 107*2

Anthracidce, 730

Agouti, 234

Anthophora retusa, 731

B.

Ai, 241

Antipathes, 1093

Baboon, 145, 154

Ailurus, 234

Aphaniptera, 656

Babyroussa, 296

Albatross, 459

Aphidce, 718

Bacillariae, 1127

Alcidce, 457

Aphis, 719

Bacteria fragilis, 667

Alcedinidce, 412

Aphrodita, 839

Bactrian Camel, 278

Alcyonian Polypes, 1083

Apidce, 698

Badger, 193

Alcyonium, 1089

Aplysia, 917

Balsena, 214

Alligator, 491

Aprophora, 718

Balcenidce, 214

Alligator-tortoise, 489

Apus, 802

Balaenoptera, 214

Alpaca, 282

Arabian Camel, 278

Balanidce, 828

Alpine Partridge, 432

ARACHNIDA, 738

Balaninus, 655

Alpine Swift, 408

Araneida, 752

Balanus, 827

American Bison, 270

Araneiformes, 812

Bald Erne, 370

American Ostrich, 437

Arenicola, 839

Balistes, 580

Ammonite, 897

Arctic fox, 196

Balistidse, 580

Ammonitidce , 897

Ardceidee, 443

Bandicoot, 311

Amnodytes, 577

Argala, 449

Bank Swallow, 407 '

Ampelidce, 398, 404

Argali, 274

Bankive Jungle Fowl, 431

Amphinome, 839

Argyroneta, 759

Banxring, 179

578

INDEX.

N.B. — The numbers refer to the paragraphs.

Barbel, 567

Bostrichus typographus, 656

Cancer, 784

Barnacle, 825, 829

Bot-Flies, 731

Canidce, 195

Barnacle Goose, 455

Bottle-headed Whale, 212

Cantharis, 654

Barracuda, 555

Bovidep, 269

Capercailzie, 482

Basilisk, 496

Boviform Antelopes, 264

Cape Hunting Dog, 196

Basse, 555

Bowerbankia densa, 1096

Cape Mole, 176

Bat, 165

Brachinus, 644

Caprella, 796

Bat-louse, 725

BRACHIOPODA, 965

Capridce, 272

Batrachia, 485

Brachelytra, 646

Capriform Antelopes, 267

Bear, 199

Brachyoura, 787

Caprimulgidce, 405, 406

Beaver, 229

Brachmin Ox, 267

Capromys, 227

Beche-de-mer, 1023

Branchiopoda, 801

Capuchins, 159

Bed-Bug, 722

Branchipus, 803

Capuloida, 921

Bee, 684

Bream, 567

Capybara, 217, 234

Bee-Bird, 707

Brent-Goose, 455

Cardbidce, 643

Bee-eater, 405, 413

Brown Bear, 199

Carcinus, 785

Beetles, 637

Brown-Creeper, 419

Cardiaceee, 953

Belemnite, 893

Brown-Gannet, 461

Cardium, 953

Bellerophon, 892

Brown- Ptarmigan, 432

Carinaria, 181

Beluga, 211

Brown-Rat, 223

Carnivora, 901

Bembicidce, 693

Buccinoidce, 922

Carp, 567

Beroe, 1035

Buccinum, 922

Carpenter Bee, 697

Biphora, 981

Buccinum undatum, 957

Cartilaginous Fishes, 551

BIRDS, 322

Buceridce, 397

Caryophyllia, 1070

Birds of Paradise, 395

Buffalo, 270

Cashmir Goat, 272

Birds of Prey, 359

Bugs, 721

Cassidariee, 659

Birgus, 787

Bulimus, 914

Cassis, 924

Bittern, 448

Bulla, 917

Cassowary, 439

Black Bear, 199

Bullaea, 917

Castoridae, 229

Blackbird, 402

Bulldog bat, 192

Cat tribe, 185

Black-cap, 400

Bullfinch, 388

Catadontidce, 213

Black-Cock, 482

Bullhead, 556

Caviare, 581

Black.Coral, 1091

Buprestis,647

Cavidce, 233

Black Rat, 223

Burrowing Owl, 382

Cayman, 491

Black- Swift, 408

Burying Beetle, 648

Cebidee, 158

Black-Scoter, 455

Bush Antelope, 266

Cebus, 159

Blaps mortisaga, 653

Bush-Goat, 266

Cecidomyia, 727

Blattidce, 665

Butcher birds, 398

CellulicoltE, 754

Blatta orientalis, 665

Butterflies, 191

Centipede, 823

Bleak, 567

Buzzard, 574

Cephalapsis, 587

Blennidce, 563

CEPHALOPODA, 877

Blepharis, 559

c.

Cerastes, 510

Blind- Worm, 502

Cercopithecus, 153

Blue Shark, 582

Caaing Whale, 211

Cercopidce, 716

Boar, 296

Cachalot, 213

Certhiadte, 419

Boat-Bill, 448

Caddice-fly, 681

Cervidce, 260

Boat-Flies, 723

Caddice-wonn, 682

Cestracion, 589

Bocydium, 718

Calandria, 655

Cestum Veneris, 1037

Bohemian Chatterer, 406

Caligus, 814

Cetacea, 207

Boidce, 507

Callichroma, 659

Cetonia, 651

Bombardier Beetle, 644

Calling Crabs, 786

Chastodon, 557

Bombi, 698

Callithrix, 160

Chaionidce, 433

Bombilius, 730

Calymene, 800

Chalcidee, 501

Bombycidce, 710

Camberwell Beauty, 706

Chalcididce, 691

Bombyx, 710

Camel, 278

Chalcis, 691

Bonito, 558

Camelidce, 275, 278

Chameleonidcc, 492

Bony-Pike, 572

Camelopardidee, 263

Chamois, 264, 267

Booby, 461

Canada Goose, 455

Char, 570

Bopyrus, 798

Canary, 388

Charadriada:, 445

INDEX.
N.B. — The numbers refer to the paragraphs.

579

Cheetah, 188

Cod, 573

Curlew, 450

Cheiromeles, 172

Codling-Moth, 711

Cur sores (Birds), 436

Cheiromys, 164

Ccelelmintha, 854

Cursores (Spiders), 755

Cheironectes, 564

Coendu, 238

Cursoria (Insects), 662

Cheiroptera, 165

Coenomyidce, 728

Curucui, 411

Chelifer, 763

Coleoptera, 636

Cushat, 428

Chelone, 488

Colidte, 391

Cyamus, 796

Chelonia, 485

Colobus, 152

Cycliea, 659

Chelonidce, 486

Coluber idee, 507

Cycloidians, 586, 590

Chevrotain, 277

Colugo, 163

Cyclobranchiata, 928

Chigoe, 735

Columbidce, 428

Cyclops, 810

Chilognatha, 824

Colymbidce, 456

Cyclostomata, 585

CMlopoda, 823

Comatula, 1016

Cydippe, 1035

Chimasra, 581

Common Fowl, 431

Cynipida;, 689

Chimpanzee, 148

Condor, 378

Cynocephalus, 156

Chinchilla, 235

Condylura, 176

Cynthia, 976

Chironomus, 727

Conger, 576

Cypraea, 922

Chiton, 928

Conirostres, 385

Cyprenidee, 567

Chlamydosaurus, 497

Cony, 294

Cypris, 808

Chlamyphorus, 248

Coot, 452

Cystecercus, 854

Chondropterygii, 581

Copepoda, 810

Chough, 394

Coral Islands and Reefs, 1073

D.

Chrysochloris, 176

Corallium, 1093

Chrysomelince, 660

Cormorant, 461

Dab, 574

Cicada, 716

Coronula, 830

Dactylopterus, 556

Cicadida, 716

Corvidce, 393

Daman, 294

Cicindelidae, 643

Coryphaena, 559

Daphnia, 804

Cidaris, 1011

Coryphium, 795

Darter, 461

Ciliobrachiata, 1095

Cossus, 709

Day-flies, 674

Cimex, 722

Cottus, 556

Darwin's Rhea, 438

Cimicidce, 722

Cowcow, 425

Darwin's theory of Coral

Cineras, 830

Cowry, 903, 922

formations, 1077

Cinereous Erne, 370

Coypu, 230

Dasyurus, 310

CIRRHOPODA, 825

Crab, 785

Dead-man's-hand, 1089

Civet, 197

Crab-eating Opossum, 309

Death's-head Moth, 707

Cladocera, 804

Crabronidce, 693

Deer, 260

Clam, 941

Cracidce, 430

Delphinidce, 210, 211

Clavicornes, 648

Crake, 452

Demoiselle, 447

Clavagella, 963

Crane, 447

Dendrophyllia, 1070

Clio, 899

Cray-fish, 784

Desman, 177

Clothes'-Moth, 712

Creeper, 419

Dermaptera, 663

Clotho, 757

Crested Curassow, 430

Dermestes, 648

Clupeidce, 571

Crested Heron, 448

Dibranchiata, 886

Clypeaster, 1011

Crepuscularia, 705, 707

Didelphis, 309

Coati, 200

Cricket, 668

Dinornis, 442

Coal-fish, 574

Crinoidea, 1016

Dinotherium, 303

Cobaya, 203

Crioceris, 657

Diodon, 579

Cobbler-fish, 559

Crocodile, 490

Diptera, 724

Cobra di Capello, 510

Crossbill, 390

Dipus, 222

Coccidce, 720

Crotalidce, 590

Discoboli, 575

Coccinella, 661

Crow, 393, 394

Divers, 456

Coccus, 720

CRUSTACEA, 767

Diving Spider, 759

Cochineal, 720

Ctenoidians, 596, 590

Diurnal Owls, 381

Cock of the Woods, 432

Cuckoo, 425

Diurnal (Lepidoptera), 706

Cockatoo, 422

' Cuckoo-spit, 718

Dodo, 437, 441

Cockchafer, 651

Cuculidce, 421, 425

Dog, 13, 14, 196

Cockle, 953

Culicidce, 727

Dog-fish, 583

Cockroach, 665

Curassow, 430

Dolomedes, 755

Cocosteus, 587

Curculio, 655

Dolphin, 211

580

INDEX.
N.B. — The numbers refer to the paragraphs.

Donax, 955

Eristalis, 731

Fulgoridce, 716

Dor, 651

Erne, 370

Fulgora lanternaria, 7 1 7

Dorcus, 652

Errantes, 757

Fur Seal, 202

Doris, 915

Esculent Swallow, 408

Dormouse, 221

Esocidai, 568

G.

Dorsibranchiata, '838

Euphrosine, 839

Gadfly, 729

Dory, 559

Eupoda, 658

Gadida, 573

Dotterel, 445

Europaean Bison, 270

Gaillonella, 1133

Douroucouli, 160

Europaean Hoopoe, 418

Galago, 162

Draco, 496

Europaean Nuthatch, 419

Galathea, 788

Dragon-flies, 672

European Wren, 420

Galeodes, 763

Dreissena, 948

Euryale, 1015

Galeopithecus, 163

Drill, 156

Exocetus, 568

Galerucin<z, 660

Dromedary, 270, 281

Gall-flies, 684

Drummer, 665

F.

Galleria, 712

Duck, 454.

Gallinacea, 429

Duck-billed Platypus, 317

Falconidce, 365

Ganoideans, 586

Dugong, 305

Fallow-Deer, 261

Gar-Fish, 568

Dunnock, 400

False Scorpions, 762

Garrulous Roller, 410

Dynastes, 651

Felidce, 186

GASTEROPODA, 902

Dysopus, 172

Felis, 186

Gasterosteus, 556

Dytiscus, 645

Ferret, 192

Gastrochaena, 963

Dzigguetai, 301

Field-Cricket, 668

Gavial, 491

Field- Mouse, 226, 228

Gazelle, 265

E.

Fifteen-spined Stickleback,

Gecarcinus, 786

Eagle, 369

556

Gecko, 490

Eagle-Owl, 382

Filaria, 853

Genet, 197

Earthworm, 842

File-Fish, 580

Geocorisce, 721,722

Earwig, 662

Filitelidce, 757

Geometrida;, 71 1

Echidna, 320

Finches, 386, 387

Geophilus, 823

Echinida, 1002

FISHES, 575

Geotrupes, 650

ECHINODERMATA, 1000

Fishing- Frog, 564

Ghost-Moth, 709

Echinus, 1000, 1002

Fissipenna, 713

Gibbon, 149

Edentata, 239

Fissirostres, 385

Giraffe, 263

Edriophthalma, 794

Fistularidte, 566

Girdle of Venus, 1037

Eel, 576

Flamingo, 454

Glaucus, 915

Eft, 513

Fiat-Fish, 574

Glead, 373

Egyptian Vulture, 378

Flea, 735

Globe-Fish, 579

Eider Duck, 455

Flounder, 674

Glomeris, 824

Elater, 647

Fluke, 574

Glutton, 193

Electric Eel, 577

Flustra, 1101

Glyptodon, 247

Electric Ray, 554

Fly, 732

Gnu, 268

Elephant, 286

Fly-catcher, 40

Goat, 272

Elephant- Seal, 202

Flying-Fish, 568

Goat-Moth, 709

Elk, 260

Flying-Lemur, 163

Goatsucker, 405, 406

Emu, 439

Flying Phalanger, 314

Goby, 563

Emidce, 486, 487

Foraminifera, 1107

Gold-Fish, 567

Emperor Moth, 710

Forest flies, 725

Golden-crested Wren, 400

Emysaurus, 487

Forficulidce, 663

Golden Plover, 445

Enchelys, 1115'

Formicidce, 694

Golden Thrush, 402

Encrinus, 1019

Fossores, 693

Goldfinch, 388

Entellus, 151

Fox, 196

Gonyleptes, 766

Entomophaga, 686

Fox-Shark, 582

Goose, 455

Entomostraca, 806

Fox-tailed Monkey, 160

Goosander, 455

ENTOZOA, 850

Freshwater Mussel, 949

Gordius, 848

Epeira, 758

Frigate-Bird, 461

Gorgonia, 1093

Ephemera, 674

Fringillidce, 386, 387

Goshawk, 372

Equidce, 299

Frog, 510

Grakle, 395

Erinaceadte, 178

Frog-hoppers, 718

Grallatores, 443

INDEX.

N.B. — The numbers refer to the paragraphs.

581

Grampus, 211

Harvest-Bug, 766

Hutia, 226

Grasshopper, 669

Harvest-Men, 762

Hyalaea, 899

Gravigrada, 244

Harvest-Mouse, 226

Hyaena, 198

Great Ant-Eater, 250

Hawfinch, 388

Hybodonts, 589 •

Great Bustard, 444

Hawk, 372

Hydatina, 860

Great Northern Diver, 456

Hawk- Moths, 707

Hydra, 1043

Great Snipe, 450

Hawk-Owl, 383

Hydrachnae, 766

Grebe, 456

Hawksbill Turtle, 488

Hydrochserus, 234

Greenland Seal, 202

Hedgehog, 178

Hydrocorisce, 723

Greenland Whale, 214

Helianthoida, 1058

Hydrometridce, 722

Green Polype, 1043

Helicina, 913

Hydroida, 1053

Green Turtle, 488

Helix, 913

Hydrophilus, 649

Grey Baboon, 156

Helmet- Shell, 923

Hyla, 512

Grey Flycatcher, 403

Hemerobius, 677

Hylobates, 149

Grey Mullet, 562

Hepialidce, 709

Hylurgus, 656

Grey Plover, 445

Hermit-Crab, 787

Hymenoptera, 683

Grey Ptarmigan, 432

Heron, 448

Hyperoodon, 212

Grey Seal, 202

Herring, 571

Hypsiprymnus, 313

Grosbeak ,'388

Heteromera, 653

Hyrax, 294

Grouse, 429

HETEROPODA, 901

Hystricidce, 232

Gruida, 447

Heteroptera, 721

Gryllidce, 668, 669

High-finned Cachalot, 213

I.

Gryllotalpa, 668

Hippidce, 787

Gryllus, 669

Hippoboscidee, 725

Ibex, 273

Guanaco,282
Gudgeon, 567
Guillemot, 457

Hippocampus, 578
Hippopotamus, 297
Hirudo, 848

Ibis, 449
Ichneumon, 197
Ichneumonidce, 691

Guinea Pig, 233

Hirundinidce, 407

Icthyosaurus, 504

Gull, 459

Hive-Bee, 698

Iguanidce, 494

Gurnard, 556

Hobby, 367

Indian Buffalo, 271

Gymnodontes, 579

Hog, 295

Indicator, 425

Gymnotus, 576

Hog-rat, 226

InferoWranchiata, S

Gymnurus, 178

Holoptychius, 537

Inia, 212

Gypaetus, 371

Holothuria, 1020

Insectivora, 174

Gypogeranus, 379

Homoptera, 715

INSECTS, 602

Gyrinus, 645

Honey-Buzzard, 374

Insessores, 384

Honey-dew, 719

Irish Elk, 261

H.

Honey-guide, 425

Isis Hippuris, 1093

Haddock, 574
Hag, 585

Honey-suckers, 417
Hooded Crow, 394

Isopoda, 797
lulus, 824

Hake, 574

Hoonuman, 151

Ixodes, 766

Halcyon, 412

Hoopoe, 418

Halibut, 574

Hop-fly, 719

J.

Halicore, 305
Haliotis, 927

Hoppers, 732
Hornbill, 397

Jacana, 452

Haltica, 660
Halys, 722

Horned Owl, 382
Horse tribe, 299

Jackal, 196
Jack Snipe, 450

Hamadryas, 510
Hammer-headed Shark, 583

Horse, 300
Horse- shoe Bat, 169

Jaguar, 189
Javelin Snake, 502

Hammer-Oyster, 944
Hamster, 226
Handfish, 564

House Cricket, 668
House Spider, 758
House Swallow, 407

Jay, 394
Jemlah Ibex, 273
Jerboa, 222

Hapale, 160
Hare, 236

Howling Monkey, 159
Humble Bee, 698

Jer Falcon, 367
Jigger, 735

Harfang, 382

Humming Bird, 414, 415

John Dory, 559

Harp- Seal, 201

Humming-bird Hawk-

-

Harpyia, 173

moth, 707 '

K.

Harrier, 375

Hunting Leopard, 188

Kahau, 151

Harry-long-legs, 727

Hunting Spiders, 754

Kangaroo, 312

582

INDEX.

N.B. — The numbers refer to the paragraphs.

Kangaroo Rat, 313

Ling, 574

Mammoth, 288

Kestrel, 367

Linguatula, 853

Man-of-war-Bird, 461

Kingfisher, 412

Lithobius forcipatus, 823,'

Manatida, 305

Kinglet, 400

Little Bustard, 444

Mandrill, 156

King Vulture, 375

Llama, 278, 282

Manis, 250

Kite, 373

Lobster, 784

Mantis, 666

Koala, 314

Locustidce, 668, 670

Margaritacece, 942

Loligo, 892

Marine Snakes, 511

L.

Long-eared Bat, 171

Marmot, 220

Labridce, 564, 693

Long- tailed Field- Mouse,226

Marmozet, 160

Labyrinthodon, 512

Longicornes, 657

Marsh Sandpiper, 450

Lacertidee, 490, 500

LopMdee, 564

Marsh Tortoises, 486

Lady-bird, 661

Lophiodon, 292

Marsupialia, 309

Lcemodipoda, 796

Lophius, 564

Marten, 192

Lagomys, 237

Lophobranchiata, 578

Martin, 407

Lagopus, 432

Lophyrus, 687

Mason Bee, 697

Lamantin, 305

Lories, 422

Mastodon, 289

LAMELLIBRANCHIATA, 930

Loricata, 246

May-Fly, 678

Lamellicornes, 650

Lorikeet, 422

Meal-Worm, 653

Lammergeyer, 371

Loris, 162

Meandrina, 1071

Lamna, 582

Louse, 736

Medusa, 1031

Lamprey, 585

Love-birds, 422

Megaderm, 169

Lancelot, 585

Loxia, 390

Megalicthys, 588

Lancet-fish, 560

Lucanus, 652

Megalonyx, 245

Land-Bug, 721

Lucina, 955

Megalosaurus, 498

Land-Crab, 786

Lumbricus, 843

Megapodidce, 433

Land Newts, 5J3

Lump-fish, 575

Megapodius, 435

Land-Rails, 452

Lutraria, 957

Megatherium, 245

Land Tortoise, 486, 487

Lycaon pictus, 169

Melasoma, 653

Laniadce, 398, 401

Lycosus, 755

Meliphagidcp, 417

Lanner, 367

Lymnaea, 914

Mellifera, 696

Lantern-Flies, 716 *

Lynx, 191

Melolontha, 651

Lapwing, 446

Lyretail, 420

Meropidce, 413

Laridce, 453

Merlin, 367

Latebricolce, 754

M.

Merganser, 455

Laterigrada, 756

Maccaw, 422

Midge, 727

Launce, 577

Machilis, 737

Millepede, 824

Leech, 847

Mackerel, 558

Minnow, 567

Lemur, 161

Macropodidce, 312

Mite, 765

Lemuridce, 146, 161

Macroura, 788

Mitred Basilisk, 495

Leopard, 188

Mactra, 955

Mocking-Bird, 402

Lepas, 827

Madrepore, 1071

Mole, 175

Lepadida>, 827

Masnura, 420

Mole-Cricket, 688

Lepidoptera, 701

Magilus, 926

Mole-Rat, 227

Lepidosiren, 514

Magot, 155

MOLLUSCA, 862

Lepidosteus; 572

Magpie, 394

Monad, 1125

Lepisma, 737

Magpie-moth, 711

Monitor, 499

Leporidce, 236

Maia, 785 *

Monkey, 150

Leptocephalus, 577

Maigre, 557

Monodon, 212

Leptotherium, 283

Malacopterygii, 537

Monomera, 720

Lernaea, 812, 813

Malacopterygii abdomi-

Monotremata, 317

lernceida, 812, 815

nales, 567

Moor-Harrier, 375

Libellulidce, 672

Malocopterygii apoda, 576

Moor-Hen, 452

Limacida, 912

Malacopterygii sub-brachi-

Moose-Deer, 260

Limax, 912

ati, 573

Morris, 577

Limnadia, 802

Mallard, 455

Morse, 203

Limnoria, 798

Malleus, 944

Moschidce, 276

Limpet, 928

Malmag, 162

Mososaurus, 498

Limulus, 817

MAMMALIA, 71

Mosquito, 727

INDEX.

583

N.B.—The numbers refer to the paragraphs.

Mother Carey's Chicken, 459

Noctilio, 172

Owl, 380

Moufflon, 274

Noctiluca, 1030

Ox, 269

Mouse, 226, 228

Noctuidce, 711

Oyster, 940

Mouse-coloured Bat, 171

Noctule, 172

Oyster-catcher, 446

Mugillidce, 562

Nocturnal Lepidoptera, 708

Mullet, 562

Notacantha, 728

P.

Murcenida;, 576

Norway Haddock, 556

Murex, 925

Notidamus, 582

Pachydermata, 285

Murida:, 223

Notonecta, 723

Paca, 282

Muscicapidce, 403

Nudibranchiata, 915

Paguridce, 787

Muscidce, 732

Numidian Crane, 447

Painted Lady, 706

Musk-Beetle, 65?

Nummulite, 1108

Palaeotherium, 291

Musk-Deer, 277

Nuthatch, 419

Palinurus, 788

Musk-Ox, 271

Nut WeeTil, 655

PALI/IOBRANCHfATA, 965

Musk- Rat, 177

NycteriUidce, 725

Palpicornes, 649

Muskquash, 228

Nycterin, 169

Paludina, 920

Musophagidee, 392

Nylghau, 268

Panda, 200

Mussel, 946

Nymphon, 816

Pangolin, 250

Mustelidce, 192

Panorpidee, 679

Mutillidce, 693

O.

Panther, 188

Mya, 957

Papilio, 706

Mycetus, 159

Oared Shrew, 177

Papio, 154, 155

Mygale, 754

Ocelot, 189

Paradiseidce, 395

Myliobates, 584

Octopus, 887

Parrakeet, 422

Mylodon, 244

Oestrus, 733

Parrot, 421

Myopotamus, 230

Old English Rat, 223

Parrot-Fish, 565

MYRIAPODA, 820

Oliva, 903, 923

Partridge, 431

Myrmecobius, 309

One-humped Camel, 278

Passenger Pigeon, 428

Myrmecophaga, 250

Ophidia, 506

Patella, 943

Mynneleonidae, 676

Ophisurus, 576

Peacock, 431

Mysis, 790

Ophiura, 1015

Peacock- Butterfly, 706

Mytilaceee, 946

Opossum, 309

Pea-Crab, 781

Mytilus polymorphus, 948

Opossum-Shrimp, 799

Peba, 247

Myxine, 585

Orhicula, 967

Peccary, 296

Orbitelce, 758

Pectinaria, 841

N.

Organ-pipe Coral, 1094

Pectinibranchiata, 918

Organist Tanager, 389

Pectinidee, 241

Nais, 846

Ornithorhyncus, 317

Pedipalpi, 760

Naja, 510

Orthagoriscus, 579

Pedunculata, 829

Nandu, 438

Orthoceratite, 896

Peewit, 446

Napu, 277

Orthoptera, 662

Pegasus, 578

Narwhal, 212

Ortolan, 387

Pelicanidce, 461

Nasica, 200

Orycteropus, 249

Penguin, 458

Natantes, 759

Osprey, 370

Pennatula, 1029, 1090

Natatores, 453

Osseous Fishes, 550

Pentacrinus, 1017

Nautilidce, 896

Ostracece, 937

Pentamera, 643

Nautilites, 896

Ostracion, 580

Peramelida, 311

Nautilus pompilius, 894

Ostrapoda, 806

Perching Birds, 384

Necrophorus, 648

Ostrich, 437

Percidce, 555

Nemestrina, 730

Otidep, 444

Peregrine Falcon, 366

Nemocera, 727

Otolicnus, 162

Perennibranchiata, 514

Nepidce, 723

Otter, 201

Perepatus, 839

Nereis, 839

Oular Carron, 507

Perrodicticus, 162

Neuroptera, 671

Ourang Outan, 144, 148

Petaurus, 314

Newt, 513

Oustitis, 160

Petricola, 955

Nigger, 687

Ovalia, 796

Pyrosoma, 1029

Night-Hawk, 406

Ovo-viviparous Mammalia,

Phacochaere, 296

Nightingale, 399

306

Phalacna, 711

Nitidelee, 757

Ovula, 23

Phalangidce, 765

584

INDEX.

N.B. — The numbers refer to the paragraphs.

Phalangistidce, 314

Porpoise, 211

Rattle-Snake, 509

Phalangium, 765

PORIFEBA, 1134

Raven, 394

Phascolarctos, 314

Port- Jackson Shark, 589

Ray, 584

Phascolomyidce, 315

Portuguese Man of War,

Razor-bill, 457

Phasianidce, 431

1038

Razor-shell, 956

Phasma fragilis, 667

Potoroo, 313

Red Coral, 1093

Phasmidce, 667

Potto, 162

Red Deer, 262

Pheasant, 431

Poulp, 887

Red Grouse, 434

Phocidce, 201

Prawn, 784

Redpoll, 387

Phryganidce, 681

Praedones, 686

Reeve, 450

Phrynus, 760

Prie-Dieu, 666

Rein- deer, 261

Phyllium, 667

Pristis, 583

Remora, 575

Phyllopoda, 801

Proboscidce, 285

REPTILES, 462

Phyllosoma, 762

Proboscis Monkey, 151

RetitelcE, 758

Phyllostomidce, 179

Promerops, 418

Rhea, 438

Physalus, 1038

Proteidce, 514

Rhinoceros, 293

Phytiphaga, 686

Proteles, 198

Rhinolophidae, 169

Pica, 137

Prowlers, 757

Rhizostoma, 1032

Pichiciaga, 248

Pseudo-scorpionidte, 762

Rhyncolites, 897

Picida, 423

Psittacidae, 422

Rhyncophora, 655

Pied Fly-catcher, 403

Psocus, 675

Ribbon-fish, 560

Pig, 295

Ptarmigan, 432

Ricinise, 766

Pigeon, 428

Ptericthys, 587

Ring-Dove, 428

Pike, 568

Pteroceras, 810, 925

Ringed-Snake, 507

Pilchard, 571

Pterodactylus, 503

River-Tortoise, 486

Pilot-Fish, 558

Pteromys, 219

Roach, 567

Pimpla, 690

PTJEROPODA, 899

Rock-fish, 564

Pine-Marten, 192

Pteropus, 173

Rockling, 573

Pinna, 945

Ptinus, 647

Rock-Pigeon, 428

Piophila, 732

Puff-bird, 412

Rodentia, 215

Pipe-fish, 566

Puffin, 455

Roller, 410

Pipe-mouthed fish, 578

Pulex, 735

Rook, 394

Pithecia, 160

Pulmonaria, 752

Rorqual, 214

Placoidians, 586

Pulmonea, 912

Rose-Beetle, 651

Plaice, 574

Puma, 189

Rose-Louse, 719

Planorbis, 914

Pupipara, 725

ROTIFERA, 855

Plantain-eaters, 392

Purpura, 926

Roussette, 173

Plant-lice, 719

Pycnogonida, 816

Ruminantia, 251

Plecotus, 171

Pyralis, 711

Plectognathi, 579

Pyrosoma, 983

S.

Plesiosaurus, 506

Python, 508

Sabella, 841

Pleurobranchi, 903

Sable, 192

Pleuronectidce, 574

Q.

Sacred Ibis, 449

Pleurotoma, 924
Plover, 445

Quadrumana, 143

Safeguard, 499
Sajou, 159

Plumatella, 1102

Quail, 431

Saki, 160

Plumed Moths, 713

R.

Salamandrida, 51 3

Pneumora, 670

Salmonida, 570

Podophthalma, 784

Rabbit, 237

Salpae, 976

Podura, 737

Raccoon, 200

Saltatores, 755

Polar Bear, 199

RADIATA, 986

Sanatoria, 668

Pole Cat, 192

Raidce, 584

Sand-Grouse, 432

Polydesmus, 824

Rail, 452

Sand-Lizard, 500

POLYGASTRICA, 1110

Rallidae, 452

Sand-Marten, 407

Polynemus, 555

Ramphastidee, 423

Sandpiper, 450

Polyphemus, 806

Raphididee, 584

Sand- Wasp, 693

POLYPIFKBA, 1040

Raptores, 361

Sapajou, 159 .

Porbeagle, 582

Rasores, 426

Sarcoptes, 766

Porcupine, 232

Ratel, 193

Sardine, 571

INDEX.

585

N.B.—The numbers refer to the paragraphs.

Saturnia. 710

Siamang, 149

Star-Fish, 1012

Sauria, 490

Silk- Worm, 710

Starling, 395

Sauroid Fish, 581

Silver-Fish, 567

Stellerida-, 1012

Saurophis, 501

Siluridce, 569

Stellio, 496

Sawfish, 583

Simiadce, 146

Stenelytra, 654

Saw-flies, 684

Siphonostoma, 813

Stentor, 1127

Scalaria, 919

Sipunculus, 1022

Sterelmintha, 852 '

Scale-Insects, 720

Siren, 514

Sterlet, 581

Scaly-finned Fish, 557

Siricidce, 688

Stickleback, 556

Scansores, 421

Siskin, 387

Stilt, 451

Scarabaeus, 650

Skunk, 193

Stilt- Plover, 451

Scarus, 565

Sky- lark, 388

Sting-Ray, 584

Scicenidee, 557

Sloth, 239

Stoat, 192

Scincidee, 502

Slow- Lemur, 162

Stock-Dove, 428

Sciolidce, 693

Slow-Monkey, 151

Stomapoda, 789

Sciurida, 219

Slow- Worm, 502

Stone-chat, 400

Scolopacida:, 450

Smelt, 570

Stork, 449

Scolopendra% 823

Snail, 913

Stormy Petrel, 459

Scomberiden, 558

Snakes, 506

Stratiomys, 728

Scorpaena, 556

Snake-Eel, 576

Strepsiptera, 714

Scorpion, 761

Snake-Fly, 680

Strigidce, 380

Scorpion-fly, 679

Snake-Lizard, 501

Striped Tunny, 558

Scoter, 455

Snapping-Turtle, 487

Strombus, 924

Screamer, 452

Snipe, 450

Sturgeon, 581

Scutella, 1011

Snow-Bunting, 388

Sturnidce, 395

Scutibranchiata, 927

Snow- Flake, 388

Stylops, 714

Sea-Bream, 557

Snow-Goose, 455

Sucking-Fish, 575

Sea- Cow, 203

Social Wasp, 695

Suctoria, 847

Sea Cucumber, 1023

Solan Goose, 461

Sugar Louse, 737

Sea-Devil, 564

Sole, 574

Suidce, 295

Sea- Eagle, 370

Solen, 956

Sun-Bird, 416

Sea-Fan, 1091

Solitary Bee, 697

Sun-Fish, 579

Sea-Mantis, 791

Solitary Snipe, 450

Swallow-tailed Moth, 711

Sea- Pen, 1090

Solitary Wasp, 695

Swift, 407

Sea-Slug, 915

Soricidee, 177

Sword-Fish, 558 *

Sea-Swallow, 460

Spalax, 227

Sylviadce, 398

Sea- Unicorn, 212

Sparidce, 177

Syndactyli, 412

Sea-Urchin, 1000

Sparrow, 387

Syngnathus, 578

Sea- Wolf, 563

Sparrow-Hawk, 372

Syrian Goat. 272

Seal, 202

Spatangus, 1011

Syrphidce, 731

Sebastes, 556

Spectacled Snake, 510

Secretary Falcon, 379

Spectre-Insects, 665

T.

Sedentary Spiders, 758

Spermaceti Whale, 213

Tabanidte, 729

Semnopithecus, 151

Sphegidce, 693

Taenia, 854

Serpents, 506

Sphinx, 707

Tcenidce, 560

Serricornes, 647

Spider, 753

Tailor-birds, 400

Sertularian Polypes, 1054

Spider-Monkey, 159

Talitrus, 795

Serpula, 839

Sponge, 1137

Talpidce, 175

Sessilia, 828

Spoonbill, 448

Tanager, 389

Shad, 571

Sprat, 5/1

Tanystoma, 729

Shark, 582

Spring-bok, 265

Tape- worm, 854

Sheath-bills, 433

Spring-tail, 737

Tapitelce, 758

Sheep, 274

Spring WildBee, 731

Tapir, 291

Short-tailed Field-mouse,

Squalidce, 582

Tardigrada, 240

228

Squamipennes, 557

Tarentula, 755

Shrew, 177

Squilla, 791

Tarsius, 162

Shrike, 401

Stag, 262

Tawny Vulture, 376

Shrimp, 784

Stag-Beetle, 652

Taxicornes, 654

Sialidce, 678

Staphylinus, 641

-Tectibranchiata, 917

586

INDEX.

N.B. — The numbers refer to the paragraphs.

Tegenaria, 758

Trilobite, 586

Vespevtilionid<et 171

Teguixin, 499

Trimera, 661, 716

Vespidce, 171

Teidce, 499

Triodon, 579

Vicugna, 282

Tellina, 955

Trionycidce, 488

Vidua, 390

Tench, 567

Tritonia, 915

Viper idee, 510

Tenebrio, 655

Trochilidee, 415

Viverridee, 197

Tenrec, 178

Trochoidee, 919

Viviparous Lizard, 500

Tenthredinidce, 687

Trogonidee, 411

Vole, 228

Tenuirostres, 414

Tropic-Birds, 461

Volvox.-lMfi, i S V<|

Terebella, 841

Trout, 570

Volute, 903

Terebrantia, 686

Trunk-fishes, 580

Vorticella, 1115

Terebratula, 965

Trygon, 584

Vorticellince, 1128

Teredo, 961

Tubicolce, 574, 840

Vulturidas, 364

Termites, 675, App.

Tubipora, 1094

Terricolcp, 842

Tubulibranchiata, 926

W.

Testacella, 912

TUNICATA, 968

Testudo, 487

Tunny, 558

Waders, 359, 443

Tetrabranchiata, 894

Tupaia, 179

Wagtail, 400

Tetracaulodon, 289

Turbo, 919

Walking-Leaf, 667

Tetramera, 642

Turbot, 574

Walking-stick, 667

Tetraodon, 579

Turdidce, 402

Walrus, 202

Tetraonidce, 432

Turkey, 431

Wandering Spiders, 756

Theliphonidce, 760

Turnip-Flea, 660

Wanderoo, 155

Thelphusa, 786

Turnip-Fly, 687

Wapiti, 262

Thetis, 915

Turnstone, 446

Warblers, 399, 400

Theutidee, 560

Turtle, 486

Wasps, 695

Thornback, 584

Turtle-Dove, 428

Water-Boatman 723

Thresher, 582

Twilight Lepidoptera, 706

Water-Bugs, 721

Thrush, 402

Two-humped Camel, 278

Water-Newts, 513

Thylacinus, 310

Tyrants, 403

Water- Rail, 452

Thysanoura, 737

Water- Rat, 228

Tick, 766

U.

Water-Scorpion, 723

Tiger, 188

Water- Shrew, 177

Timarcha, 660

Unau, 241

Water-Snake, 506

Tinamou, 434

Ungka-puti, 149

Water-Spiders, 759

Tineidce, 721

Unionida, 949

Weasel, 192

Tipulidee, 727

Upholsterer Bee, 697

Weever, 555

Titmouse, 400

Upupidee, 418

Weevil, 655

Toad, 510

Urchin, 178

Wentle-trap, 919

Todidce, 410

Ursal, 202

Whales, 211

Tomicus, 656 i Ursidee, 199

Whale-bone Whale, 214

Toothless Ant-eater, 250 Ursine Dasyurus, 310

Wheatear, 400

Torpedo, 586 Ursine Opossum, 310

Wheel-Animalcule, 855

Tortoise, 485 Ursus, 199

Whelk, 922

Tortricidce, 711

Urus, 279

Whidah-nnch, 390

Toucan, 423

Utia, 226

Whimbrel, 450

Toxodon, 303

Whip-poor- Will, 406

Trachearia, 762

y_

White Ant, 672 ; App.

Trachelides, 654

White-bait, 571

Trachinus, 555

Vagantes, 755

White-bellied Swift, 408

Tragopan, 431

Vampyre, 170

White-fronted Lemur, 162

Tree-Frog, 512

Vanessa, 706

White headed Erne, 370

Tree-Pigeon, 428 Varanidee, 498

White-Shark, 582

Trepang, 1023

Venantes, 754

White- Whale, 211

Trichecus, 203

Venomous Snakes, 509

Whiting, 574

Trichoptera, 684

Venerupis, 955

Widow-bird, 390

Tridacne, 952

Venus, 955

Wild Bee, 698

Trigla, 555

Vermetus, 926

Wild Cat, 190

Trigonocephalus, 510

Vermiform Classes, 831

Wild Duck, 455

INDEX.

587

Wild Goose, 455
Wing-shell, 945
Wolf, 195
Wombat, 315
Woodcock, 450
Wood-eater, 656
Wood-louse, 799
Wood pecker, 423
Wood- pigeon, 428
Wood-wasp, 693

AT.B. — The numbers refer to the paragraphs.

Wood-wren, 400

Y.

Wrasse, 564

Yapack, 309

Wren, 420

Wryneck, 423-

z,

Zebra, 301

X.

Zebu, 268

Zeid<K, 559

Xylocopa, 697
Xylophagi, 656

Zeuglodon, 303
Zimb, 729

Xyphosura, 817

Zorilla, 192

Zygaena, 583

THE END.

LONDON I
BRADBURY AND KVANS, PRINTERS, WHITKKRIARS.

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