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CORNELL
UNIVERSITY
LIBRARY
DEPARTMENT-oF-ZOOLOGY
STIMSON HALL
Cornell University Library
QL 48.P11 1897
WON HUN
CORNELL
UNIVERSITY
LIBRARY
m7, Nar rf 7.
The Dept. of Zoology
CHARACTERISTIC MAMMALIA OF THE AMERICAN PRAIJRIES.—4fter Wallace.
AMERICAN SCIENCE SERIES, BRIEFER COURSE
LOOLOG Y
BY
A. S. PACKARD, M.D., Px.D.
Member of the National Academy of Sciences, Professor of Zoology
and Geology in Brown University
SEVENTH EDITION, REVISED
EVISED
eee EVISED
NEW YORK
HENRY HOLT AND COMPANY
1897
Copyright, 1883, 1897,
BY
HENRY HOLT & CO.
PREFACE.
Tus brief compendium of Zoology is designed for use
in grammar and high schools. It is introductory to the
author’s larger Zoology. Though partly rewritten, and
with additions regarding the habits of birds and mammals,
portions of the larger book have veen retained, the more
difficult parts being omitted so as to adapt it for younger
pupils, or those whose time is limited.
No class in the study of Zoology should depend on a
book alone, but specimens should be in constant use,—the
text-book being rather for reference,—as all school work
in Zoology should be object-teaching. Before taking up
the book, each member of the class should be required to
examine a fish—a perch, cunner, smelt, or any common
fish; the pupil should then draw it with all the fins ex-
panded; then with the aid of the directions on pages 154
to 157%, by means of a small scalpel, forceps, and scissors,
the student should dissect the fish, drawing the heart,
stomach, etc., and a transverse section; a preparation of
the brain can be easily made with the aid of a com-
petent teacher. Having thus obtained some notion of the
structure of a common vertebrate animal as a basis
of comparison, the class can begin to study the book:
meanwhile once or twice a week, if not oftener, taking a
laboratory lesson, drawing and dissecting a star-fish, clam,
iv PREFACE.
or fresh-water mussel; a lobster or crayfish; a horseshoe
crab, locust or grasshopper; and finally a fish, frog, and
cat. A small collection of corals, shells, and a few typical
dried or alcoholic insects, and skeletons of a fish, frog,
reptile, bird, and cat, should also be examined and referred
to constantly in using this or any other text-book. In this
way, and with an occasional field excursion after living
animals, the study of Zoology can be made of the highest
interest and value, calling out both the observing and
reflective faculties.
For collateral reading, the teacher or student is re-
ferred to the works of Huxley, Gegenbaur, Darwin, and
Brooks’ Invertebrate Zoology; for a work on shells,
Woodward’s Manual of Mollusca; on insects, Packard’s
Guide to the Study of Insects; on birds, Coues’ Key to
the Birds of North America; for a magazine of natural
history, to the American Naturalist. A further list is
given in the author’s larger Zoology.
While most of the cuts are taken from the larger Zoology,
where their source has been already acknowledged, a few
are borrowed from Litken’s Zoology (in Danish); Brooks’
Invertebrate Zoology ; Emerton’s Life on the Sea-Shore,
published by 8. E. Cassino; and Nordeaskiéld’s Voyage
of the Vega, published by Macmillan & Co.; a few cuts
of Crustacea are from Hayden’s Twelfth Annual Report
U.S. Geological Survey of the Territories, and Fig. 137 is
from the Second Report of the U. 8. Entomological Com-
mission: these and others thus copied are duly acknowl-
edged under each cut. A few of the illustrations are new.
PROVIDENCE, Sept. 25, 1883.
PREFACE. v
PREFACE TO THE SECOND Eprrion.
The most important discovery made since this book was
published is that the two lowest mammals, 7.¢., the duck-
bill and Echidna, both lay eggs which are introduced into
the mammary pouch, where the young are hatched in a
very rudimentary condition; the eggs have a soft parch-
ment-like shell, and in the case of the spiny ant-eater, or
Echidna, are nearly an inch (13-24 cm.) in length. Refer-
ences to these points are incorporated in the text. More-
over, the nervous system of Echinoderms has been found
to consist of a delicate sheet lying under the soft integu-
ment, the thickenings seen by the naked eye forming the
nervous ring and radial branches heretofore regarded as
forming the nervous system of these animals. These and a
few other corrections have been made in the present edition.
PRovIDENCE, March, 1885.
PREFACE TO THE THIRD EDITION.
Recent discoveries, now generally accepted, have ren-
dered necessary the following important changes in this
work: The Tunicates are placed in the same sub-kingdom
(Chordata) as the Vertebrates; the Merostomata and Trilo-
bites are regarded as together forming a class of Arthrop-
oda called Podostomata; the sub-kingdom Arthropoda is
subdivided into six classes; the Malacopoda, Myriopoda,
Arachnida, and Insecta being regarded as classes, instead
of sub-classes, ag in the former edition. The orders of in-
sects have been increased from eight to sixteen. Numerous
minor corrections have also been made.
PROVIDENCE, June, 1886"
PREFACE TO THE SEVENTH EDITION.
The book has been enlarged by the addition of a chapter
on the relation of animals to their surroundings, on varia-
tion, and the factors of organic evolution, as well as a brief
chapter on heredity. It is believed that the attention of
pupils should be called to the wonderful harmony and
adaptation in nature, and to the apparent causes of such rela-
tions; and that they should be led to observe for themselves,
where possible, examples of adaptation in common shells,
insects, birds, etc. Suitable collections can be made for
this purpose and exhibited or examined in the classroom.
A number of corrections have been made, the most
important change being in the position of the Echino-
derms, which are placed after the Vermes.
Provipence, R. 1., July 15, 1897.
vi
CONTENTS.
INTRODUCTION. PAGE
Definition Of Zoolo wy occ wes ccs portato e hale a d'eoS ayeiscecatealencisctee’s 1
Meth Oat ORs Study s.c ius Accu teontecons taal aan orem cots onuntochusueracspceetel 1
CVAaSSiNCAU OM s(a524-3.5 acesea aie daseacunedand.cs s bullae Ohivaaa eee canes 2
Pale Ont GORY: cye-cme occ 3 Gen daoanteoas salale aaa esa a Rbeiedaicladey ste een aWeresa 4
Geographical Distribution .......... 0... cece eee ee ee pista otitets 4
How to Begin the Study of Zoology................. niseahas ts 5
CHAPTER I.
BRANCH 1. “ProtozOdsyeniscam eens yee i804 RCRA SRA Rae CRE 6
CHAPTER II.
Branca 2. Porifera (Sponges) .......... cece cece eee eens 15
CHAPTER III.
Brancu 8. Celenterata (Hydroids, Jelly Fishes, and Polypes) 19
CHAPTER IV.
Brancw 4. Vermes (Wornmis)........... ccc eens cececce ee ceees 37
CHAPTER Y.
BrancwH 5. Echinodermata (Crivoids, Starfish, Sea-urchins,
LCi) s58 sa% Ge BPRS CRR Gy Brae tis S WieNe Be:8: 8S Wels te 54
CHAPTER VI.
Brancu 6. Mollusca (Bivalves, Snails, Cuttles).............-. 64
CHAPTER VII.
Brancu 7. Arthropoda (Crustaceans and Insects)............. 78
CHAPTER VIII.
Brancw 8. Vertebrata........eeeeree eens CRETE Trax 133
viii CONTENTS.
PAGE
CHAPTER IX.
Relation of Animals to their Surroundings. Variation, and the
Factors of Organic Evolution....... 0.0.0 e cece eee eee 316
CHAPTER X.
FRere diy: sie: eiec.s.s:sie:0:0' sie 0:00 srneverere acakevsceianeveieus iereiecs giaiareveieicveteneieueee 340
ZOOLOGY.
INTRODUCTION.
DEFINITION OF ZooLOGY.—The study of nature comprises
the examination both of minerals and of living beings, 7.e.,
plants and animals. Every natural object in this world
which is lifeless belongs to the mineral kingdom: such are
rocks, soils, water, air, and gas. Since plants and animals
live and grow and have organs, or distinct parts which per-
form acts called functions, as the eye which sees, the hand
which grasps, etc., all living beings are said to be organic,
and all mineral bodies are said to be inorganic. It is cus-
tomary to speak of the Mineral Kingdom, the Vegetable
Kingdom, and the Animal Kingdom; but it is better to
speak of the inorganic and the organic worlds, since all liv-
ing beings or organisms have much in common which
distinguishes them from mineral substances.
The study of plants is called Botany, and the study of
animals Zoology; while the study of living beings in gen-
eral, whether plants or an‘mals, is termed Biology, which
means the science of living beings.
METHOD OF STUDY.—We study an animal, if it be a dog,
for example, by observing its form, noticing its head, trunk,
its four legs, etc. After a long and patient examination of
the outer body we dissect it, examining the heart, stomach,
brain and nerves, etc., and theskeleton. After a thorough
study of a single specimen we should then compare it with
a cat, and thus make our studies comparative. After such
2 ZOOLOG f£.
an examination we shall obtain a fair idea of the form and
structure of the great class of mammalia, or mammals, of
which the dog and cat are examples. Moreover, we should
study how the animal walks, how its heart beats, or its eyes
see. This is studying the physiology of the animal. Then
we should learn how the animal grows or develops from
the_egg, and this is called Hmbdryology, the germ of an ani-
mal being called an embryo. The bodies of animals are
made up of cells. A cell is a microscopic portion consist:
ing of a jelly-like substance called protoplasm. Animal-
cules are composed of but a single cell; such creatures are
said to be wnitcellular, but most animals are formed of bone
or shell, muscles, nerves, etc. These parts are made up of
cells. Hence these animals are many-celled. The cells
form fisswes, such as muscular or nervous tissue. The
study of cells and tissues is called Histology. Finally, we
should acquaint ourselves with the habits and mental traits
of the animal, and this is called Psychology.
A fish is the most convenient vertebrate for ordinary
school laboratory work. The object of these lessons is to
induce the scholar to depend as far as possible upon the
use of his own eyes and brains, He should observe with care
some of the common animals here described, most of which
he can readily obtain, and then study their form, habits,
and the leading features of their anatomy. By examining
a worm, a starfish, clam, lobster, insect, and fish, and read-
ing about their mode of grewth, he will obtain a knowl-
edge of the principal groups of the animal kingdom which
he will remember throughout life.
CLASSIFICATION.—There are estimated to be upwards of
250,000 species of animals now living on the surface of
the earth. How all these forms are related and how they
differ comprises what is called the classification of animals
or SYSTEMATIC ZOOLOGY.
When Linneus, the father of natural history, undertook
to classify animals he divided the animal kingdom into
classes, orders, genera, and species. Thus at present all
SYSTEMATIC ZOOLOGY. 3
animals, such as fishes, birds, or mammals, which have a
backbone, are placed together in the branch or sub-kingdom
of Vertebrates; those vertebrates, such as the cat,'horse,
or cow, which suckle their young, are placed in the class
of Mammals; those mammals which have claws and teeth
adapted for seizing and chewing flesh, 7.¢., are carnivorous,
belong to the order of Carnivora. The order of Carnivora
is composed of a number of families, such as the cat family,
the dog family, etc. A family is composed of a genus, and
a genus is made up of species and varieties, the latter being
composed of individuals.
Thus the principle of zoological classification consists in
placing animals which are alike by themselves into distinct
groups. The following table expresses the zoological posi-
tion of the cat:
Kingdom of Animals;
Sub-kingdom or Branch, Vertebrata;
Class, Mammalia;
Order, Carnivora;
Family, Felide;
Genus, Felis;
Species, Felis domesticus;
Variety, Angorensis;
Individual, a single Angora cat.
The animal kingdom is divided into two series of branches:
those for the most part composed of a single cell are repre-
sented by a single branch, the Protozoa (animalcules).
Those animals whose bodies are formed of many cells are
called Metazoa.* The series of Metazoa comprises the
seven higher branches—z.e¢., the Porifera, Coelenterata,
Vermes, Echinodermata, Mollusca, Arthropoda, and Ver-
tebrata. Their relationships may be expressed by the fol-
lowing .
*TIn the latter group the cells are arranged in two, mostly three,
fundamental cell-layers. Of these cell-layers the outermost is called
the ectoderm, the middle the mesoderm, the innermost the endoderm,
4 ZOOLOGY.
TaBULAR VIEW OF THE E1GHT BRANCHES OF THE ANIMAL KINGDOM
VIII. Vertebrata.
Ascidians to Man.
VIL. Arthropoda.
Crustaceans and Insects.
VI. Mollusca.
Clams, Snails, Cuttles.
V. Echinodermata.
Crinoids, Starfish, ete,
|
IV. Vermes.
Worms,
Ill. Celenterata. Il. Portfera.
Hydra, Jelly-tishes. Sponges.
|
METAZOA.
Many-celled animals, with 3 cell-layers,
I. Protozoa.
Single-celled animals,
PALEONTOLOGY.—The existing animals were preceded in
the earth’s history by multitudes which are now extinct.
Their remains in the shape of bones, teeth, or shells, etc.,
are called fossils, and the study of fossil animals and plants
is called Paleontology.
GEOGRAPHICAL DIsTRIBUTION.—Animals are not arbi-
trarily scattered over the earth’s surface, but form assem-
blages of species which people any given spot or country.
Such an assemblage of animals inhabiting a given place or
area is called a fauna. Thus we may speak of the fauna
of New York, or of the United States, or of North Amei-
ica. The animals of the arctic region belong to the arctic
fauna; those of the tropics constitute the tropical fauna.
We may also speak of the fauna of the land or of the
ocean,
SYSTEMATIC ZOOLOGY. 5
How to Begin the Study of Zoology.—In our rapid survey
of the animal kingdom, in order to obtain a clear idea of
what an animal is, and of the structure of some common,
well-known type or example, we would earnestly advise the
student to study some human physiology, such as Martin’s
“The Human Body,” or any other at hand, and then to
read the account of the anatomy of the fish in this book,
and also study the skeleton and dissect a perch or any
common fish. The student will thus have a standard of
comparison, a standpoint from which to survey the animal
world as a whole. He will thus learn the relations of the
skeleton or solid framework of an animal to the muscles,
etc., and learn what a heart, lung, or eye is. Then he can
the better understand the structure of the lower animals.
This book begins with the lower, simpler, one-celled
forms and ends with the most complicated, 7.¢., birds and
beasts, as it is believed that this is the most natural and
philosophical method. In geological history the inverte-
brates, 7.¢., those animals without a backbone, appeared be-
fore the vertebrates. It is better to lead the student from
the simpler to the more complex animal forms, just as in
studying hitsory we begin with the origin of mankind and
trace the history of the earlier nations which have preceded
existing peoples; or in the history of our own country, be-
gin with the discovery and first settlement by our European
ancestors. To begin the study of zoology by first taking
up the mammals and birds is like reading history back-
wards. Besides this, the student, being more familiar with
the birds and mammals, will find the subject growing more
interesting as he gets nearer the end of the book.
GENERAL WORKS ON ZOOLOGY.
T. H. Huxley. A Manual of the Anatomy of the Invertebrated
Animals, 1877. A Manual of the Anatomy of the Vertebrated
Animals, 1871.
C. Gegenbaur. Elements of Comparative Anatomy. 1878.
C. Claus. Elementary Text-book of Zoology. 2 vols, 1884-85.
A, Lang. Text-book of Comparative Anatomy. Pt. I. 1891.
Coues and Kingsley’s Standard Natural History. 6 vols. 1884-85.
Also, Darwin’s Origin of Species, and the works of Lamarck, Sem-
per, Haeckel, Wallace, Weismann, and Eimer.
CHAPTER I.
Brancw I.—Prorozoa (Animalcules, Infusoria, Monads,
etc.).
GENERAL CHARACTERS OF PROTOZOANS.—Few of the
Protozoans can be seen without the aid of the microscope;
they are microscopic animals or animalcules. One of the
simplest forms is a very minute being called Ame@ba. It is
to be sought for in standing pools, where it lives on the
leaves or stems of submerged plants or in the mud or ooze
at the bottom. Taking up a drop of water from the bot-
tom of such a pond and placing it under high powers of
the microscope, we may, after close examination, detect a
very small moving mass of jelly-like substance or proto-
plasm. As it glides over the glass the sides of its body
bulge out, or it suddenly throws out lobes or projections
from various parts of its body as if it were falling apuait;
then it retracts these transparent rvot-like processes, which
are called pseudopodia, or fulse feet, and becomes smooth
and rounded, like a drop of thick syrup. Throughout the
body-mass are granules which have a rude sort of circula-
tion. There is also in or near the middle a clear round
body called the nucleus, In all respects the Ameeba isa
cell, t.e., a bit of protoplasm with a nucleus in the middle.
Besides the nucleus, a clear, hollow, round, pinkish space
which enlarges and contracts is usually present. This is
called the ‘‘ contractile vesicle.”
The food of the Ameba consists of one-celled plants
THE AMG@BA, 7
such as diatoms and desmids, and of portions of thread-like
plants, or of animalcules. After selecting its food, as for
example a minute plant, it engulfs or swallows it by mov-
ing towards the object and gradually closing around it,
Fic. 1.—Amoba proteus. a, endosarc; c, ectozarc; b, simple pseudopod; /;
branched pseudopod; g, food vacuole; d,a pseudopoa beginning to grow out,
e, one a little more develoned; food vacuole; h, food-ball; 7, nucleus; k, con-
tractile vesicle. Magnified 200 diameters. After Brooks.
until the object is enveloped within the body, which is so
transparent that the food-object can be seen through it.
8 ZOOLOGY.
The Amoeba has the power of digesting and of distributing
and absorbing the food (Fig. 1, 4, food-ball) when digested.
The Amoeba reproduces
its kind by simply dividing
into two portions, as seen
in Fig. 3. After becom-
ing encysted or forming a
round mass as at B, it
breaks out of the ccll-wall
and becomes free and _ ir-
Fic. 2.—Ameba proteus. A, the left- regular in shape as at A.
pend ngure, the most usual form; the r
right shows the broad, flat pseudopo- -di o1lns
dia; the arrows indicate the direction Self division then begins
of circulation of the granules. Highly ag at OC, the nucleus divid-
magnified. z Bee %
ing into two, until at Da
and Dd two separate individuals are formed.
When the Ameeba is touched it (1) contracts its body—it
Fic. 3.—Amoeba spherococcus. A, before divisi i i
Z § s. A, vision. B, the same in its restin
stage; a, cyst or cell-wall; d, body-mass; c, nucleus: b, nucleolus. CG: AGneSbe
ne divided. D, two young Amcebe, the result of division. Highly mag:
is thus said to be contractile—and (2) performs automatic
movements; also, like the higher animals, (3) it swallows
THE RHIZOPODS. 9
food; (4) chemical changes in the food take place: in other
words, it digests its food, 7.¢., separates or secretes the por-
tion necessary to nourish its body from those portions which
it rejects as waste; (5) it may also be said to breathe, the
changes involved in tuking food, especially oxygen, caus-
mg the production and excretion of carbonic acid; (6) and
finally, it can reproduce its kind. Thus we have foreshad-
owed in this exceedingly simple organism all the important
functions of animal life.
CLASSES OF PROTOZOA.
i. Body formless, usually shelled......... Rhizopoda.
2. Body cylindrical; parasilic............ Gregarinida,
8: Body? ciliated sce ciceeisis vies Servers ea gs Infusoria.
Ciass I.—Rurzopopa (Loot-antmaleules).
General Characters of Rhizopods.—Besides the Ameba,
which is a representative of this ciass, there are a number
Fia. 4.—A Foraminifer. Globigerina bulloides, magnified 70 diameters.
of fresh-water forms which have simple, silicious shells;
but in the sea there are thousands of species whose shells
are partitioned into chambers, and are usually perforated
with holes like a sieve, through which the animal protrudes
its false feet or pseudvpods. These shelled Rhizopods are
10 ZOOLOG ¥.
called Foraminifera (Latin, foramen, a hole or aperture;
JSerens, bearing).
In some forms, as the fossil Nammulites, the chambers
are numerous and regular, the shells being flat and consist-
ing of eight coils situated in the same plane.
malcules, slightly magnified. B, one of the animalcules magnified 250 diam
eters. p, the stem; d, the flat spiral of vibrating cilia at the edge of the disk:
ms, the muscle; m to s, the depth of the digestive cavity; m, the mouth; g, yg},
the throat; cv, the contractile vesicle; n, the reproductive organ.
CHAPTER II.
Branco II].—PoriFrera (Sponges)
GENERAL CHARACTERS OF SPONGES.—Sponges are now
known to be composed of numerous cells, arranged in three
layers, the embryo arising from an egg, and passing through
a blastula and a gastrula stage, as in all the higher animals.
A sponge, then, is a cellular sac (Fig. 13) with digestive
chambers or minute rude stomachs lined with ciliated cells,
the whole sponge-mass being propped up by an irregular
basket-work of needle-like bodies called spicules. Upon
cutting a dry sponge in half there are to be seen large canals
which have large openings called oscula; these are really
* See Kent’s Manual of the Infusoria, London, 1880- 82,
ié6 ZOOLOGY.
Fia. 13.—a, longitudinal section through a simple calcareous sponge, showing its
simple central cavity; b, showing a single osculum at the top, and the many
mouths over the surface. After Haeckel.
Fic. 14.—Microscopic section of a bit of sponge, 1, canals leading to the cham
bers; 2, section of the same enlarged; 2, the ciliated cells, high] ii i
From Liitken’s Zoology. yMehly magnified:
HOW SPONGES GROW. 17
openings for the exit of waste matters. Among these large
openings are multitudes of minute openings which serve as
mouths. These mouths lead by branching canals into little
pockets or chambers which are lined with digestive, ciliated
Fie. 15.—Development of a sponge (Sycon ciliatum). .4, B, morula seen in sec-
tion; c, segmentation cavity; C, blastula stage; D, gastrula about to be-
come stationary, with a few spicules; HZ, sponge become stationary, with
spicules. High!y magnified.
cells; the sponge, then, has myriads of mouths and stom-
achs (Fig. 14).
Sponges develop, like all the
higher animals, from true eggs.
The egg, after fertilization,
begins to grow, and divides into
mulberry, which seen in section
isas in Fig. 15, A,B. This isthe
segmentation stage or morula.
The cells farther multiply, and
arrange themselves into a single Fie. 16.—Ciliated embryo or blas-
: tula of a sponge (Sycaudra ra-
layer, when the embryo is called phanus). (Highly magnified.)
a blastula. Some of the cells are
ciliated, and as a blastula the embryo leaves the parent
sponge and swims about in the sea (Fig. 16 and Fig. 15, C’).
18 ZOOLOGY
After invagination the blastula becomes a gastrula and
fixed to the bottom, the spicules growing as in Fig. 15, #.*
Sponges may have horny spicules as in those i in domestic use,
or caleareous or silicious spicules. Fig. 17 represents a
fine silicious sponge from the West Indies. The most
eibu
GON
Vi eas al i
Le
Fic. 17.—Pheronema Anna, half natural size, with stellate and anchor-like
spicules, much enlarged.
beautiful of all silicious sponges is the Venus’ flower-basket
(Zuplectellum aspergillum), which lives anchored in the
mud atthe depth of about 10 fathoms, near the Philippine
Islands
A sponge called the Cliona bores into shells, causing them
* Sce Haeckel’s Die Kalkschwitmme. 3 vols. 1872.
COMMERCIAL SPONGES. 19
to disintegrate. For example, Cliona sulphurea, a yel-
lowish sponge, has been found by Verrill boring into
various shells, such as the oyster, musscl, and scallop; it
also spreads out on all sides, enveloping and dissolving the
entire shell. It has even been known to penetrate one or
two inches into hard statuary marble.
Of the marketable sponges there are six species, with nu-
merous varieties. They are available for our use from being
simply horny or fibrous, having no flinty or silicious spi-
cules. The Mediterranean sponges are the best, being the
softest; those of the Red Sea are next in quality, while our
West Indian species are coarser and less durable. Our
West Indian glove-sponge (Spongia tubulifera) corresponds
to Spongia Adriatica, which is the Turkey cup-sponge and
Levant toilet sponge of the Mediterranean. Spongia gos-
sypina, the wool sponge of Florida and the Bahamas, is
used as a horse or bath sponge.
CHAPTER III.
Branenw II].—Ca@nenterata (Hydroids, Polyps, etc.}.*
’ GENERAL CHARACTERS OF CELENTERATES.— We now come
to animals of more definite shape than sponges, while their
structure is more easily understood. A common type or
representative of the group is the fresh-water Hydra. Its
body is like a slender cylindrical sack, with a mouth in the
middle surrounded by a circle of feelers or tentacles. The
mouth leads into a simple stomach-like cavity; whatever is
not digested, such as pieces of shell, etc., is rejected from
the mouth. The walls of this very simple body consist
of two cell-layers, the ectoderm and endoderm; the middle
layer (mesoderm), found in higher animals, not being pres-
ent. From the fact that the digestive cavity or stomach is
simple, being hollowed out of the body, there being no
genuine separate digestive canal, as in the higher animals,
all the species of this branch are called Celenterata (Greek,
Koihos, hollow; and €vTepor, digestive track).
ee ie CORE PRES ERI
* See the works of Darwin on Coral Reefs, Dana’s Corals and
Coral Islands, A. Agassiz’s Seaside Btudies in Natural History, 1871.
20 ZOOLOGY.
Crass I.—Hypnrozoa.
Characters of Hydrozoans,—The common Hydra (Fig. 18)
may be found in fresh-water ponds attached by its base to the
F1a. 14.—Hydra fusca, with two young (ac) budding from it; b, the base; s, the
digestive cavity; t, tentacles. Magnified.
under side of the leaves of aquatic plants. It ‘s not fixed
permanently, but can move freely about. It is very small,
just large enough to be seen without a magnifying glass;
it is usually pile green, but is sometimes brown, The
THE HYDRA. 21
mouth is surrounded with from five to eight tentacles or
feelers, which are hollow, the mouth opening into the cen-
tral cavity or stomach. The Hydra, attached to some leaf,
reaches its tentacles out in all directions; a minute insect
or young snail or Infusorian passing by will, if touched by
these feelers, be instantly paralyzed, and then the feelers
close over the helpless victim and it is drawn into the stom-
ach and digested. This power of paralyzing and thus easily
capturing active living creatures is due to the presence in
the skin of the tentacles and body of what are called lasso-
- cells or nettling organs (Fig. 20, ¢, d, e), which are minute
cells containing a long barbed thread coiled up within the
cell. When the Hydra touches an animal swimming near
it, thousands of these little barbed cords are darted into
the vietim, which is instantly paralyzed, and thus falls an
easy prey to its captor. These nettling organs are found
in all Colenterates, such as jelly-fishes and coral polyps.
The Hydra, like some other animals of simple structure,
is capable to a wonderful degree of reproducing itself when
cut into pieces. ‘Trembly, as early as 1744, not only cut
Hydras in two, each part becoming a perfect Hydra, but
on slicing them across into thin rings he found that from
each ring grew out a crown of tentacles; he split them into
longitudinal strips, each portion becoming eventually a well-
shaped Hydra, and finally he turned some inside ont, and
in a few days the Hydra swallowed and digested bits of
meat, its former stomach-lining having now become its
skin. The Hydra reproduces by budding as well as by
eggs.
The process of budding is but a modification of that in-
volved in natural self-division, and it is carried on te a
great extent in Hydra, a much larger number of individuals
being produced in this way than from eggs. Our figure
(18) shows two individuals budding out from the parent
Hydra; the smaller bud (a) is a simple bulging out of the
body-walls, the bud enveloping a portion of the stomach,
until it becomes constricted and drops off, the tentacles
29 ZOOLOGY.
meanwhile budding out from the farther end, and a mouth-
opening arising between them, as at c. Budding in the
Hydra, the Actinia, and other polyps, and in fact all the
lower animals, is simply due to an increase in the growth
and multiplication of cells at a special point on the outside
of the body.
The Hydra, exactly as in the vertebrates, including man,
arises from an egg which, after fertilization, passes through
Fic. 19.—Colony of Hydractinia echinata on a shell tenanted by a hermit crab,
natural size.
a blastula and then a gastrula stage, the germ consisting
at first of two cell-layers.
In all the Hydroids except Hydra the sexes are separate,
and we for the first time in the animal kingdom meet with
two sorts of individuals, ¢7.¢., males and females.
The simplest form next to Hydra is Hydractinia, a Hy-
droid encrusting shells (Fig. 19). In this form the indi-
vidual is composed of three parts, each endowed with dif-
ferent functions, and called zoo’ds—namely, a, hydra-like,
sterile or nutritive zooids; & and e, the reprodcetive zooids,
one male and the other female, both being much alike ex-
ternuly, having below the short rudimentary tentacles sev-
CORAL-FORMING HYDROIDS. 93
eral round sacs, or ‘‘medusa-buds” which produce either
male or female meduse. These medusa-buds are like the
free medusz of Coryne. The marine Hydroids, then, are
Fie. 20.—Animal of Millepora nodosa. a, nutritive zooid; b, reproductive
gooid; c, lasso-cell; d, the same coiled up in its cell; e,a thirdform. All
highly magnified.
usually of distinct sexes, growing by colonies, which are
either male or female.
The minute animals of Afillepora
secrete large coral-like masses on the
reefs of Florida and the Pacific Ocean.
The name is derived from the num-
berless minute holes or pores scattered
over the surface in which the nutritive
(Fig. 20, a) and reproductive zooids
(Fig. 20, 6) live. On breaking off pieces
of the living coral one’s hand is stung
and made sore for days by the stings
from the lasso-cells, so poisonous is this
coral-like growth (Fig. 20, ¢, d, e).
A common Hydroid on our north- Fie. 21.—Polypite of Co-
ern shores is the Coryne (Fig. 21), WS uae tad ae a
which differs from the foregoing kinds “4 *™/ATe°*-
in producing a free bell-like form called a medusa or
94 ZOOLOGY.
jelly-fish (Fig. 22). All jelly-fishes are more or less bell
or umbrella shaped, and are delicate transparent creatures
which move about in the water, by opening and closing
the edge of the disk-like body. From the centre of the
body hangs down a hollow proboscis-like tube, the stom-
ach, from the base of which radiate four canals or passages
which open into a circular passage around
the edge of the disk. This is the water-vas-
cular system, and the fluid it contains is sea-
water mixed with the digestive fluid; this
fluid thus rudely corresponds to the blood of
higher animals. Four long thread-like ten-
tacles in the Coryne hang down from the
edge of the disk. These delicate jelly-fishes
possess a nervous ring passing around the
edge of the disk, and also eyes and simple
ears (o¢focysts) situated at intervals on the
edge of the disk.
The meduse arise from little bud-like
swellings on the young or Hydroid (Fig.
21, a); these enlarge, and finally become
detached and swim about as at Fig. 22.
Some Hydroids like Sertularia (Fig. 23)
are encased in horn, and closely resemble
delicate sea-weeds. They are commonly
thrown upon sea-beaches.
Our common large jelly-fish or ‘‘sun-fish”
so often thrown ashore on sandy beaches is
Be ee hoes the Aurelia (Fig. 27). It grows eight or
long tentacles, ten inches in diameter. Its tough, jelly-like
Enlarged. convex disk is smooth above, but hollowed
out beneath into a broad stomach with a square mouth,
the edge of which is minutely fringed, bearing four fringed
broad, short tentacles. On the fringed margin are elght
covered eyes situated in indentations, which divide the disk
into eight slightly marked lobes. The four main water-
vascular canals subdivide .as seen in Fig. 27, into numer-
HOW JELLY-FISH GROW. 95
ous branches, which connect with the marginal vessel
The Aurelia spawns late in the summer.
The eggs pass out of the mouth into the water along the
channelled arms, and in October the ciliated sac or gastrula
becomes pear-shaped and attaches itself to rocks, dead
shells, or sea-weeds, and then assumes a Hydra form with
often twenty-four very long tentacles. ‘This stage wags
Fia. 23.—Sertularia abietina of Europe. A, natural size; B, magnified, show
inz the cells containing the animals.
originally described as a distinct animal under the name ol
Scyphistoma. In this Scyphistoma stage (Fig 24) it re-
mains about cighteen months. Toward the end of this
period the body increases in size and divides into a series of
cup-shaped disks. These saucer-like disks are scalloped on
the upturned edge, tentacles bud out, and the animal as-
sumes the Strobila stage (Fig. 25). Finally, the disks sep-
arate, the upper one becomes detached and dies, but the
26 ZOOLOGY.
others swim away in the Ephyra form (Fig. 26), when
about a fifth of an inch in diameter, and toward the mid-
dle or end of summer become adult Aurelie (Fig. 27).
Fia. 24.—Scyphistoma of Au- Fia. 25.—Strobila of 4u- Fic. 26.—Ephyra or ear-
relia. See ee Mag- liest free condition of
nified. Aurelia. Magnified.
An example of the compound Hydroids, called Siphono-
phora, is the Physalia, or Portuguese man-of-war (Fig. 28),
which is common in the tropics, and is sometimes carried
Fig. 27,—Avrelia flavidula. Natural size.
northward by the Gulf Stream. It is excessively poisonous
to the touch. In picking up specimens stranded on the
PORTUGUESE MAN-OF-WAR. ye
shores of Key West, Florida, our hands have been severely
stung by them, the burning, smarting pain lasting for hours.
A Siphonophore, such as Phy-
salia, for example, may be com-
pared to a colony of Hydrac-
tinia, in which there are nutritive
and reproductive zooids and me-
dusa buds. In Physalia, how-
ever, there are four kinds of
zoolds—t.é., (1) locomotive, and
(2) reproductive, with (3) barren
medusa buds, which are called
the ‘‘swimming bells,” and (4)
the nutritive zooids or ‘‘ feeders,”
a set of digestive tubes which
nourish the entire floating col-
ony.
The Portuguese man-of-war
consists of long locomotive ten-
tacles, which, when the animal
is driven by its broad sail or
float before the wind, stretch out
in large individuals from thirty
to fifty feet. These large Hydra-
like zooids are arranged in small
groups, arising from a hollow
stem communicating with the »>
stomach extending between the ‘
inner and outer wall of the float. Fie. 28—Physalia, or Portuguese
The ‘‘ feeders” are of two kinds, ™@™0f war. Natural size.
large and small, and are clustered in branches growing
from a common hollow stem, also communicating with the
stomach.
Cuass II.—Actinozoa (Sea-Anemones and Coral Polyps).
General Characters of Actinozoans.—The Actinia or sea-
anemone is the type of this class, the different kinds of
28 ZOOLOGY.
Actinians and coral polyps having the same general shape
and structure.
The common Actinia of our coast (Metridium margina-
tum, Fig. 29) is to be found between tide-marks on rocks
under sea-weeds, or in tidal pools, but grows most luxuri-
antly on the piles of bridges. It readily lives in aquaria,
where its habits may be studied. An aquarium may be
improvised by using a preserve-jar or glass globe, covering
Me
wy, sey,
SO, AU
SSSaavtor ty ay wy AME
ON Wty \\s iN tf, i fads Ny VEE
SEN \ LG 2
SSS}
aS }})
SN
SS
x
Ny
< oS
SS
SS
Ee
Fie. 29.—Common Sea-Anemone. Natural size, with the tentacles expanded.
After Emerton.
the bottom with sand, with a large flat stone for the at-
tachment of the sea-anemone. By placing a green sea-weed
attached to a stone in the jar, and filling it with sea-water,
the animal may be kept alive a long time.
After observing the movements of the crown of tentacles as they
are thrust out or withdrawn, and the eve-spots at the base of some of
the tentacles, specimens may be killed expanded by the gradual intro-
duction of fresh water, or by plunging them into picric acid. They
should then be transferred to the strongest alcohol, and allowed to
STRUCTURE OF SEA-ANEMONES. 29
soak in it for two or three days until the tissues become hard enough
to cut well. Then verticaland transverse sections may be made with
asharp knife. The first fact to ob erve is, that an alimentary canal
is much more clearly indicated than in the Hydrozoa, there being a dis-
tinct digestive sac, separate from the body-walls, hanging suspended
from the mouth-opening, and held in place by six partitions (mesen-
teries), which divide the pody-cavity into a number of chambers.
The digestive sac is not closed, but is open at the bottom of the body,
connecting directly with the chambers, so that the chyme, or prod-
uct of digestion, passes down to the floor of the body, and then into
each of the chambers, On the free edges of the shorter meseuteries,
which do not extend out to the stomach, there is a mass of long coiled
filaments, the mesenterial filaments (Fig. 30, cr), which contain lasso-
cells. In dissecting the sea-anemone these mesenteria! filaments are
always more or less in the way, and have to be carefully removed so
as to expose the ovaries and adjoining parts. They press out of the
mouth and e7zelédes (cé, small openings through the body-walls), not
always present, and end of the tenta-
cles, and thus come in contact with
animals forming their food. The fig-
ure shows at the base of the body the
free edges of the mesenteries (m) of
different heights, with the spaces be-
tween them through which the chyme
passes into the body-cavity. For the
complete passage of the circulating
fluid the six primary mesenteries are
perforated by a large orifice (op) more
or less oval or kidney-shaped in out-
line (Fig. 80). The digestive sac is di-
vided into two divisions, the throat
and stomach proper, the latter when Fie. 30.—-Partly diagrammatic
the animal is contracted being much sev tg a) emerenengts ae
shortened, and with the walls verti- tentacles disproportionately
cally folded, as seen in the cut. enlarged. 8 cesonhags: mame.
senteries, or septa; 0, ovary; ci,
In the tentacles are lodged the lasso- _cinclides; cr, mesenterial fila-
ments; e, eyes; op, orifice
cells, and the tentacles are hollow, through the septa.
communicating direct'y with a cham-
ber or space between the mesenteries, and are open at the end. When
a passing shrimp, small fish, or worm comes in contact with these
tentacles, the lasso-threads are thrown out, the victim is paralyzed,
other tentacles assist in dragging it into the distensible mouth, where
it is partly digested, and the process is completed in the second or
lower division of the digestive canal. The bones, shells, or hard
30 ZOOLOGY.
covering of the animals which may be swallowed by the Actinia are
rejected from the mouth after the soft parts are digested.
Sea-anemones have been found to have a slight sense of
smell. Nearly all sea-anemones, besides arising from eggs,
increase by budding, new individuals arising at or near the
base of the large one.
The coral polyps only differ from the sea-anemones in
secreting a limestone support or coral-stock. Corals are
either cup-shaped and single, or are compound, forming
Fie. 31.—Coral polyp (Astroides calycularis) expanded. From Liitken’s
Zoology.
branching or rounded masses. The soft parts are supported
by limestone partitions secreted in the chambers of the
polyp.
All Actinozoans develop from eggs, and at first appear
as little oval, ciliated, free-swimming embryos (gastrule),
which eventually become attached to the bottom of the
sea.
Before the embryo becomes fixed and the tentacles arise,
the lime destined to form the partitions begins to be de-
HOW CORALS GROW. 31
posited. Fig. 32, C, shows the twelve rudimentary parti-
tions. These, after the young polyp has become stationary,
finally enlarge and become joined to the external walls of
the coral now in course of formation (Fig. 32, C), form-
ing @ groundwork or pedestal on which the polyp rests.
D represents the young polyp resting on the limestone ped-
estal, with the tentacles well developed.
But little is positively known as to the rate of growth of
corals. .A common brain coral (Meandrina labyrinthica),
measuring a foot in diameter and four inches thick in the
most convex part, attained its growth in twenty years.
Fia. 32.—Development of a coral polyp, Astroides calycularis. A, ciliated
gastrula; B, young polyp with 12 septa; C, D, young polyp farther advanced,
with 12 tentacles; C, the corallum and limestone septa beginning to form.
Magnified.
To the order of alcyonoid corals, which have but eight
tentacles, belong the ‘‘sea-fans,” ‘‘sea-pens,” etc. In the
family of sea-fans (Gorgonide) the coral-stock is horny
or calcareous, branching tree-like, or forming a flat net-
work. Gorgonia flabellum is red or yellow, and abundant
on the Florida reefs. In the Arctic seas and the deeper,
colder waters of the Newfoundland Banks and St. George’s
Banks, Primnoa reseda and Paragorgia arborea grow; the
latter being of great size, the stem as thick through as one’s
wrist, and the whole cora!lum over five feet in height.
32 ZOOLOGY.
The common red coral (Corailium rubrum) of the Med-
feomeneet es is worked into various ornaments. The
wen ci coral fishery is pursued on
iid the coasts of Algiers and Tu-
Al i) nis, where assemble in the
| nM
‘i i lia y
ial
#
a ie
\
winter and spring from two
hundred to three hundred
vessels. The coral fishermen,
with large rude nets, break
off the coral from the sub-
merged rocks. About half
a million dollars’ worth of
coral is annnally gathered.
Of the larger corals the
Madreporaria in the main
are the true reef-builders.
They are confined to waters
in which through the coldest
winter months the tempera-
ture of the water does not
fall below 68° F., though
usually the waters are much
warmer than this, the mean
annual temperature being
about 734° F. in the North
Pacific and 70° F. in the
South. Coral reefs are abun-
dant in the West Indies, but
| still more so in the Central
ih n
\ IM i Hi it
cs |
‘ ¥ ii ih
| “4
ni H
Fic. 33.—High volcanic island with a barrier and fringing reef.
Pacific, where there are a
He i much greater number of spe-
il cies of corals. Along the
!
5 4 Nf : Brazilian coast, as far south
ee i ei as Cape Frio, are coral reefs.
‘an
nN Mh In depth living coral-reef-
builders ais not se more than fifteen or twenty fathoms
below the surface,
CORAL REEFS, 33
Coral reefs are divided by Dana into outer or barrier
reefs (Fig. 32) and inner reefs. The barrier reefs are
formed from the growth of corals exposed to the open
geas, while the inner or fringing reefs (Fig. 33) are formed
34 . ZOOLOGY.
in quiet water between a barrier reef and the island. As
coral reefs are usually built upon islands which are slow-
ly sinking, barrier reefs are simply ancient fringing reefs
fornied when the island stood higher above the sea, hence
they are built up as rapidly as the land sinks, and thus the
top of the reef keeps at the level of the sca. The reefs are
often of great thickness, for, as Dana says, ‘‘ could ve raise
one of these coral-bound islands from the waves, we should
find that the reefs stand upon the submarine slopes, like
muassy structures of artificial masonry; some forming a
broad flat platform or shelf ranging around the land, and
others encircling it like vast ramparts, perhaps a hundred
miles or more 1n circuit.” Darwin has estimated that some
reefs in the Pacific Ocean are at least 2000 feet in thickness.
Thus far we have spoken of reefs surrounding moun-
tainous islands; coral islands or atolls (Fig. 34, 4) resemble
such reefs, except that they surround a lake or lagoon in-
stead of a high island, the coral island itself being seldom
more than ten or twelve feet above the sea, and usually
supporting a growth of cocoanut trees, while the sea may
be of great depth very near the outer edge of the atoll,
which ‘usually seems to stand as if stilted up in a fathom-
less sea” (Dana). These reefs and atolls are forined and
raised above the sea by the action of the winds and waves,
in breaking up the living corals, comminuting it, and form-
ing, with the débris of shells and other limestone-secreting
animals and plants, banks or deposits of coral mixed with
a chalky limestone, as the base of the reef. When it rises
above the waves, cocoanuts and other seeds are caught and
washed up on the top, and gradually the island becomes
large enough to support a few human beings. The Ber-
mudas are the remnants of a single atoll, and are situated
farther from the equator than any other recfs. Some bar-
rier reefs and coral islands or atolls are formed in an area
of subsidence, where the bottom of the ocean is gradually
sinking; this accounts for the peculiar form and great
thickness of many reefs. On the other hand, the coral
CORAL REEFS. 35
reefs of the West Indies are, generally speaking, in an area
of elevation.
A section of a coral reef is shown by Fig. 34, B: n is the
point where the shore slupes rapidly down within the la-
goon (which lies to the right), and m is where the reef sud-
denly descends toward the open ocean. Between dc and
de lies the higher part of the reef. The shore toward the
lagoon slopes away regularly from d to ; while toward the
open ocean there is a broad horizontal terrace (a to dc)
which becomes uncovered at low water.
Darwin’s theory of the formation of barrier reefs is shown
by the diagram (Fig. 35). The island, for example, the vol-
canic island Coro, which is slowly sinking, at the ancient
sea-level Tis surrounded by a fringing reef f f, a small
Fig. 35.—Schematic section of an island with reefs.
rock-terrace at the former level of the sea. Where the
island has sunk te the level of the water-line II, the reef
appears at the surface as at 0’ f’, 6 f. There is nowa
fringing ard a barrier reef, with a narrow canal between
them; 0’ is a section of the barrier reef, e’ of the canal or
lagoon, and /”’ of the fringing reef. After a farther sub-
mergence to the sea-level III, the canal e’’ becomes much
wider. On one side (ff) the reef is present, on the other
side it has disappeared, owing to the agency of ocean-cur-
rents. Finally, at the water-level IV, there are two small
islands surrounded by a wide lagoon, with two reef-islets
a’, a/"’, resting upon two submarine peaks. The coral
reef has now grown to great dimensions, and covered almost
the entire original island, and though the reef-building
coral polyps cannot live below a point fifteen or twenty
96 ZOOLOGY.
fathoms below the surface, yet owing to the slow sinking
of the island, they build up the reef as rapidly as the
former subsides, and in this way after many centuries a
coral reef sometimes two thousand feet thick may be built
up in mid-ocean.
Without doubt ocean currents modify the forms of coral
islands and reefs, and have much to do with their arrange-
ment and distribution.*
Cuass IIJ.—Crenopnora (Comd-bearers).
General Characters of Ctenophores.—These beautiful ani-
mals derive their name from the vertical rows of comb-like
paddles (ctenophores), situated on meridional bands of
muscles which serve as locomotive organs. Their digestive
tract passes through the body, with two posterior outlets.
Our commonest example of this class is the Pleurobrachia
rhododacyla. It is a beautiful animated ball of transpa-
rent jelly moving through the water by
means of eight rows of minute paddles,
throwing out from a sac on each side of
the body two long ciliated tentacles. It
is abundant in autumn; sometimes thou-
sands may be seen stranded on the shore
at low water.
In Bolina alata the body is plainly bi-
lateral and the water-vascular tubes are
very distinct. In Jdyta roseola (Fig. 36)
Fia. 36.—Idyia rose- the mouth is large, the stomach wide, and
ola, natural size. z = a
a. anal opening: b. oe body Is of an Intense roseate hue.
cular canal; d.'e.f, This beautiful species after death, late
gforowsofpaddles. iy summer, is very phosphorescent; all
Ctenophores, however. even their eggs and embryos, are
phosphorescent,
* See Semper’s Animal Life, A. Agassiz’s Three Cruises of the
Blake (vol. i.), and the works of others who deny the theory of Dar-
win and of Dana, that subsidence is necessary to account for the for-
mation of atolls, anc claim that they are due to ocean currents,
wave action, ete., subsidence only being necessary in the formation
of reefs over one hundred feet thick,
CHAPTER IV.
Branouw IV.—Vermes (Worms).
GENERAL CHARACTERS OF WoRMs.—In order to obtain
an idea of worms in general the student may dig up in the
garden or fields acommon earth-worm, and then place it on
the table or desk in a flat dish and watch its movements
Q
q save weopiey k
Fia. 87.—Transverse section through the body of the earth-worm (Lumbricus ter.
restris), near the middle of the intestine. a, cuticle; b, hypodermis; ec, circu-
lar layer of muscles; d, layer of longitudinal muscles; e, dorsal band; f, ven-
tral band; g, lateral bands; h, typhlosole; 7. cavity of intestine; j, epithelium
of intestine; k, layer of circular-muscular fibres around intestine; l, layer of
longitudinal muscular fibres around intestine; m, green layer on outer sur-
face of intestine; n, heart; o, liver; ng, nervous ganglion. After Claparéde.
and appearance. The body will be seen to be formed of
numerous joints or segments; these are due to infold-
ings of the muscular skin at regular intervals. Though
both ends of the long, slender, cylindrical body are much
38
Fic. 38.—“‘ Brain” and part of
the nervous or ganglionated
cord of the earth-worm. h,
brain, or first pair of gang-
lia; g, nerves to pharynx;
d, cesophageal collar; f,
Space occupied by the pha-
rynx; 5-8, the ganglia of the
5th to 8th segments respec-
tively; 7, nerves to first seg-
ment; nerve-threads or com-
missures. From Brooks, af-
ter Lankester.
G
Fie. 39.—Planaria torva, en-
larged; and e, egg capsule,
natural size. Gissler del.
ZOOLOGY,
alike, the observer will soon be able
to distinguish the head-end from the
tail-end; he will also notice that both
sides of the body repeat each other,
and that there is an upper (dorsal)
and lower (ventral) side, the worm
lying on the latter side. The stu-
dent will now be able to understand
the following short definition of the
branch of worms, to which there
are some exceptions, which need not,
however, be here mentioned. A
typical worm is bilateral, with a well-
marked dorsal and ventral side and
a head-end and tail-end, with the
body divided into segments.
By dissecting the body and tracing
with needles the internal anatomy,
and also by cross-sections of the
body, the following relations of the
most important internal organs will
be observed. The digestive tract
(z) is a slender tube lying free in
the body-cavity, and extending from
the mouth to the vent. Above it
lies a long delicate, pulsating tube
called the dorsal vessel or heart.
The brain is small, and is situated
in the upper part of the head, while
behind the throat on the floor of the
body lies the main nervous system,
a double white coru with swellings
called ganglia (Fig. 38), one for
nearly each segment. A worm may
or may not have eyes: some kinds of
worms have them scattered all over
the body; others have eyes both in
THE FLAT-WORMS. 389
the head and tail; many worms have ears. All worms
grow from eggs, and many have a free swimming embryo
entirely unlike the parent worm, thus passing through a
“metamorphosis.”
CLASSES OF VERMES.
- Body flat, often not segmented; no body-cavity .. Platyhelminthes.
. Body round, thread-like; a body-cavity......... Nemuatelminthes,
Body microscopic, moving by two ciliated flaps. . Rotutoria.
Body minute, in a solid cell................000. Polyzoa.
Shell-worms, attached by a stalk, with two arms. .Brachiopoda.
. Body rounded, or ribbon-like, with a proboscis... . Nemertina.
Body jointed, with feelers, eyes, and gills ....... Annulata,
ee
Cuass J.—PLATYHELMINTHES (/Jat-worms, Fluke-worms,
Tape-worms, ete.).
General Characters of Flat-worms,—The commonesi ex-
ample of this class is a small dark flat-worm which may be
found in any pond on the under side of sticks or stones.
This flat-worm is called Planaria torva (Fig. 39). It is
about 7 mm. (4 in.) in length, oblong, flat, with two black
eye-spots, each with an oblong whitish space in front. Its
body is covered with microscopic hairs (cilia), enabling it
to move easily in the water. These worms have a rudi-
mentary brain, from which pass backwards two slender ner-
vous-threads, which do not have nervous swellings, as in
the earth-worm. The digestive canal is also much branched.
Besides these organs all the worms of this class have a so-
called water-vascular system, somewhat like that of Echino-
derms. ‘These systems consist of two main tubes which
branch throughout the body. Many if not most Plana-
rians or free flat-worms have nettling organs somewhat like
the lasso-cells of jelly-fishes, except that the rods are short
and stiff, and are not known to be barbed.
Many flat-worms live as parasites in the bodies of other
animals. They differ from ordinary Planarians in not be-
40 ZOOLOGY.
ing ciliated, while there is a large sucker on the under side
of the body. ‘hese are called fluke-worms. asciola he-
patica (Fig. 40) lives in the liver of the sheep, causing the
disease known as “‘rot.” It is most abundant in the spring,
several hundred occurring in the liver of a single sheep.
At this time it passes into the intestine, and thence is car-
ried out with the excrement. The eggs or flukes in many
cases drop into pools, ditches, or ponds;
here the ciliated young is liberated, and
soon the cilia are absorbed, when it be-
comes inert, and probably soon afterward
enters the body of a pond snail (Limneus),
where it transforms into a large sac, and
develops new larve in its interior. This
sac-like larva is called a ‘‘ nurse,” or, when
more highly developed, a ‘‘redia.” The
progeny of the redia is termed a ‘‘ cerca-
ria.” The cercarize are tadpole-like, and
are restless, migrating from the bodies of
their snail-host, and have been known in a
few instances to penetrate the skin of hu-
man beings. They are probably more usu-
ally swallowed by sheep and cattle while
Fic.40.—Fasciolahe- drinking or grazing, when snail-shells may
patica, enlarged. : é =
a, branched intes- be accidentally swallowed. From the di-
ae gestive canal of sheep, etc., the cercaria
penetrates into the liver, where it probably loses its tail
and becomes encysted, after many weeks or even months
becoming a mature fluke-worm. From the liver it passes
out through the liver-ducts into the intestine, and is finally
expelled, thus completing its cycle of life.
The tape-worms represent the order of Cestodes. They
are large parasitic worms, with no mouth or digestive tract;
the joints are very numerous, sometimes over a thousand
‘n number.
The common human tape-worm, Tenia solium, varies
THE TAPE-WORM. Al
from ten to thirty feet in length; there are upward of
eight hundred joints in a worm
ten feet long. The head ends
in a proboscis armed with a
double crown of hooks; the
first proglottis or sexually ma-
ture segment begins at the
450th. While in some persons
the presence of a tape-worm is
simply an annoyance, in ner-
vous and irritable persons it
causes restlessness, undue anx-
iety, and various dyspeptic
symptoms. Among the pre-
ventive remedies against tape-
worms is the disuse of raw or
underdone pork, and ‘‘ measly”
pork—z.e., the flesh of swine
containing the little bladder-
like vesicles. Cysticerci, or
young tape- worms, can be
readily distinguished, but when
thoroughly cooked are harm-
less, as the temperature of
boiling water is sufficient to
kill them. As a matter of
course, in the use of drugs to
expel a tape-worm they should
be pushed so as to carry off the
entire animal, as new segments
grow out from near the head
as rapidly as the joints are de-
tached.
The history of the human
tape-worm, Tenia solium (Fig. Fie. 41.—Tenia solium. Natural size,
41), is as follows: The eggs
with the head magnified. Strobila
stage.
492 ZOOLOGY.
eaten by the hog are developed in its body into the larval
tape-worm (called in this species Cysticercus cellulose, Fig.
42). The head with its suckers is formed, and the body
becomes flask-shaped; the Cysticerci then
bury themselves in the liver or the flesh of
pork, and are transferred living in uncooked
pork to the intestines of man. The body
now elongates and new joints arise behind
the head until the form of the tape-worm is
attained, as in Fig. 41.
The hinder joints then become filled with
eggs and break off, becoming independent
joints comparable with the ‘‘ parent-nurses”
of the Cercarias, except that they are not
contained in the body of the Tenia (as in
Fie, 42. ~Custicer- the Cercaria), but are set free. The inde-
Tape-worm. pendent joint is called a ‘‘proglottis.” It
escapes from the alimentary tract of its human host, and
the eggs set free, in and about privies, are swallowed by
that unclean animal, the pig, and the cycle of generations
begins anew.*
Crass I].—NEMATELMINTHES (Round- or Thread-worms).
General Characters of Round-worms.—In these worms the
body is round and thread-like, not being joimted. Many
are parasitic: such are the Ascarids.
The round-worm most dangerous to human life is the
Trichina spiralis (Fig. 43). It is very minute, the female
being 3mm. in length, and the male worm half aslong. The
female is capable of producing a thousand young. The
eggs are eaten by rats, dead rats are sometimes devoured by
pigs, and pork thus infested when exten by man, either
raw or partly cooked, often causes the death of their hu-
man host.
The hair-worms (Gordius aquaticus, Fig. 44) resemble a
piece of a horse’s hair, and are so-called because they are
THE ROTIFERS. 43
popularly supposed to be ‘‘ a horse-hair come to life.” They
occur tied up in a ‘‘ Gordian knot” at the bottom of pools.
a NNN
om
ge
mM
WN
IM
\V
Fie. 44.— The Hair-worm. Fic. 45.—Rotifer vulga-
Fie. 48. — Trichina
ris c, ciliated flaps or
encysted in hu- K. natural size; J. end
man muscle. of body of G. aquaticus; wheels; ¢, mastax; g,
Greatly magni- H, G. varius. Much digestive canal; &,
fied. enlarged. eees. Highly magni-
ed.
They live as parasites in the bodies of grasshoppers, crick-
ets, beetles, etc.
Crass III.—Roratorra (Rotifers).
General Characters of Rotifers.—The Rotifers, or wheel-
animalcules, are abundant in standing water, in damp
moss, etc., and in the ocean, and are so transparent that
44 ZOOLOGY.
their internal organs can readily be seen through the skin,
while they are so minute, being from one fortieth to three
hundredths of an inch in length (3 to # mm.), that high
powers of the microscope are needed in studying them.
They are of special interest from the fact that after being
dried for months to such a degree that little if any moist-
ure is left in the body, they may be revived and become
active. Professor Owen has observed the revivification of
a Rotifer after having been kept for four years in dry
sand.
Their body is often broad and flat, divided into a few
segments of unequal size. They perform their rapid move-
ments by means of two ciliated flaps, one on each side of
the head, and which in motion resemble wheels, whence
their name, wheel-animalcules. By means of the rotatory
movements of the hairs on the edges of the flaps the micro-
scopic Rotifer is whirled rapidly around.*
Crass IV.—Poryzoa (Moss Animals).
General Characters of the Polyzoans.—The Polyzoa,
though not usually met with in fresh water, are among
Fia. 46.—Cells of Sea- Fia. 47.—Branching marine Polyzoon. (Natural size.)
mat, enlarged.
* See the works of Hudson, Gosse, Buleusky, Hyatt, ete. a
THE BRACHIOPODS. 45
the commonest objects of the sea-shore. They are minute,
almost microscopic creatures,social, growing in communi-
ties of cells, forming patches
on sea-weeds and stones (Fig.
46, Membranipora solida). Cer-
tain deep-water species grow in
coral-like forms (Fig. 47, Myrio-
zoum subgracile), while the chit-
inous or horny Polyzoa are often
mistaken for sea-weeds on the
one hand, and Sertularian Hy-
droids on the other.
The animals inhabiting the
microscopic cells are worm-like
creatures (Fig. 48), with the di-
gestive canal bent on itself and
ending near the mouth, the lat-
ter surrounded, as in the larger
fresh-water species (Fig. 48, dr),
with a horseshoe-shaped crown,
or in the smaller marine forms
a circle of slender ciliated ten-
tacles. The fresh-water forms
(Plumatella, etc.) secrete no
solid shell, and are either moss-
like, or form large rounded
masses of a jelly-like substance.*
Fria. 48.—-Organization of a Poly-
zoon. A, Paludicella Ehrenbergii.
B, Plumatella fruticosa. br, ten-
tacular branchiz of lophophore;
@, csophagus; v, stomach; r, in-
testine: a, anus; Zz, cell; 2, poste-
rior, x}, anterior cord, at the in-
sertion of which into the body the
generative products are devel-
oped; t, testes; 0, ovary; m, re-
tractor muscles of the anterior
portion of the cell; mr, principal
retractor muscle.
Ciass V.—Bracuropopa (Lamp Shells).
General Characters of Brachiopods.—This group is named
Brachiopoda, from the feet-like
arms, fringed with tenta-
cles, coiled up within the shell, and which correspond to
the horseshoe-shaped crown of the Polyzoa and the crown
of tentacles of the Sabella-like worms. From the fact that
the animal secretes a true bivalved, solid shell, though it
is usually inequivalve, 7.¢., the valves of different sizes, the
* See the works of Allman, Hinks, Smitt, Salensky, Sars, etc,
Ve WA
46 ZOOLOGY.
Brachiopoda were generally, and still are by some authors,
considered to be mollusks, though aberrant in type. The
shell of our common northern species, Terebratulina sep-
tentrionalis (Fig. 49), which lives attached to rocks in fron
ten to fifty or more fathoms north of Cape Cod, is in shape
somewhat like an ancient Roman lamp, the upper and
larger valve being perforated at the base for the passage
through it of a peduncle by which the animal is attached
to rocks. The shell is secreted by the skin, and is com-
posed of carbonate (Terebratulina) or largely (Lingula,
Fig. 50) of phosphate of lime. It is really the thickened
Fic. 49.—Terebratulina or lamp-shell. Upper, and side view, natural size.
From Emerton, after Morse.
skin of the animal, the so-called mantle being the inner
portion of the skin.
The Brachiopods may be briefly described as shelled
worms, with a limestone or partly chitinous, inequivalve,
hinged or unhinged shell, enclosing the worm-like animal;
with two spirally coiled arms provided with dense ciliated
tentacles, and capable of reaching to or beyond the edge of
the gaping shell; the alimentary canal has the mouth open-
ing between the arms; there is an esophagus, a stomach with
a liver-mass on each side, and a short intestine ending in a
blind sac. The nervous system consists of a ganglion above
and beneath the cesophagus, and two lateral ventral widely
separated threads. There are no eyes in the adult, but they
are present in the young; auditory sacs are present in Lin-
gula. There is no circulatory system. The germ passes
through a morula and gastrula stage, becoming a segmented
THE BRACHIOPODS. 47
ciliated larva like that of the true worms, which after swim-
ming about finally becomes fixed by a stalk to rocks.
While in their development the Brachiopods recall the
larve of the true worms, they resemble the adult worms in
the general arrangement of the arms and viscera, though
they lack the highly developed nervous system of the Anne-
lids, as well as a vascular system, while the body is not
jointed. On the other hand they are closely related to the
Polyzoa, and it seems probable that the Brachiopods and
Fic. 50.—Lingula pyramidata with its sand-tube; natural size.
Polyzoa were derived from common low vermian ancestors,
while the true Annelids probably sprang independently
from a higher ancestry. They are also a generalized type,
having some molluscan features, such as a bivalved shell,
though having nothing homologous with the foot, the shell-
gland or odontophore of mollusks.
The class of Brachiopods is a very ancient one, nearly
2000 species of fossil Brachiopods being known. One living
species of Lingula (Fig. 50) differs but slightly from the
most ancient fossil species. It lives buried in the sand,
where it forms a tube of sand around the stalk, just below
low-water mark, extending from Chesapeake Bay to Florida.
LITERATURE.
A. Hancock. On the Organization of the Brachiopoda. Phil.
Trans. 1858.
E. 8. Morse. On the Systematic Position of the Brachiopoda.
Proc. Boston Soc. Nat. Hist., xv. 1878.
With the essays of Brooks, Lacaze-Duthiers, Kowalevsky. Dall,
etc.
48 ZOOLOGY.
Cuass VI.—NeEmurtina (Nemertean Worms).
General Characters of Nemerteans.— The Nemertean .
worms occur abundantly under stones, etc., between tide-
marks and below low-water mark; they are of various col-
ors, dull red, dull green and yellowish, and are distinguished
by the soft, very extensile, more or less flattened, long and
slender body, which is soft and ciliated over the surface,
the skin being thick and glandular.
The mouth forms a small slit on the ventral surface im-
mediately behind the aperture for the exit of a large pro-
boscis. The cesophagus leads to a large digestive tract,
which often has short lateral pouches or cceca.
The nervous system is quite simple, consisting of two
ganglia in the head united by a double commissure; from
each ganglion a thread composed of nerve-fibres and gan-
glion-cells passes back to the end of the body.
Crass VII.—ANNULATA (Leeches, Harth-worms, and Sea-
worms).*
General Characters of the Annulates——This group, rep-
resented by the leeches, earth-worms, and nereids or bris-
tled sea-worms, tops the series of the classes of worms.
With their regularly segmented bodies, their eyes and ears
and complicated appendages, they stand nearer the Crus-
tacea and Insects than any other class of invertebrate ani-
mals, their internal anatomy on the whole being nearly or
quite as complicated.
* Class Hnteropneusta and Class Glephyrea are small groups of
worms, Which are described in the author's larger Zoology. They
may be omitted in an elementary course for want of space.
LEECHES. 49
In the leech, which is the type of the first and lower
order, the body is somewhat flattened and divided into
numerous short, indistinctly marked segments, not bear-
ing any bristles or appendages. The head is small, with no
appendages, bearing five pairs of simple eyes, while each
end of the body terminates in a sucker. The mouth is
armed internally with three teeth arranged in a triradial
manner (Fig. 51, ¢’), so that the wound made in the flesh of
persons to whom the leech is applied consists of three short,,
deep gashes radiating from a common centre. Our com-
mon pond leech (Macroddella decora, Figs. 52, 53) is of a
Fic. 51.—Common fish-leech. a, Fig. 52.—Young Macrobdella de
natural size; b, head with two cora. Body unnaturally flat
eyes; c, teeth. Gissler, del. tened. Gissler, del.
rich deep olive color above, and orange red on the under
side. It is four inches in length. Another common pond
leech is Nephelis, of which we have several species.
The eggs of leeches are laid in sacs, or, as in Clepsine
(Fig. 51), the fish-leech, are covered with a transparent
fluid substance, which hardens and envelops the eggs. The
Clepsine remains over the eggs to protect them until they
hatch; and the young fix themselves to the under side of
the parent, and are thus borne about until they are fully
developed and able to provide for themselves,
50 ZOOLOGY.
The common earth-worm (Fig. 54) is cylindrical and
many-jointed. The small mouth opens on the under side
of the first segment. The earth-worm is able to climb per-
pendicularly up boards or the sides of buildings by minute,
Fie. 53.—Large leech, natural size. a, a tooth; e, head enlarged with the eyes,
t, triradiate teeth; t’, view of the three teeth, enlarged. Gissler, del.
short, curved bristles, which are deeply inserted in the mus-
cular walls of the body, and arranged in two double rows
along each side of the body (Fig. 37s). In burrowing it
thrusts the pharynx into the end of the head, causing it to
EARTH: WORMS. 51
swell out, and thus push the earth away on all sides, while
it also swallows the dirt, which passes through the digestive
canal. In this way it may descend from three to eight
feet in the soil.
While earth-worms are in the main beneficial, from their
habit of boring in the soil of gardens and ploughed lands,
bringing the subsoil to the surface and allowing the air to
get to the roots of plants, they occasionally injure young
seedling cabbage, lettuce, beets, etc., drawing them during
the night into their holes, or uprooting them.*
Earth-worms lay their eggs in June and July, at night.
a SRR sy
Qin
Sta aere a
Fie. 54.—Earth-worms, nat. size. a,embryo (blastula) soon after segmentation
of the yolk; b, embryo further advanced; 0, mouth; c, embryo still older; k,
primitive streak; d, neurula;o, its mouth.
The eggs of the European Lumbricus rubellus are laid in
dung, a single egg in acapsule; LZ. agricola lays numerous
egg-capsules, each containing sometimes as many as fifty
eggs, though only three or four live to develop. The de-
velopment of the earth-worm is like that of the leech, the
germ passing though a number of stages, the worm, when
hatching, resembling the parent, except that the body is
shorter and with a much less number of segments.
The sea-worms have larger, more distinct bristles, as in
Clymenella (Fig. 55), which lives in tubes in soft mud.
*Darwin’s Formation of vegetable mould through the action of worms.
59 ZOOLOGY.
Dia
Our commonest sea-worm, sometimes called the ‘clam-
worm” is Nereis virens (Fig. 56). It lives between tide-
marks in holes in the mud, and can be readily obtained.
The body, after the head, eyes, tentacles, and bristle-bear-
Fig. 55.—Clymenella torquata, natural size.
ing feet have been carefully studied, can be opened along
the back by a pair of fine scissors and the dorsal and ven-
tral red blood-vessels with their connecting branches ob-
served, as well as the alimentary canal and the nervous
system.
This worm is very voracious, thrusting out its pharynx
Fic. 56.—Transverse section through the body of a Nereis. d, dorsal vessel or
heart; c’, circular blood: vessel ; hy ventral vessel; n, nervous cord or ganglia;
qs artery tose EN EUDE, foot s’’; 7, intestine; s, setae or bristles. After Turn-
WRG a emerton.
and seizing its prey with its two Jarge pharyngeal teeth.
It secretes a viscid fluid lining its hole, up which it moves,
pushing itself along by its bristles. At night it leaves
its hole, swimming on the surface of the water.
SHA- WORMS. 58
The body consists of from one hundred to two hundred
segments. The head consists of two segments, the first
Fia. 57.—Euchone elegans, Fig. 58.— Amphitrite ornata, natural size.
enlarged.
with four eyes and two pairs of tentacles. The second seg-
ment bears four tentacles. Each of the other
segments bears a pair of paddle-like append-
ages, which may be best studied by examining
one of the middle segments (Fig. 56).
In certain kinds, as Huchone (Fig. 57), the
gills form a beautiful feathery crown on the Fre. 59.—ciliatea
head; while in Amphitrite (Fig. 58) the ten- ‘88.5, 88"
tacles are very numerous, and the bushy red @°?
gills grow out by their side. Some sea-worms are beauti-
fully phosphorescent. The young of all sea-worms (Fig.
59) are ciliated, and swim on the surface of the sea.*
* See Verrill’s works in U. 8. Fish Commission Reports, etc.
CHAPTER V.
BrancH V.—EcHINODERMATA (Star-fish, Sea-urching,
Sea-cucumbers, etc.).
GENERAL CHARACTERS OF ECHINODERMS.— We now come
to animals of much more complicated structure than any
of the foregoing branches, and in which the radiated ar-
rangement of the parts of the body is in most cases as
marked as the jointed or ringed structure of worms or
insects; for not only are the body-walls of the star-fish or
sea-urchin, or even many of the Holothurians (though less
plainly), divided into five wedge-shaped portions, or pro-
duced into five arms as in the common star-fish or five-
finger, but the nervous system, the reproductive organs,
the blood and water-vascular systems, and the locomotive
organs, are usually arranged in accordance with the star-
like form of the body. The most trenchant character which
separates the Echinoderms from the Colenterates, and
allies them to the worms, is the genuine tube-like digestive
canal which les free in the body-cavity, and may be sev-
eral or many times the length of the body.
The student can gain a correct idea of the general structure of the
Echinoderms froma careful examination of the common star-fish
(Asterias vulgaris), which is the most common and accessible Echino-
derm to be found on the New England shores. After placing a star-
fish in some sea-water and noticing its motions, the thrusting out of
the ambulacral feet or suckers by which it pulls or warps its clumsy
body over the mussel-beds, or rocks, or weeds, the arms being capa-
ble of slightly bending; after observing the red eye-spot at the end
of each arm or ray, and the movements of the numerous spines which
are attached by asort of ball-and-socket joint to the calcareous frame-
work of the body-walls, and examining the movements of certain
modified spines called pedicelluri@, which are pincer-like bodies situ-
STRUCTURE OF STAR-FISH. 55
ated among the spines, the student will be ready to study the external
and internal anatomy.
First, as to the calcareous framework of the star-fish. In order
to study this, a transverse section should be made through an arm,
and a vertical one through the body and along the middle of a single
arm, and finally the animal should be divided into two halves, an
upper and lower. It will then be seen that the calcareous frame-
work or so-called skeleton consists of a great number of limestone
plates or pieces attached by a tough membrane and covered by the
skin. Between the plates are small apertures by which the water
enters the body-cavity. These plates are arranged so as to give the
greatest strength and lightness to the body. There is also to be seen
an oral (under) side on which the mouth is situated, and an aboral
(upper) side. Each arm or ray is deeply channelled by the ‘“‘ambu-
lacral furrow” containing four rows of suckers or ‘‘ambulacral feet,’
which are tentacle-like protrusions of the skin growing out through
Fic. 60. —Longitudinal section through the body and one arm of Asterias vulgaris.
m, mouth; s, stomach; 1, lobe of stomach extending into the arm; a, anus;
nr, nervous ring; ”, radial nerve; vr, water-vascular ring, sending a radial
vessel (v) into the arm; mp, madreporic plate; t, stone canal; h, heemal
canal; ov, oviduct; 0, ovary; am, ampulla, the ambulacral feet projecting
below; 6, coeca or liver.
orifices in the ambulacral plates, and are a continuation of the
water-sacs or ‘‘ampulle” within. The ‘‘madreporic plate” is a flat-
tened hemispherical body situated on the disk between two of the
arms. It is perforated by canals.
We are now ready to examine the internal organs and to study
their relations to one another and to the body-walls. The nervous
system may be seen without dissection. By closely examining the
mouth a pentagonal ring is seen surrounding it, each angle slightly
enlarging and sending off a nervous cord to the eye at the end of the
ray. It may be discovered by pressing apart the ambulacral feet
along the median line of each arm. Fine nerves are sent off to each
sucker, passing through the opening between the calcareous plates
and extending to each ampulla, thus controlling the movements of
the suckers. The visible nerves belong to a nervous subcutaneous sheet.
The mouth (Fig. 60, m) is capacious, opening by a short cesophagus
into a capacious stomach (Fig. 60, s) with thin distensible walls, and
sending a long lobe or sac (Fig. 60, ¢) into the base of each arm ;
56 ZOOLOGY.
each sac is hound down by two retractor muscles attached to the
median ridge lying between the two rows of water-sacs (ampullie, see
also Fig. 61). The stomach ends in a short intestine, the limits be-
tween the two not distinctly seen. The intestine suddenly contracts
and ends in a minute rectum situated in an angle between two of
fiv> fleshy ridges radiating from the centre of the disk. Appended
to the intestine are the ‘‘ceeca” or ‘‘liver” (Fig. 60, 2), consisting of
two long, tree-like masses formed of dense branches of from four to
six pear-shaped follicles, connecting by a short duct with the main
Fia. 61.—Diagram of the water-system of a star-fish. a, madreporic body; b,
stone-canal, c, circumoral water-tube; d, radial water-tubes; e, ampulle; f,
feet or ambulacra. After Brooks.
stem, The two main ducts unite to form a short common opening
into the intestine. The cceca are usually dark, livid green, and
secrete a bitter digestive fluid, representing probably the bile of the
higher animals.
The ovaries (Fig. 60, 0) are long racemose bodies lying along each
side of the interior of the arms, and the eggs are said to pass out by
short narrow oviduct (0v) through an opening between two plates on
each side of the base of the arms, the opening being small and diffi-
cult to detect.
The water-vascular system consists of the madreporic body, the
‘“stone-canal” (Fig. 60, t), the ring or circumoral canal (vr), and the ra-
CRINOIDS. 57
dial vessels (v) ending in the water-sacs (am) and ambulacral feet. The
stone-canal begins at the outer and under side of the sieve-like madre-
poric body, passing directly forward
and downward in a sinuous course
to the underside of the circumora)
plates. The madreporic body (md)
is externally seen to be perforated
by linear apertures radiating and
subdividing toward the periphery.
The sea-water in part enters the
body-cavity through the fissures in
the madreporic body, while most of
it enters the stone-canal, which is a
slender tube scarcely one fourth the
diameter of the entire madreporic
body. The water entering the stone-
canal (Fig. 60, ¢) passes directly into
the water-vascular ring (Fig. 60) and
then into the ten Polian vesicles and
the five radial canals, whence it is
conveyed to each water-sac or am-
pulla (Fig. 61, c; compare also Fig.
60). These pear-shaped water-sacs,
when contracted, are supposed to
press the water into the long slender
suckers or ambulacral feet, which are
distended, elongated, and by a suck-
er-like arrangement at the end of the
prehensile foot act in conjunction
with the others to warp or pull the
star-fish along. Besides locomotion, the ambulacral feet serve for
respiration and perception. The star-fish has the sense of smell.
It will thus be seen that the water-vascular system in the star-fish
is in its functions partly respiratory and partly locomotive, while it
is in connection with the vascular system, and thus partly aids in
circulating the blood and chyle. There is, besides, a complicated
system of true blood-vessels, which are, however, difficult to dis-
cover.
Fia. 62.—Encrinus or Stone-lily.
Cass I—Crinoipga (Stone-lilies, Encrinites, etc.).
General Characters of Crinoids—These are stalked star-
fishes, the stalk or stem being jointed. Most Crinoids are
extinct or fossil; such is the Stone-lily (Pig. 62),
58 ZOOLOGY.
CLASssEs OF ECHINODERMATA.
1. Body mounted on a stalk. .............. cece eee Crinoidea,
2. Body with five arms; free............. cece eee eee Asteroidea.
3. Body spherical, with long spines...... ........... Echinoidea,
4. Body elongated; skin soft, hardened by minute plates. Holothuroidea,
Fig. 63.—a, Pentacrinus ep a half natural size; b, calyx-disk seen
rom above, natural size.
The existing Crinoids live in very deep water. Penta-
crinus caput-meduse (Fig. 63) lives attached to rocks in
the West Indies; others live in the Atlantic Ocean, some-
times at the great depth of nearly three miles.
a large part of it, forced into the capillaries, is collected by
the ventral venous sinus, and thence passing through the
gills (Fig. 97, gill), where it is oxygenated, returning to
the heart.
The gills are appendages of the three pairs of maxilli-
pedes and the five pairs of feet, and are contained in a
chamber formed by the carapace; the sea-water passing into
the cavity between the body and the free edge of the cara,
ANATOMY OF THE LOBSTER. 83
pace is afterwards scooped out through a large opening or
passage on each side of the head, by a membranous ap-
pendage of the leg, called the * gill-paddle” (flabellum,
Hig. 99).
The digestive system consists of a mouth, opening between
the mandibles, an esophagus, a large, membranous stom-
ach, with very large teeth for crushing the food within the
large or cardiac portion, while the posterior or pyloric end
forms a strainer through which the food presses into the
long, straight intestine, which ends in the telson. The
liver is very large, dark
green, with two ducts emp-
tying on each side into the
junction of the stomach
with the intestine.
The nervous system con-
sists of a brain situated di-
rectly under the base of the
rostrum (supracesophageal
ganglion), from which a
par of optic nerves go to
the two eyes, and a pair to
each of the four antenne.
The mouth-parts are sup-
Fig. 98. — D, second maxillipede; ex, exo ‘ i peer
podite; end, endopodite; flab, epipodite plied with nerves from the
tl
SEAN sath On caveats infrawsophageal ganglion,
which, with the rest of the nervous system, lies in a lower
plane than the brain. There are behind these two ganglia
eleven others; the cephalo-thoracic portion of the cord is
protected above by a framework of solid processes, which
forms, as it were, a “‘false-bottom” to the cephalo-thorax;
this has to be carefully removed before the nervous cord
can be laid bare. A sympathetic nerve arises on each
side of the oesophagus and distributes branches to the
stomach.
The nerves of special sense are the optic and auditory
nerves. The eyes are compound, namely, composed of
84 ZOOLOGY. 5
inany simple eyes, each consisting of a cornea and erystal-
line cone, connected behind with a long, slender connective
rod, uniting the cone with a spindle-shaped body resting
on or against an expansion of a fibre of the optic nerve,
and is ensheathed by a retina or black pigment mass.
The lobster’s ears are seated in the base of the smaller
or first antennee; they may be detected by a clear, oval
space on the upper side; on laying this open, a large cap-
sule will be discovered; inside of this capsule is a project-
ing ridge covered with fine hairs, each of which contains a
Crp °
Fig. 99. — B, third maxillipede, cxrp, coxopodite; bp, basipodite; ip, ischiopodite;
mp, meropodite; cp, carpopodite; pp, propodite; dp, dactylopodite; c, muk
tiarticulate extremity of exopodite or palpus; flab, epipodite or flabellum.
minute branch of the auditory nerve. The sac is filled
with water, in which are suspended grains of sand which
find their way into the capsule. A wave of sound disturbs
the grains of sand, the vibrations affect the sensitive hairs,
and thus the impression of a sound is telegraphed along
the main auditory nerve to the brain.
The fine hairs fringing the mouth-parts and fegs are
organs of touch. The seat of the sense of smell in the
Crustacea is not yet known, but it must be well developed,
as nearly all Crustacea are scavengers, living on decaying
MOULTING OF THE LOBSTER. - 85
matter. Crabs also have the power of finding their way
back to their original habitat when carried off even for
several miles,
The lobster spawns from March till November; the
young are hatched with much of the form of the adult, not
passing through a metamorphosis, as in most shrimps and
crabs. They swim near the surface until about one inch
long, afterwards remaining at or near the bottom.
The lobster probably moults but once annually, during
the warmer part of the year, after having nearly attained
its maturity, and when about to moult, or cast its skin, the
carapace splits from its hind edge as far as the base of the
rostrum or beak, where it is too solid to separate. The
lobster then draws its body out of the rent in the anterior
part of the carapace. The claw—at this time soft, fleshy,
and very watery—is drawn out through the basal joint,
which is partly absorbed to allow the flesh to pass through
the joint. In moulting, the stomach, witb the solid teeth,
is cast off with the old integument.
CRDERS OF CRUSTACEA.
Order 1. Feet leaf-like, body usu-
ally with a bivalve shell........Branchiopoda: Brine Shrimp, etc.
Order 2. Small, active, with free
limbs; some parasitic.........Hntomostraca: Cyclops, Fish-lice.
Order 3. Large, fixed, body pro-
tected by a shell of several
PIECES he iecls ats te ava acteonsinreea'e Cirripedia : Barnacles.
Order 4. Body flat or compressed;
no carapace; eyes sessile...... Tetradecapoda: Pill-bug, Beach-fleas.
Order 5. Thoracic feet leaf-like;
thorax covered by a carapace. .Phyllocarida : Nebalia.
Order 6. Body partly covered
with a large carapace; feet
with gills; eyes stalked....... Thoracostraca : Shrimps, Crabs.
Lirerature.—Milne-Edwards, Histoire Naturelle des Crustacés.
8 vols. 1834-40.—Dana, Crustacea of the U. 8. Exploring Expedi-
tion. 2 vols. 1852.—Gerstaecker, Arthropoden (in Bronn’s Classen
und Ordnungen des Thierreichs, 1866-91. 2 vols.—Husley, The
Crayfish, 1880.—Packard, Monograph of North American Phyl-
lopod Crustacea, 1888.—Also the writings of Say, Dohrn, Sars,
Claus, Brooks, Hagen, Faxon, Smith, Kingsley, etc.
86 ZOOLOGY.
Order 1. Cirripedia.—The barnacles would, at a first
glance, hardly be regarded as Crustacea at all, so much
modified is the form, owing to their fixed, parasitic mode
of life. The barnacle is, as in the common sessile form
(Fig. 100), a shell-like animal, the shell composed of sev-
eral pieces, with a conical movable lid, having an opening
through which several pairs of
long, many-jointed, hairy ap-
pendages are thrust, thus cre-
ating a current which sets in
towards the mouth. The com-
mon barnacle (Balanus balanot-
des) abounds on every rocky
shore from extreme high-water
mark to deep water, and the
student can, by putting a group
Fre. 100.-A bernacte. Bolanus of them in sea-water, observe the
poncatus aN aro Size: opening and shutting of the
valves and the movements of the hairy appendages.
The metamorphosis of the barnacle is remarkable. After
leaving the egg, it swims about asa minute Nauplius or
Fia. 101.—Nauplius of Bal- Fria. 102.—Pupa of Lepas. Much
anus balanoides. Much enlarged.
enlarged.
larva (Fig. 101), with three pairs of legs. Finally the larva
attaches itself by its antennae to some rock, and now a
strange transformation follows. ‘The body and legs (the
ENTOMOSTRACANS. 87
number of legs having meanwhile increased, are enclosed
by two sets of valves, so that the animal appears as if bi-
valved (Fig. 102), and at last the barnacle-shape is at-
tained.
Order 2. Entomostraca (Water-fleas).—The type of this
group 1s Cyclops (Fig. 103), in which the body is pear-
os
\ ov
. 103.— lops. e,eye;h, heart; Fie. 104.—Lernea of Fig. 105.—Fish
eee feet. Highly mag- the cod. h, head; ov, louse of the
nified. -*° ovary. Nat. size. menhaden.
shaped, with a single bright eye in the middle of the head;
it has two pairs of antenne, used for swimming as well as
feelers; biting mouth-parts, and short legs. The females
swim about with two egg-masses attached to the base of
the abdomen. The young is a Nauplius, much like that
represented in Fig. 112), the mouth-organs, the legs and
88 ZOOLOGY.
abdominal segments arising after successive moults, until
the adult form is attained.
Many Entomostraca are parasitic, living on the gills of
fishes, etc., and consequently undergo a retrograde devel-
opment, losing the jointed structure of the body, the ap-
pendages being more or less aborted, while the body in-
creases greatly in size. Such are the fish-lice, represented
en
Fie 106.—Section through the thorax of Apus: en, 1-6, the six endites; ex, ex-
opodal or respiratory portion of the limb forming the flabellum, fb; c, cara-
pace; ht, heart; int, intestine; ng, nervous cord.
by the Lerncea of the cod (Fig, 104) or the fish-louse of the
menhaden (Fig. 105).
Order 3. Branchiopoda (Bivalved Crustacea).—All the
Crustacea hitherto mentioned breathe through their skin,
having no gills; we now come to Crustacea whose body is
protected by a rather thick shell or carapace, and which
breathe by gills attached to the legs, or by broad gill-like
expansions of the legs. In this order the number of seg-
ments varies from about 12 to 60; and the shield or carapace
mostly covers the legs. Vig. 106 represents a section
through the body of Apus; C' is the carapace concealing
SHELLED CRUSTACEANS. 89
the body and feet; 1-6 are the six lobes of the legs, to the
outer side of which are attached the gill and the broad ac-
cessory gill (fd).
The simplest Branchiopods are bivalved, and are usually
Fia. 107.—Limnetis brevifrons. Much enlarged.
less than a tenth of an inch in length. They are called
Ostracoda.
Rather larger forms are the water-fleas (Daphnia), which
represent the sub-order Cladocera.
. The most interesting sub-order is the
\ Phyllopoda. In them (Fig. 107, Lim-
} nefis) and Estheria (Fig. 108) the body
yy and legs are entirely concealed by the
“large bivalve shell. In Apws (Fig. 109)
Fie. 108,—Shell of Hstheria 20d Lepidurus (Fig. 110) the shield
Bernese a shelled jg broad and flat, concealing bunt a
part of the body. In Branchipus (Fig.
111), which is common in roadside pools and in ponds in
the cooler parts of the year, there is no carapace. The
Phyllopods swim on their backs. Apws is remarkable for
having 47 segments in all, and 60 pairs of limbs; certain
segments bearing as many as six pairs of limbs. All the
90 ZOOLOGY.
Phyllopods hatch in the form of a minute Nauplius (Fig.
112), additional segments and limbs being acquired during
Fie. 109.—Apus cequalis. Natural size. Fia. 110.—Lepidurus Couesii, sido
and dorsal view. Natural size.
successive moults or changes of skin. The brine shrimp
(Fig. 113) resembles Branchipus, but is much smaller; it
Fia. 111.—Brauchipus vernalis. a’, 1st antenna; a’, 2d antenna, Slightly
enlarged.
inhabits Great Salt Lake in Utah and other salt lakes in
the West and in the Old World, as well as tubs on railroad
SOW-BUGS AND BEACH-FLEAS. 91
bridges, where salt water has evaporated and become
briny.
Order 4. Tetradecapoda.—To this order belong the sow-
bugs (Jsopoda) and the beach-fleas (Amphipoda). They
have no carapace, but the head is small, bearing two pairs
of antenne, and a pair of jaws, and three pairs of maxille.
| re
i Ue >
Fig. 112.—Nauplius of Branchi- Fie. 113.—Brine Shrimp( Artemia gracilis),
pus stagnalis. ant}, Ist an- seen from above, much enlarged. e,
tenna; ant?, 2d antenna; md, eye; ant, Ist antennas; ant!, 2d anten-
mandible; /b, under lip. Much ne; md, mandibles; mx, maxille; pes,
enlarged. foot; 0, ovisack.
The thorax is continuous with the abdomen. They breathe
by leaf-like gills, which are situated on the middle feet in
the Amphipods, or on the hinder abdominal feet in the
Isopods. The various species of Porcellio (sow-bug) live
under stones on land; and allied to Asellus, the water sow-
bug, is the marine Limnoria terebrans, which is very in-
jurious to the piles of bridges, wharves, aud any submerged
92 ZOOLOGY.
wood. The highest Isopods are Idotea, of which I. irro-
ratus is our most abundant species, being common in eel-
grass, etc., between and just below tide-marks. While the
Fia. 114.—Gammarus robustus, from fresh water. Much enlarged.
Isopods are broad and flat, the Amphipods are compressed,
and the back is usually more or less arched. Such is the
Fig. 115.—Nebalia bipes. Enlarged 6 times.
Gammarus, or beach-flea (Fig. 114), found in salt and fresh
water.
Order 5. Phyllocarida.—This group is represented by a
little Crustacean, with a compressed body, and broad leaf-
PHYLLOCARIDANS, 93
Fia. 116.—Partly diagrammatic section through the thorax of Nebalia. en, th
axial-jointed endopodite; ex, exital portion or gill (above irregularly dotted
and flabellum below with transverse rows of dots; c, carapace; ht, heart;
int, intestine; ng, nervous system,
Fig, 117,—Zoda of the common Crab (Cancer irroratus), Much enlarged.
94 ZOOLOGY.
like feet covered by the carapace. The Nebalia bipes (Figs.
115, 116) occurs along our coast.
Order 6. Thoracostraca (Shrimps, Lobsters, Crabs).—
This order includes the Decapods, which have ten feet ar-
ranged in five pairs, the first pair enlarged, forming “ nip-
pers;” the head and thorax are covered by a solid, thick
carapace; while the gills are attached to the hinder maxil-
lipedes and to the thoracic feet. The Decapods pass through
a metamorphosis, the young being termed a zoéa (Fig. 117).
Fia. 118.—Common Hermit Crab. Natural size. After Morse, from Emerton.
A curious creature is the hermit crab (Fig. 118, Hupa-
gurus bernhardus; see also Fig. 19), which, selecting an
empty shell, thrusts its soft hind-body into it, and uses it
as a protection—like Diogenes, carrying its house about
with it. Small hermit crabs are abundant in little shells in
tidal pools along our coast.
In the crabs (Fig. 119) the abdomen is very small and
folded to the under side of the head-thorax (eephalo-thorax).
Shrimps and crabs are sensitive to shocks and sounds. The
sense of touch resides in the hairs on the mouth-parts,
THE HORSESHOE CRAB. 95
Crass IIl.—Popostomata (King-crab, Hurypterus, and
Trilobites).
Order 1. Merostomata.—The only living representative
of this order is the horseshoe or king-crab (Limulus Poly-
phemus, Fig. 122), which ranges from Casco Bay, Maine,
to Florida and the West Indies.
The body of the king-crab is very large, sometimes nearly two
‘ya, 119.—Common Shore-crab (Cancer irrovratus). Natural size. From Emerton
feet in length; it consists of a head composed of six segments and
an abdomen with nine segments, the ninth (telson) forming a long
spine. The head is broader than long, in shape somewhat like that
of Apus, with a broad flat triangular fold on the under side. Above
are two large lunate compound eyes, near the middle of the head,
but quite remote from each other, and two small compound eyes sit-
uated close together near the front edge of the head. There are no
antennee, and the six pairs of appendages are of uniform shape like
legs, not like mandibles or maxille, and are adapted for walking;
the feet are provided with sharp teeth on the basal joint for retain-
96 ZOOLOGY.
ing the food, which the horseshoe obtains by burrowing in the mud
or sand. The mouth is situated between the second pair; the first
pair of legs are smaller than the others. All end in two simple
Fic. 120.—Actual section through the head of Limulus, showing the second pair
of appendages and their relations to the shell or carapace. ht, heart; liv,
liver; end, appendage homologous with the endopodite of Decapoda.
Fia. 121.—Section through the abdomen of Limulus. c, carapace; ht, heart; int,
intestine; ny, ganglia (lettering being the same as in Fig. 123); en, axial.
jointed endopodite; ec, exital or respiratory portion bearing the gill-lamelleo;
the outer division (ex) homologous with the exoyodal portion of the Phyllo-
pod and Phyllocaridan leg.
laws (Fig. 120), except the sixth pair, which are armed with several
spatulate appendages serving to prop the creature as it burrows into
the mud. Appended to the abdomen are six pairs of broad swim-
ming feet (Fig. 121, ez), of which all but the first pair bear on the
THE TRILOBITES. gy
(
under side a set of about one hundred respiratory leaves or plates,
into which the blood is sent from the heart, passing around the outer
edge and returning around the inner edge.
In order to examine the internal anatomy the student can readily
with a knife cut the body iuto transverse sections, as in Figs, 120,
121, and also divide it longitudinally so as to show the parts as in
Fig. 128.
The alimentary canal consists of an cesophagus, which rises
directly over the mouth, a stomach lined with rows of large chiti-
nous teeth, with a large conical, stopper-Iike valve projecting into
the posterior end of the body; the intestine is straight, ending in the
base of the abdominal spine. The liver is very voluminous, ramify-
ing throughout the cephalothorax. The nervous system is quite un-
like that of other Crustacea; the brain is situated on the floor of the
body in the same piane as the rest of the system, and sends off two
Fic. 122.—Horseshoe Crab. Side view.
pairs of nerves—a pair to each pair of eyes. The feet are all sup-
plied with nerves from a thick nervous ring surrounding the cesoph-
agus. The nerves to the six pairs of abdominal legs are sent off
from the ventral cord.
The eggs of the horseshoe crab are rather large, and laid
in the sand between high and low water. Just before it
hatches it strikingly resembles a trilobite. After leaving
the egg (Fig. 124) it swims about on its back or burrows in
the sand; at first it has no tail-spine, this growing out at
successive moults. In casting its shell the latter splits open
in front, so that during the process it appears as if spewing
itself out. Specimens a foot long are probably several
years old.
Order 2. Trilobita.—The members of this group are all
extinct. The body has a thick dense skin like that of
ZOOLOGY.
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98
THE TRILOBITES. 99
Limulus, and is often variously ornamented with tuber-
cles and spines. ‘The body is divided into three longi-
tudinal lobes, the central situated over the region of the
heart as in Limulus. The body differs from that of the
Fia. 124.—Young Horseshoe Crab. Fia. 125.—Young Trilobite.
Natural size and enlarged. Natural size and enlarged.
horseshoe cral) in being divided into a true head consisting
of six segments bearing jointed appendages, somewhat like
those of the Merostomata, with from two to twenty-six dis-
tinct thoracic segments (probably bearing short jointed
Fia. 126.—Restored section of the thorax of a trilobite (Calymene) after Wal-
cott. c, carapace; en, endopodite; en’, exopodite, with the gills on the exo-
podal or respiratory part of the appendage.
limbs not extending beyond the edge of the body). The
abdomen consists of several (greatest number twenty-eight)
coalesced segments, forming a solid portion (pygidium),
sometimes ending inaspine The larval trilobite (Fig. 125)
100 ZOOLOGY.
was like that of a king-crab, and after a number of moults
acquired its thoracic segments, there being in most of them
a well-marked metamorphosis. The Trilobites occur in
the oldest fossiliferous rocks. Fig. 126 is an attempt by
Mr. C. D. Walcott to represent a restoration of a cross-sec-
tion of a trilobite, showing the relations of the feet and
gills to the body; the gills being spirally twisted filaments
growing from the base of the legs.
InsECTA AND OTHER AIR-BREATHING ARTHROPODA.
General Characters of Insects—In the insects the head
is separated from the rest of the body, which is divided
into three regions, the head, thorax, and hind-body (ab-
domen); hence the name insect, from insectwm, cut into
or divided. Insects breathe by internal air-tubes which
open through breathing-holes (spiracles) in the sides of the
body. The six-footed insects also have two pairs of wings.
The number of body-segments in winged insects is seven-
teen or eighteen—i.¢., four in the head, three in the thorax,
and ten or eleven in the hind-body. In spiders and mites
there are usually but two segments in the head, four in the
thorax, and a varying number (not more than twelve) in
the abdomen; in Myriopods the number of segments varies
greatly—i.e., from ten to two hundred. The appendages
of the body are jointed.
Of the winged insects there are two types: first, those in
which the jaws and maxille are free, adapted for biting,
as in the locust or grasshopper; and, second, those in which
the jaws and maxilla are more or Jess modified to suck or
lap up liquid food, as in the butterfly, bee, and bug.
Nearly all insects undergo a metamorphosis, the young
being called a larva (caterpillar, grub, maggot); the larva
transforms into a pupa (chrysalis), and the pupa into the
adult (imago).
In order to obtain a knowledge of entomology, the be-
THE INSECTS. 101
ginner should make a careful study of a locust or grasshop-
per with the aid of the following description; and after-
ward rear from the egg a caterpillar and watch the different
Al
ea) .
Tarsusl Pedpus Le Nead C\itandible f
wNA TIE
Trbida om &preranium. Cy
ja Prothorox. Le
oenante g Bo 2
Coxa Nee as
SS\ Wesothorax
Seidel
Avdiomen.
—
Fic. 227.—External anatomy of Caloptenus spretus, the head and thorax dis:
jointed. wp, uropatagium; /, furcula; c, cercopod.
102 ZOOLOGY.
steps in its metamorphosis into a pupa and adult, The
knowledge thus acquired will be worth more to the student
than a volume of descriptions.
On making a superficial examination of the locust (Caloptenus
femur-rubrum), its body will be seen to consist of an external crust,
or thick, hard integument, protecting the soft parts within. This
integument is at intervals segmented or jointed, the segments more
or less like rings. These segments are most simple and easily compre-
hended in the abdomen or hind-body, which is composed of ten of
them. On examining the abdomen, it will be found that the rings
are quite perfect, and that each segment may be divided into an
upper (tergal), a lateral (pleural), and an under (sternal) portion or
arc (Fig. 127, A).
As these parts are less complicated in the abdomen, we will first
study this region of the body, and then examine the more complex
thorax and head. The abdomen isa little over half as long as the
body, the tergum extending far down on the side and merging into
the pleurum without any suture or seam. The pleurum is indicated
by the row of spiracles, which will be noticed further on. The
sternum forms the ventral side of the abdomen, and meets the
pleurum on the side of the body.
In the female (Fig, 127, B), the abdomen tapers somewhat toward
the end of the body, to which are appended the two pairs of stout,
hooked spines, forming the ovipositor (Fig. 127, B, 7, 7’). The vent
is situated above the upper and larger pair, and the external open-
ing of the oviduct, which is situated between the smaller and lower
pair of spines, and is bounded on the ventral side by a movable tri-
angular acute flap, the egg-guide (Fig. 127, B, eg).
The thorax, as seen in Fig. 127, consists of three segments, called
the prothorax, mesothorax, and metathorax, or fore, middle, and
hind thoracic rings. They each bear a pair of legs, and the two
hinder each a pair of wings. The upper portion of the middle and
hind segments, owing to the presence of wings and the necessity of
freedom of movement to the muscles of flight, are divided or differ-
entiated into two pieces, the sevtum and seutellum* (Fig. 127), the
former the larger, extending across the back, and the scutellum a
smaller, central, shield-like piece. The pronotum, or what is usually
in the books called the prothorax, represents either the scutum or
* There are in many insects, as in many Lepidoptera and Hymenop-
tera and the Neuroptera, four tergal pieces, ¢.e., preescutum, scutum,
scutellum, and postscutellum, the first and fourth pieces being usu-
ally very small and often obsolete.
Fia, 128,—Male Locust, Caloptenus spretus, with the thorax separate from the head and abdomen, and divided into its three segments.
104 ZOOLOGY.
both scutum and scutellum, the two not being separately developed.
The fore wings are long and narrow, and thicker than the hinder,
which are broad thin, and membranous, and most active in flight,
peing folded up like a fan when at rest and tucked away out of
sight under the fore wings, which act as wing-covers.
Turning now to the side of the body (Fig. 128), we see that the
side of each of the middle and hind thoracic rings is composed of
two pieces, the anterior, episternum, resting on the sternum, with
the epimerum behind it; these pieces are verticaily high and narrow,
and to them the leg is inserted by three pieces, called respectively
cova, trochantine, and trochanter (see Fig. 128), the
latter forming a true joint of the leg.
The legs consist of five well-marked joints, the
femur (thigh), t2o/a (shank), and tarsus (foot), the
latter consisting in the locust of three joints, the
third bearing two large claws with a pad between
them. The hind legs, especially the femur and
tibia, are very large, adapted for hopping.
The sternum is broad and large in the middle
and hind thorax, but small and obscurely limited
in the prothorax, with a large conical projection
Fia 129.—Front view between the legs.
of the head of C. The head is mainly in the adult locust composed
spretus. EH, Epicra- : : ; 5 3
nium; C, clypeus; Of a single piece (called the epicranium, Figs. 128
Pron ean nae and 129 #), which carries the compound eyes,
tenna; md, mandi- ocelli, or simple eyes (Fig. 129, e), and antenne.
plese pORMOn Of While there are in reality four primary segments
by the labrum; p. in the head of all winged insects, corresponding
a oa oo to the four pairs of appendages in the head, the
posterior three segments, after early embryonic
life in the locust, become obsolete, and are mainly represented by
their appendages and by small portions to which the appendages
are attached. The antenne, or feelers, are inserted in front of the
eyes, and between them is the anterior ocellus, or simple eye, while
the two posterior ocelli are situated above the insertion of the an-
tenn. In front of the epicranium is the clypeus (Fig. 129), a piece
nearly twice as broad as long. To the clypeus is attached a loose
flap, which covers the jaws when they are at rest. This is the upper
lip or labrum) Fig. 129). There are three pairs of mouth-appendages:
first, the true jaws or mandibles (Fig. 127), which are single-jointed,
and are broad, short, solid, with a toothed cutting and grinding edge
adapted for biting. The mandibles are situated on each side of the
mouth-opening. Behind the mandibles are the maxille (Fig. 127),
which are divided into three lobes, the inner armed with teeth or
ea — aN
R. reelunn
vh AS o
” bo. eae guide.
Fig. 130.—Internal anatomy of Caloptenus femur-rubrum. at, antenna and nerve leading to it from the ‘brain’ or supra-cesophageal
panetion (spy; oc, ocelli, anterior and vertical ones, with ocellar nerves leading to them from the ‘ brain;” @. esophagus; m, mouth;
b, labium or under lip; if, infra-cesophageal ganglion, sending three pairs of nerves to the mandibles, maxilla, and labium respec-
tively (not clearly shown in the engraving); sm, sympathetic or vagus nerve, starting from a ganglion resting above the cesophagus,
and connecting with another ganglion (sg) near the hinder end of the crop; sal, salivary glands (the termination of the salivary duct
not clearly shown by the engraver); nv, nervous cord and ganglia; ov, ovary; ur, urinary tubes (cut off, leaving the stumps); ovt, ovi-
duct; sb, sebaceous gland; bc, bursa copulatrix; ovt’, site of opening of the oviduot (the left oviduct cut away); 1-10, abdominal see-
ments. The other organs labelled in full. Drawn from his original dissections by Mr, Edward Burgess.
106 ZOOLOGY.
spines, the middle lobe unarmed and spatula-shaped, while the outer
formsa five-jointed feeler called the mazillary palpus. The maxille
are accessory jaws, and probably serve to hold and arrange the food
to be ground by the true jaws. The floor of the mouth is formed by
the labiwm (Figs. 127 and 128), which in reality is composed of the
two second maxille, grown together in the middle, the two halves
being drawn separately in Fig. 127.
Within the mouth, and situated upon the labium, is the tongue
(lingua), which is a large, membranous, partly hollow expansion of
the base of the labrum; it resembles a beech-nut in shape, being
slightly keeled above, and covered with fine, stiff hairs, which, when
magnified, are seen to be long, rough, chitinous spines, with one or
two slight points or tubercles on the side.
The internal anatomy may be studied by removing the dorsal wall
of the body with fine scissors, and also by hardening the insect sev-
eral days in alcohol and cutting it in two longitudinally by a sharp
scalpel.
The esophagus (Fig. 130, e) is short and curved, continuous with
the roof of the mouth. The two salivary glands consist each of a
bunch of follicles, emptying by a common duct into the floor of the
mouth,
The csophagus is succeeded by the crop (‘ngluvies). It is in the
crop that the ‘‘ molasses” thrown out by the locust originates,
The proventriculus is very small in the locust, easily overlooked in
dissection, while in the green grasshoppers it is rather large, and
armed with sharp teeth. The true or chyle-stomach is about one
half as thick as the crop.
From the anterior end arise six large pockets (gastric cwca), which
arise from the true chyle-stomach, and probably serve to present a
larger surface from which the chyle may escape into the body-cavity
and mix with the blood, there being in insects no lacteal vessels or
lymphatic system.
The stomach ends in a slight constriction, at which point the
urinary tubes (Fig. 180, wr) arise. These are arranged in ten groups
of about fifteen tubes, so that there are about one hundred and fifty
long, fine tubes in all. The stomach is succeeded by the ileum,
colon, and rectum (Figs. 180, 131).
The nervous system of the locust, as of other insects, consists of
a series of swellings or nerve-centres, or so-called brains (ganglia),
which are connected by two cords (commissures), the two cords in
certain parts of the body in some insects united into one. There are
in the locust ten ganglia, two in the head, three in the thorax, and
fivein the abdomen. The first ganglion is rather larger than the
others, and is called the ‘‘ brain,” The brain rests upon the cesoph-
iq. 131.—Internal anatomy of Anabrus. t, tongue; fg, frontal ganglion: br, brain, the nervous cord passing backward from it; sr, salivary reser-
voir; pv, proventriculus; ur, origin of urinary tubes; sb, sebaceous gland. Burgess del.
108 ZOOLOGY.
agus, whence its name, supra-cesophageal ganglion. From the brain
arise the nerves to the eyes and feclers, and from it the nervous cord
extends back to the end of the body.
Fig. 132._A Carabus beetle in the act of walking or running. Three legs (L,
FR}, L3) are directed forward, while the others (R!, L2, ft), which are directed
backward toward the tail, have ended their activity. ab,cd,ande fare
curves described by the end of the tibiae and passing back to the end of the
body; bh, di, and fg are curves described by the same legs during their
passive change of position.
All insects breathe by means of a complicated system of
air-tubes ramifying throughout the body, the air entering
through a row of spiracles or breathing-holes (stigmata)
THE INSECTS. 109
in the sides of the body. There are in many insects two
pairs of thoracic and eight pairs of abdominal spiracles.
The anatomy of the grasshopper may also be compared
with that of the western cricket (Fig. 131).
The antenne are both organs of touch and also of smell,
the olfactory organs being little pits; some insects, how-
ever, hear with their antenne. The locusts have a pair of
large ears situated at the base of the abdomen (Fig. 128).
Insects produce sounds in various ways, either as in
locusts by rubbing the legs against the closed wings, or by
rubbing the upper on the under or hind wings; while some
insects produce creaking sounds by rubbing the harder
parts of the body together.
In walking or running, an insect, as a beetle (Fig. 132),
raises and puts down its six legs alternately, as may be
seen by observing the movements of any large insect.
The wings are broad thin bags or expansions of the skin.
They are strengthened by hollow rods called veins, of
which there are six principal ones. The veins are hollow,
usually containing an air-tube.
The wing of an insect in making the strokes during flight
describes a figure 8 inthe air. A fly’s wing makes 330 rev-
olutions in a second, executing therefore 660 simple oscil-
lations.
According to M. Plateau, who has recently made ingen-
ious experiments regarding the strength of insects, the
smallest of these animals are proportionally the strongest.
A cockchafer can pull 21 times more, proportionally, than
a horse, while a bee pulls thirty times more. (The ani-
mals were attached to a cord passing over a pulley to a
weighted scale.) The horse lifts 6-Tths of its weight, the
cockchafer 14 times its weight, and the bee 20 times.
Insects are very prolific, laying hundreds of eggs. Some
insects, as the cricket, grasshopper, and ichneumon fly,
possess a horny tube called an ovipositor, by means of
which they bore into wood cr the earth and deposit their
eggs one after another.
110 ZOOLOGY.
After hatching from the egg, insects pass through a
series of changes of form called a metamorphosis. The
butterfly passes through four stages: 1, the egg; 2, the
caterpillar or larva: 3, the chrysalis or pupa; and, 4, the
Jmago or adult insect. In the grasshopper the perfect or
adult insect differs chiefly from the larva in having wings;
in such insects the metamorphosis is said to be incomplete;
while the butterfiy and bee have a complete metamorphosis,
the larva or caterpillar being entirely unlike the imago or
perfect insect.
Insects are both useful and injurious to vegetation.
Were it not for certain bees and moths, orchids and many
other plants would not be fertilized; insects also assist in
the cross-fertilization of plants. For full crops of many of
our fruits and vegetables, we are largely indebted to bees,
flies, moths, and beetles, which, conveying pollen from
flower to flower, ensure the production of abundant seeds
and fruits. Mankind, on the other hand, suffers enormous
‘losses from the attacks of injurious insects. Within a
period of four years, the Rocky Mountain locust, migrating
eastward, inflicted a loss of $200,000,000 on the farmers of
the West. In the year 1864 the losses occasioned by the
chinch-bug in the corn and wheat crop of the valley of the
Mississippi amounted to upward of $100,000,000. It is
estimated that the average annual losses in the United
States from insects is about $100,000,000. On the other
hand, hosts of ichneumon flies and Tachina flies reduce
the numbers and usually prevent undue increase in the
numbers of injurious insects.
The number of species of insects in collections is about
200,000. Of these there are about 25,000 species of Hyme-
noptera (bees, wasps, ete.); about 25,000 species of Lepi-
doptera (butterflies and moths); about 25,000 Diptera (two-
winged flies), and 90,000 Coleoptera (beetles); with about
4600 species of .lrachnida (spiders, ete.), and 800 species
of Myriopoda (millepedes, centipedes, etc.).
fnusects ure distributed all over the surface of the earth,
: _ The common garden spider (Epeira): a, leg; b, maxillary palpus;
, poison-jaws; e, spinnerets. 2. Front view of head with the eight simple
eyes and the poison-jaws. 3. End of a jaw: a, outlet of the poison-canal. 7.
Palpus of female; 8, of male spider. 6. Spines and claws at end of a leg.
4. Spinnerets, highly magnified. 5. A single silk-tube.—After Emerton.
Structure of a centipede.
A, Lithobius americanus, natural size.
B, under side of head aad first two body
-segments and legs, enlarged: ant,
antenna; 1. jaws; 2. first accessory jaw; c, lingua; 3, second accessory jaw
and palpus; 4, poison-jaw. (Kingsley del.) C, side view of head (after New-
port): ep, epicranium; 1, frontal plate; sc, scute; p, first leg; sp, spiracle,
(To tace page 110.)
Ww
Metamorphosis of the Locust. 1
, 2, larva; 3-5,"pupa; 6, imago.
(To face page 111,)
THE MYRIAPODS. 111
Most of the species are confined to the warmer portions of
the globe, becoming fewer as we approach the North Polar
regions. Many are inhabitants of fresh water; a very few
inhabit the sea.
The Myriapods are all terrestrial, and occur in all parts
of the earth except the polar regions. On the other hand,
spiders and mites occur in tolerable abundance in the arctic
regions, as well as on the summits of lofty mountains, but
the scorpions are confined to the hotter parts of the earth.
Unlike the winged insects, the Myriapods and Arachnids
do not pass through a well-marked metamorphosis.
Cuass III.—Maacopopa.
General Characters of Malacopoda.—This group is repre-
‘sented by a single animal, the Peripatus of the tropics, in
which the soft worm-like body has rudimentary jaws. There
is a pair of fleshy feet, ending in two claws, to each seg-
ment; it breathes by minute air-tubes.
Ciass ITV.—Myriapopa.
General Characters of Myriapods.—The centipedes and
millepedes are distinguished by their cylindrical body, the
abdominal segments being numerous and similar to the
thoracic segments, all provided with a pair of feet. The
head is free, with a pair of antenne, and two or three pairs
of jaw-like appendages.
Order 1. Chilognatha.—To this group belong the mille-
pedes, Julus, etc. (Fig. 133). The segments are round or
flattened, and the feet are inserted near together, and there
appear to be two pairs to each segment. Millepedes feed
on dead, sometimes fresh leaves, and on fallen fruit.
Order 2. Chilopoda.—This group is represented by the
centipede, in which the body is flattened. In Geophilus
{Fig. 134, G. bipwncticeps) there are from thirty to two
hundred segments. Our most common form is Lithobius
112 ZOOLOGY,
Americanus, found under logs, etc. The centipede (Scolo-
pendra heros) is very poisonous, the poison-sacs being
lodged in the two large fangs or second pair of jaw-legs.
Fie. 133.—Julus. Fie 134.—Geophilus,
Natural size.
Ciass V.—ARACHNIDA.
General Characters of Arachnids.—The bodies of spiders
and scorpions, etc., are divided into two regions, a head-
thorax and abdomen, the head being closely united with
the thorax. There are no antenne, only a pair of mandi-
bles and a pair of maxille, with four pairs of legs. There
are never any compound eyes. The young are usually like
the adult, except in the mites, in which there isa slight
metamorphosis, the young being born with but three pairs
of legs, while the full-grown mite has four pairs.
An example of the sub-class is the spider, which is char-
acterized by having two or three pairs of spinnerets, out
of which the silk is drawn in spinning their webs. Besides
breathing by air-tubes, spiders have so-called lungs com-
posed of several leaves, into which the blood flows,
MITES AND SCORPIONS. 1138
ORDERS OF ARACHNIDA.
1. Body small, rounded ; no distinct abdomen. Acarina, Mites.
2. Body with a jointed abdomen............ Arthrogastra, Scorpion.
3. Body with a thick unjointed abdomen..... Araneina, Spiders.
Order 1, Acarina.—The mites (Fig. 135) are the sim-
plest Arachnida, the body being oval in form, the head
usually small, more or less merged with the thorax, while
the latter is not separate from the abdomen. The tick
Fic. 135.—Sugar-mite. Fia. 136.—Cattle-tick (Ixodes bovis).
Much enlarged. Natural size and enlarged.
(Fig. 186) is a large mite. It infests cattle, sometimes
burying itself in the skin of human beings.
Order 2. Arthrogastra.—This group embraces the scor-
pion (Fig. 137), the false-scorpions, the whip-scorpions, and
the harvest-men (Phalangium). In all these forms the ab-
domen is plainly segmented, the segments not being visible
in the mites or spiders. Usually the maxillary palpi are
much enlarged, and end in claws. The scorpion is vivipa-
rous, the young being brought forth alive. The young scor-
pions cling to the back of the mother. The sting of the
scorpion is lodged in the tail, which is perforated, and con-
tains in the bulbous enlargement an active poison. Though
114 ZOOLOGY.
producing sickness, pain, and swelling in the part wounded,
the sting of the scorpion is seldom fatal.
The little false-scorpions (Chelifer, Fig. 138) often occur
in books, under the bark of trees, and under stones. The
whip-scorpion is confined to warm countries; Thelyphonus
gigantews occurs in New Mexico and Mexico. Its abdo-
men ends in a long lash-like appendage. Its bite is poi-
sonous. The harvest-men, or daddy-long-legs, are common
j
i
r
)
i
Fic, 137.—Carolina Scorpion (Buthus Fic. 188.—Chelifer can-
Carolinianus). Natural size. croides. Magnified.
in dark places about houses. They feed on plant-lice. Ouz
common species is Phalangium dorsatum.
Order 3. Araneina.—The spiders are always recognizable
by their round abdomen, attached by a slender pedicel to
the head-thorax. They breathe, like the scorpions, both
by lungs as well as by trachew, and the young resemble
the parents in having four pairs of feet. The man-
dibles end in hollow points, through which the poison
exudes, the two poison-glands being situated in the head,
THE SPIDERS. 115
The male spider is usually much smaller than the fe-
“male; the latter lay their eggs in silken cocoons. The
tarantula (Lycosa) usually lives in holes in the ground, and
sometimes conceals the opening by covering it with a few
dead leaves, The common garden spider is Epetra vulga-
Fia. 189.—Mygale. Trap-door Spider.
ris, It lives about houses and in gardens; its geometrical
web is very regular. The large trap-door spider (JMygale)
has four lung-sacs instead of two, as in the other spiders,
and only two pairs of spinnerets. Mygale Hentzit (Fig.
139) inhabits the Western plains and Utah; the gigantic
116 ZOOLOGY.
Mygale avicularia of South America is known to seize
small birds and suck their blood. There are probably
about eight hundred species of spiders in North America;
their colors are often brilliant, and sometimes, from the
harmony in their coloration with that of the flowers in
which they hide or the leaves on which they may rest,
elude the sight of insectivorous birds. John Burroughs, in
his ‘*Pepacton,” says that one sunny April day his ‘‘atten-
tion was attracted by a soft, uncertain purring sound” made
by little spiders travelling about over the leaves,
Cuiass VI.—INSEcTA.
General Characters of Insects——Winged insects have a
separate head, thorax, and abdomen. They have compound
as well as simple eyes, two pairs of wings, and three pairs
of thoracic legs. There are sixteen orders.
ORDERS OF INSECTS.
1. Wingless, often with a spring. Thysanura : Spring tails, etc.
2. Fore wings minute, elytra like. Dermaptera : Karwig.
3. Wings net-veined; fore wings
narrow; hind wings folded. . Orthoptera: Locusts, Grasshoppers.
4. Four net-veined wings; mouth-
parts adapted for biting..... Platyptera : White Ants, Bird-lice.
5. Wings net-veined, equal...... Odonata: Dragon-flies.
6. Wings net-veined, unequal....Plectoptera: May flies.
7. Mouth beak-like, but with palpi Thysanoptera : Thrips.
8. Mouth-parts forming a beak
for sucking; no palpi....... Hemiptera: Bugs.
9. Wings net-veined ; metamor-
phosis complete............. Neuroptera: Lace-winged Fly, etc.
10. Wings long and narrow...... Mecoptera: Panorpa.
11. Wings not net-veined......... Trichoptera: Caddis-fly.
12. Fore wings sheathing the hind-
ET ONCSS ne ences 4 eee sg BA ete Coleoptera: Beetles.
13. Wingless, parasitic........... Siphonaptera: Flea.
14. One pair of wings............ Diptera: Flies.
15. Four wings and body scaled. . Lepidoptera : Butterflies.
46. Four clear wings; hinder pair
small; a tongue ............ Hymenoptera: Bees, Wasps, ete.
THE ORTHOPTERA. 117
Order 1. Thysanura.—The spring-tails (Podura) and
Smynthurus (Fig. 140) and bristle-tails (Lepisma) are ex-
amples of this order. The Podurans have a
peculiar forked appendage in the end of the
body, which is held in place by a hook; when
set free the spring darts backward, throwing
he minute insect high in the air.
Order 2. Dermaptera.—The earwig (for-
ficula) is the representative of this small
group, which is characterized by the small,
short, elytra-like fore wings, and the large
i 3 i . Fia. 140.—Smyn-
peculiar hind wings, while the body ends in a ee
forceps-like appendage. j
Order 3. Ortheptera.—Locusts, grasshoppers, crickets,
etc., are called Orthoptera (straight-wings) from their nar-
row, straight, fore wings; the broad hinder pair being
folded fan-like under the fore pair.
Many Orthoptera, as the crickets, green grasshoppers,
fe
Oe S
L | lh Zi
‘ gh Sy
te
Fie, 141.—A Katydid-like form resembling a leaf.
katydids (Fig. 141), etc., and locusts (Fig. 142), produce
loud, shrill sounds. The sound is made in three ways, v.e.,
first, by rubbing the base of one wing-cover on the other
(crickets and green grasshoppers); second, by rubbing the
118 ZOOLOGY.
inner surface of the hind legs against tne outer surface of
the front wings (some locusts); third, by rubbing together
Fig. 142.~Rocky Mountain Locust; b, Red-legged Locust.
—
Fia, 143.—An African Mantis, or soothsayer, with its egg-mass.
the upper surface of the front edge of the hind wings and
the under surface of the wing-covers during flight (some
locusts).
THE PSEUDO-NEUROPTERA. 119
Other examples of Orthoptera are Mantis (Fig. 143), the
curious leaf insect (Fig. 144), and the stick insect (Fig. 145).
Fia. 144.—Leaf insect (Phylium). Fia. 145.—Stick insect.
Half natural size.
Order 4. Platyptera.—The white ants live in stumps
and fallen trees, and in the tropics do much harm by un-
Fig. 146.—Dragon-fly (Diplax Elisa). Fie. 147.—Agrion. Nat. size.
dermining the timbers of houses, and destroying furniture,
books, etc. Their colonies are very populous. In our white
ant there are, besides males and females, workers and sol-
120 ZOOLOGY.
diers, the latter with large heads and long jaws. The white
ants in Africa build conical hills six feet or more in height.
Order 5. Odonata.—Dragon-flies (Figs. 146, 147) rep-
resent this order. They have broad, net-veined wings and
free biting mouth-parts. The metamorphosis is incomplete,
the pupe (Fig. 148) being active and feeding on smaller
insects, only differing from the larve in having rudiments
Fic. 148.—Pupa of a Dragon-fly Fie. 149.—May-fly and larva, the latter
(4tschna). enlarged.
of wings. Dragon-flies are constantly on the wing in
pursuit of insects; they are sometimes called ‘ mosquito
hawks.”
Order 6. Plectoptera.—May-flies (Fig. 149) are so called
from their shortness of life, as they live but a day or two.
The young live in the water, and breathe by feathery gills
on the side of the body.
ZOOLOGICAL LABORATORY, McGRAW HALL
THE THYSANOPTERA., 121
Order %. Thysanoptera.—Thrips and its allies were re-
ferred by Haliday to a distinct order. The mouth-parts
form a sort of beak; the mandibles are bristle-
like; the maxille flat, triangular, bearing two- to
¥ three-jointed palpi; the labial palpi are very
' 1 short, two- to three-jointed. The wings are small,
‘\ long and narrow, fringed; both pairs of equal
size, usually without veins. The antenne are
five- to nine-jointed.
Order 8. Hemiptera.—The bugs (Fig. 150) have
a long beak bent on the breast. They suck the
Thrips. juices of plants and blood of insects. The chinch-
bug (Fig. 151) is fearfully destructive in
certain years to corn and wheat; collecting
under the base of the leaves in great num-
bers, it sucks the sap and kills the plant.
While most insects live but one and some
live two years, the seventeen-year Cicada
(Fig. 152) lives over sixteen years as a larva,
becoming a pupa and finally acquiring
wings in the seventeenth year, Seis Nepal
The Aphis or plant-louse (Fig. 153) is 8%
provided with two tubes on the end of the body from which
=
Fia. 151.—Chinch-bug. a, b, eggs; c¢, e, larva; jf, g, pupa; 7, beak.
“‘honey dew” drops, which attracts ants, wasps, etc. In
summer the female plant-lice bring forth young alive, and
as there may be nine or ten generations, one virgin Aphis
122 ZOOLOGY.
may become the parent of millions of children and grand-
children.
7 ae ms Fia. 155.—Case-worm.
roup of stalked eggs, a, case.
Order 9. Neuroptera.—These are net-veined insects with
a complete metamorphosis, the chrysalis residing in a
Fia. 154.—Chrysopa and g
THE MECAPTERA, 123
cocoon. Such are the lace-winged fly (Fig. 154), the ant-
lion, and Corydalus. The aphis-lion is the larva of the
lace-winged fly, and devours large numbers of plant-lice.
Order 10. Mecoptera.—The type of this group is Panorpa.
Order 11. Trichoptera.—The case-worms are the larve of
moth-like insects called Caddis-flies. Their wings are veined
much as in the smaller moths. ‘Their larve resemble cater-
pillars, but live in water, in cases (Fig. 155).
Order 12. Coleoptera.—In beetles the fore-wings are thick-
ened, not used in flight, and form sheaths (elytra), which
Wy Annan 1
Fia. 156.—Metamorphosis of the May-beetle; 2, larva; 1, pupa.
protect the under or hinder pair. Their young are called
grubs; the pup usually rest in cocoons of earth, etc., their
metamorphosis being complete (Fig. 156). The tiger and
ground beetles have long sharp jaws for seizing other
insects; they are the tigers of the insect world. The bury-
ing-beetles are scavengers, and useful insects they are.
The leaf-beetles are very numerous, and comprise as in the
potato-beetles (Fig. 157) some of our most destructive in-
sects. Injurious to trees and fruit are the boring-beetles
and the weevils. The latter with their long beak, at the
194 ZOOLOGY.
end of which are the thick powerful jaws, bore into nuts
and seeds or fruit. Such are the plum-weevil (Fig. 158),
Fig. 157.—Colorado potato-beetle; a, eggs; 6, b, b, larva: c, pupa; d, beetle;
e, & Wing-cover.
and the chestnut, acorn, and hickory-nut weevils. These
weevils when disturbed instantly feign death; and they also
Fia. 158.—Plum Weevil. a, larva; b, pupa; c, beetle, enlarged; d, natural size,
puncturing a plum. i
escape the attacks of the ever-watchful birds by their resem-
blance to buds. A few beetles are beautifully phosphores-
THE DIPTERA. 125
cent. Such are the fire-flies, the cucuyo of the West
Indies, and the glow-worm.
5 A
: 7 sp A
a. f
Nh
IT
:
ft
Fig. 159.—The early stages of the common House-fly. A, dorsal and BP, side view
of the larva; a, air-tubes; sp, spiracle. C, the spiracle enlarged. F, head of
the same larva, enlarged; bl, labrum (?); md, mandibles; mx, maxille; at,
antenne. H,a terminal spiracle much enlarged. D, puparium; sp, spiracle.
All the figures much enlarged.
Order 13. Siphonaptera.—Fleas represent this group.
Order 14. Diptera.—The common house-fly (Fig. 159)
is a type of this group, all the members of which have but
Fie. 160.—Bot-fly of the ox and its larva.
two wings, while the tongue is especially developed for lap-
ping up liquids. The common house-fly lives one day in
126 ZOOLOGY.
the egg state, from five days to a week as a maggot, and
from five to seven days in the pupa state. It breeds
about stables.
The Tachina-fly is beneficial to man, from its parasitism
in the bodies of caterpillars and other injurious insects.
The bot-fly (Fig. 160, Hypoderma
bovis) is closely allied to the house-fly,
but the maggot is much larger. The
larval bot-fly of the horse lives in the
stomach; that of the sheep in the
frontal sinus, a cavity in the forehead.
The Syrphus flies (Fig. 161, Syr-
e 5 phus politus) mimic wasps; their mag-
Fia. 161.—Syrphus politus gots are most useful in devouring
be aphides.
The fleas are wingless flies, allied to winged forms which
are intermediate between the house-flies and crane-flies.
In the two-winged gall-flies (Cecidomyia, ete., Fig. 162,
C. tritici, Hessian-fly) the body is small and slender, with
long antennew. The crane-flies (Zipwla) are large flies,
standing near the head of the order, and, like the flea and
Fie. 162.—Hessian-fly. a, larva; 6, pupa; c, incision in wheat-stalk for larva.
gall-fly, the chrysalis is enclosed in a cocoon, there being
no puparium or pupa-case, as in the lower flies. Lastly,
we have the mosqnito (Figs. 163, 164), whose Jarva is
aquatic, and breathes by a process on the end of the body,
containing an air-tube.
BUTTERFLIES AND MOTHS. 127
Order 15. Lepidoptera.—The butterflies and moths are
known by their scaly bodies, the spiral maxilla or tongue
Fia. 163.—A, larva; c, its respiratory tube. B, pupa; d,respiratory tube. a, two
paddles at the end of the body.
rolled up between the two large labial palpi, and by their
usually broad scaly wings.
The larger moths are represented by the canker-worm,
the grass army-worm and the cotton army-worm (Fig. 165),
Fig. 164.—Head and mouth parts of mosquito. e, eye; a, antenna; br, labrum;
h, hypopharynx; m, mandibles; mx, maxilles;’ map, maxillary palpus; 10, la-
bium. (Magnified.)
so destructive to vegetation; the silk-worm moth (Bombyx
mort) of the Old World, and the American silk-worm (Télea
Polyphemus).
The hawk-moths (Sphinc) are distinguished by their large
128 ZOOLOGY.
size and very long tongue. The butterflies differ from the
moths in having knobbed an-
tenne, while their chrysalides
are often ornamented with
golden or silvery spots.
Order 16. Hymenoptera.—
The bees stand at the head of
the insect series in perfection
of parts, especially those of the
mouth.
The Hymenoptera are repre-
Fic. 165.—Egg, caterpillar, and moth
of Anomis xylina, the Cotton sented by the saw-flies, the gall-
Army-worm. i . :
flies, the ichneumon-flies and
the ants, the sand-wasps, mud-wasps, paper-making wasps,
and bees.
The lowest family is the Uroceride, or horn-tails (Fig.
Fig. 168.—Gall-fly of oak.
j/
Fie. 166.—Horn- Fia, 167.—Pear Slug, Fia. 169—An Ichneumon-fly.
tail: larva of natural size, gnaw-
Tremex co- ing leaves. a, lar-
lumba. Nat. va enlarged; b, the
size, *
ICHNEUMON FLIES. 129
166, larva of Tremex columba), whose fleshy white larvee
bore in trees. The adults are large, with a long, saw-like
ovipositor. In the saw-flies (Tenthredinide, Fig. 167 the
pear-slug, Selandria cerasi) the larva strongly resembles a
caterpillar, having eight pairs of abdominal feet.
The gall-flies (Fig. 168, Cynips) are small Hymenoptera
which lay eggs in the leaves or stems of the oak, etc., |
UN S
Oi . YY
\y af
ip
A
Fia. 170,—Cicodoma, or Leaf-cutter Ant of Nicaragua.
which, from the irritation set up by their presence, causes
the swelling termed a gall.
The ichneumon-flies (Fig. 169) are very numerous in
species and individuals; by their ovipositor, often very
long, they pierce the bodies of caterpillars, inserting sey-
eral or many eggs into them; the larve feed only on the
fatty tissues of their host, but this usually causes the death
of the caterpillar before its transformation.
The family of ants is remarkable for the complexity of
130 ZOOLOGY.
the colony, the division of labor and the reasoning powers
manifested by the workers and soldiers, which, with the
males and females, constitute the ant-colony.
Certain ants enslave other species; have herds of cattle, _
the aphides; build complicated nests or
formicaries, tunnel broad rivers, lay up
seeds for use in the winter-time, are
patterns of industry, and exhibit a readi- -
ness in overcoming extraordinary emer-
gencies, which show that they have suf-
ficient reasoning powers to meet the
exigencies of their life; their ordinary
acts being instinctive—namely, the re-
sults of inherited habits. The leaf-cutter
ants of Central and South America (Fig.
170) are famous from their leaf-cutting habits; the soldiers
have large triangular heads, while the workers have much
smaller rounded heads.
The mud-daubers (Pelopeus, Fig. 171) build their nests
Fia. 171.—Mud-dauber.
Fic. 172,—Sand-wasp (Sphexr). Natural size.
against stone walls, of pellets of mud, while the sand- and
mud-wasps dig deep holes (Fig. 172, Sphea ichneumonea)
WASPS AND BEES. 131
in gravelly walks, and have the instinct to sting grass-
hoppers in one of the thoracic nerve-centres, thus paralyzing
the victim, in which the wasp
lays her eggs; the young hatch-
ing, feed upon the living but
paralyzed grasshoppers, the
store of living food not being
exhausted until the larval wasp
is ready to stop eating and
finish its transformations.
The genuine paper-making
wasps are numerous in species;
here the workers are winged,
and differ from the females or
queens in being rather smaller.
Odynerus builds cells of mud.
The genuine paper-making
wasps, such as Vespa, build
several tiers of cells, arranged
mouth downward, and envel-
oped by a wall of several thick-
nesses of paper. In the Vespe,
the females found the colony,
and raise a brood of workers,
which early in the summer
assist the queen in completing
the nest.
The bees also present a grad-
ual series from those which
are solitary, living in holes in
the earth, like the ants (Fig.
173), and forming silk-lined
earthen cocoons, to those
which are social, with winged
workers, slightly differing from
the queens. The queen hum-
Fic. 173.—Nest of Andreva. g, level
of ground; a, first-made cell, con-
taining a pupa; 3, l, larve; e, pol-
len mass with an egg laid on it; f,
pollen mass freshly deposited by
the bee.
ble-bee hibernates, and in the spring founds her colony by
132 ZOOLOG ¥.
laying up pellets of pollen in some subterranean mouse.
nest or in a stump, and the young hatching, gradually eat
the pollen, and when it is exhausted and they are fully fed,
they spin an oval cylindrical cocoon; the first brood are
workers, the second males and females. The partly hex-
agonal cells of the stingless bees of the tropics (Melipona)
are built by the bees, while the hexagonal cells of the honey-
bee are made by the bees from wax secreted by minute
glands in the abdomen. Though the cells are hexagonal,
they are not built with mathematical exactitude, the sides
not always being of the same length and thickness.
The cells made for the young or larval drones are larger
than those of the workers, and the single queen-cell is large
and irregularly slipper-shaped. Drone-eggs are supposed
not to be fertilized. Certain worker-eggs have been known
to transform into queen-bees. On the other hand, worker-
bees may lay drone-eggs. The maximum longevity of a
worker is eight months, while some queens have been
known to live five years. The Jatter will often, under fa-
vorable circumstances, lay from 2000 to 38000 eggs a day.
The first brood of workers live about six weeks in summer,
and are succeeded by a second brood.
LITERATURE oF ARTITRopoDA. (For Crustacea see p. 85.)
Podostomata,—Van der Hoeven’s Recherches sur ]’Histoire Natu-
relle des Limnles, 1838; Milne-Edwards’s Recherches sur ]’Ana-
tomie des Limules, 1872; Packard's Four Memoirs on the Anatomy
and Embryology of Limulus, 1872-91; Kingsley’s Notes on the Em-
bryology of Limulus, 1885; works of Walcott, Beecher, Lunkester.
Arachnida.—Hentz’s Spiders of the United States, Boston, 1875;
Emerton’s Structure and Habits of Spiders, 1883, and his various
essays, with those of G. W. and E. G@. Peckham; McCook’s American
Spiders and their Spinning Work, 8 vols., 1889-92; with the works
of Walckenaer, Blackwall, Thorell, Simon, Keyserling, Marx, ete.
Myriapoda,—W 000’s The Myriapoda of North America, 1865; witk
essays by Newport, Harger, Latzel, Haase, Packard, ete.
Insecta. —Kirby and Spence’s Introduction to Entomology, 4 vols.,
1828; Burmeister's Manual of Entomology, 1836; Westwood’s Modern
Classification of Insects, 2 vols., 1839-40; Harris’ Treatise on In-
sects injurious to Vegetation, 1886; Packard's Guide to the Study of
Insects, 1888; Entomology for Beginners, 1890; Graber’s Die Insek-
ten, 1877; Lubbock’s Ants, Bees, and Wasps, 1882. For economic
entomology, the works of Harris, Fitch, Riley, Le Baron, Lintner.
CHAPTER VIII.
Branc# VITI.—Vertesrata (Back-boned Animals).
GENERAL CHARACTERS OF VERTEBRATES.~—We have scen
that most of the foregoing types of animals have the body
protected by a crust or shell, enclosing the muscles and
other internal organs; but now we come to animals which
have an internal bony support or skeleton. The skeleton
consists of a backbone (Fig. 174) with bones forming a
skull and a series of bones supporting the limbs. Fishes,
reptiles, birds, and mammals or beasts, are familiar exam-
ples of vertebrates, while man himself is a vertebrate. Ver-
tebrates in general have bodies which are symmetrical, 7.¢.,
the two sides repeat each other; they nave a brain-box or
skull containing the brain and the mouth and pharynx,
with two eyes, two ears, and usually two nasal openings.
To the trunk are attached two pairs of limbs; the tore-
arms in man corresponding to the fore legs of the horse or
dog.
Now if we cut a fish in two, and closely examine the sec-
tion, we shall notice that above the hackbone is a little cav-
ity containing the nervous cord, and below a much larger
cavity containing the viscera, t.e., heart, liver, stomach or
intestine. Thus there are two cavities, the nervous one
above, and the visceral one beJow the backbone (Figs. 175,
176). In this respect the backboned animals differ from
the backboneless or invertebrate animals, in which there is
but one body-cavity, with the nervous system situated on
the floor of this cavity.
Vertebrates have a true heart, with one, generally two,
auricles, and one or two ventricles, and, besides arteries and
ZOOLOGY.
sit
th
wy
Fie. 175.—Diagrammatic longitudinal
section of the body. a, the neural
tube, with its upper enlargement in
the skull cavity at a’; N, the spinal
49 cord; N’, the brain; ee, vertebra
forming the solid partition between
Fic. 174.—Side view of the dorsal and ventral cavities; b, the
the vertebral column pleural, and c. the abdominal divisions
or back-bone of man. of the ventral cavity, separated from
From Martin. one another by the diaphragm, @; %,
the nasal, and o, the mouth chamber,
opening behind into the pharynx,from
which one tube leads to the lungs, l,
and another to the stomach, f; h, the
heart; k, a kidney; s, the sympathetic
nervous chain. From the stomach. f,
the intestinal tube leads through the
abdominal cavity to the posterior
Opening of the alimentary canal,
VERTEBRATES, 135
veins, a system of capillary vessels, which are minute tubes
connecting the ends of the smaller arteries with the smaller
veins. There are no genuine capillaries in the lower ani-
mals exactly comparable with those of vertebrates.
The blood is red in all the vertebrates except the lance-
let, and besides white corpuscles contains red corpuscles.
While fishes and tadpoles breathe by gills, all land and am-
phibious vertebrates breathe the air directly by lungs con-
nected by a windpipe (trachea) with the mouth. The
nervous system consists of a brain and spinal cord. The
brain consists of four pairs of lobes, 7.e., the olfactory
Fic. 176.—A diagrammatic section across the body in the chest region. 2, the
dorsal tube, which contains the spinal cord; the black mass surrounding it is
a vertebra; a, the gullet, a part of the alimentary canal; h, the heart; sy,
sympathetic nervous system; JJ, lungs; the dotted lines around them are the
pleure; rr, ribs; st, the breastbone. From Martin.
lobes, cerebral hemispheres, the optic thalami with the
pineal gland, and the optic lobes; besides these lobes, which
are arranged in pairs, there are two single parts of the
brain, the cerebellum and the beginning of the spinal cord,
called the medulla oblongata.
The limbs each consist of a single long bone, succeeded
by two long bones, followed by two transverse rows of
short wrist or ankle bones, and five series of long finger or
toe bones called phalanges. For example, in the fore limb
of most vertebrates, as in the arm of man, to the shoulder
girdle is articulated the humerus; this is succeeded by the
ulna and radius; these by the wrist-bones or carpals, and
136 ZOOLOGY.
the finger-bones or phalanges, the single row of phalanges
forming the digit (finger or toe). To the pelvis are at-
tached the hind limbs, consisting each of a femur or thigh,
which is succeeded by the ¢idia and fibula (shank-bones),
which are followed by the tarsal and metatarsal bones
(ankle-bones), and by the phalanges or bones forming the
toes.
CLASSES OF VERTEBRATES.
1. Young with a nervous and dorsal cord........... Tunicata.
2. No skull or brain; blood colorless..............- Leptocardi,
3. Notocord persistent; no jaw-bones; six to ten pairs
Of Purse Ika PI Sv aes seksi seca eee Marsipobranchii.
4. Swimming by fins; with gills; a movable under
SEW sat choke: area iels an oe ateie team temas cinntene agi wrt Pisces
5. Amphibious; true limbs and lungs; skin smooth,
NO-SCalesNOsClAW Sc sraiac eos ve erosnie hirer waar Batrachia.
6. Claws and scales present ............. cece ee eens Reptilia.
7. Body covered with feathers; forelimbs forming
WADE Ss aioe os awh teeters Spied oats eine AOES:
8. Body covered with hair ; suckling their young. . - Mammalia.
Ciass I.—Tunicata (Ascidians, Sea-squirts).
General Characters of Tunicates.—While the Tunicates
were formerly supposed by some to be mollusks, and by
others worms, they have been found to possess in the lar-
val stage a notocord, above which lies a
rudimentary brain, with a spinal cord, and
even spinal nerves. A tadpole-like form
(Appendicularia) retains the fundamental
vertebrate features we have just noticed,
while all other Ascidians which undergo
a metamorphosis lose their tails, notocord,
Fig. 177.—Molgula. and nervous cord, and degenerate into or-
An Ascidian. . oer
dinary Ascidians.
The Ascidians are common just below low-water mark,
either hidden in masses of mussels, attached to the rocks
under sea-weeds, or the compound species may be found
forming bright-colored masses on the piles of wharves and
bridges, while the star-like Botryllus grows on the leaves
THE TUNICATES.
of eel-grass. On placing a good-sized As-
cidian in a vessel of fresh sea-water it will
be found to consist of a semi-transparent or +
quite opaque test with two openings, one
lower than the other, as seen in Molguia,
which looks, when the two orifices are pro-
truded, likeadouble-necked bottle (Fig. 177).
The anterior or higher orifice or mouth is
for the passage of currents of water into the
respiratory sac; and the posterior, usually
lower, excurrent orifice for the passage out-
wards of fecal matter. The test or outer
skin is either delicate and semi-transparent,
or it may be quite tough and opaque.
The Tunicates may in general terms be
characterized as having a usually rounded or
sac-like body, which is sometimes barrel-
shaped, bilateral, with a dorsal and ventral
symmetry, protected by a transparent or
dense test, containing cellulose, lined within
by a tunic surrounding the body-cavity.
There are two openings in the test, one oral,
the other ‘‘atrial;”’ the mouth leads into a
capacious pharyngeal respiratory sac, open-
ing posteriorly by an cesophagus into the
stomach, which is provided with a liver;
the intestine is flexed, and ends near the
esophagus. The nervous system is bilat-
eral, forming a double ganglionated chain
in Appendicularia, but is reduced in the
typical Ascidians to a single ganglion, sit-
uated within the tunic between the two open-
ings. There is a tubular heart, opening at
each end, and its beatings are often reversed,
the blood flowing in and out at either end.
A singular group of Tunicates is repre-
sented by Salpa, which is a pelagic form.
ra
d,
eff
Al
aA
be
Bo
rR ¥
i
it
=~:
ATE
ert
os
ae
a
1)
rH
=
SlCr
Fie. 178—Structure
of a compound
Ascidian, Ama-
recium. A, bran-
chial sac; m,
stomach; k,
intestine; ce,
mouth; o’, testis;
rr’, efferent duct
of the testis; C,
ovary; p’, egg in
the body-cavity;
p’, eggs in the
atrium; n, anus;
o shows the site
of the heart; J,
liver; e, openings
in walls of bran-
chial chamber,
138 ZOOLOGY.
There are in Salpa two kinds of individuals, i.e., the
solitary and the aggregated or chain Salpe.
The young of many Ascidians are born with a tadpole-
shape, in which there is a notocord, which, however, does
not extend to the brain, and the mouth-opening is dorsal
rather than ventral (Fig. 180), otherwise the larval Ascid-
ian is strikingly like the embryo lamprey: in both, the
ne el BO ES
a ht spt
Fia. 180.—Diagram of larval Ascidian. Lettering as in Fig. 179. m, mouth; i,
digestive tract; sp, spiracles in the pharyngeal portion; ht, heart; e, eye; er, ear;
br, brain; 2c, nervous cord; b’, b’’, mid brain; cl, cerebellum; spn, spinal nerves;
n, notocord, ol, nasal cavity; s, suckers (their homologues also occur in young
gar-pikes and tadpoles).
mouth leads into a pharynx with gill-openings; both have
. a rudimentary brain, and a notocord situated beneath the
nervous cord. The young Ascidian, then, is seen to have
the fundamental characters ascribed to the vertebrates,
though it loses them before growing up.
Ciass IJ].—Leprocanrprt (Lancelet).
The lancelet is the only type of this class. The body is
four or five centimetres in length, slender, compressed,
pointed at each end. The muscular segments are distinct
to the naked eye. From the mouth to the vent is a deep
ventral furrow, and a slight fin extends along the back and
ventrally as far front as the vent.
THE LANCELET, 139
The mouth is oval, surrounded with a circle of ciliated
tentacles supported by semi-cartilaginous processes arising
from a circumoral ring. The mouth leads directly into a
large broad pharynx or “ branchial sac” (Fig. 183, g), pro-
tected at the entrance by a number of minute ciliated lobes.
The walls of this sac are perforated by long ciliated slits,
comparable with those of the branchial sacs of Ascidians
and of Balanoglossus. The water which enters the mouth
passes out through these slits where it oxygenates the blood,
and enters the peribranchial cavity, thence passing out of
the body through the abdominal pore (Fig. 183, p). The
pharynx leads to the stomach (/f), with which is connected
the liver or cecum. ‘There is a pulsatile vessel or tubular
Fie. 183.—a, vent; f, stomach; g, pharynx; n, nervous cord; p, pore; 7, noto-
cord; ¢, tentacles. From Liitken’s Zoology.
heart, beginning at the free end of the liver, and ex-
tending along the under side of the pharynx, sending
branches to the sac and the two anterior branches to the
dorsal aorta, ‘‘On the dorsal side of the pharynx the
blood is poured by the two anterior trunks, and by the
branchial veins which carry away the aérated blood from
the branchial bars, into a great longitudinal trunk or
dorsal aorta, by which it is distributed throughout the
body.” (Huxley.) There are also vessels distributed to
the liver, and returning vessels, representing the portal
and hepatic veins. The blood-corpuscles are white and
nucleated,
The vertebral column is represented by a notocord
which extends to the end of the head far in front of the
nervous cord; and also by a series of small semi-cartilagin-
ous bodies above the nervous system, and which are thought
to represent either neural spines or fin-rays. ‘The nervous
cord lies over the notocord; it is not divided into a true
140 ZOOLOGY.
brain * and spinal cord, but sends off a few nerves to the
periphery, with nerves to the two minute eye-spots. There
are no kidneys like those of the higher Vertebrates, but
glandular bodies which may serve as such. The reproductive
glands are square masses attached in a row on each side of
the walls of the body-cavity. The eggs may pass out of the
mouth or through the pore. Kowalevsky found the eggs
issuing in May from the mouth of the female, and fertil-
ized by spermatic particles likewise issuing from the mouth
of the male. The eggs are very small, 0.105 millimetres
in diameter. The eggs undergo total segmentation, leay-
ing a segmentation-cavity which becomes the body-cavity.
The blastoderm now invaginates and the embryo swims
about as a ciliated gastrula. The body is oval, and the
germ does not differ much in appearance from a worm,
star-fish, or ascidian in the same stage of growth. No ver-
tebrate features are yet developed.
Soon the lively ciliated gastrula elongates, the alimentary
tube arises from the primitive gastrula-cavity, while the
edges of the flattened side of the body grow up as ridges
which afterwards, as in all vertebrate embryos, grow over
and enclose the spinal cord. When the germ is twenty-four
hours old it assumes the form of a ciliated flattened cylin-
der, and now resembles an Ascidian embryo, there being a
nerve-cavity, with an external opening, which afterwards
closes. The notocord appears at this time.
In the next stage observed the adult characters had ap-
peared, the mouth is formed, the first pair of gill-openings
are seen, eleven additional pairs appearing. It thus appears
that while the lancelet at one time in its life presents
Ascidian features, yet, as Balfour states, “all the modes of
development found in the higher Vertebrates are to be
looked upon as modifications of that of Amphioxus.”
* Langerhans has figured an olfactory lobe; and all observers
agree that a ventricle is present; thus there is a slight approximation
to a brain.
THE LAMPREYS. 141
Crass IIT.—Marsrpoprancui (Lampreys, or Cyclostomi).
General Characters of the Cyclostomatous Vertebrates. —
In the hag-fish and lamprey, representatives of the jawless
Vertebrates, the body is long and slender, cylindrical, the
skin smooth, scaleless, with only a median dorsal and ven-
tral fin (or in Myzine only a small lower median fin); the
mouth is circular, and in the lampreys armed with numer-
ous conical teeth. There is no bony skeleton; the spinal
column is represented simply by a thick rod (dorsal cord,
notocord) surrounded by asheath. The skull is cartilag-
inous, not movable on the vertebral column; is very imper-
fectly developed, having no jaws, the hyo-mandibular bones
and the hyoid arch existing in a very rudimentary state.
The few teeth present in the hag-fish are confined to the
palate and tongue; those of the lamprey are numerous,
conical, and developed on the cartilages supporting the lips.
The nervous system is much as in the fishes, the brain
with its olfactory, cerebral lobes, thalami, optic lobes, and
medulla being developed, the cerebellum in Myxine blended
with, in the lamprey free from the medulla. The digestive
canal is straight, with no genuine stomach, but the liver is
much as in higher Vertebrates. The respiratory organs
are very peculiar, being purse-like cavities (whence the
name Marsipobranchti), in the lamprey seven in num-
ber on each side of the pharynx, opening externally by
small apertures; internally they connect with a long cay-
ity lying under the esophagus, and opening anteriorly
into the mouth. The heart is like that of fishes, as are
the kidneys. The eyes are minute, sunlsen in the head and
under the skin in the hag (Myzine), but. larger in the
lamprey.
Another extraordinary feature in the class is the single
nasal aperture, as opposed to the two occurring in all higher
Vertebrates. The aperture leads to a sac, which in the
Myzine communicates with the mouth (pharnyx), but in
the lamprey forms a cul-de-sac.
142 ZOOLOGY.
The ovaries and male glands (the sexes being distinct)
are unpaired plates suspended from the back-bone, and have
no ducts, the eggs breaking through the walls of the ovary,
falling into the abdominal cavity and passing out of the
abdominal pore. The eggs of My«ine are very large in
proportion to the fish, enclosed in a horny shell, with a fila-
ment at each end by which it may adhere to objects.
The hag-fish is about a foot long and an inch thick, with
the head small, a median palatine tooth, and two comb-like
rows of teeth on the tongue. There isa single gill-opening
a long way behind the head; there are large mucous or
slime-glands on the side of the body, for these fishes are
very slimy. The hag lives at considerable depths in the
sea; we have dredged one at 114 fathoms in soft deep mud
off Cape Ann. It is often parasitic, attaching itself to the
bodies of fish, and has been found to have made its way
into the body-cavity of sturgeons and haddock.
The lamprey lives both in fresh and salt water. The
eggs of the common lamprey, Petromyzon marinus (Linn.),
are laid in early spring, the fish following the shad up the
rivers, and spawning in fresh water, seeking the sea in
autumn; small individuals, from five to seven inches long,
have been seen by Dr. Abbott attached to the bellies of
shad, sucking the eggs out of the oviducts.
The lamprey when six inches long is quite unlike the
adult, being blind, the eyes being concealed by the skin;
it is toothless, and has other peculiarities. It is so strangely
unlike the adult that it was described as a different genus
(Ammocetes). P. nigricans Lesueur is smaller, and oc-
curs in the lakes of New York and eastward, while P. ‘ger
Rafinesque is still smaller, and lives in the Western States.
Crass IV.—Pisces (Sharks, Rays, Sturgeons, Garpikes,
and bony fishes).
General Characters of Fishes.—We now come to verte-
brates which have genuine jaw-bones and fins in pairs, and
SHARKS AND RAYS. 143
which, m short, are allied to the Batrachians, and through
them with the reptiles, birds, and mammals. All the fishes
agree in having a true skull, to which is attached a mova-
ble lower jaw. The brain is well developed and the blood
isred. Fishes breathe by gills, which form four arches on
Dorsal fin.
Caudal.
Anal. Ventral. Pectoral.
Fie. 184.—The Mud-Minnow, with the names of the fins.
each side of the throat. The body is usuaily scaled. They
are mostly oviparous; some bring forth their young alive.
SuB-CLASSsES OF FISHES.
1. Skeleton cartilaginous; 5-7 pairs of
gill-Openin gs... i625 ssap coisa acess Hlasmobranchii: Sharks, Rays.
2. Skeleton cartilaginous or bony;
scales often square, enamelled. .Ganoidei: Sturgeon, Garpike.
8. Skeleton bony, of numerous sep-
arate bones; 4 pairs of gills...... Teleoste’: Cod, Perch, etc.
Sus-Ciass I—ELAsMoBRANCHII (Selachians, or Sharks
and Rays).
These are called Elasmobranchs from the strap-like
gill-openings (edasma, strap, and branchia, gill). The
sharks, though fish-like, are very different from ordi-
nary bony fish. Their skeleton or skull is so soft that it
can be cut with a knife, while the tail is one-sided, the ver-
tebral column ending in the larger upper lobe. They also
have from five to seven gill-openings or slits, whereas the cod
or perch has but one. The skin is either smooth, or with
minute scales, forming shagreen. Both jaws are armed
with numerous sharp, flattened teeth. arranged in rows and
144 ZOOLOGY.
pointing backward, enabling them to seize and retain their
prey.
Sharks and skates are engines of destruction, being the
terror of the seas. Their entire structure is such as to
enable them to seize, crush, tear, and rapidly digest large
Fia. 185.—Cestracion, or Port Jackson Shark. From Liitken's Zoology.
fishes or other marine animals. Hence their own forms are
gigantic, soft, not protected by scales or armor, as they
have few enemies. Hence they do not need a high degree
of intelligence, nor special means of defence or protection,
Fia. 186.—Mackerel Shark.
though from their activity the circulatory system is highly
developed, the muscular aortic bulb being provided within
with three rows of semi-lunar valves.
The eggs of sharks and rays are very large compared with
those of bony fishes. The Cestracion (Fig. 185) is an old-
fashioned form, which inhabits the Australian seas.
THE SHARKS. 145
Order 1. Plagiostomt—Our most common shark is the
mackerel shark (Jswrus punctatus, Fig. 186). It is from
four to eight feet in length, and is often taken in fish-nets,
being a surface-swimmer. In the thresher shark (Alopecias
vulpes), the upper lobe of the tail is nearly as long as the
body of the shark itself. It grows twelve or fifteen feet in
length, and lives on the high seas of the Atlantic.
Nearly twice the size of the thresher is the great basking
shark, Selache maxima, of the North Atlantic, which be-
comes nine to thirteen metres (thirty or forty feet) in
length. It has very large gill-slits, and is by no means as
ferocious as most sharks, since it lives on small fishes, and
Fia. 187.—Carcharias. From Liitken’s Zoology.
in part, probably, on small floating animals, straining them
into its throat through a series of rays or fringes of an elas-
tic, hard substance, but brittle when bent too much, and
arranged like a comb along the gill-openings, the teeth
being very small.
Among the smaller sharks is the dog-fish (Squalus Amert-
canus), distinguished by the sharp spine in front of each
of the two dorsal fins. It is caught in great numbers for
the oil which is extracted from its liver. The dog-shark
(Mustelus canis), which is a little larger than the dog-fish,
becoming over a metre (four feet) long, brings forth its
young alive.
The hammer-headed shark is so called from the head
projecting far out on each side, the eyes being situated in
the end of each projection.
146 ZOOLOGY
It grows to the length of twelve feet, and is one of the
most rapacious and formidable of sea-monsters. Among
the largest sharks are the species of Carcharias (Fig. 187)
One species frequents the Ganges, occurring sixty leagues
from the sea.
Of the rays and skates, the saw-fish (Pristis antiguorum)
approximates most to the sharks. Its snout is prolonged
into a long, flat, bony blade, armed on each side with large
teeth (Fig. 188). The common saw-
fish inhabits the Mediterranean Sea
and the Gulf of Mexico; it is vivipa-
rous (Caton). Pristis Perroteli lives
in the Senegal River.
The genuine skates or rays have
the body broad and flat and rhom-
boidal, owing to the great extension
of the thick pectoral fins. They
swim close to the bottom, feeding
upon shell-fish, crabs, ete., crushing
them with their powerful flattened
teeth. The smallest and most com-
mon skate of our northeastern Atlan-
tic coast is Raja erinacea. It is one
half of a metre (twenty inches) in
length, and the males are smaller
than the females. The largest species
is the barndoor skate, Raja levis,
which is over a metre (forty-two
inches) long. Raja eglanteria (Fig.
189) ranges from Cape Cod to the
Caribbean Sea. The smaller figures
in Fig. 189 represent respectively the
eae mouth and gill-slits, and the jaws of
Fie. 188.—Beak of Saw-fish, Myliobatis fremenvillit.
Fee Oe Perea aan In the torpedo the body is some-
Jateraliveeth: what oval and rounded. Fig. 196
represents Torpedo marmoratus of the Mediterranean Sea.
THE TORPEDO. 147
Our native specics, found mostly in winter, especially on
the low sandy shores of Cape Coda is Torpedo occidentalis.
Its batteries and nerves are substantially as in the Euro-
pean species. The electrical organs are constructed on the
principle of a Voltaic pile, consisting of two series or layers
Fig. 189.—Raja eglanteria, male. Mouth and gill-slits, jaws and teeth of Mylio
batis fremenvilliz
of six-sided cells, the space between the numerous fine
transverse plates in the cells filled with a trembling jelly-
like mass, each cell representing, so to speak, a Leyden jar.
There are about 470 cells in each battery, each provided
with nerves sent off from the fifth and eighth pairs of
nerves. The dorsal side of the apparatus is positively elec-
trical, the ventral side negatively so. The electrical cur-
rent passes from the dorsal to the ventral side. When the
448 ZOOLOGY.
electrical ray is disturbed by the touch of any object, the
impression is conveyed by the sensory nerves to the brain,
exciting there an act of the will which is conveyed along
UN ae
Hy eI Naseer a
ig neh
yt
rel ta
iy Ki) lly
wt
i
Fia. 190.—Torpedo marmoratus. a, brain; b, medulla oblongata; c, spinal cord;
d and b’, electric portion of the trigeminate or fifth pair of nerves; ee’, elec-
tric portion of the pneumogastric or eighth pair of nerves; /, recurrent nerve,
g, left electric organ entire; g’, right electric organ dissected to show the dis-
tribution of the nerves; hk, the last of the branchial chambers; 7, mucus-
secreting tubes.
the electric nerves to the batteries, producing a shock.
The benumbing power is lost by frequent exercise, being
THE TORPEDO 149
regained by rest; it is also increased by energetic circula-
tion and respiration. As in muscular exertion the electri-
cal power is increased by the action of strychnine.
Marey has more recently made interesting experiments
on the torpedo, examining the discharge of this fish with
the telephone. Slight excitations provoked a short croak-
ing sound. uch of the small discharges was composed of
a dozen fluxes and pulsations, lasting about one fifteenth
ofasecond. The sound got from a prolonged discharge,
however, continued three to four seconds, and consisted of
Fia. 191.—The Devil-fish. (Ceratoptera). From Liitken’s Zoology.
a sort of groan, with tonality of about m7 (165 vibrations),
agreeing pretty closely with the result of graphic experi-
ments,
Marey has also studied the resemblance of the electrical
apparatus of the electrical ray or torpedo and a muscle.
Both are subject to will, provided with nerves of centrifugal
action, have a very similar chemical composition, and re-
semble each other in some points of structure. A muscle
in contraction and in tetanus executes a number of succes-
sive small movements or shocks, and a like complexity has
been proved by M. Marey in the discharge of the torpedo.
The sting-rays (Zrygon) have no candal fin, but the
spinal cclumn is greatly elongated, very slender, and armed
150 ZOOLOGY.
with a long, erect spine or ‘‘sting.” Some live in fresh
water.
The devil-fish (Cephalopterus diabolus) of the coast of
South Carolina and Florida is the largest of our rays, being
eighteen feet across from tip to tip of its pectoral fins, and
ten feet in length, weighing several tons. It sometimes
seizes the anchors of small vessels by means of the curved
processes of its head and swims rapidly out to sea, carrying
Fia. 192.—Chimera vulgaris. From Liitken’s Zoology.
the craft along with it. Closely allied to our devil-fish is
the Ceratoptera (Fig. 191).
Order 2. Holocephali.—This small but interesting group
of sharks is represented by the Chimera (Fig. 192) of the
North Atlantic, and Callorhynchus of the antarctic seas.
In these fishes the four gill-openings are covered by a
membrane, thus approaching the true bony fishes; there
are but four teeth in the upper and two in the lower jaw.
Sup-Crass I].—Ganorpet (Garpikes, Lung-fishes*).
The term Ganoid was applied to these fishes from the
form of the scales, which in most of the species are angular,
square, or rhomboidal, and covered with enamel, as seen in
* The lung: fishes or Dipnoi now form Class V of Vertebrates,
LUNG-FISH. 151
the common garpike. In others, 2
however, as in the Amia and Dip- S
noans, the scales are rounded or 3
cycloid. The sturgeons (Fig. 193) 3
have the snout long and pointed, a
with the mouth underneath, and Ee
toothless, while the body is pro- v8
tected by very large scales. Aci- é4
penser sturio is the common sea- Wy): 3
sturgeon of our coast, ascending YA st
rivers. The shovel-nosed sturgeon, yy ss
Scaphirhynchops platyrhynchus, Yi Ae
has a spade-like snout. It inhab- Us ba
its the waters of the Mississippi Bis Bg
Valley. YA iy 3
The singular spoon-bill, Polyo- Yi ee
don folium (Fig. 194), is five feet Me es
long, smooth-skinned, has a snout Ws = z
one third as long as the body, and ii : fee
spatulate, with thin edges. It has
a very wide mouth, with minute
teeth, and lives on small Crus-
tacea. It abounds in the Missis-
sippi and its larger tributaries.
The Dipnot or lung-fishes are
so-called from the fact that often
being in pools and streams liable
to dry up, they breathe air directly,
having true lungs, like those of
frogs, as well as gills. From the
nature of their brain and 3-cham-
bered heart, the Dipnoans are quite
different from all other fishes, while
on the other hand the notocord
is persistent.
The body of the Dipnoans is
somewhat eel-shaped, though not
very long in proportion tv its thick-
1, 8, shoulder arch; 6, gill arches; a, upper,
the fin; e, heterocercal caudal fin; f, anal fin; g,
geon.
Fic. 193.—Stur
152 ZOOLOGY.
ness, and is covered with round scales. The pectoral and
ventral fins are long, narrow, and pointed, and the verte-
bral column extends to the end of the caudal fin, which
ends in a point, not being two-lobed as in other fishes.
The Australian lung-fish (Fig. 195) has but a single lung,
It attains a length of six feet. It can breathe either by
gills or lungs alone. Ordinarily it uses its gills, but when the
Fia. 194.—Spoon-bill fish. From Liitken’s Zoology.
fish is compelled to live during droughts in thick muddy
water charged with gases which are the product of decom-
posing organic matter, it is obliged to use its lungs. It
lives on the dead leaves of aquatic grasses, ete. The local
English name is ‘‘ flat-head,” the native name being “ bar-
ramundi.”
The African lung-fish (Fig. 196) has two lungs. It lives
EAD. 1 a
Fig. 195.—Ceratodus, or Australian Lung-fish. (The tail in nature endsina
point.)
on leaves in the White Nile, the Niger, and Gambia rivers,
where it buries itself in the mud a foot deep. A similar
lung-fish (Lepidostren) lives in the rivers of Brazil, and
the closely allied Protopterus in tropical Africa. Ceratodus
makes use of the lungs mainly when the muddy water is
saturated with gases from organic matter.
Finally we come to those American Ganoids whose skele-
GARPIKES. 153
ton is solid and bony. These are the garpikes and mud-
fish.
The garpikes (Fig. 197) have large mouths and large,
conical, sharp teeth, and the body is encased in -in enamelled
coat of muil. They are the terror of the Mississippi River
and its branches, as they destroy all the smaller fish. The
largest species is the alligator gar (Lepidosteus spatula),
Fig. 196.—Protopterus annectens, a Lung-fish of Africa. One third natural
size.
which is sometimes nearly three yards (three metres) in
length, and sometimes weighing several hundred pounds.
So hard is its armor, that a blow with an axe cannot pene-
trate its back, the only vulnerable point being its throat or
the back of itshead. It inhabits the lower Mississippi and
the stagnant bayous and sluggish streams entering it. The
So
oe Sa
Fie. 197.—Garpike.
spawn resembles that of the toad, forming long ropes sev-
eral inches in diameter, which are hung on old snags or
roots. The eggs are laid in December’ and January, the
young appearing in the spring, becoming fourteen inches
long by the end of August.*
* See an interesting account of this remarkable fish, by G. P. Dun-
bar, in the American Naturalist for May, 1882.
154 ZOOLOGY.
The mud-fish of Western and Southern waters (Ama
calva) is a connecting link between the Ganoids and com-
mon or bony fishes. It bears a general resemblance to and
is about the size of a bass. Its tail is less ‘‘ heterocercal ”
than that of the garpike, and thus it comes nearer to the
bony fishes.
Svus-Cxiass II].—Texzostet (Bony Fishes, Perch, Cod, ete.)
These are our common fishes, of which there are nearly
ten thousand species. The bones are small and exceedingly
numerous, a number of small bones forming the skull and
Fie, 198.—Auatomy of the Cunner, male. L, lateral line; Ht, heart; Ps, pseudo-
branchia; Sp, spleen: S, air-bladder; Ki, Ki’, kidney; bl, bladder; 7 testis;
A, aorta; B, brain; In, intestine; Li, liver; G, gills. Drawn by C. 8. Minot,
supporting the fins, so that we may in a single fish count
upwards of five hundred separate bones. In these fishes
there are four gills on each side, the single gill-opening
being covered with a lid or operculum composed of four
thin bones.
We would advise the student to dissect a perch, smelt, or any fish,
with the aid of the following description of the anatomy of the sea-
perch, which closely resembles the fresh-water perch. With a pair
of forceps, sharp scissors and knife the student, by the exercise of
care, may make a very fair dissection.
To dissect a perch the side-well of the mouth must be removed,
then the gill-cover; study the arrangement of the gills. Next make
ANATOMY OF FISH. 155
an incision along the median ventral line from the level of the pec-
toral fins to just before the anus, and following the upper edge of the
body-cavity upward and forward cut away the body-wall, taking
care not to injure the large swimming-bladder above, nor the heart
in front. Now open the pericardial cavity, which lies immediately
behind and below the gills (see Fig. 198, HZ). Cut away the muscular
masses around the back of the head; expose the cavity of the brain,
and remove the loose cellular tissue around the brain. If the gills
of one side are cut away and the intestine drawn out, the dissection
will appear very much as in Fig. 198.
The cavity of the mouth widens rapidly, becoming behind the bran-
chial chamber or pharynx, whence we can pass a probe outward
Fie. 199.—Anatomy of the brain of the Cunner, dorsal and side view. B, Ol,
olfactory lobes; the crura and the thalami not represented; H, cerebral hem-
ispheres; Q, optic lobes; Cb, cerebellum; M, medulla.
through any of the gill-slits. There is a single row of sharp-pointed
teeth in front on both the under and upper jaws; in the pharynx
above and below there are rounded teeth. At the side of the pharynx
are the four gill-slits aud the four arches. ‘The entrance of each slit
is guarded in front and behind by a row of projecting tubercles
appended to the arches. On the outside of each arch, except the
fourth, isa double row of filaments, richly supplied with blood-ves-
sels which, shining through, give a brilliant red color to the gills; on
the fourth arch there is butasingle row. At the upper and posterior
corner of the pharynx is the small opening of the short cesophagus,
The branchial chamber has an upward extension on the sides of
which lie the false gills (Ps), which are accessory respiratory organs
156 ZOOLOGY.
not connected with the gills proper, aud receiving their blood-supply
from distinct arteries.
The cesophagus dilates almost immediately to form the stomach
(partly concealed in the figure by the liver, Zz), which is hardly
thicker than the intestine (Zn). This last is of nearly uniform size
throughout, and after making three or four coils terminates at the
anus, immediately in front of the urinary and genital apertures,
The liver (Zz) forms an elongated light-brown mass resting upon the
stomach. The elongated gall-bladder lies between the liver and
stomach, somewhat imbedded in the substance of the former. There
is no pancreas, though it is present in sume fishes. The spleen (Sp)
lies between the stomach and intestine, in the mesentery; it is dark
reddish-brown in color.
The air-bladder (8) isa single large glistening sac, placed in the
dorsal part of the body-cavity. The air-bladder normally contains
only gases. It conceals most of the kidneys, which extend the
whole length of the body-cavity on either
side of the middle line, as two long strips
of a deep though dull red. They project
beyond the air-bladder in front (Av) and
behind (A7’).
The ovary is single, and varices greatly in
size according to the season. In the male
the sexual glands (testes) are double.
The heart (Zt) lies in the triangular peri-
cardial cavity; it consists of two portions,
the dark-colored venous chamber, or auri-
cle, above, and the lighter-colored arterial
chamber, or ventricle, below. The auri-
cle receives from above two large veins,
one from either side; these veins are called
__ the Cuvierian ducts. Furthermore, a large
ous ie ae vein, the sole representative of the vena
body ofa Cunner. Drawn cava of higher vertebrates, passes from
by C. 8S. Minot. < : : ‘
the liver, near its anterior end, through
the pericardium, and empties into the Cuvierian ducts near their
common auricular orifice.
The brain should be exposed from above by carefully removing by
a knife the skin and thin bones covering the brain-cavity. Begin-
ning in front, we notice the minute olfactory lobes and the olfactory
nerves proceeding to the nasal cavities. Behind the olfactory lobes
lie in succession the cerebral hemispheres (IL), optic lobes (Q), the sin-
gle cerebellum (Cb), and, lastly, the medulla oblongata (M).
A general idea of the two body-cavities, the nervous and visceral,
SOUNDS PRODUCED BY FISH. 157
will be obtained by cutting the fish through transversely. The ner-
vous cord is seen to lie above the vertebral column, the nervous canal
being formed by the interarching spinous process. Below the 7erte-
bral column is the large cavity containing the heart, stomach, 3tc.,
while the rest of the section is occupied by muscles. (C. 8. Minot.)
The noises produced by certain fishes are due to the
action of the pneumatic duct and swimming-bladder (Fig.
201, S, 8’), though different kinds of noises are made acci-
dentally or involuntarily by the lips or the bones of the
mouth, as in the tench, carp, and a large number of other
fishes. Over fifty species of fish are known to produce
sounds of somesort. The swimming-bladders of Trigla and
Fre. 201.—Swimming bladder (S, anterior, S’, posterior division) of the bleak; @,
cesophagus; l, air-passage of the air-bladder leading into the cesophagus.
From Semper.
Zeus have a diaphragm and muscles for opening and clos-
ing it, by which a murmuring sound is made. The loudest
sounds are made by the drum-fish. In some minnows,
pouts, and eels the sound is made by forcing the air from
the swimming-bladder into the cesophagus. In the sea-
horse, the sounds are caused by the vibrations of certain
small voluntary muscles.
The mud sun-fish (Acantharchus pomotis) utters a deep
grunting sound; the gizzard shad (Dorosoma cepedianum,
Fig. 202) makes ‘‘an andible whirring sound;” the chub-
sucker or mullet (Hrimyzon oblongum) ‘‘utters a single
prolonged note accompanied by a discharge of air-bubbles;”
the cat-fish produces ‘‘a gentle humming sound;” eels
158 ZOOLOGY.
utter a more distinctly musical sound than any other of
those observed by Abbot, who states that ‘‘it is a single
note, frequently repeated, and has a slightly metallic reso-
nance.” It should also be noticed that the organs of hear-
ing in many musical fishes are said to be unusually well
developed, hence these sounds are probably love-notes; and
Abbot notices the fact that these fishes are dull-colored
during the reproductive season, as well as at other times,
while voiceless fishes, such as the perch, common sun fish,
chub, rvach, ete., are highly colored during the breeding
Fie. 202.—Gizzard Shad.
season, and thus the sexes are mutually attracted in the
one case by music, and in the other by bright colors.
Finally, the sounds of fishes may be compared with those
of reptiles, birds and mammals, the air-bladder correspond-
ing to the lungs of the higher Vertebrates, while the pneu-
matic duct is comparable with the trachea of birds and
mammals.
In swimming, the propelling motion is mainly exerted
by the tail, the movements of which are somewhat hke
those of an oar in sculling. The spines of the tail-fin are
movable, and are capable of being brought into such a
position that the fin will meet with less resistance from the
BREEDING HABITS OF FISH. 159
water while the tail is bent; they are then straightened, and
it is when being straightened that the fish is propelled.
The movements of the pectorals and ventrals are to steady
the fish and to elevate and depress it, while the dorsal and
anal fins steady the body and keep it upright, like a dorsal
and ventral keel.
Among viviparous bony fishes are certain Cyprinodonts
(as Anableps and Pecilia), the eel-like Zoarces, and the
blind-fish of the Mammoth Cave.