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| Cornell alniversity Library
BOUGHT WITH THE INCOME
FROM THE
SAGE ENDOWMENT FUND
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Henry W. Sane
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ELEMENTS OF ZOOLOGY
THE MACMILLAN COMPANY
NEW YORK + BOSTON + CHICAGO
SAN FRANCISCO
MACMILLAN & CO., Limited
LONDON + BOMBAY + CALCUTTA
MELBOURNE
THE MACMILLAN CO. OF CANADA, Lrtp.
TORONTO
Kano Tiorta,
(JROUP OF BUTTERFLIES ON GOLDEN-ROD, TO ILLUSTRATE DISPLAY OF COLOR
ON WINGS.
Above, a fritillary (Areynnis); to the right, a nymph (Brenthis bellone); below, the
monarch (Anosia plexippus) ; to the lelt, a wood nymph (Satyrus),
ELEMENTS OF ZOOLOGY
TO ACCOMPANY THE
FIELD AND LABORATORY STUDY OF
ANIMALS
BY
\ 2 7O my 1r 7 r > s
CHARLES BENEDICT DAVENPORT, PH.D.
DIRECTOR OF THE DEPARTMENT OF EXPERIMENTAL EVOLUTION
CARNEGIE INSTITUTION OF WASHINGTON, AND OF THE
BIOLOGICAL LABORATORY OF THE BROOKLYN INSTI-
TUTE OF ARTS AND SCIENCES, COLD SPRING
HARBOR, LONG ISLAND
AND
GERTRUDE CROTTY DAVENPORT, B.S.
FORMERLY INSTRUCTOR IN ZOOLOGY AT THE
UNIVERSITY OF KANSAS
WITH FOUR HUNDRED AND TWENTY-ONE ILLUSTRATIONS
REVISED EDITION
Netw Bork
THE MACMILLAN COMPANY
1911
All rights reserved
Copyrient, 1900 and 1911,
By THE MACMILLAN COMPANY.
Set up and electrotyped. Published February, 1911.
Norwood ¥Press
J. 8. Cushing Co. — Berwick & Smith Co.
Norwood, Mass., U.S.A.
PREFACE
Tus book has been rewritten to make certain additions that
the experience of teachers has indicated would be useful
and to introduce some of the newer topics of general bionomic
or ecological importance whose study has marked the past
decade. Zoology is a rapidly growing science, and text-books
for secondary schools, no less than for colleges, must fre-
quently be rewritten to give a proper view of the subject.
The additions relating to anatomy are intended to round
out the student’s knowledge as gained from a first-hand dis-
section of certain type-forms. What these forms should be
is left to the teacher, but they are suggested in the treatment
of each chapter dealing with “anatomy and physiology.”
Some work in dissection of types is undoubtedly beneficial,
but the danger must be avoided of making the course primarily
anatomical. There is this great importance of anatomical
study — properly made by the student—that it gives him
an understanding of the internal mechanism of organisms,
including himself. In the modern development of medicine,
which is undertaking more and more to educate the general
public so that it may avoid disease, a knowledge on the part
of every child of the organs and functions of the body will
be of the greatest value. Indeed, it is hardly too much to
predict that some day the importance of the dissection by
every high-school child of a series of types leading to the
mammal shall be regarded as essential for carrying out the
v
vl PREFACE
programme of eliminating or at least diminishing the ravages
of tuberculosis and venereal disease upon our population.
On the other hand, an acquaintance with a variety of ani-
mals may well heighten an interest in nature and lift the
mind away from the sordid and petty things of which our
modern life in great cities is all too full. Fia. 90.— Cecidomyia, the Hessian-
ing from the water, the mosquito fly. a, larva; b, pupa. From
Hoste ak oes pupal sli: mk tis the ‘‘ Standard Natural History.”
legs and wings harden. Since a disturbance in the water at
this time would jeopardize
the life of the mosquito, this
insect always breeds in quiet
waters (Fig. 92). From the
habits of the larve it follows
that they can be easily killed
while in the pond by pour-
ing kerosene oil on the
water, for this forms a film
Fic. 91.— Culex, the mosquito. A, larva;
c, its respiratory tube. B, pupa; d, the
respiratory tubes; a, the end of the on the surface and prevents
abdomen with the two oar-like swim- : A a ‘ll
ming appendages, dorsal view. After respiration. Minnows wi
drawing of E. Burgess. free a pond from larve if the
edges of the pond are kept free from grass so as to allow the
fish to get to them.
Mosquitoes are not merely a nuisance, but are disseminators
of some of the most dangerous of human diseases. Malaria
86 ZOOLOGY
is due to germs of microscopic organisms that live in the
salivary glands of some kinds of mosquitoes (Anopheles) and
are injected into the blood of its victim at the time of biting.
The mosquito gets the malaria germs from the blood of infected
persons. Another genus (Stegomyia) found in the tropics dis-
seminates the germs of yellow fever. Still another species
Fic. 92.— A quiet water where mosquitoes breed.
conveys about a minute round worm, Filaria! hominis,’ allied to
the vinegar eel, which thrives as a parasite in the blood-vessels
of men living in the tropics, and causes a painful and usually
fatal swelling of the arms and legs. The embryos are found
in the surface circulation only at night, during which time man
is most defenceless toward the mosquito. At this time they
are sucked out of the blood by the mosquito and develop in
its alimentary tract. Later they are deposited in stagnant
1 fiium, thread. 2of man.
THE FLY 87
water with the eggs of the mosquito, and reach man’s body
again if the water be drunk by him.
The crane-flies (Tipulide,! Fig. 93) look like mosquitoes,
but can easily be distinguished from them by the fact that
they have a V-shaped groove on the back of the thorax. They
are larger, and have relatively longer legs than the mosquito.
Their legs are easily broken, and seem to be so much in the
Fic. 93.— A crane-fly. Nat. size. Photo. by W. H.C. P.
way that flight is clumsy. The adults are quite harmless, but
some of the larve work destruction by feeding upon tender
plants and causing them to wither and die.
There remain to be considered a number of degenerate flies —
degenerate because parasitic in the adult state. The first
family we may consider is that of the louse-flies.2 These
small insects have a firm proboscis used for piercing, and stout
legs. Only certain of the genera develop wings, and some of
these lose them after they gain their hosts. They live, like
lice, in the fur of mammals or the feathers of birds. They
1Latin, tipula, water-spider. 2 Suborder Pupipara.
8S ZOOLOGY
are viviparous, the larve being ready to pupate at the time
of birth. The sheep-tick is one of the best-known forms.
Diptera allied to the foregoing live as parasites on the body
of the honey-bee.
Fleas are likewise wingless, blood-sucking parasites. The
body is compressed from side to side, so that it can move easily
amongst the hairs of its host. The hindermost legs are strongest
and are used in springing. Fleas develop in dust in the cracks
of the floor and about the sleeping-places of domestic pets.
One species prefers mankind and is believed to disseminate
certain diseases such as the bubonic plague. They may be
combated by means of cleanliness and Persian insect powder.
The foregoing study of the Diptera shows how great a men-
ace they are to man’s health. But indirectly they are inju-
rious to man by attacking domestic animals and cultivated
plants. Thus the tsetse-fly is a menace to the commerce of a
large part of a continent. The horse-fly, the horn-fly, which
worries cattle, the buffalo-gnat, which worries or even kills
domestic animals, and the dangerous bot-fly are all causes
of great loss to industry. Also the larve of some flies infest
vegetables, such as cabbage, radish, cauliflower, onion,
as well as various fruits, and cause great damage. The
gall-enats destroy clover and its seed; and, worst of all, the
Hessian-fly infests wheat and Indian corn. This last-named
scourge, so called because of a tradition that it was imported
in the straw bedding of the troop-ships which brought over the
Hessian mercenaries in 1775, has spread, within a century,
over the eastern half of the United States, and has at various
times injured the wheat crop to the value of millions of dollars.
The larve of certain Muscidz! attack, in Europe, the stems,
1 Of the genus Chlorops.
THE FLY 89
leaves, and ears of wheat, rye, and barley, and cause in some
years great destruction, especially in Scandinavia.
Over against the injury wrought by the Diptera may be
placed certain benefits bestowed by them. In the first rank
come certain species which prey upon injurious insects, either
in the larval or adult stage. The robber-flies prey on the Dip-
tera, Hymenoptera, and certain beetles, but they are not care-
ful to choose alone injurious species. The larvee of the Syr-
phide prey on the injurious plant-lice; those of horse-flies are
carnivorous, and feed on insect larva. The larvee of certain
small flies are internal parasites of bugs, beetles, and other
(mostly injurious) insects. Finally, the larvae of some crane-
flies, robber-flies, and Syrphidx, by boring into rotten wood,
help in the work of forming forest mold. The Diptera, like
almost every other insect group, has its economically injurious
and beneficial species. However, the good that they do is so
small in comparison with the destruction that they directly
cause to animals and plants by worrying or feeding upon them
or by bringing to them various noxious and fatal diseases
that, on the whole, the world would be a better place to live
in if there were no Diptera.
CHAPTER VI
LITHOBIUS
A STUDY OF LIGHT-SHUNNERS
Man is a diurnal animal, loving the sunlight. The animals
that we know best are those that are active in the daytime
since we ourselves are most active at that time. But many
Fic. 94.— A colony of light-shunners under an upturned stone. From above
downward in the figure, an earthworm, a short-winged beetle, a Julus, an
ant with pups, and a carabid beetle.
classes of animals are entirely nocturnal. This is true because
their organization is such that a strong light is disagreeable
to them. They shun a strong intensity of light, and so in the
daytime are found hidden under stones (Fig. 94) or the bark
90
LITHOBIUS 91
of trees (Fig. 94 a), in deep woods or in caves. If one of these
light-shunners is placed on a table near a window, through
which the sunlight is falling, it will turn tail to the sun and
move away from the window. If one goes out at night with
a lantern, however, one will find many animals running about
on the surface of the ground seeking for food or for their mates.
Many light-shunners, such as those that live in caves, remain
Fic. 94a.— A colony of light-shunners on the under side of an upturned piece
of wood. From left to right, Armidillidium, Oniscus, Helix, and Lithobius.
there during their entire life, never experiencing rays of natural
light. They get into the caves in the first place because they are
light-shunners and because their organization fits them to live in
the dark. Like most light-shunners, cave animals love not only
darkness but contact and moisture as well; all of these con-
ditions they find in caves, particularly in damp crevices and
corners. Very many close relatives of cave animals are to be
found outside of caves in greenhouses, secreted under boards
during the daytime, just because they find in greenhouses the
conditions of equable temperature, moisture, and contact
which their nature demands,
co
Lo
ZOOLOGY
The principal large cave animals are various bats, which are
found clinging to the walls ; a few salamanders, allied to our
little red salamander of the woods (Fig.
many of which are blind.
LD
95); and certain fishes,
A number of insects live in caves.
fs > The commonest are two or three kinds of
e ie small beetles that live under stones and a
4 few flies that live in decaying matter; a
% ro) cricket-grasshopper, already referred to on
ee aa page 20; a little ‘‘spring-tail,” the minute
ew . aes X insect which swarms on the damp rocks.
a \* There are also a few myriapods, which we
! ie \ shall study further in this chapter; some
faye spiders; a blind cray fish, which lives in the
he, streams that usually flow through caves;
pete and a few smaller crustaceous animals.
i ie? ‘Pes\ Each of these groups is more fully con-
ee a4 sidered in the following paragraphs.
ma Hy The bats, of which about 500 species from
* all parts of the globe are known, constitute
“an one of the most specialized groups of Mam-
Xo mals. They are able to
“hs =, fly, owing to the great
Se OTe elongation of their fin-
Fig. 95.— Adult of Spelerpes maculicaudus, 2ePS and to a delicate
the-cive aalerinnider: membrane stretched he-
They fly almost exclusively
dusk ; and they seem to be guided less
tween them. at night or toward
by their eyes than by
the vast number of delicate organs of touch that are scattered
over the wing membrane. Also the tip of the nose is crowded
with touch organs, which are often borne on a fantastically
folded membrane. The outer ears are usually very large,
LITHOBIUS 93
indicating an acute sense of hearing. These peculiarities
are special adaptations to a nocturnal life in which other
senses replace that of sight. During the daytime bats lie
hidden in hollow trees, crevices of rocks, in caves, and behind
window blinds of houses. Little explanation can be given
for their peculiar relation to light; it does not seem to be an
adaptation to feeding on nocturnal animals, for many bats
are frugivorous. Doubtless they gain from their nocturnal
habits a certain immunity from attack by hawks and other
birds of prey. The most primitive of the living bats fly late
in the day. As the group evolved the habit of flying at night
was subsequently acquired, and this suggests that bats have
been getting more and more sensitive to light. In caves, bats
fly back and forth but pass often into the free air to capture
flying insects. Then, before dawn breaks, they return to the
darkness of the cave.
The commonest salamander that inhabits our caves belongs
to the species Spelerpes maculicaudus. This genus is wide-
spread, being known from New England to Minnesota and
into the Southern States. In New England, where there are no
caves, it lives among the rocks and, like its relatives of the
same genus, prefers moist crevices and lies concealed during
the day. Wherever there are caves, as in Indiana and Ken-
tucky, this salamander is found inhabiting them in great num-
bers, just because the caves offer the conditions to which they
are adapted. The eyes of this salamander are functional, but
there are other, less common, cave salamanders whose eyes
are degenerating.
The cave fishes of the United States all belong to one family.’
Those members of the family that live in caves have a
1The Amblyop’side (Fig. 95a).
94 ZOOLOGY
colorless body and eyes that are rudimentary or concealed
beneath the skin. Their behavior has been thus described:
“ Tf these Amblyopses be not alarmed, they come to the surface
to feed, and swim in full sight, like white aquatic ghosts.
They are then easily taken by the hand or net, if perfect
silence is preserved, for they are unconscious of an enemy
except through the medium of hearing; this sense, however,
is evidently very acute, for at any noise they turn suddenly
downwards, and hide beneath stones, etc., on the bottom ”
(Cope). There is, however, reason for thinking that their
Fic. 95 a.— Amblyopsis, the cave blind-fish, from Blatchley : ‘‘ Glean-
ings from Nature.”
tactile sense is acute, for the head is provided with numerous
tactile warts. These fishes spend their whole life in the caves,
never seeing the light of day, and the question arises, whence
did they come, how did they get into the caves, and why are
they blind? As to the first question it is certain that they must
have come from surface streams, because all their numerous
close relatives still live above ground. To learn how the blind
fishes got into caves we must study their relatives above ground,
and we shall find that some inhabit dense swamps and others
occur under stones in springs. The whole family of Ambly-
opsidze are light-shunners and, being such, a cave has offered
the best possible place for one of this family. As to why they
are blind it appears that it is not due to their cave life, since
some of the relatives above ground in regions where there are
LITHOBIUS 95
no caves have degenerating eyes. One may say that Ambly-
opsis came to inhabit caves because it was going blind rather
than that it became blind because it got into a cave. ‘
Of the cave beetles one belongs to the genus Quedius. It
is found not so far within the cave but that a dim light reaches
it. The adults are not wholly blind. It feeds on excrement
or decaying remains of cave animals. Now Quedius is a
large genus of the family of Staphylinide (page 66), most of the
members of which are scavengers. As Quedius
above ground is usually to be found under or
embedded in decaying matter where it is in the
dark, it involves no change of habits to be
a scavenger of the caves. Another beetle —
Anophthalmus '— has gone further ; it is found
at the darkest part of the cave and is wholly
blind. It belongs to the family of Carabide
(page 64) which are predaceous beetles that Aes
hunt chiefly at night. Anophthalmus mayhunt from —_Blateh-
é sais é ley: ‘‘Glean-
all day and all night, for it livesin eternal dark- ings from
ness, and can get a supply, although all too Nature.”
scanty, of living prey such as spiders, mites, and springtails.
The flies are among the most abundant of the inhabitants
of caves. The commonest species are short-horns, which
congregate in moist places on the walls and are exceedingly
sluggish in their movements. Their larve live in the excre-
ment of the larger animals or in carcasses. Outside of caves
these flies are found under wood or stones.
The cave crickets belong to the genus Ceuthophilus (page
20). Their sight is defective, but they are sensitive to touch.
Since the other members of the genus that live above ground
1Fig. 96.
96 ZOOLOGY
hide during the day, it is easy to understand that the cave
affords a favorable environment for such a light-shunning
species.
The springtails, some of which live in caves, are among the
smallest and simplest of insects, and perhaps the most numer-
ous in individuals (Fig. 97). On a single bare beach one-fourth
of a mile long the number of springtails living
between high and low tide has been estimated
at 100,000,000. The group as a whole loves
moisture. They also love contact, so one sees
them burrowing into the sand. They are
seen to be most numerous at night; they
shun the light. Finally, they feed on any
organic débris. This is evidently a group
that is fitted to live in caves, and so the
springtails are found in the caves of both
Fic. 97.-A spring- America and Europe. Some of them in the
tail. (From Parker Gayes are blind and colorless. But this con-
and Haswell’s
Text-book of dition is not to be attributed only to the
Zoology.)
absence of light, for some of the allies of the
cave springtails that live above ground are colorless and blind.
Also some of the individuals of one species, at least, live above
ground, while other individuals live in caves. Both sets shun
the light of day; but it is only certain fortunate individuals
that have got into caves.
Most of the spiders that live in caves are related to those
that. build cobwebs in our cellars and barns. It is easy for
such lovers of darkness and moisture to find a suitable home
in caves. But the cave species live under stones and make
only a few strands of web. They seem to feed on the larger
springtails.
LITHOBIUS 97
Finally, the blind crayfish deserves a further word besides
the brief reference in Chapter VIII. Most boys know that
all crayfishes love the darker parts of streams, and when placed
in strong light, they act as though it were painful to them.
As they live in streams they would, in cavernous countries,
often be brought to the point where a stream issues from a
cave. The darkness of the cave would be a lure to them.
Consequently some of them in time would come to be perma-
nent inhabitants of it. The loss of sight and pigment would
follow.
Thus we see, in general, that the fauna of caves is not an
accidental one, nor one made up of accidentally associated
animals. It is a society of light-shunners. They are lucky
to have a cave to live in.
Lithobius belongs to the group Myriapoda,! which is closely
allied to insects, but is characterized by life in dark, moist
places. The Myriapoda differ from most insects in being
wingless and in having the body divided into two regions,
head and trunk, and in having either one or two pairs of legs
on each segment of the trunk, so that there are, all together,
many pairs of legs instead of only three as in insects.
There are two principal groups of Myriapoda, the Centipedes
and the Millipedes. The Centipedes (Chilop’oda *), to which
group Lithobius belongs, have only one pair of appendages
to each body segment. They are active and ferocious animals.
All are terrestrial and live chiefly under stones and bark, within
or under decaving wood, among barn-yard refuse, in loose
soil, and under fallen leaves. Chilopods feed upon living
1 myrios, very many; pous, foot.
2 More correctly Cheilopoda, from cheilos, lip, and pous, foot; because
the mouth parts (modified feet) are partially united to form a sort of lip.
H
98 ZOOLOGY
insects, mollusks, and worms, and may be useful to agriculture
through the destruction of injurious insects. Lithobius has
been observed to spend hours in killing an earthworm, whose
juices it sucked as food. _Bluebottle flies also serve it as food
while in confinement.
Litho’bius! is of world-wide distribution, and over one
hundred species are recognized. Our common straw-colored,
Fig. 98.— A piece of upturned bark with a colony of light-shunners, — Litho-
bius, a sow bug, a pill bug, and a small snail.
Eastern species, Lithobius forficatus? (Fig. 98), is found also in
South America, as well as over most of Europe. It seems
to be replaced south of Virginia by another species, spinipes.
Scutig’era * is easily distinguished by its long legs; its hind
legs, indeed, are longer than its trunk (Fig. 99). Our common
Itastern species (rare north of New York City) is about 25
centimetres long, and is of a light brown color, with stripes on
the back. It is very active, and feeds especially on spiders.
It looks something like a spider itself when in rapid movement.
1lithos, stone; bios, to live. 2 provided with shears, forfex.
3 scutum, shield; gerrere, to bear.
LITHOBIUS
—_
>
Lae
\
oe
\\
are
ca
ca Re en ea
Fic. 99.—Scutigera. Nat. size.
From Wood.
99
The Scutigeras are characteristic
_ of the tropics, where they live
preferably in cellars, crawling up
horizontal walls.
Scol’opendra! includes longer
and stouter myriapods than Litho-
bius (Fig. 100).
belong the poison-
ous centipedes of
tropical countries.
Among these is the
giant Scolopendra
of our Southern
States, South
America, and the
West Indies, which
reaches a length of
25 centimetres or
more. This ani-
mal has a poison-
ous bite, which is
fatal to insects and
other small ani-
mals, and causes painful and even dangerous
wounds uponman. The biting apparatus is the
first pair of feet, modified to form sharp hooks,
and provided with poison-glands, which open
near the apex of the claw.
According to Hum-
boldt, the Indian children of South America tear
off the heads of large centipedes and eat the remaining portions.
1 Greek name for milliped.
To this genus
Fic. 100. — Scolo-
pendra. Nat.
size. From
Leunis.
100 ZOOLOGY
Geoph'ilus' includes relatively slow-moving species, often
attaining great length, having up to two hundred segments to
the trunk (Fig. 101). The species are common in
Europe and America. They live mostly under
stones. There is a European species, Geophilus
electricus, which is phosphorescent and shines
in the dark like a glow-fly.
The Millipedes, or Diplopoda, have, as the
name implies, two pairs of legs to each segment
of the trunk. They are usually more or less
cylindrical animals. The antenne are rather
short, and the jaws, which are somewhat shorter
than the centipede’s, lack the poison-glands of
Pes. nee that group. Accordingly we find the muillipedes
ophilus mor- feeding not upon animal but upon vegetable
dav. Nat.
size. Photo.
by W.H.C.P. parts are well adapted. The following millipedes
substances, for the chewing of which their mouth
representing two families, can be found under boards in almost
any greenhouse.
Julus is commonly known as the galley-worm (Fig. 102).
The members of this genus crawl rather
slowly, and when at rest coil the body. *
When disturbed, they give out a strong
odor through lateral openings of the body.
They feed on dead snails and earthworms ; p,4. 102. — ulus eana-
some species, on ears of Indian corn or — densis. Nat. size.
: é sau Photo. by W.H.C.P.
strawberries. Their eggs are laid in holes
in the ground in the spring; consequently they may be easily
dug up at this season.
Pol’ydesmus ” includes somewhat flattened species, which,
1ge, the earth ; phileo, to love. 2 polys, much; desmos, band.
LITHOBIUS 101
when disturbed, roll up spirally. P. canadensis, of the northern
United States, is deep brown, with hairy antennze (Fig. 103).
These myriapods are destructive to agri-
culture, especially to cabbage and straw-
berries.
Two genera of myriapods which stand
somewhat isolated deserve a passing
notice. Pau’ropus! and allied genera
include a few animals, about 1 millimetre
long, found on the moist loam of woods.
They are intermediate between chilopods
and diplopods, inasmuch as they have only
one pair of legs to a segment, but the Leta
segments tend to unite in pairs. Scol/open- eG, - oe
drella? is a small, white species, having tus). » 1.5. Photo. by
very large antenne and a pair of back- WD ESE
ward-directed stylets. The mouth parts are very much like
those of the lowest insects, so that Scolopendrella bridges the
gap between myriapods and true insects. The presence of
these connecting species indicates that the groups that are now
separated are of common origin.
rf
al
yy
a
CO ae aT mr A Nu
Ge: ae i A ae
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eat
Fic. 104. — Peripatus, the air-breathing, wormlike animal that bridges the
gap between Myriapods and worms.
Finally, the myriapods seem to be connected with the
worms by a peculiar air-breathing tropical animal known
as Perip’atus (Fig. 104). In many details of structure this
resembles a polychaetous worm (Chapter XI).
1 pauros, small; pous, foot. 2 Diminutive of Scolopendra.
CHAPTER VII
THE SPIDER— A STUDY OF ANIMAL ARCHI-
TECTURE
Most plants are rooted to the soil, while most animals are
free to move from place to place. Nevertheless many species
of animals, particularly the higher ones, have some place to
which they repeatedly return and which may be called their
Home. This home is usually the place which serves to rear
the young and to shelter both them and their parents.
The simplest sort of a house consists of a lot of agglutinated
particles of sand enveloping the body of the animal. Within
this sand-tube the eggs may be laid. Such a tube of sand is
constructed by many worms (page 188). Certain mollusks,
which are protected by hard shells, make burrows in rocks
in which they pass a part of their lives. When these mollusks
are very numerous (page 230), the rocks may be quite honey-
combed by their burrows. Many of the higher crustaceans
form more or less permanent burrows in the sea bottom, where
they may dwell and protect their eggs during the breeding
period. All of these sorts of homes, however, are very simple
architecturally compared with those of some insects, spiders,
and vertebrates.
Certain burrowing insects, like the termites (page 26) and
ants (page 53), build complicated communal homes within
the earth. Others, like the wasps (page 51) and bees (page
49), construct nurseries of mud, paper, or wax. In the group
of spiders complicated structures have been developed, less for
102
THE SPIDER 103
the purpose of protecting the young or forming a communal
home than for the purpose of entrapping prey. The forms of
webs invented by spiders are very numerous and their study
is full of interest. We shall consider them further on, after we
have learned something of their structure (Fig. 105).
In the vertebrates the simplest homes are those made by
Fig. 105. — Web of Tetragnatha, placed horizontally over a fish-way. Photo.
by W. BAG. P.
fishes. These may be merely piles of pebbles to cover the eggs
or they may rise to the complexity of nests woven of plant
fibre, as in the case of the sticklebacks (Fig. 315). The compli-
cated nests built by birds, for the purpose of rearing their
young, reach their highest| expression in our Baltimore
oriole and in the tailor bird of Australia. Finally among
the mammals we find examples of animals that burrow
like the wood rat of the Great Basin; that build houses
104 ZOOLOGY
of sticks, like the muskrat and beaver; that build nests
in trees, like the squirrel; and that rear houses of skins,
thatch, brick, stone, and wood, like man.
Fic. 106.— Mygale, a tunnel-weaver, allied to the ‘‘ trap-door spider.”
Nat. size.
In the present chapter we shall consider a group of Arthro-
pods, in which some sort of architecture is nearly universal.
This is the group of Spiders (Araneina). They are charac-
terized by the fact that the head and thorax are united in
one piece, called the cephalo-thoraz. The abdomen is con-
nected with the cephalo-thorax by a stalk and bears the spin-
ning organs (called spinnerets) at its hinder end (Fig. 106).
THE SPIDER 105
Compound eyes and antennz are absent, and so we see that
spiders are very unlike insects. The first pair of mouth
appendages are called chelt’cere and end in claws, at whose
apices the poison-glands open to the exterior. The second
pair of mouth parts, called pedipalps, are long and seem to
take the place of antenne. Near the stalk of the abdomen
on the ventral side is a pair of slits
which open into two lung sacs. In
a few spiders there is a second pair
of slits; such spiders have four
lung sacs.
All spiders spin a nest, but all do
not spin webs. The large webs
that attract our notice are the per-
fected product in the evolution
of spinning. The most primitive
spiders appear to be those that rive WA eee
burrow in the earth and line their mon grass spider. Nat. size.
Photo. by W. H.C. P.
tubes with silk. Such spiders are
known as tunnel-weavers. They are found in our Southwest-
ern States and are commonly known as trap-door spiders. The
lid of the tube or tunnel is made of dry clay and is penetrated
through and through by the spun silk. When the lid is closed, it
looks exactly like the ground around it, so that the opening is easily
overlooked. Some of these spiders acquire great size (Fig. 106).
A step in advance is seen in the tube-weavers (Fig. 107).
The tube-weavers spin in the grass their tubes of silk, at the
bottom of which they live, while at the outer end they build
over the grass a platform, which serves them mainly as a trap
for jumping insects. Such are the webs that one sees in the
grass on a dewy morning (Fig. 108).
106 ZOOLOGY
Next we have certain spiders which build irregular webs.
Such are the line-weavers. To this group belong the common
cobweb spiders of our cellars and outhouses. The web consists
of a fine irregular mesh with strands running above and below
it in various directions. The spider stands below the main part
Fie. 108.— Web of a tube-weaver Tegenaria ; looking down upon the web,
which is in a corner between two vertical walls. The tube is in the angle.
Photo. by W. H. C. P.
of the web, hanging back downward. Such a web serves to
entangle and hold flying insects upon which the spider preys
(Figs. 109, 109 a).
Finally the orb-weavers (Orbitelariz') spin a web lying
mostly in one plane and having a geometric form often of re-
markable perfection and symmetry. Such extraordinary struc-
tures deserve careful attention. Foundation lines (Fig. 110) of
unusual strength are first laid down to form the outer frame
lorbis, circle; tela, web.
THE SPIDER 107
of the web. Then radii are spun from a central little ball of
floss to the frame. The radii are, often at least, laid down
alternately on opposite sides of the centre. The number of radii
formed by a species of spider is not perfectly constant, but
Fria. 109.— Web of a line-weaver. Photo. by Emerton.
varies within limits. It would be an interesting occupation
to sketch a number of webs of Argiope, showing the variations
in the number of radii and the other details of form. After the
radii are placed, the spiral lines are laid down. In the com-
pleted web four regions are distinguishable, as follows, passing
from the centre outward: (1) the inner spiral zone, consisting
of four to eight turns at the centre; (2) the free zone inwhich
108 ZOOLOGY
no spiral is laid down; (3) the outer spiral, the main part of
the spiral framework ; (4) the foundation space, beyond the
spiral lines, and at the outer margin of the web (Fig. 111).
No study is more interesting than that of the details of
a
NN
Fic. 109a.— Web of Linyphia, one of the cobweb spinners, in a spruce tree.
Photo. by Emerton.
construction of these parts of the spider-web, while they are
being made out of doors or in large glass jars.
The web of the orb-weaver has undergone, in different species,
very striking modifications. Thus, in some cases only frag-
ments, asit were, of an orb are built (Fig. 112). In one case
the spider lives in a recess behind the web and keeps in touch
with the web by means of a line running to its centre. By pull-
ing upon this line the centre is drawn back towards the
THE SPIDER 109
spider. If an insect should enter the web, the spider releases
its pull upon the central part, and the web springs out-
ward, strikes the insect, and causes it to adhere to the
threads.
While, on the one hand, some spiders have evolved in the
direction of the construction of complicated webs, some, on
the other hand, have never ac-
quired the web-spinning habit.
Such, for example, are the wander-
ing spiders, which may be classi-
fied into three chief groups.
(1) Crab spiders are so called
because they run sideways. They
make nests by fastening together
leaves by threads of silk. Their
young are reared in these nests,
and watched over by the mother
Fra. 110.— Diagram on nomencla-
(Fig. 113). ture of partsof anorb-web. FS,
(2) Running Spiders. — These foundation space; SS, spiral
: space; CS, central space; FZ,
are for the most part large and freezone; NZ, notched zone; H,
powerful species which wander entte-_ From MeCook.
over fields or along watercourses in search of prey. Our North-
ern species are chiefly “wolf spiders” (Lycoside,’ Fig. 114).
The female carries her eggs about in a special cocoon attached to
ge Pp
the end of the abdomen. The young are borne on the back
of the mother. The great size, black color, and hairiness of
some of these spiders have given them an apparently unjusti-
fied reputation of being very poisonous. Naturalists who have
allowed these spiders to bite the hand report that the bite is
rarely more poisonous than that of the mosquito. Some of
1 lykos, wolf,
110 ZOOLOGY
the Lycoside live on sandy wastes (Fig. 115), where they make
holes in the ground lined with silk (Fig. 116).
(3) Jumping Spiders (At’tide!).—This family includes
many familiar, active species of high intelligence. Some of
Fic. 111.— Orb-web of Epeira. a, first spiral line ; b, second spiral line ;
c, line to nest. From Emerton.
these of grayish color live in houses, and are recognized as mem-
bers of this family by their half-running, half-jumping gait
(Fig. 117). The cocoon is attached to some object and enclosed
in a sort of tent, in which the mother also lives to guard the
young.
Other Uses of the Spinning Instinct. — We have seen that
1 }rom Latin, Aéta, club-footed man.
THE SPIDER 111
spiders make webs of the silk that they spin and that many
ground spiders line their nests with silk. Silk is, however, used
for many other purposes, and it would be difficult to say
which is the principal use. The mass of eggs that the female
lays is always covered by a
cocoon of silk. The silky
threads may serve also to
suspend the spider while it
drops from a tree, or they
may, by their friction with
the air, serve to suspend cer-
tain spiders in aerial migra-
tions.! This latter use is es-
pecially noteworthy. A small
spider, when desirous of tak-
ing flight, climbs up some
high object, such as a fence Fre. 112.— Web of Hyptiotes in a
post, elevates the spinnerets, eee ae CE 1G eae
and spins loose silk into the
air (Fig. 118). After enough of it has been thus formed, the
spider lets go, and is supported by the currents in the air
while it is wafted great distances. Thus Darwin, on his
voyage in the Beagle, saw cobwebs bearing up spiders floating
in the air over his vessel more than sixty miles from shore.
1 The ballooning habit of spiders has been noticed since early times, but
it was formerly misinterpreted. Thus Pliny speaks of wool being rained.
The poet Spenser wrote : —
“ More subtle web Arachne cannot spin;
Nor the fine nets, which oft we woven see,
Of scorched dew, do not in th’ ayre more lightly flee.”
Thompson writes:
“ How still the breeze! save what the filmy threads
Of dew evaporate brushes from the plain.”
112 ZOOLOGY
The method of spinning deserves careful attention. The
spinning-organs consist of a set of glands lying in the hinder
part of the abdomen, and opening to the exterior through
a number — often several hundred — of spinning “ spools.”
These spools are the modi-
fied mouths of glands, and
are grouped upon and be-
tween tubercles called spin-
nerets. The secretions of
the glands, as they are poured
out into the air, fuse together
and harden into a thread.
The thickness of the thread
is determined by the number
of glands secreting together.
The economic importance
of spider webs is consider-
osc able. First of all, they are of
the greatest importance in
Fic. 113.—Thomisus, a crab spider. 2 |
Diagram showing arrangement of eyes capturing many destructive
at bottom of figure. From Emerton. insects, such as flies, mosqui-
toes, and moths. Another use to which they have been
put is in making silk cloth. The silk of the spider is smoother
and glossier than that of the silkworm, but it is much harder to
collect in quantity. A spool is passed against the spinnerets of
an individual spider and slowly revolved, winding the silk upon
it. The difficulty comes in rearing the spiders, for they are ex-
tremely voracious, and if the supply of flies is insufficient, they
attack and devour one another. Consequently they must be
kept isolated and fed individually, and yet vield in the end only
an ounce or so (about 30 grammes) of silk. Other uses of spiders’
THE SPIDER 113
silk are: in the construction of cross-hairs in telescopes and,
in medicine, asa narcotic in case of fevers, — a temporary fad.
Poisonous Spiders. — Spiders are feared by many people
from a belief that they are very poisonous, even fatally so.
Spiders have, indeed, biting jaws
provided with poison-glands, and
their bite is often fatal to insects
and even to small birds and mam-
mals. But most spiders cannot
spread the jaws sufficiently to make
a bite in the human skin, and even
the largest forms seem to inflict but
a slight wound, scarcely ever greater
than that of a mosquito. The
stories of the severe effects of the
bite of the Tarantula, one of the Ly- Fre. 114. — Ocyale (Pisaurina)
cosidze, are entirely fabulous. eo ee
Spiders show a marked sexual using it as a sort of artificial
web. Photo. by Emerton.
dimorphism. Particularly among
the orb-weavers the males are much smaller than the females
of the same species, but the legs of the male are rela-
tively the longer and stronger. The male is usually shorter
lived than the female, for the latter has often to watch the
egg-cocoons, or carry them about with her until the
young hatch out. The male also builds less perfect. webs than
the female. The relation existing between mated pairs is
often peculiar. The male is frequently killed and eaten by the
female; but if the male can overcome the female she may
fall his victim. Among wandering spiders there is often a
selection by the female from among several rivals, which en-
gage in severe battles with each other.
I
114 ZOOLOGY
The Position of Spiders in the Zoological System. — Spiders
clearly belong to the arthropods because, like the grasshopper,
they have a thick cuticula (which is molted as the animal
erows) and jointed legs. Spiders differ from insects, however,
in several important respects. They possess four pairs of
legs instead of three. The head and thorax are united. The
Fig. 115.— A sandy waste (dune region of Fire Island Beach, Long Island)
where many spiders burrow in the sand.
antennz are absent. Consequently it is an error to speak of
spiders as insects; rather they, together with several allied
groups, belong to a distinct division of the arthropods, the
Arachnida. The Arachnida, indeed, breathe air, but the air
passes into a little pouch on the under side of the abdomen and
in between numerous thin sheets, like the leaves of a book,
so that the whole breathing apparatus is often called a lung
book. They have also a system of air-tubes which is much
THE SPIDER 115
less developed than that of insects. Although they belong
to the air-breathing arthropods they are without wings, and
are therefore confined to the surface of the ground, except in
the case of the ballooning species just described. In conse-
Fig. 116.— The entrance of the vertical tube ta the sand-Lycosa.
quence, the thorax is not a distinct and prominent part of
the body, as in insects, but is indistinguishably united with
the head. The abdomen never carries legs as does that of the
water arthropods. In this respect the Arachnida agree with
the insects rather than with the water-inhabiting crustaceans.
Although the spiders are the largest group of the Arachnida,
there are several other kinds of animals included in this class.
116 ZOOLOGY
The scorpions (Fig. 119) and their allies are more primitive
than the spiders, since their bodies are longer and more worm-
like. The abdomen is divided into two regions: in front, a
broader and, behind, a narrower called the post abdomen.
The scorpions are animals of the tropics and of the deserts,
Fic. 117.— Attus, a jumping spider. Fia. 118. — Young Lycosa about
From Emerton. to fly. From Emerton.
and are found during the day under sticks and stones. Their
thick skin enables them to resist the dry air of the desert which
tends to wither all it touches. The tip of the tail bears a
sting. Into this sting a poison sack empties. The wound of
the large scorpions, such as are found in the tropics, is fatal
to many animals upon which the scorpion preys. The wound
is very painful to man and occasionally fatal. We have only
one species of scorpion (Bu'thus) in our Southeastern States,
but there are several species in the southwest.
THE SPIDER 117
The harvestmen, or
daddy-long-legs (Phal’-
angidea) are extremely
common (Fig. 120). They
are somewhat spider-like,
but differ in having legs
Hand
iar,
Tibia | palp.
Femur
Troch.
many times the length of
the body. Their long legs
enable them to walk over
the foliage of trees and
smaller plants by stepping 7 .
from leaf to leaf. They Ge i
wander over fields also s
and not uncommonly are
Dorsal ridge. —
Lateral ridge ~~
Dorsal furror --
seen on porches of houses.
They are rapacious ani-
mals, feeding on small
insects, and are highly
beneficial to agriculture. Bla.
The mites and ticks Spacek)
(Acarina) have their ab- Fig. 119.— Buthus, a European scorpion.
domen united into one Dorsal view. Mz., maxillary; Cephth.,
‘ eh he ts ceepkalo-thorax ; Troch., trochanter ; Tars.,
piece with the head and tarsus ; Abd., abdomen ; Bla., poison blad-
thorax, so that the body der ; St, sting. From Kraepelin in ‘‘ Das
. a Tierreich.
is round. They exhibit
great diversity of form and habits, most being of very small
size. All are terrestrial, excepting one group of aquatic
mites (Hydrachnids). They are often of a bright red
color. The free-living species prey on smaller animals as
well as dead organic substances. Others are parasitic in
animals or plants, living in fur or feathers (Fig. 121), and
118 ZOOLOGY
Fie. 120.— Liobunum dorsatum, one of the harvestmen. The long legs are
apt to be thrown off in handling the living animal. The second left leg is
accordingly absent in this specimen. Nat. size. Photo. by W. H.C. P.
Fic. 121.—Psoroptes, the sheep scab, female. Right ficure, dorsal view ;
left figure, ventral. Much enlarged. After Salmon, Bulletin 21, Bureau
Animal Industry.
THE SPIDER 119
even penetrating into the skin, as the small red
“jigger”’ or “ chigger”’ of our Southern States
does.
Finally, there lives in the sea an aberrant
family of spiders which crawl on the sea-
. . Fic. 122.— Pal-
bottom or over hydroids, and thus have for- “Jeno, a sea-
saken a terrestrial life for a completely aquatic spider. = 1.5.
‘ Photo. living
one (Fig. 122). by W.H.C.P.
CHAPTER VIII
THE ANATOMY AND PHYSIOLOGY OF
CRUSTACEA: THE LOBSTER
General Form of the Lobster.— The lobster closely
resembles the crayfish (Fig. 123) except it is much larger.
Like the cockroach it is approximately bilaterally symmetrical
and is segmented. We may distinguish in the body the trunk
_and the appendages. The trunk is divided into two main
regions: the abdomen and a united head and thorax (cephalo-
thorax). The segments of the abdomen are distinct like those
of the cricket, but unlike the latter each segment bears a pair
of appendages. There are seven segments in the abdomen of
the lobster. Since the segments of the cephalothorax are not
distinct, they cannot be counted directly, but by assuming that
each pair of appendages corresponds to a segment, as in the
case of the abdomen, the number of cephalothoracic segments
is estimated to be thirteen.
The appendages of the body show a diversity of form in
accordance with the various kinds of work they have to do.
At the front of the head are the two pairs of long organs of
touch — antenne; then come the stout. crushing jaws (mandi-
bles) ; next are five pairs of appendages concerned in holding the
food while it is being devoured. Then follow five pairs of walking
appendages and, on the abdomen, a number of pairs of flappers
(swimmerets), the series terminating in the great tail flappers.
As can be inferred from the structure of the appendages the
lobster can both walk over the rocks at the edge of the sea or
120
Fie. 123. — Median longitudinal section through the European crayfish show-
ing parts of body appendages and internal organs. aa, artery to antenna;
ab, abdomen ; an, anus; bd, bile duct ; bfy, great claw ; bm, ventral nerve ;
cs, stomach ; cth, cephalothorax ; em, muscles of back ; fm, muscles of ven-
tral side; g, brain; h, heart ; hd, large intestine; Ir, liver ; md, small intes-
tine ; 0, opening in heart ; oa, artery to eye; oaa, dorsal artery to abdomen ;
oe, gullet; pl, 1-5, swimmerets; pl,, tail; ps, hinder part of stomach ; sa,
artery along sternum ; ¢, testis (also tail) ; waa, artery to abdomen ; vd, duct
from testis; vdo, outer opening of duct.
121
122 ZOOLOGY
in shallow water, or it can swim free in the water. By suddenly
striking the tail fin forward the lobster can dart backward,
trailing the great clawsin the wake. The strokes of the power-
ful tail also tends to roil the mud of the bottom and thus to
hide the retreat of the animal. Although the body is encased
in a cuticula of great thickness and firmness, yet the presence
of thin-skinned joints makes not only the abdomen but also
the largest of the appendages capable of complex movements.
Organs and Functions of Nutrition. — The lobster feeds
principally upon fish, either dead or alive, upon various other
crustacea and mollusks, and also upon marine plants. The
food, held in place by the mouth-parts, is triturated by the
jaws and passes by a short gullet into the stomach. The
outer cuticula is turned in at the mouth and lines not only the
gullet but also the stomach. In the stomach it is thickened
”
and hardened in three points to form ‘ teeth ”’ which, in the
muscular movements of the stomach, clash together in such
a way as to crush any larger particles that have escaped the
mincing of the jaws. Digestion takes place in the succeeding
part of the food canal which runs nearly straight to the last
segment of the body. A great gland (liver) secretes the diges-
tive juices and empties them at the beginning of the intestine.
Beyond the opening of the gland the absorption of the digested
food takes place through the wall of the canal.
Organs and Functions of Respiration. — Owing to the fact
that the lobster lives in the water from which it takes its
oxygen, the respiratory organs are outgrowths of the body
instead of internal tubes as in insects. Such outgrowths are
called gills. Gills must have thin walls to allow of the passage
of gases through them ; they must be much branched to make
1 Fig. 123.
ANATOMY AND PHYSIOLOGY OF CRUSTACEA 123
as great a surface as possible for the passage of these gases, and
they must be protected from injury, such as being bitten off
by fishes. Consequently we find the gills of the lobster tufted
and hidden under a fold of the skin — the carapace. From
Fic. 124.— Respiratory organs of Astacus fluviatilis. The gill cover removed,
and gills undisturbed. a ,, small antenna, a2, large antenna; ab, abo, first
and second abdominal segment; eps, ‘‘scaphognathite”’; plb, ‘‘ pleuro-
branch”; pdb;, 42, ‘‘podobranchs’’; ply, first pleopod ; 6-13, thoracic ap-
”
pendages. From Lang, ‘‘Comparative Anatomy.
or near the base of each leg one to four gills arise and lie in the
gill chamber. The water is pumped through this gill chamber
by the motion of certain fanlike organs. Each gill contains
a vessel carrying blood from the body to the gill (afferent)
and one from the gills to the body (efferent). The total
number of gills (Gk. branchia) varies with the species (Fig. 124).
Usually one or two spring from the foot itself (podobranch) ;
one or two from the joint (arthron) connecting foot to trunk
(arthro-branch); and one from the side wall (pleuron) of the
body (pleurobranch!).
1Get a lobster or crayfish and see how many gills of each of these classes
occur on each segment of the thorax (Fig. 125).
124
ZOOLOGY
Organs and Function of Circulation. — The circulatory
organs of the lobster, as of the higher Crustacea in general, are
Srey
Fig. 125.—Cross section of thorax of
Astacus fluviatilis of Europe, diagram-
matic. abm, ventral muscles of the ab-
domen; bf, leg; bm, main or ventral
nerve cord; d, intestine; dbm, dorsal
muscles of abdomen ; ep, wall of thorax ;
h, heart; k, gills; kd, gill cover ; J, liver ;
ov, ovary; pc, space around heart; sa,
sn, artery running along sternum; vs,
ventral blood space. The arrows show
the direction of blood flow. From Lang,
‘“Comparative Anatomy.”
gills.
highly developed. The
heart is a long, muscular
tube lying in the dorsal
part of the thorax. It is
perforated by several pairs
of lateral openings through
which the body fluid passes
from the surrounding body
into the
Thence it is forced down-
wards by a great artery to
the ventral system, for-
ward to the
glands, stomach, mouth-
parts, and eyes, and back-
wards to the muscles of the
The blood that
enters these various organs
oozes out into the general
cavity of the body, streams
cavity heart.
digestive
abdomen.
into the gills, and is thence
returned to the heart.
Thus the heart and the tis-
sues receive blood full of
oxygen acquired in the
The blood of the lobster is not colored red like our
“blood because it lacks the blood corpuscles that give our blood
its color.
Nevertheless the blood is able to absorb oxygen
from the water and give it off again to the tissues.
ANATOMY AND PHYSIOLOGY OF CRUSTACEA 125
Excretion. — The elimination from the blood of the waste
products of tissue changes takes place in a pair of organs lying
at the base of the antenne, and known
as the green glands. Into these organs,
which contain coiled tubules, the arteries
enter and give up the waste products.
These products accumulate in a bladder
lying over the gland and from time to
time pass out through a duct whose
opening may be seen at the base of the
great antenne.
Reproductive Organs. — The sexes
are separate in the lobster. The eggs
are produced in a pair of great sacs
which run along on top of the other
viscera and are united by a connecting
strand (Fig. 126). Each sac has its own
duct to the exterior, and this opens at
the base of the third pair of walking
appendages. The sperm is formed ina
pair of sacs resembling the ovary in
general shape, but opening by a duct at
the base of the last thoracic appendage.
It will be noticed that excretory gland,
oviduct, and sperm duct all open out at
the base of appendages, and we shall see
Fic. 126. — View of ovaries
and oviduct (od) of Ameri-
can lobster, dorsal part
of carapace removed.
in studying the structure of ringed worms (‘ annelids ”’) that
nearly every segment has its duct. Consequently the three
paired ducts of the lobster may be regarded as a rudiment
of the condition found in ringed worms.
Musculature of the Lobster. — As the outer cuticula of the
- 4>—Con,
Fic. 127.— A single facet
or elementary eye of
the lobster. crn, clear
cuticula; nl.crn, nuclei
of cuticula ; con, cone
cell; nl.con, its nuclei ;
nl.dst, nuclei of outer
pigment cells (retina) ;
nlpx, nuclei of inner
pigment cells; rhb, rod;
mb.ba, membrane lying
at base of rods; fbr.r,
new fibre to pigment
cells. G. H. Parker.
ZOOLOGY
lobster is very thick and strong it affords
correspondingly powerful support for the
well-developed musculature, for, as in the
grasshopper so in the lobster, the muscles
are attached to and pull upon the cutic-
ula. The powerful muscles are able to
make the strong strokes of the abdomen
In the abdomen the
dorsal muscles run longitudinally from
used in swimming.
the front edge of one segment to the front
When they contract,
the abdomen is straightened.
edge of the next.
The ven-
tral muscles are very complicated. They
run from one segment to the next and,
as they are attached below the hinge of
the segments, when they contract the
abdomen is bent. The musculature of
the appendages is well developed and
complicated.
The nervous system is arranged essen-
tially like that of the cricket. From the
dorsal brain two nerves pass around the
gullet forming the esophageal ring and
then pass as a pair of nerves near to the
ventral line as far as the hinder opening
(anus) of the food canal. The two nerves
are tied together by ganglia in most of
the segments, and nerves are given off
to the appendages, body muscles, viscera,
and sense organs.
Of the sense organs touch seems to
ANATOMY AND PHYSIOLOGY OF CRUSTACEA 127
be located chiefly in the long antenne which serve, like a
blind man’s cane, to inform the creature of what lies some
distance in front of him. The location of the chemical sense
seems to be in the smaller antenne. The eyes are well
developed and are placed on long stalks capable of a certain
degree of rotation and of retraction out of danger. The
Fie. 128.— Upper figure, young lobster with otocyst in place showing
normal behavior. Lower figure, the same with otocyst removed; keeps
upright with difficulty. From Loeb.
eye is compound like that of the cricket, and as many
partial images are formed on the sensitive part of the eye
—retina—as there are facets or elemental eyes (Fig. 127).
There seems to be no true sense of hearing in the lobster;
but it has a special organ of equilibrium and apparently a keen
sense of position. This organ is the otocyst and is located in
the basal joint of the smaller antenne. The young of the
lobster does not have an active otocyst (Fig. 128). The animal
tends to roll from side to side except as the hanging appendages
aid in keeping it stable. At a later stage its otocyst becomes
active, and then the larva keeps its appendages stretched out
in front and swims without rolling over. The otocyst is the
chief organ that enables it to tell when it is right side up.
CHAPTER IX
THE CRAYFISH: A STUDY IN GEOGRAPHICAL
DISTRIBUTION
Every animal is adjusted to particular conditions of temper-
ature, moisture, light, contact, food, and other factors of
environment. These adjustments determine, as has been
abundantly illustrated in the preceding chapters, the exact
situation an animal shall occupy. The situation is known as
its habitat. The number of different kinds of habitats is very
great. They may, however, be grouped into certain large
classes, so that we may distinguish marine animals, fresh-
water animals, terrestrial animals, subterrestrial animals,
aerial animals, and so on. A particular species lives normally
in one of these classes of habitats, and its distribution on the
earth is imited by the bounds of its habitat. Thus the dis-
tribution of the brook trout follows branching lines on the map
because the streams themselves do so. There are very few
animals, either in the sea or on the land, whose distribution
is ubiquitous, just because their suitable habitats are widely
separated.
But not all of the similar habitats all over the whole world
are occupied by a single species adapted to such a habitat.
The trout of the brooks of one continent are not exactly the
same as those of another continent. We find rather, in widely
separated areas, different species which occupy precisely
the same kinds of habitats. Consequently the traveller who
journeys from his native land to a foreign country meets there
128
THE CRAYFISH 129
a collection of strange animals. The American leaves behind
him such wild animals of the woodland as the Virginia deer,
the skunk, the woodchuck, porcupine, and opossum, and, if he
goes to Europe, may see instead the roebuck, the polecat,
and the hedgehog, but no representative of the group to which
the opossum belongs. If he goes to Africa, his familiar forms
will be replaced by still stranger ones. Instead of the deer he
will meet with antelopes and a lot of new groups represented
by the elephant, rhinoceros, and hippopotamus. If he journeys
to Australia, he will find that practically all the wild animals
belong to the same group as does our opossum. The deer are
there represented by kangaroos and the porcupine by the
wombats. This dissimilarity even of the land quadrupeds in
different parts of the globe has made it possible to divide the
land into certain life-regions. Thus we have the North Amer-
ican; the Eurasian (?.e. Europe + northern and central Asia) ;
the Oriental, south of the Himalayas ; the Ethiopian, including
that part of Africa south of the Sahara; the South American
which stretches north into Mexico, and, finally, the Austra-
lian (Fig. 129).
These different life-regions are land areas more or less com-
pletely separated from each other by barriers of some kind,
such as water, mountain chains, vast desert tracts, or sudden
changes of temperature. In each of these isolated regions
a peculiar and characteristic collection of animals, known as its
fauna, has come to develop. The faunas of some of these re-
gions are more closely interrelated than those of others, and this
interrelation often gives an important clew to land connections
in former geologic times. Thus the North American animals
are much more closely related to those of Eurasia than are the
African. This similarity of animal forms speaks for a former
K
130 ZOOLOGY
land connection between Europe and America by Behring’s
Strait or by the way of Greenland.
The comparison of the animals of a new country in which
one may be journeying with those of one’s native land gives
yy ed
Fic. 129. — The zoological regions of the globe. 1, North American; 2, South
American; 3, Eurasian; 4, Ethiopian; 5, Oriental; 6, Australian.
the keenest zest to travel. We see, therefore, how important
it is to be acquainted with the native fauna of our own
country.
As a specific example of geographical distribution the cray-
fish 'may be considered. This animal, which is closely related
to the marine lobster,? is an inhabitant of fresh-water lakes,
rivers, and pools. It thrives in diverse surroundings; for
1 The old English spelling of this word was ‘“crevis” or “crevice.” The
cre came to be spelled phonetically cray, while vis became changed to fish in
accordance with the popular nomenclature of all aquatic animals.
2? The English word “lobster’’ is from the old English lopystre, which is
probably corrupted from the Latin locusta, by which term Pliny refers to
the lobster.
THE CRAYFISH 131
some species prefer cool mountain streams and others muddy
pools, while certain species, both in Europe and America, are
found in brackish as well as fresh water. Indeed, the Euro-
pean Astacus fluriatilus is said to be frequently caught off the
Livonian coast, even some distance out at sea. Individuals
of an American species have been taken from a mineral spring
impregnated with sulphur and magnesia at a temperature of
70° F. (21° C.), while several kinds of the American “ bur-
rowing ” or ‘chimney ”-forming species have been found
in meadows and clay bottoms, often at great distances from
streams. Certain species that are blind inhabit caves only.
In England, according to Huxley, ‘in granite districts, and
others in which the soil yields little or no calcareous matters
to the water which flows over it, crayfishes do not occur.
They are intolerant of great heat or of much sunshine; hence
they are most abundant in those parts of rivers which flow
east and west, and thus yield the most shade from the midday
sun.”
There are two great groups of subfamilies of crayfishes.
One, restricted to the Northern Hemisphere, is found in
Europe, Asia, and North America. The other is found in the
Southern Hemisphere, in Australia, Tasmania, New Zealand,
Fiji Islands, Madagascar, and South America. No crayfishes
have been found on the continent of Africa or in the rivers of
northern Asia that flow into the Arctic Ocean, or in those of
southern Asia. These Asiatic rivers are populated by fluviatile
crabs, to which the crayfishes of the region have probably
succumbed. All the islands now inhabited by crayfishes, such
as England and Japan (excepting Cuba), were probably once
connected with the mainland (Fig. 130).
The northern subfamily of crayfishes contains, according
132 ZOOLOGY
to Faxon, two genera— As’tacus and Cam’/barus— of which the
latter can be subdivided into the subgenera Cambarus and
Cambaroides. These groups occupy distinct geographical
areas. The genus Astacus is found, in the Old World, in
Europe and western Asia as far south as the Aral and Caspian
seas, and in America in the region west of the Rocky Moun-
Fic. 130.— The distribution of erayfishes. The shaded areas are inhabited
by various genera as described in the text.
tains, draining into the Great Salt Lake and the Pacific Ocean.
It is thus seen to occupy the western sides of the two northern
continents. Likewise Cambarus and Cambaroides occupy the
two eastern coasts of the northern continents; for Camba-
rus is found in North America east of the Rocky Mountains
in the region bounded on the north by Lake Winnipeg and
New Brunswick and on the south by Guatemala and Cuba,
while Cambaroides is limited to the Amoor River basin in
Asia, and to Japan.
We thus find among the crayfishes what is known as dis-
THE CRAYFISH 1383
continuous genera; that is, genera which now occupy widely
separated areas, like Astacus in Europe and Pacific North
America, but which once ranged over the intervening regions
as well. From some cause, the struggle for existence became
too severe in the intervening regions, so that Astacus and Cam-
barus were annihilated on the eastern and western sides of
the continents respectively. In southern Asia we find that the
struggle was doubtless with the successful river-crab. It is
interesting to note that, probably on account of the preserving
influence of climate, the other animals and the plants of the
eastern sides of the two continents and those of the western
sides are more alike than those from opposite sides of the same
continent. One of the best pieces of evidence for the conclu-
sion of a former hemispherical distribution of the two genera
of crayfishes is that there occur in the caves of Carniola in
southern Austria crayfishes! belonging to the genus Cambarus ;
—the only known hving representatives of this type in
Europe. The mere fact that it lives in a cave is not sufficient
to make the crayfish Carniola of a Cambarus, for in North
America the genus has certainly not originated under the in-
fluence of subterranean life ; it is more likely that the caves of
Carniola have protected these crayfish from the widespread
destruction which has overwhelmed their fellows outside.
Only one crayfish, Cambarus bartonti, is found in New England,
and here only in the rivers of Maine, Vermont, and central and west-
ern Massachusetts. The common species of the Middle States is
C. affinis. C. diogenes and C. immunis are common burrowing species
of the Central States. C. pellucides is the blind species found in
Mammoth and Wyandotte caves.
The food of the crayfish is very varied; it may be living or
1 These crayfishes are blind, like the cave-inhabiting Cambarus of America.
134 ZOOLOGY
dead, animal or plant. On account of the need of calcareous
matters in the food, crayfishes are especially fond of the
stoneworts (Chara) and various succulent roots, like the carrot.
It is said that crayfishes sometimes make excursions inland in
search of plant food. They likewise devour shells of snails,
their own cast-off skins, and occasionally one another, shell
and all.
The crayfish belongs to the class of Crustacea, since it
breathes by means of gills, possesses two pairs of antenne,
a pair of mandibles bearing palps, and a pair of appendages
on all body segments excepting the last. The Crustacea are
divided into two subclasses, — Entomos’traca, of which
Daphnia is an example, and Malacos’traca, to which the cray-
fish belongs. All the Malacostraca! have nineteen pairs of
appendages.
The lobster (Homa’rus) is, as we have already seen, the
nearest living salt-water relative of the crayfish. There are
only two species of the genus Homarus. One, Homarus
americanus, occurs on our Atlantic coast; the other, H. vulgaris,
is the lobster of Europe. On our Pacific coast there is the
“spiny lobster,” but this is not closely related to the Eastern
lobster (Fig. 131). The national government has transplanted
the Atlantic lobster to several localities on the Pacific coast,
but it is not yet known whether it will thrive there. The
American lobster ranges from Labrador to Delaware Bay,
and from near shore to a depth of 100 fathoms. It attains
its greatest size on the rocky shores in the cooler waters from
Maine to Labrador. It migrates but little along the coast;
in the fall, however, it moves out into deep water, and in the
1From malakos, soft, ostrakon, shell; since the shell is less hard than that
of mollusks.
THE CRAYFISH 135
spring back again into the shallower bays; the time of migra-
tion depending upon the length of the season. It is saicl to be
a nocturnal animal, searching most actively for its food at
vem!
Fig. 131.— Palinurus, the spiny lobster. One-fourth nat. size. From Rath-
bun; drawn by H. L. Todd.
night. The sense which probably aids it most in this search
is the chemical one, as the attraction of the bait in the traps —
the so-called lobster-pots — testifies. In respect to food it is,
like the crayfish, omnivorous.
Protection of the Lobster.— There has been much dif-
ference of opinion in regard to the size at which a lobster
136 ZOOLOGY
becomes mature and before which, therefore, it cannot be
caught without danger of extermination. The legislation on
the matter has accordingly been very varied. In Connecticut
the law makes the limit six inches, while in Massachusetts
and New York it is placed at ten and one half inches. Her-
rick has carefully investigated the relation of length to maturity,
and concludes that, on the Massachusetts coast at least, the
lobster becomes mature between the limits of eight and twelve
inches, and hence that all present legislative protection is
insufficient. The rarity of large lobsters in our markets
testifies to the correctness of this conclusion.
Enemies of the Lobster. — Besides its worst enemy, man,
both the adult (particularly the egg-bearing female, called by
fishermen the ‘ berry lobster”? or “berry hen”) and young
lobsters are attacked by many kinds of fish. Two or three
internal parasites are known to infest the lobster, while some-
times it is greatly hampered in its movements by the number
of messmates it carries about attached to its shell. Barnacles,
mussels, tube-forming worms, and various sea weeds are all
found at times attached to the shell of the lobster. Upon
molting, however, the animal is enabled to rid itself of all
these hangers-on; but this process is attended with great
dangers to the lobster, since the animal is, during molting, so
soft bodied as to be able to offer little resistance to its enemies.
The molting process in the lobster and crayfish is
accomplished in the following manner: previous to the
throwing off of the old skin a new soft one is formed in-
side, the lime is absorbed from the old shell in a dorsal
line along the carapace, reaching from the rostrum to
its posterior margin. Absorption also takes place at the
joints of the limbs. Such absorptions give a greater flexi-
THE CRAYFISH 137
bility to the shell, which is useful in the act of molting.
When the lobster has attained this stge, it is dark in color, and
known by fishermen as the “ black lobster.” The soft cutic-
ula now breaks transversely immediately behind the carapace,
the blood leaves the limhs, which are thus made flabbier, and
by involuntary muscular movements they are drawn, large
claw and all, through the joints of the old shell. The anterior
portion of the body is first drawn out through the break behind
the carapace and, lastly, the tail. Not only is the entire outer
covering cast off, but the lining of the esophagus, stomach, and
intestine as well, since these organs are formed by an infolding of
the skin. By means of the return of the blood to the limbs and
rapid absorption of water, the body of the lobster soon swells
to a size far beyond that of the old shell. There remains
in the stomach, after molting, a calcareous nodule which has
long been known by the name of ‘crab’s-eye.”’ These “ crab’s-
“charms ”’ against
eyes”’ were formerly much sought after as
ill health. Their function was for a long time rather
obscure. It is now believed that during the time of ab-
sorption of lime from the shell, previous to molting, the
blood becomes strongly impregnated with lime. If all the
lime that must be removed were to remain in the blood,
it would probably be fatal to the animal; hence it is taken
up by secreting cells located in the wall of the stomach,
and there deposited. After the old skin is cast, the gastro-
lith is soon absorbed, probably to aid in strengthening
the new shell. Bits of water-worn shells, entire gastropod
shells, parts of lobster coverings, spines of sea-urchins, etc.,
have been found in the stomachs of lobsters and crayfish,
which likewise would probably have been dissolved and used
in hardening the shell.
138 ZOOLOGY
Shrimps and prawns! belong to a thin-skinned, long-tailed
family of Crustacea.2. They are extremely common in bays
along our coast, and even penetrate into rivers. Two river
shrimps ? are found in the United States east of the Mississippi
River. These Crustacea are able to maintain their enormous
numbers only by virtue of their great reproductive capacity,
which is the more necessary since they furnish almost the
entire food supply for many kinds of fishes and other foes.
Fic. 132. — Palemonetes vulgaris, a common shrimp.
Even in the principal shrimping grounds of the United States
—such as San Francisco and New Orleans — there is said to
be no diminution in the numbers of shrimps.
The burrowing shrimps (Thalassinide‘) are crayfish-like
species that burrow in the mud flats of our coast. They
remain concealed during the day. They are much smaller
than crayfishes and are difficult to obtain, so they have no
market value and are commonly little known.
The hermit-crabs (Paguride®) occupy a position inter-
mediate between the long and short tailed decapods in respect
1The term ‘‘shrimp”’ is applied to the smaller species, and ‘‘ prawns” to
the larger.
2 Fig. 132.
3 Palemon Ohionis and Paleomonetes exilipes.
4 thalassinos, color of the sea.
5 pagouros, a kind of crab.
THE CRAYFISH 139
to the length of their abdomen. The abdomen is soft, and
the young animal, which is at first free-living, protects it by
inserting it within the coiled shell of some gastropod. The
abdomen becomes unsymmetrical, being coiled to one side
to correspond with the shape of the borrowed house (Fig. 133).
The abdominal feet become degenerate, with the exception of
Fic. 133.— Eupagurus longicarpus. Two individuals in shells. Photo. while
alive by W. H.C. P.
the posterior pair, which are each modified into a sort of hook,
by means of which the crab maintains itself securely in the
shell. When one shell becomes too small, it is abandoned for
a larger one. Numerous species of hermit-crabs occur on our
coast, ranging from the shore line to a depth of several hundred
fathoms. HEupagurus longicarpus is the active little hermit
found in almost any tide-pool from Massachusetts Bay to the
Gulf of Mexico. Hydroids, polyps, sponges, often attach
themselves to these borrowed shells (Fig. 133); indeed, one
Chinese species always bears an anemone on its large claw,
with which it plugs up the aperture when obliged to retreat
within its shell. One of the East Indian hermit-crabs, the
140 ZOOLOGY
so-called palm-crab, feeds upon cocoanuts, which it opens by
inserting its claws into the eyes and then breaking the shell
upon the rocks.
The mole-crabs (Hippide!) include certain oval animals
that burrow in sandy beaches, head first like a mole. The
abdomen is partly turned under the body in a position some-
Fic. 134.— Eupagurus longicarpus removed Fia. 135. — Hippa talpoides.
from shell. 13. Photo. by W. H.C. P. Nat. size. Photo. by
Ww. FG BP.
thing like that of the crabs. Therefore these animals make an
interesting link between the long-tailed (Macrura) and short-
tailed (Brachyura) crustaceans (Fig. 135).
The crabs (Brachyura) are represented on our shores by
three principal families, which may be designated as triangular
crabs, arched crabs, and square crabs.
The spider-crabs, or sea-spiders, as they are sometimes
called, belong to the triangular crabs. As their name implies,
1Trom hippos, horse; used by Aristotle as the name of a kind of
crab,
THE CRAYFISI 141
their legs are very long and slender. These crabs frequent
oyster-beds and sea-bottoms in general. When seen stalking
over such uneven surfaces, the advantage of these stilt-like
legs is at once evident. The surface of the body of some
species of spider-crabs is hairy, entangling inorganic matter,
while hydroids, barnacles, and algz attach themselves to the
shell, so that the crab, when quiet, is concealed by them, while
2 te,
td, Ep Sie “ Be ha bs HLM
Fic. 136.— The smaller spider-crab, Libinia dubia. Two specimens lying on
the beach.
these attached organisms, in turn, gain by their association
with the crab most of the advantages of locomotion. Libin'ia
dubia (Fig. 136), which ranges from Cape Cod to the Gulf
of Mexico, is the commonest of our species that undergo such
concealment. The great Japanese spider-crab is said to be
the largest of all the Crustacea, some individuals measuring,
from tip to tip of the first pair of legs, 18 to 20 feet.
The edible crab is a typical arched crab. It is so called
1Fig. 136.
142 ZOOLOGY
because the carapace is arched in front. The carapace is also
broader than long, and narrower behind than in front. The
legs of this family are short and
broad, and in some species the pos-
terior pair is especially broad — an
adaptation for swimming. These
crabs may be divided into two
groups—the burrowing crabs and
swimming crabs. To the burrowing
Fic. 137.—Panopeus sayi, al- crabs belongs the genus Cancer
lied to Cancer. The mud- oN Laie 3 ht ane e
crab. One-half nat. size. (Figs. 137, 138), which includes the
Photo. by W. H. C. P. edible crab of Europe, especially
prized in England, together with several American species ;
while our common edible, soft-shelled or blue crab, Callinec’tes
by W. H.C. P.
hasta’tus of the East, and the beautiful “ lady-crab” (Fig. 139),
belong to the swimming group. Crabs of other families are,
THE CRAYFISH 143
however, eaten in various localities and by various peoples.
For example, our little oyster-crab (Fig. 140), found in the
Fig. 139.— Platyonichus ocellatus, lady-crab. Reduced to one-third. Photo.
by W. H.C. P.
mantle chamber of the oyster, is eaten by us together with the
oyster or separately.
The fiddler-crabs are representative of the square crabs.
These are the familiar animals which crowd salt-marshes and
run sideways to and from their
burrows (Fig. 141). One claw
is much larger than the other.
When the crab is disturbed, the
large claw is brandished in a
manner which has been likened Teaaes nie ‘
GC. : innotheres ostreum. x 4.
to the movements of a fiddle From Rathbun.
as one plays uponit. Gelast’/mus pug'naz is the most abundant
species, and ranges from Cape Cod to the Gulf of Mexico.
Together with Cambarus it does much damage by burrowing
in the levees of the Mississippi River (Fig. 142).
144 ZOOLOGY
There remain to be considered a number of orders of the
higher crustacea (Mal’acostraca) other than decapods. The
Fie. 141.—Gelasimus pugnaz. Nat. size.
Fronto-dorsal view. Photo. by W. H. C. P.
a crayfish. Being hard to catch, it
Fie. 142.— Fiddler-crabs and their burrows.
large claw at the opening of the burrow is shown.
mantis shrimp (Sto-
map’oda) is so called
because of a certain
resemblance to the
mantis insect (Fig.
143). This animal is
found on our east
coast, where it bur-
rows in the sand. It
is a little longer than
is not much used as
The method of exposing the
THE CRAYFISH 145
food. The Isopoda! include certain marine and fresh-water
groups, and the sow-bugs or wood-lice (Fig. 144), note-
worthy as the largest group of land
Crustacea. The Amphipoda? are
exclusively aquatic creatures, found
under decaying vegetation on
beaches of lakes or the sea (Fig. 145),
and crawling amidst marine hy-
droids. Being laterally compressed,
the Amphipods tend to lie on one
side when at rest.
The economic importance of the
decapods may be inferred from the
fact that the receipts for the Atlantic
lobsters taken and sold by United
States fishermen was estimated for
the year 1901 at $1,400,000.
Formerly the American lobster
was more numerous
and attained greater
size than now, but
excessive fishing has
so depleted the sup-
ply that the lobster
so-called Norwegian
Nh i:
Fia. 143. — Squilla empusa, the
mantisshrimp. Dorsal aspect.
From Rathbun.
is in danger of extermination. In Europe the
lobster is much used as
food, while on our Californian coast the so-called
Fic. 144.—Onis- spiny lobster or sea-crayfish takes the place
cus, the sow-
bug. Dorsal
of our true Atlantic lobster and, like the latter,
view. Nat.size. jg said to be in danger of extermination on
Photo. by
W.H.C.P. 1 ¢sos, equal ; pous, foot.
L
2amphi, both; pous, foot.
146 ZOOLOGY
account of overfishing. The crayfish is not as much used
for food in America as in Europe. In Paris it is so much
esteemed that the enormous crayfish farms throughout France
are unable to supply that city; consequently crayfishes are
imported from Germany.
In America, it is our French
population mainly that
makes a market for the
crayfish.
Of the crabs which reach
our market the most im-
portant is the blue crab.
These crabs are kept moored
in floating boxes until they
have molted, and then they
are sent to market as soft-
Fic. 145.— Talorchestia longicornis, the
beach flea. Nat. size. Photo. by shelled crabs. The value of
W.H.C. P.
the blue-crab fisheries on the
Atlantic and Gulf coasts was almost half a million dollars.
The shore-crabs (Cancer) are little eaten in the United States.’
The shrimps and prawns have within recent years begun to
appear in large numbers in the Eastern markets. For many
years the Pacific species have been dried and shipped by the
Chinese in large quantities to China.
Development of Lobsters. — Lobsters lay eggs in July and
August. In the fall they migrate to deep water, and pass the
1 Very unfortunate is the destruction of the ‘“king-crab”’ (Limulus), which
is only distantly related to the Decapoda. In Delaware Bay they are caught
in great numbers and ground up as fertilizer. As they are taken only during
the breeding season, they are being rapidly exterminated. The American
Limulus belongs to an order entirely unrepresented on the European coast
(Fig. 146).
THE CRAYFISH 147
winter there. In the spring they migrate back to the shore —
the female tarrying behind the male until the eggs of last
summer, which she still carries attached to her swimmerets,
shall be further grown. In June the young hatch out, molt,
Fic. 146. — Limulus polyphemus, the king-crab or horseshoe-crab.
and swim to the surface. The female now molts, but does
not spawn again for a whole year; that is, she spawns in
alternate years. The number of eggs carried varies with the
age of the female; middle-aged lobsters may carry up to one
hundred thousand eggs, but the old or young ones as few as
three thousand. The egg as freshly laid is about 1.5 milli-
metres in diameter and is stored with food material, called
yolk, much as in the case of the hen’s egg. As in the chick,
the development takes place, as it were, on top of the egg
(Figs. 147, 148). Eyes and mouth appendages early make
148 ZOOLOGY
their appearance ; then the other appendages, and the tail (Fig.
149). For a long time the back of the thorax is greatly dis-
tended by the yolk stored there, and the eyes are huge (Fig.
150). During the early moltings (Fig. 151) the young lob-
sters undergo a terrible mortality, so that out of ten thousand
embryos hardly two, on the average, survive. After the fifth
Fic. 147.— An early stage of devel-
opment of egg of thelobster. Ap-
pendages becoming bifid. Paired
dotted areas above indicate eyes;
Fia. 148.— Surface view of egg nau-
phius. Antenne show beginning of
these are followed by the first three segmentation; mandibles and max-
paired appendages: Autenmules ane illee seen on each side of the abdo-
tenne, and mandibles. Below in re Embryo teas days old.
the middle line is the forming tail ; x 25. From Herrick.
above isthe mouth. After Herrick.
or sixth molt the little lobsters sink to the bottom, and then
begin their journey shoreward. From this time until they are
about four inches long, only very few individuals have ever
been seen. This is due, it is said, to the fact that they hide
deep down among the rocks, where they cannot be dredged.
When they are four inches long or so, they become bolder,
leave the rocks, and, like the adults, make burrows for them-
selves in the sand or under stones.
Development of Crayfish. — The crayfish develops simi-
THE CRAYFISH 149
larly to the lobster, —from a large egg filled with yolk. The
early stages are much like those of the lobster; but those
changes which in the lobster take place during the first three
stages of free life are in the crayfish passed in the egg. Con-
sequently at the time the crayfish hatches it is almost, but
not exactly, like an adult crayfish except in size. The tail-
Fic. 149.— Surface view of embryo Fie. 150.— Lobsterembryo. 61 days
with all of thoracic appendages old; eyes have developed pigment.
formed. The forked telson partly x 15. From Herrick.
overlies the brain. Note the large
eyes, which are yet without pig-
ment. Embryo about 21 days old.
x 25. From Herrick.
fin of the just-hatched crayfish has, to be precise, a somewhat
more oval form, and the first pair of swimmerets are undevel-
oped; but these differences soon disappear.
Regeneration of Lost Parts. —If you attempt to pick up
a crab by one of its claws, you frequently find yourself in
possession of a portion of the leg only, while the crustacean
has made good its escape. Moreover, it will be seen that the
leg always separates at a certain place; namely, between the
second and third segments. This is the place where a fusion
150 ZOOLOGY
occurs between two segments which are free in the first larval
stage. This power of protective mutilation occurs in those
appendages which are most apt to be seized, — namely, the
and is wholly under the control of the
reflex nervous system, for it may occur when the entire volun-
five thoracic legs,
tary nervous system has been removed. The leg of a dead
Fia. 151.— Larval view of lobster, extracted from an egg
which was about ready to hatch. The concretions in the
intestine are destined to go into the new cuticula after
molting. » 25. From Herrick.
crustacean shows no such capacity. If the leg of a lobster is
cut off at some point beyond that of normal rupture, the limb
will later be found cast off up to this point. Here a sort of
double membrane or diaphragm exists, with a central opening
only large enough to admit the passage of nerves and blood-
vessels. \Upon rupture this passage is soon plugged up by
coagulated blood — clearly a device to prevent excessive
hemorrhages. Soon after a leg is cut off a papilla-like body
THE CRAYFISH 151
grows out from the stump of the limb, develops into the shape
of a small limb, and grows larger, with each successive molt,
until the normal size is reached.
The antennz, too, are much exposed
to injury, but with them autotomy
is not practised. They begin to
grow out at the place of injury, and
at least one molt is necessary for
their complete restoration.
Abnormalities in the claws of the
lobster are not uncommon. The
thumb-like protuberances of the
next to the last of the joints of the
great claw is sometimes bifid, or
carries a large wart. The finger
which opposes the thumb is also
sometimes forked (Fig. 152). Many
of these abnormalities are probably
due to injury of the claw; but others
cannot be explained in this way.
For instance, cases have been ob-
served of lobsters having crushing
claws of equal size on the two sides
of the body. Similar abnormalities
are found in other arthropods.
They are always instructive be-
cause, being natural phenomena,
Fie. 152.—Two abnormal claws.
Upper figure shows a double
outgrowth to the finger. In
lower figure there is an extra
finger. From Herrick.
they must have a cause, and this lies in the altered conditions
of development.
Physiological Division of Labor. — The difference between a
“highly developed ” animal and a lowly organized one is not
152 ZOOLOGY
first of all a difference of size nor a difference in the number
of parts, —just as a large population or numerous cities are
not the primary characteristics of a highly civilized state. But
just as a complex civilization is one in which each of the
different citizens has his own special task to perform for the
commonwealth, so a highly developed organism is one in which
each different organ has its special réle to play. The worm
Nereis! has more segments to the body than the crayfish, but
these segments are very nearly alike —the fins especially are
quite similar. In the crayfish, on the other hand, the append-
ages are dissimilar. Each pair has a special function to perform
and is specially adapted, often complexly fashioned, to meet
this need. What is true of the appendages is likewise true, to
an equal degree, of the internal organs. The internal organs
of Nereis are repeated in each segment; but in the crayfish
the egg ducts le in one segment, the heart in another part of the
body, and so on. Some of the segments have given up one or
more functions to perfect a single one in which it has specialized.
There has been a division of labor between the different parts
of the body, and in consequence a greater perfection in the
performance of each function. More perfect fulfilment of
function is the result of physiological division of labor, just
as a higher civilization is the result of individual division
of labor.
1 Compare Figure 161.
CHAPTER X
DAPHNIA: A STUDY OF THE FOOD OF FISHES
Ir one sweeps the long grass in a field with a stout, fine net,
one will gather in a minute or two great numbers of insects.
In this way one gets a notion of the vast abundance of insects
that there must be on all the land. Little wonder then that
vegetation suffers so from insect attacks or would suffer were
the number of insects not kept down by birds, lizards, and
toads which find their principal subsistence on them.
What insects are to the land the water-fleas or Entomostraca
are to the water; they are ubiquitous there. And what in-
sects are to the birds Entomostraca are to fishes. How numer-
ous they may become is shown when a fine silk net is drawn
through the water and the small Entomostraca are strained
out. By these means the volume of small organisms in one
cubic centimetre of water has been determined for various
localities. It appears, in general, that the organisms are more
numerous in lakes than in streams (Fig. 153). Thus in studies
made in the middle Illinois River and adjacent lakes the
volume of organisms in 1 cu. metre of water was, for a
small stream, 0.3 of a cubic centimetre; for a large river
(the Illinois) 3 cu. em. ; for five lakes in Illinois, 2 to 23 cu. em.
In one year the river (at Havana, Illinois) discharges 75,000
tons of microscopic organisms (Kofoid). In studies on the
small lakes of Wisconsin, Birge has calculated the number of
Entomostraca in a cubic metre at different levels and at different
153
154 ZOOLOGY
times of the year. The average for all localities and periods
is about 40,000 individuals per cubic metre of water in the
lakes. In the late spring the population of the lakes may rise
to 250,000 per cubic metre near the surface; near the bottom
Fie. 153.— A typical lake, exposed to the sunlight and swarming with alge
and Entomostraca.
it may fall to 500 or even less. Ina lake of 80 square kilometres
there may be 160 billion Entomostraca weighing all together
about 20 tons, and this mass of organisms is renewed several
times each summer.
The abundance of Entomostraca in a lake varies with the
time of year. The numbers are relatively small during the
winter, but with the melting of the ice at the end of March
DAPHNIA: A STUDY OF THE FOOD OF FISHES 100
or in April they begin to increase, reaching a maximum in May.
During the midsummer a marked decline occurs, to be followed
by arise at the end of September or in October; after that
the numbers decline for the winter. The reason for these two
maxima is that the spring and autumn are periods of rapid
growth of the food of the Entomostraca, and this in turn is due
to the mixing up of the waters at those periods, and conse-
quently of the salts and organic stuff upon which, in last
analysis, the Entomostraca depend. This mixing up of the
waters depends on the variation of the density of water
as its temperature changes. Water is heaviest at 4° C.
above the freezing-point and tends to settle below water
that is warmer or colder than 4° C. In the spring the bot-
tom waters remain near the freezing-point (0° C.), while the
surface temperature rises. As it approaches 4° the surface
water grows heavier and falls to the bottom, forcing the colder
water up, and this goes on until the whole mass of the water
has reached the temperature of 4°,— this constitutes the spring
circulation of the water; after that, the surface water, becom-
ing still warmer, remains on top. In the autumn the whole
mass of water, even to the bottom, has at first a higher tem-
perature than 4° C., but as the frost comes the surface water
gredually approaches 4° C. and begins to fall, forcing the
warmer, lighter water to the surface. Eventually the densest
(4° C.) water is at the bottom, while the surface water freezes
(at 0° C.) and floats ontop. This is the autumnal movement
of the waters. By means, then, of these remarkable vertical
movements of the waters of lakes the bottom food is made
available for the surface swarms of Entomostraca.
Entomostraca live not only in fresh water, but also in the
sea — that greatest consumer of the sun’s energy. Living
156 ZOOLOGY
in a rich soup of smaller green organisms upon which they can
feed, they multiply enormously. As many as 20,000 of the
adults of one species of Copepod have been counted in one
cubic meter of sea water, and of larval Entomostraca, nearly
200,000. And the total volume of the Entomostraca of the
ocean, if brought together, would make a conical hill about
12 kilometres in diameter and 300 metres high. The
Entromostraca of the sea if driven into Long Island Sound,
which is 80 miles long and 10 miles wide, would fill it full from
the bottom to the present sea-level, leaving no room for water,
and this vast bulk of organisms is frequently renewed.
This enormous mass of Entomostraca is made available
for man, since it forms the principal food of many edible fishes.
As the fish swims through the sea near the surface it opens its
mouth and lets the water flow into it and out at the sides
through the gills. In passing out the small solid particles
are strained from the water by the gill-rakers and are then
swallowed. As the young fish feed they grow, and so the
Entomostraca are transformed into food for man.
The group of Entomostraca includes a great variety of or-
ganisms which are all of small size with a variable number of
body segments and appendages. There are five orders which
we will next consider.
The fairy shrimps or Branch’iopoda' include long, mostly
macroscopic organisms with 10 to 40 pairs of legs. The legs
are leaf-like and serve both as paddles and as breathing organs.
These animals are found in the spring in pools that dry up
later in the year. They produce eggs which have such thick
shells that they can withstand drying for a year or even several
years; indeed they will not hatch until thev have been dried.
1 Latin, branchium, gill; Greek, pous, foot,
DAPHNIA: A STUDY OF THE FOOD OF FISHES
157
One genus (Artemia) loves water that is even denser than sea-
water.
is crystallizing out.
largest of our fairy shrimps,
which is conspicuous because of
its broad shell.
The water-fleas or Cladoc’era
include Daphnia and numerous
other very short Entomostraca
that are much flattened from
side to side (Fig. 155). They
live in ponds and lakes all over
the globe. During the autumn
in northern latitudes certain
species lay fertilized eggs that
may lie dormant for a year or
more. During the greater part
of the year females alone occur,
and unfertilized eggs (called also
“ narthenogenetic ”’ or ‘‘ sum-
mer” eggs) are alone produced.
The body of Daphnia is en-
This
makes the Daphnia so heavy
that it tends to sink in the water
and is only kept up by the vig-
orous swimming strokes of the
closed in a heavy shell.
Fic. 154.— Apus
It lives in the Great Salt Lake and in vats where salt
To the genus Apus (Fig. 154) belongs the
glacialis, ventral
aspect. abd.f, abdominal feet;
ant. 1, antennule ; ant. 2, antenna;
lbr, labrum; md, mandible; mz,
first maxilla; 0v, aperture of ovi-
duct; s.f.pl, sub-frontal plate;
sh.gl, shell-giand; th.f, thoracic
fect; thf. 1, first thoracic foot.
After Bernard.
legs and its great antenne or feelers which increase the friction
with the water, so that falling is less rapid.
The family of bivaive entomostraca or Os’tracoda! comprise
1gstrakon, shell of a testacean ; eidos, like.
158 ZOOLOGY
some very abundant, minute, bean-shaped little crustaceans,
which have to move their appendages very vigorously to sup-
port their heavy bodies in the water. The Ostracods are found
in almost all pools and streams, especially in the early spring.
Many of them seem to be ex-
clusively parthenogenetic.
Of the Copep’oda‘! the
commonest fresh-water
genus is Cyclops, which
occurs in a similar habitat
with Daphnia and is some-
times found even in pure
drinking water. The fe-
male carries a conspicuous
egg-sac on each side of the
abdomen, and reproduc-
Daphnia tion occurs with such rapid-
Fic. 155.—Daphnia. ant. 1, 2, first and ity that one Cyclops might,
second antenne ; br, brain; br.p, brood-
pouch ; d.gl, gland; f, spines on the fect; under the most favorable
ht, heart; sh.g, shell gland. After Claus. conditions, have 5 billion
descendants in one year. It is consequently easy to understand
how Cyclops often becomes the most abundant entomostracan
in our waters, and how in some lakes it has been found that
there are over one million of them to each square metre of
water surface. Large numbers of the Copepoda are marine.
One of the most common is Acartia (Fig. 156), which swarms
to such an extent on the surface of the water as to make great
phosphorescent areas.
Barnacles are the only attached non-parasitic Crustacea.
Certain species of them are found fastened to rocks on the
1kdpe, oar; pous, foot.
DAPHNIA: A STUDY OF THE FOOD OF FISUES 159
Fic. 156.— Acartia, a marine Copepod. Greatly magnified. Photo. by
W.H.C. P.
seashore between tide-marks (Fig. 157). If you watch barna-
cles in rock pools, you can see them open the valves of their
Fia. 157.— Mussel-shell bearing barnacles (Balanus). Photo. by W. H.C. P.
160 ZOOLOGY
shells, protrude their elongated appendages, which together
form a sort of rake, and pull in particles which happen to be
floating about them. Other species of barnacles attach them-
selves to floating seaweed, ship bottoms, and whales; under
these circumstances, despite their sessile habit, they enjoy
a constant change of locality. Barnacles doubtless gain great
protection from the circumstance that they are sessile and
enclosed in shells; but their peculiar habits have given rise to
certain peculiarities in reproduction. They are hermaphro-
ditic ; i.e. both male and female germ cells occur in the same
individual. Despite this fact, dwarf male individuals are
occasionally found inside the shell of the barnacle; these are
known as “ complemental males.” The general form of the
barnacles has also become greatly
modified by their sessile habit,
so that they were long regarded
as mollusks, until it was shown
that the larvee are almost exactly
like those of other Entomostraca.
Trilobites! are extinct giant
Entomostraca, closely allied to
Branchiopods. They were im-
mensely abundant in early geo-
logic times, and their remains
form a large part of certain rocks.
They had a segmented body, with
bifid appendages and long an-
tenn, and their compound eyes
Fic. 158. A restoration of the Were borne on the great frontal
ventral aspect of a Trilobite. shield. Some of them were nearly
Note in particular the character ‘ F *
of the appendages. After Beecher. half a metre long (Fig. 158).
1 Having three lobsters.
CHAPTER XI
THE ANATOMY AND PHYSIOLOGY OF ANNELIDS
General Form of the Body.— The annelids or ringed worms
(Fig. 159) are of especial interest because they seem to be
the ancestors of all the higher animals having a body composed
of rings or segments. Such are all Crustacea, Tracheata
(including insects), and Vertebrates. The origin of the
ringed condition of the body is uncertain; the lower worms do
not have it, so it must have arisen from the unseemented con-
dition. We can help to understand how segmentation of the
body arose by inquiring as to its present meaning. The rings
are more distinct when the worm contracts, less so when it
expands in any part; consequently the rings are due to the
muscles of the body wall. Now in the most perfect annelids
the cavity of the body is divided by partitions into a series
of compartments, resembling the water-tight compartments of
an ocean steamer (Fig. 161). The muscles of the body-wall
run in each compartment from one partition to the next, so
when they contract, swelling, like all muscles, chiefly in the
middle and little at the attached ends, they cause the wavy
outline of the body that we see in the contracted worm. From
one constriction (partition) to the next is one segment. The
reason why the body muscles run in this way is to permit the
worm to writhe — a mode of locomotion very useful in moving
through mud or even water. The writhing, or S-shaped move-
ment of the body (Fig. 182) necessitates, however, contract-
M 161
162 ZOOLOGY
Fic. 159.— An annelid (Eunice).
Anterior and posterior ends of
the body only ; dorsal view. fa
unpaired feeler; fp, paired feeler;
a, eyes; fe, feeler-cirri ; k, gills;
pe, dorsal parapodia; p, para-
podia ; ac, anal cirri. After Lang.
ing certain parts of the body-wall
and expanding others on the same
side of the body at the same time,
and this is possible only with short
muscles. When the muscles run
continuously from head to tail, as
in the “ vinegar eel,” the body
flops from one side to the other as
a whole.
The segmentation of the body
has led to important consequences.
Each segment contains not only
its own muscles, but a pair of ap-
pendages that are moved by the
muscles, nerves to control the
muscles, blood-vessels to supply
them with food, and a pair of
excretory organs to carry off waste
products. Each segment is, in-
deed, a nearly complete organism,
and, consequently, even small
parts of an annelid cut out from
the rest of the body may live a
long time and even regenerate the
lost head and tail.
The head of the annelid is simple
in the earthworm and the other
herbivorous forms; but in Nereis
and the other carnivorous species
(Fig. 160) it gains a great size
and is provided with various sense
ANATOMY AND PHYSIOLOGY OF ANNELIDS 163
organs — tactile organs known as dorsal tentacles and ventral
“valps ”’ and eyes and taste organs. The tail segment, which
contains the anus, frequently bears a pair of tentacles which
are useful when the worm moves, as it often does, backward.
The lateral appendages of the more perfect annelids are
stout, fleshy, paired protuberances on each segment of the
trunk. These are covered with a thin skin to permit of ex-
change of gases with the water, and so they would be without
support were it not for great dark bristles, one of which lies
Fic. 160.— Diagrammatic representation of pharynx of a carnivorous
Annelid. g, brain; k, jaw; ph, pharynx; m, mouth; rt, retractors; pt,
protruders; vf, extrusible part of pharynx; p, its papille. A, pharynx
retracted. B, pharynx protruded. In B, ct, retractors; pt, flexible part of
pharynx. After Lang.
in the axis of each of the two main lobes of the appendage and
serves for the direct attachment of the muscles that move the
appendages. In addition, the appendage carries many finer
bristles (cheetze, whence the name “‘chetopod,” applied to the
group to which Nereis belongs), and these are exceedingly
diverse in form in the different families of chetopods. In
certain species the bristles cover and protect the body (Fig.
179).
The organs of nutrition consist of a food-canal and its glands.
The food-canal usually begins in a mouth cavity at the hinder
end of which is a thick muscular pharynx, the entrance to which
is guarded by a pair of jaws made of the same substance as the
164 ZOOLOGY
cuticula. The remarkable thing about this front end of the
food-canal is that it can be rolled out, carrying the jaws to
some distance in front of the head, where they can seize their
prey and drag it back into the mouth (Fig. 160). Behind the
pharynx comes a short gullet into which glands pour digestive
fluids, and then comes the long intestine, extending through the
middle of the trunk to the last segment. The food-canal of
the polychetes behind the pharynx is characterized by great
simplicity (Fig. 161).
Respiration in polychetes is effected through the skin,
particularly that of the swimming appendages. It is impor-
tant to notice that this is the primitive condition out of which
the respiratory organs of Crustacea have arisen, but in the
latter group, owing to the thick cuticula of the legs and the
larger size of the animal, special outgrowths of the appendages
(gills) have been evolved. We see the beginnings of such
gills in certain polychetes (Fig. 159). In sessile polycheta
(page 188) respiration is confined to certain appendages which
have become greatly enlarged so as to extend beyond the
mouth of the tubes in which they live.
The circulatory system of polychetes is highly developed.
A contracting vessel extends along the whole of the mid-dorsal
line and a smaller tube runs along the midventral line (Fig.
161). These are connected in each segment (Nereis) by a
pair of vessels which (in Polychzetes) break up into capillaries
in the swimming appendages or gills to facilitate respiration.
Blood-vessels also run to the intestine to absorb the digested
food. The heart pulsates rhythmically, forcing blood toward
the head. The blood contains a few corpuscles, but the fluid
is itself red and capable of uniting chemically with oxygen at
the skin and yielding it to the tissues.
Aors.vess—
vert. vess
TL, CO—
Fia. 161.— Semi-diagrammatic view of anterior part of body of Nereis with
dorsal wall removed so as to show alimentary canal, oes, int; the septa;
blood-vessels (dors. vess, vent. vess.); and the nephridia (neph). Behind,
intestine removed to show ventral blood-vessel and nerve cord (ne. co) ; gl,
glands of esophagus; para, swimming fect; perist, peristome; perist. tent,
tentacles of the peristome ; ph, pharynx and its jaws; praest, part of head
lying above mouth. From Parker and Haswell.
165
166 ZOOLOGY
The execretory organs are little coiled tubes of which typi-
cally a pair lies in each segment (Fig. 161). The inner mouth
of the tube opens into the body-cavity, where it sucks in parti-
cles floating in the body-cayity. The wall of the tube, which
is richly supplied with blood-vessels, extracts from the blood
the waste products, thus purifying it. The inner end and
cavity of the tube is lined by little beating hairs (cilia) which
maintain a movement of fluids toward the outer end of the
tube. It is to be noted that the excretory tubes are repeated
in nearly every segment, for we have seen that in the higher
animals — Crustacea — tubes are found in various segments
but performing diverse functions. This is a law of evolution
of organs — at first a repetition of similar ones with a common
function and then a reduction of the total number with a special-
ization of function and structure to each.
The reproductive organs of annelids are relatively simple.
Although the sexes are separate in Polycheetes and in the
earthworm and its allies (Oligochetes) both eggs and sperm
are formed in the same individual; nevertheless any egg of
an individual is not fertilized by a sperm-cell of the same indi-
vidual. The egg and sperm-cells develop in the lining of the
body-cavity and when ripe, fall into the body fluid. They
are sometimes picked up by the excretory tubes and cast into
the sea, where fertilization occurs; but sometimes the ripe
individuals break in two in order to allow the sexual products
to escape. In certain annelids the escape of thé egg and sperm
occurs in thousands of individuals at the same hour, so that
the sea swarms with eggs and sperm; thus the chances of their
getting together are increased. The special case of Autolytus
is referred to on page 187. From the fertilized eggs embryos
covered with cilia arise, which swim free in the sea as they
ANATOMY AND PHYSIOLOGY OF ANNELIDS 167
develop. There is abundant food for them here, but the
danger is great, for the surface is constantly being swept by
fishes that live on the pelagic fauna.
The musculature of annelids has been treated of in the intro-
duction to this chapter. The nervous system is of the same
type as that we have studied in the lobster—a dorsal brain
and a double ventral nerve chain connected by a nervous ring
around the pharynx. From the ventral nerve-cord in each
segment branches go off to the two lobes of the paddles.
The sense-organs of annelicls vary greatly in the different
orders. In the earthworm they are few and simple. The
whole surface of the body bears sensory hairs, and as these
are the only sense-organs known in the earthworm they
are probably (in different regions of the body) capable
of being irritated by mechanical, chemical, thermal, or
luminous stimuli. Nereis, on the other hand, has special
sense-organs. Four eyes rest on the brain. Each is a cup-
like depression of the skin. At the bottom of each are the
special sensitive cells connected with a prominent nerve going
to the brain. The tentacles of Nereis are doubtless tactile, and
the palps probably have also a taste sense. Thus we see that
a carnivorous form like Nereis has well-developed sense-organs,
enabling it to find its prey; while herbivorous species, like
the earthworm, lack such special sense-organs. Each species
has organs agreeing with its needs.
CHAPTER XII
THE EARTHWORM: A STUDY IN SUBTERRESTRIAL
ORGANISMS
THERE is every reason for believing that the primitive organ-
isms lived in water, for we find the simpler organisms living in
water to-day. Indeed, the small ancestral organisms would
dry up if exposed to air. Whether the very earliest organisms
developed in fresh water or in salt water is uncertain and im-
material, but it is quite certain that the principal branches of
the animal kingdom originated in the sea, on or near the shore.
From the shallow seas their descendants passed on the cne
hand into the depths of the sea and on the other either up the
estuaries and into the rivers or, in a few cases, directly upon
the land. Of the forms that thus came to inhabit fresh water
many have succeeded in reaching the shallow pools and small
streams which dry up during a part of the year. Such animals
have been forced, in order to protect themselves from desic-
cation, to penetrate into the muddy bottoms. This habit of
living in the ground is now common to many kinds of animals.
The elementary instincts with which the burrowing habit is
associated are, first of all, a love of contact and of darkness
and, usually, of moisture also. The food of burrowing animals
is usually any sort of organic débris and roots, but the higher
types, like the moles, feed on lower subterrestrial organisms.
Even at the seashore many kinds of marine animals have
acquired burrowing habits. Thus, many of the simplest
organisms, such as sponges, burrow into solid objects at the
168
THE KARTHWORM 169
bottom of the sea. Perhaps the commonest burrowers, how-
ever, are those elongated animals — elongated in association
with the burrowing capacity — that we call sea-worms. A
fuller account of many of them is given in another chapter.
Many of the Crustacea burrow and feed upon the burrowing
worms.
The burrowers of the land are the best known to us. They
have been derived from organisms that lived in fresh water.
Fie. 162.— Flash-light photograph of earthworm and slug crawling on a
pavement at night. Photo. by D. and 8.
Among the land burrowers are the earthworms; certain
Crustacea, like the crayfish; many insect larve; and a few
mollusks and vertebrates. In the present chapter we have
especially to consider the earthworm (Oliogocheta !).
Earthworms, as the name implies, are inhabitants of the
ground, through which they burrow and in which they gain
their food. They sometimes come to the surface at night in
search of companions and food (Fig. 162). Even during the
day in rainy weather they extend the anterior end of the body
out of their burrows. Earthworms, found on the surface at
other times, have, for the most part, been parasitized by a
1 oligos, few ; chete, hair.
170 ZOOLOGY
fly, and are in consequence weak or dying. During the day-
time, if the surface moisture permits, they le near the mouth
of their burrows, probably for the sake of the sun’s warmth.
In this position they can be seen by looking down into the
holes. At such times they are often caught by birds. In dry
weather, or when the ground is freezing, earthworms burrow
deep to a moist stratum, or to below the frost-line, and hiber-
nate there.
Food. — Earthworms are omnivorous. As they burrow
through the ground, the earth is taken into the food tract, and
the digestible particles are dissolved out and absorbed as food.
Earthworms can, however, be fed upon green and dead leaves,
decaying wood, seedlings, bits of flesh, and even filter paper.
Earthworms have the habit of dragging into their burrows
leaves which they intend to devour. There the leaves are
moistened with a fluid excreted by the worm. This fluid
partially digests the food. After being taken into the alimen-
tary tract, the food reaches an organ of the canal known as the
gizzard. This part has thick muscular walls, and contains
in its cavity small stones; by the action of both the muscular
gizzard and the small stones, the food is ground up in much the
same way as are the grains of corn by the aid of stones in the
gizzard of a hen.
Resistance and Regeneration. — Earthworms have a re-
markable power of resisting certain untoward conditions.
Thus they may be kept for months in a moist vessel without
food, or with only filter paper, without starving. On the other
hand, they die in a dry atmosphere in a few hours, whereas
they may be submerged in water for several days without
injury. Very remarkable is their power of healing after injury.
If an earthworm be cut in two near the middle, and the halves
THE EARTHWORM 171
be kept under favorable conditions, each half may develop
its missing organs, so that two complete worms will result.
The anterior half of one worm may be attached to the hinder
end of a second worm by the cut edges, owing to the fact that
the cut edges grow together. This operation is called grafting.
Economics. — Earthworms are, to a certain extent, inju-
rious to vegetation, since they eat tender seedlings and roots;
but, on the other hand, they are almost indispensable to agri-
culture. Their burrows permit rain to percolate deep into the
ground, instead of running off on the surface. They keep the
soil loose, facilitating the penetration of the roots of plants.
The earth that passes through their bodies is ejected on the
surface of the ground near the openings of their burrows, and
is called a “ casting.”” By means of castings the deeper-lying
earth is brought to the surface, and the surface layer of rich
earth, called “ vegetable mold,”
is in this way increased in
thickness by additions to its upper surface. The thickness of
the layer of mold which the castings of one year, if uniformly
spread out, would make has been estimated by Darwin to be
in England about two-tenths of an inch. Most of these
castings are merely taken from the deeper-lying mold, but
they are enriched by the intestinal secretions in passing
through the body of the worm. These intestinal secretions
are said to have the power of slowly dissolving sand and
thus of turning it into soil. Darwin says: “It is a mar-
vellous reflection that the whole of the superficial mold over
any smooth expanse has passed, and will again pass, every few
years, through the bodies of worms. The plow is one of the
most ancient and most valuable of man’s inventions, but long
before he existed the land was, in fact, regularly plowed,
and still continues to be thus plowed, by earthworms.”
df ZOOLOGY
Earthworms are also a source of disease. They burrow into
the carcasses of buried animals that have died of infection
and bring the disease germs to the surface, where they may
infect healthy animals. They are believed to carry the germs
of gapes — a worm parasitic in chicks.
Earthworms belong to the sub-kingdom of ringed worms
(Annelids!). The annelids are divided into two orders, one of
which lives chiefly in the sea and is called Pol’ychexta,? while
the other lives chiefly in fresh water or in the ground and
is known as Ol’igocheta. Earthworms belong to the latter
order. This order is distinguished, in addition to its non-
marine life, by the absence of foot-pads and parapodia, by
having few bristles, and by the absence both of tactile append-
ages at the head end and of gills.
The Oligocheta are either aquatic or terrestrial. The
aquatic Oligocheta are among the commonest inhabitants of
ponds and ditches, living sometimes in the mud and sometimes
at the surface of the water.
Tubifex * is common in slow-running brooks, and lives in the
mud of the bottom, forming tubes in it. The thread-like
bodies of the worm are stretched up beyond the surface of the
mud and wave in the water in graceful undulations. Often
the worms are so numerous that their reddish color gives a
decided tinge to the bottom. They thrive well in fresh-water
aquaria.
Dero ‘ is very common on the surface of ponds, particularly
in the midst of duckweed (Lemna), the leaves of which it
cements together to form a floating tube in which it lives, and
by which it is accompanied in all its migrations. Dero can
lannulus, a little ring. 3 tubus, tube ; facere, to make.
2 poly, many ; cheta, hair, 4dero, to skin or flay.
THE EARTHWORM 173
also be told by the sort of funnel at the hinder end of the trans-
parent body, from the margins of which finger-like filaments
arise which aid in respiration (Fig. 163).
Fic. 163.— Dero, the duck-weed worm. Enlarged. After Reighard. The
lettering is as follows: or., mouth; phz., pharynx; oe., esophagus; sg.o.,
segmental organ; in., intestine; pav., pavilion or tunnel; dg.app., finger-
like appendages. From Reighard.
Nais! does not construct tubes, and it has no respiratory
filaments at the hinder end of the body (Fig. 164). It also
has eyes; while Dero has none. Both Dero and Nais have
the interesting habit of reproducing by dividing the body trans-
versely. Jn the middle of the body tentacles hegin to arise,
a new mouth is formed, and the worm constricts into two.
Indeed, sometimes several new heads may be forming in the
1nais, a water-nymph.
174 ZOOLOGY
midst of a single worm. This habit is of advantage not only
in multiplying the number of individuals of the species, but
also as a means of protection. For if, by chance, the larva
of the water-heetle (Dytiscus) seizes a Nais and bites it in
two, the part which es-
capes can go on devel-
oping new individuals.
The terrestrial Oligo-
chete include the com-
mon earthworm and, in
addition, worms that
live on the seashore be-
tween the tides and
even in places which are
rich in vapors of am-
monia arising from de-
caying stuff.
There is another
group of fresh-water
Fic. 164.— Nais. a, mouth; 0, anus; ¢, in-
testine. From Leunis. worms which is closely
related to the Oligocheta but which has a very different
”
are flattened
worms, which, like the earthworm, show metamerism; that
appearance. The leeches, or ‘“ bloodsuckers,
is, there is a repetition of the internal organs. They are also
segmented; that is, the body has external rings, although
they may be obscure. One segment does not, however, as in
the earthworm, correspond with one set of internal organs
(metamere), but there are three, four, or five segments to a
metamere. Tceches have no appendages and no _ bristles;
but they have a sucking disk at the posterior end of the body
for the purpose of sticking to things (Fig. 165). They usually
THE EARTHWORM 175
have a smaller, anterior sucking disk around the mouth, which
may or may not be provided with teeth, for the purpose of
cutting through the skin. When
there are no teeth, the pharynx
can be thrust out, forming a pro-
boscis. With a few exceptions, all
leeches live in water; but in Cey-
lon there is a land-leech which
lives in foliage and attacks man
and other animals. Other leeches
may live in damp places at a con-
siderable distance from water.
Such a leech has been described in
this country that was dug up ina
garden at a point about 60 metres
from the nearest rivulet, where
it was feeding on earthworms.
Leeches suck the blood of fishes
and other aquatic animals.
Certain kinds devour worms, in-
sects, and other small creatures.
Rarely do they feed on plants.
The commonest of the larger blood-
suckers of our waters is Nephelis,
which is not distinctly segmented.
It varies from black to slate color,
spotted. It lives in running water,
{. Pontobdella 2. Clepsine
Fic. 165. — Two leeches, Clepsine,
found in ponds, often parasitic
on frogs; and Pontobdella, a
marine species living on fish.
From Parker and Haswell.
and is sometimes striped or
ditches, and ponds.
Clepsine ? is a very flat and broad leech, which is common under
floating wood. It feeds on snails and creeps like the inch-worm.
The female carries its young attached to its under-surface (Fig. 165).
1 Nephele, wife of Athamas.
2From klepto, to steal.
176 ZOOLOGY
In conclusion brief mention must be made of certain worm-
like animals still more distantly related to the earthworm.
The first of these is marine, but has the same slow-moving,
burrowing habits as the earthworm. These animals have
become more modified in connection with their burrowing
habits than the earthworm, for they
Gephyrea.!
This group con-
tains several rather
rare animals, some of
Fia. 166.— Phasco-
losoma, a Gephy-
which are edible, and
are held in esteem by
rean. One-fourth
nat. size. From the Chinese. One of
Leunis.
the commonest is
Phascolosoma,? which is a tough but
smooth-skinned, cigar-shaped worm,
which one can dig up on our sandy sea-
beaches (Fig. 166).
from the other a great proboscis ending
One end is pointed;
in tentacles surrounding a mouth can be
extruded. Another species found on our
beaches after a storm, something like a
small cucumber in shape and size, has a
row of bristles at each end, indicat-
ing its relationship with the bristle-
bearing worms. This. striking species,
lgephyra, bridge ; because they were once
considered to bridge the gap between holothu-
rians and worms.
2 phaskolos, sac; soma, body.
have lost not only their
appendages, but in the adult stage even the
segmentation of the body. This is the class
Y a
Fia. 167.— Echiurus.
About
one-half nat. size. prob,
proboscis; ant. set, anterior
sete; post. set, posterior
sete. After Greef, from
Parker and Haswell’s Text-
book.
THE EARTHWORM 177
Echiurus,' is segmented when young like Nereis, but eventually
it loses its segmentation (Fig. 167).
Possibly allied to the Gephyrea is the group of Bryoz’oa,?
or moss-animals. These are noteworthy from the fact that
Fic. 168. — Pedicellina americana, an endoproctous bryozoan. is spindle-shaped, and bears a lash at
' its anterior end. At the base of the
lash is a red “ eyespot.”’
Allied to Euglena is Volvox,! a
Pe = spherical, multicellular organism, half
‘Ss Eee | animal and half plant, and forming a
a —” | sort of connecting link between the
Nis ete nea
Protozoa (or one-celled animals) and
Fic. 272. — Volvox globator. a : ;
Much magnified. Photo. the multicellular higher organisms.
of the living animal. Volvox occurs abundantly in our
ponds, and gets its name from its manner of revolving in the
water (Fig. 272).
To the fourth or highest class of Protozoa has been restricted
the name Infusoria formerly applied to all Protozoa. In the
Infusoria the body has a definite and more or less permanent
form. The hair-like appendages (cilia), by which they move
about or seize their prey, cannot be retracted.
Of all the Infusoria, none is more abundant than Para-
meecium. It occurs everywhere, principally in stagnant fresh
water, but also in salt water. It lives entirely on vegetable
food, and is sure to abound wherever plant matter is under-
going decay. When a culture is once started from a hay in-
1 From volvere, to roll,
PARAMECIUM 287
fusion, which takes one or two weeks, it will be found to
thrive well on corn-meal.
Since the cilia of Paramcecium are of nearly uniform size
and occur all over the body, it has been assigned to the order
Holotricha. In another order of Infusoria the cilia are greatly
“a g EDR LEE,
Fic. 273. — A stalked Vorticella, Carchesium. Greatly magnified.
From a photograph of the living animals.
enlarged around the mouth, and on account of this difference
in size the order is named Heterotricha. As an example of the
Heterotricha, the trumpet-animalcule (Stentor!) may be
mentioned. This is found attached to vegetable débris —
sticks, stones, water-weeds, and other objects—occurring in
pools, ponds, lakes, and sluggish streams. These things should
be gathered and placed in an aquarium, when the Stentors, if
present, will attach themselves to the glass sides of the vessel.
1 Stentor, a Greek at Troy, known for his loud voice.
288 ZOOLOGY
The attachment of Stentor to objects is not permanent, for it
may loose its hold and swim free. When the animal is stained
in hematoxylin, the characteristic nucleus, looking like a chain
of beads, becomes evident.
The bell-animalcule (Vorticella) is found in pools or infu-
sions, permanently attached by a long stalk. When the ani-
mal is irritated, it contracts its stalk, which twists into a close
spiral. In other species, colonies are formed, so that a num-
ber of heads is attached to a central stalk (Fig. 273). A
colony, when fully expanded, appears like a fine, white mould
attached to a submerged object. In both of these types the
food consists of small organic particles, which are swept
into the gullet by the circlet of cilia placed around the upper
end of the body.
The Suctoria are sessile Infusoria, from whose upper surface
numerous remarkable sucking tentacles arise. By means of
these tentacles the animal can hold on to Paramecia and
other free-swimming Infusoria, from which it extracts the
body fluids. Some Suctoria are stalked, while others are un-
stalked. They are found most abundantly in standing water,
either fresh or salt, and are often attached to other animals, —
Bryozoa, entomostracans, and pulmonate mollusks.
CHAPTER XXI
THE ANCESTRY OF VERTEBRATES
SOMEWHERE out of the great variety of phyla of invertebrates
the vertebrate stem arose. The origin of this branch of the
animal kingdom has a special interest for us because to it
belong not only man but also the most of our favorite fellow-
creatures, our domestic animals, the birds, and the fishes. We
have now to consider what is known of the ancestry of verte-
brates.
In seeking the origin of any phylum we must first separate
out what is essential and universal in it from what is secondary
and special. And first of all, the phylum of vertebrates is
distinguished by the possession of an internal skeleton whose
simplest forerunner is a rod of tissue lying in the axis of the
body and running from the head to the end of the tail. This
rod is called the chorda. It is found in some simple animals
which have no other internal skeleton, and so they and verte-
brates are often classed together as Chordates. The essential
feature of Chordates are four: (1) the chorda just referred to ;
(2) gill-slits passing through the wall of the throat so that
water taken into the mouth passes out through the neck, as is
seen in fishes; (3) a nervous cord that lies wholly on the dorsal
side of the animal; and (4) a heart which lies on the ventral
side. Any animal which can show this combination of charac-
ters, or any of them, thereby reveals its affinity to the verte-
brates, no matter how lowly it may be.
U 289
290 ZOOLOGY
Not less important are the points in which chordates resem-
ble other animals. First of all they are bilaterally symmetrical
animals, at least in their young stages; secondly, they are seg-
mented animals, and they have ventral organs repeated as in
other externally ringed animals. Consequently they show
their affinities to the great groups to which annelids and ar-
thropods also belong. A diagram showing the relationship
of chordates to the invertebrate groups already studied would
be something like this:
Chordata
y
JY.
Arthropoda fe
Annelida
|
Echinodermata Mollusca
tet
Scolecida !
Coelenterata
Porifera
ae
Protozoa
Applying now the four criteria of chordates enumerated
above, we find that they discover strange associates for the
vertebrates. Of these the most remarkable is a group long
known as Tunicates, animals which in some cases are attached
and in others float on the surface of the sea. Tunicates show
a great variety of external forms (Fig. 274), but they all reveal
their chordate nature in their youthful forms. Thus in the
tadpole stage (Fig. 275) we see the chorda (noto) in the axis
of the body, the nerve-cord (med) above it; and one of the
throat slits (sé7g) already formed. When the animal attaches
itself, it loses its tail and chorda, but the number of gill-slits
1 Includes flatworms, roundworms, rotifers, bryozoans, and brachiopods.
THE ANCESTRY OF VERTEBRATES 291
greatly increases. The body now shows (Fig. 276) two open-
ings; one inhalent (0), and one exhalent (at). Some species,
THALIACEA>
a
t Ascidiids CGynthiids Compound
Molgulids Ascidians
Fre. 274. — A group of Tunicates showing the attached forms (Ascidiacea)
both simple (left-hand side of picture) and compound (at right); the
oceanic forms (Thaliacea) that swim near the surface; and the small tailed
forms (Larvacea) that look like the larval stages of higher Tunicata. Frrom
Cambridge Natural History.
after becoming attached, form colonies by budding new zooids
upon the side of their body. The whole colony may have a
common exhalent opening (Fig. 277, cl).
Below the tunicates is a small group of worm-like animals
bo
we)
bo
ZOOLOGY
Fic. 275. — Diagram of the metamorphosis of the free, tailed larva into the
fixed Tunicate. A, stage of free-swimming larva; B, recently fixed larva;
C, older fixed stage; adh, papilla for adhesion to the rock; afr, ‘‘atrial”’
cavity; cil.gr, ciliated groove on wall of pharynx; end, glandular groove
in pharynx; ht, heart; med, ganglion of heart; n.gn, brain; noto, noto-
chord; or, mouth; rect, rectum; sens.ves, sense space; stig, throat
(gill) slits; sol, shoot from which buds arise; ¢, tail. From Korschelt and
Heider.
THE ANCESTRY OF VERTEBRATES 293
whose affinity with chordates is a little less certain. These
animals belong to the genus Balanoglossus (Fig. 278); they
ij live in the mud of the seashore
and have doubtless lost many
organs as a result of their
burrowing habit. The elon-
Fie. 276.— Ciona, a simple Fie. 277. — Two small colonies of
Tunicate. 0, mouth; at, open- compound Tunicates (Botryllus).
ing of atrium, or exhalent The ‘‘zooids”’ are grouped about a
opening; st, stolon. After center, have a common cloacal
Leuckart and Nitsche’s dia- opening (cl), but separate mouths
gram. (or). After Milne-Edwards.
gated body is divisible into three parts: the proboscis at the an-
terior end; the collar; and the trunk. In the trunk an anterior
region containing gill-slits (br, Fig. 279), and a posterior region
that is without gills can be distinguished. The mouth lies
between the proboscis and collar and leads into a nearly
294 ZOOLOGY
straight food-canal, in the anterior part of which there are
numerous openings to the exterior — the gill-slits. There is
a small sac, lying dorsal to the
pharynx, which is regarded
as a chorda. The brain is
dorsal, and there are both
dorsal and ventral nerves.
If Balanoglossus is indeed a
chordate, it isa degenerate de-
scendant of a primitive form.
Above the tunicates, and
showing the clearest possible
affinities to the fishes, is a re-
markable animal about 5 zen-
timetres long. It lives almost
buried in the sand of the sea-
shore in various parts of the
world, and is known as Am-
phioxus (Fig. 280). It is
bilaterally symmetrical, or
nearly so, and has a distinctly
segmented body. The food-
Fia. 278. — Balanoglossus, the acorn- canal runs nearly straight
tongued worm. The proboscis at the .
anterior end is at the top of the figure through the body and is
(arty outside); behind an 2 perforated in the pharynx
long, brown-red trunk. Nat. size. by 90 or more pairs of gill-
Photo. of livinganimal by W. H.C. P.
shits. These do not, however,
open directly to the exterior, but into a large chamber that has a
single posterior connection with the outer world. Through the
axis of the body, from the tip of the snout to the end of the tail,
runs the chorda, which, in this animal, is a sort of jelly-like rod
THE ANCESTRY
(Fig. 281, nch).
tem (br and sp. cd) lies above the
chorda; it begins in a slight en-
largement whose cavity communi-
cates with the exterior by a nasal
pit and carries a large pigmented
“eyespot”’ (e. sp). The blood
system consists of a ventral vessel
The nervous svs-
carrying blood forward and a dor-
sal one carrying it backward.
The ventral vessel connects with
the dorsal vessel by a pair of
vessels running along each gill-
arch (br.sep, between the gill-
shits), and from the pharynx the
The
direction of the dorsal current in
blood runs toward the tail.
the trunk of Amphioxus is thus ex-
actly opposite to that of worms.
There is a series of kidney tubules
(nph) much resembling those of
annelids, and the reproductive
cells are formed in glands that are
repeated in many segments of the
body.
vertebrates, the outer skin con-
In Amphioxus, as in in-
sists of a single layer of cells, below
which lie cells of a connecting
nature. Finally, on the exterior a
pair of folds, like fins, runs con-
tinuously from near the mouth to
the outer pore of the gill-chamher.
OF VERTEBRATES 295
ws
BUTI
Fic. 279. — Drawing of entire
Balanoglossus. br, gills; co,
collar; gen, genital ridges;
hep, ridges lying over liver;
pr, proboscis. From Parker
and Haswell; after Spengel.
296 ZOOLOGY
This is believed to be the forerunner of the appendages of
vertebrates.
This review of the most primitive chordates indicates that
the ancestors of vertebrates were elongated, worm-like, seg-
ml, pl
alrp venl fr
G
cir’ “i ih rhd gon ae any
Fic. 280. — Amphiorus lanceolatus. A, ventral; B, side view of the entire
animal. an, anus; atrp, atriopore; cd.f, caudal fin; c?r, cirri; dors.f,
dorsal fin; dors.f.r, dorsal fin-rays; gon, gonads; mtpl, metapleure;
myom, myomeres; nch, notochord; or.hd, oral hood; vent.f, ventral fin;
vent.f.r, ventral fin-rays. After Kirkaldy.
mented animals. In this respect they resembled annelids,
but in certain respects the internal organs of vertebrates are
inverted as compared with those of invertebrates thus : —
INVERTEBRATES VERTEBRATES
Main nerve-cord . . . . . «| ventral dorsal
Heath. A As dorsal ventral
Direction of flow in reual v Seal
i brulee toward head toward tail
Direction of flow in dural Seca
intrunk . .. . . . . .{ toward tail toward head
It will be seen that the relations of the above parts in verte-
brates become the same as in Invertebrates if we think of the
former as turned on their backs. It seems, at first sight,
2
RTEBRATES
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CHAPTER XXII
THE SMELT: A STUDY OF FOOD SUPPLY
GREEN plants only can transform inorganic substances into
living matter with the aid of the energy of the sun. Yet it is
upon such inorganic substances that all living matter eventu-
ally depends for its increase, and it is from solar energy that
all vital energy sooner or later comes. Accordingly, animals,
including man, must get their energy either from plants or
from plant-devouring animals.
The total amount of energy clerived from the sun is enor-
mous. On the land this energy is absorbed by forests, by the
grasses of prairies and meadows, and by growing crops; and
is by them transformed into new, living material. Man is
constantly working to increase the proportion of solar energy
that becomes fixed in the crops, but only a very small propor-
tion of the surface of the land is yet under cultivation. There
are great tracts, such as deserts and rocky places, where the
falling energy seems to be quite wasted, and the same seems
to be true of the water surface of the earth, which amounts to
three-fifths of the whole (Fig. 282). It is, however, very far
from the truth that the solar energy falling on the sea is lost,
for the entire surface of the sea swarms with microscopic green
organisms which are to the sea what the grass of the fields is
to the land. The green plants of the ocean are the food of the
small Crustacea called Entomostraca (p. 156), and these,
as we saw in Chapter X, in turn are the food of fishes. In
298
THE SMELT 299
employing fish as food man is utilizing the energy that falls
on the sunlit ocean (Fig. 282 a).
So great is the expanse of the ocean that the amount of
surface algw and of the fishes is practically unlimited. No
nation has utilized to the utmost the possibility of fish food
from the sea, yet some derive their main sustenance from fish-
Fig. 282. — The Open Sea.
eries. This is particularly true of Holland, and it is an old
proverb in that country ‘that the foundation of Amsterdam
was laid on herring bones.”
The principal fisheries in the United States are those of cod,
herring, mackerel, and salmon. Boston and Gloucester fish-
ing fleets alone in the year 1902 supplied about 33,000 tons of
codfish to our markets, and probably twice as much was taken
by other nations combined. The herring fishery, which reaches
its greatest importance on the northwestern coast of Europe,
has engaged annually 100,000 men and over 300 larger vessels
during the past quarter of a century. As many as 22 million
herring have been caught in two days by fishermen of a single
English town, One of the greatest fisheries of the United
300 ZOOLOGY
States is that of the salmon; over three million cases con-
taining thirteen to fifteen million fish are packed annually on
our Pacific coast. Over 43 million salmon were caught in
Alaska in one year (1908). These figures, which are so large
Fic. 282 a.— The Return of the Fishermen. From a painting by Ber-
thelemy.
as to be difficult to grasp, give us a faint idea of the vast-
ness of the process by which the energy absorbed by the
microscopic organisms of the sea is utilized as food by man.
Fish are employed by man, not only as food, but, heing some-
times obtained in greater numbers than the market requires,
they have been used to fertilize the land. Most coastal
states have declared it illegal to use fish as fertilizers of land,
and there is now little excuse for doing so. Modern canning
methods make it now possible to utilize even the largest
THE SMELT - 301
catches; the excess is immediately preserved to be used in
periods of scarcity. The
bones and scraps from can-
ning factories may well be
used in the manufacture of
fertilizers, for they are rich
”
in phosphorus and other im-
eye; ex.br.ap, external
branchial apertures; 1.1, lateral line; mth, mouth; myc, myocommas; mym, myomeres; na, nasal aperture ;
Biology.
portant foods for plants.
“
Fish culture. — Excessive
fishing has depleted many
rivers in which fish were
formerly abundant. An at-
tempt has been made, with
more or less success, to re-
stock such streams. Fish
are artificially hatched, and
the young (or fry) are
shipped to the streams need-
ing to be restocked. The
United States maintains 49
such fish hatcheries, which
in 1964 distributed
From Parker :
ay d
I TR Ti
Oe a i a
ont
Side view of dogfish (Afustelus antarcticus), with a strip of skin in the middle of the body removed
an, anus; c.d.f, caudal fin; d.f.1, d.f.2, dorsal fins; e,
pet.f, pectoral fin; pv.f, pelvic fin; sp, spiracle; v.f, ventral fin.
1,250,000,000 fish. In ad- - =
dition, many states maintain e
independent hatcheries, so 8
that the total number of z
young annually hatched and A
set free by all our hatcheries 3
must approach two billion. % &
Of course a large proportion ae
oy
of these young fish are de-
02 ZOOLOGY
eo
stroyed before they reach maturity, but there can be little
doubt that vast numbers survive to breed.
Fishes are one group of the vertebrates, or back-boned ani-
mals. Vertebrates are characterized by the possession of an
internal skeleton that supports the soft parts of the body, by
the possession of two pairs of limbs, and by paired openings
leading from the throat to the outside, which last are found
in the higher forms in the embryonic stage only. In the fishes
Fig. 284. — Salmo fario. a.l, adipose lobe of pelvic fin; an, anus; c.f, caudal
fin; d.f.1, first dorsal; d.f.2, second dorsal or adipose fin; 1.1, lateral line; op,
operculum ; pet./, pectoral fin; pv.f, pelvic fin; v.f, ventral fin. After Jardine.
these openings are lined by finger-like processes into which the
blood flows. These are known as gills and it is in them that
the blood takes oxygen from the water. The appendages of
fishes are used as paddles in the water and are known as fins.
The tail is well developed and, by its powerful side-blows in
the water, propels the fish rapidly forward.
Classification. — Fishes are classified into five groups, the
lowest of which contains the lamprey eels. The next higher
in organization (cartilagenous fishes) includes the sharks,
skates, and rays.'. The third group (the bony fishes) includes
the vast majority of our common fishes. A fourth group —
1 Fig. 283.
TUE SMELT 30:
QO
(armored fishes) Ganoids — was in former geological times
much more abundant than now, but still populates the waters
of our Central States. The fifth group is that of the Lung-
fishes (Dipnoans), which includes a few rare fishes that live
in the mud. As the bony fishes are the best
known and most widespread we may take
one of them, the brown trout (Fig. 284), for
an anatomical study.
The general form of body.—- Three regions
may he distinguished ; viz. head, trunk, and
tail. The head bears the mouth and many
organs of special sense. Its conical form
facilitates passage through the water. The
head is encased in large, bony plates; the
trunk is covered by scales; and the tail
carries a thin membrane.
Fic. 285. — One of
Die: trumle bears: ts avranar vfortst
two pairs of appendages and three median
appendages in addition to the tail. The
plates and scales constitute the external
skeleton, which is developed in the skin.
bre of the tail of
the trout. CN, the
centrum ; N.A,
neural arch; WN.
SP, neural spine;
H.A, hemal arch
: eae Beats eas (because toward
The internal skeleton consists of an axial Tena Ae ae.
portion replacing the chorda. Thisismade From Parker and
: Haswell.
up of dice-box (or hour-glass) shaped bodies,
each of which bears above a bony arch, which protects the
main or dorsal nerve and supports the median fin (Tig. 285).
Below, each bears a pair of slender bones, the ribs in front of the
anus and the ventral arches behind. The brain-case consists of
numerous bones, some of which arise in the skin and others be-
long to the axial skeleton (Tig. 286). Here on the head skeletal
parts of widely different origin come together into one cranium,
and even form parts of one and the same bone. In ourownskull
ZOOLOGY
304
skin origin, and
the same is true of the thin bones that make the sides and roof
bones that carry teeth are of
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THE SMELT 305
In addition to the axial skeleton there is the skeleton of the
anterior and posterior appendages. The skeleton of each
pair of appendages is borne upon a bony ring which nearly
encircles the body. These are called respectively the shoulder
and pelvic girdles. The skeleton of the fin consists of a row
of cylindrical bones which bear at their outer extremities
the horny rays that support the fins.
Organs and function of nutrition (Fig. 287).— The large
mouth bears teeth not only on its Jaws but also on its roof (vo).
The whole of the interior of the mouth was, in the ancestors
of fishes, covered with scales of the same sort as those that
covered the body just outside the mouth. All teeth have their
origin in such fish-scales. In early fishes the number of teeth
was large and the position undefined, but in the higher animals
the number has become limited to a single row on each jaw.
At the hinder part of the mouth are four vertical gill-slits
(ph), fringed by a bony straining apparatus, the gill-rakers.
The water that has been taken in through the mouth is forced
out through the gills by closing the mouth in front and raising
its roof so as to expel the water. The remainder of the food-
canal consists of a stomach that is twisted on itself and of
an intestine which usually forms either no convolutions or
only the simplest. The liver (l) communicates by a tube
with the anterior part of the intestine, and is provided with
a large gall-bladder (g.bl). Immediately below the liver
opening is a bunch of hollow tubes called the ceca (py.c).
These are also digestive in function. An air-bladder (a.6/) lies
just over the intestine, and in front it opens into the pharynx
(pn.d). The air-bladder of fishes functions so as to enable
the fish to vary the volume of gases in the body and thus to
vary its specific gravity. It is often spoken of as an organ of
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THE SMELT 307
flotation, and in it the lungs of land vertebrates seem to be
foreshadowed.
Respiration. — The first stage in respiration is carried out
in the gills, where the oxygen in the water is picked up by the
blood which circulates in them. The second stage of the res-
piratory process occurs in the tissues to which the blood gives
up its oxygen.
Organs of circulation. — Beneath the pharynx of the trout
there is a heart, consisting of two chambers, an auricle and a
ventricle. The auricle receives the venous blood from the
trunk directly and that from the intestine after it has passed
through the liver, where it relinquishes most of its food. The
ventricle is more muscular and passes into the aorta, as the
main vessel leading out from it is called. Together they force
the blood through the gills, where it is purified and from which
it passes to the head, trunk, trunk-walls, and viscera. The
blood, as in other vertebrates, contains red blood corpuscles.
The organs of excretion are a pair of kidneys (Ad), lying all
along the dorsal wall of the abdomen above the air-bladder.
In early development each kidney consists of a series of tubules,
one for each segment of the body, as in annelids. These
tubules collect fluids from the body-cavity as well as from the
blood-vessels and convey it to the outside.
Organs of reproduction. — The number of eggs laid by
most fishes is very great, and so fishes have correspondingly
large ovaries. The germ-glands both of the female and male
lie along the sides of the body-cavity, and both open to the
exterior at a point immediately behind the vent (w.g.s). The
eggs and sperm are both thrown out into the water. There
fertilization of the eggs (7.e. union with a sperm) takes place
and development begins.
308 ZOOLOGY
Musculature.— The muscles may be classified, like the
general parts of the body, into muscles of the trunk (Fig. 283)
and tail and muscles of the head, including those of the jaws,
tongue-bones, operculum, and gill-arches.
The nervous system consists of the brain and spinal cord
and of the nerves supplying the skin, sense-organs, viscera,
and limbs. The brain (Fig. 287, crb, etc.) is by far the largest
mass of the nervous system because it receives nerves of general
sense and probably has a general control over the behavior
of the animal. It is divided into three parts, sometimes called
fore, mid, and hind brain. In the higher vertebrate classes
these parts develop in different. proportions.
Sense-organs. — The organs of chemical sense reside in the
olfactory sac on the snout. The lips of the sac have closed
near the middle, leaving a front and rear opening through
which the water rushes. Other organs of chemical sense are
the organs of the lateral line, which at its anterior end di-
vides into many branches running over the head. Originally
the sense-organs of this line were distributed along the bot-
tom of a sort of trench. Now, however, the trench is cov-
ered over by the skin and scales forming a canal. The scales
are perforated at intervals to connect the outside with the
interior of the canal. There is good reason for thinking that
the ear is only a specialized part of the lateral line organ, and
that is where it got its semicircular canals. There is also an
otolith in each ear which probably assists in the equilibrium
of the fish. The eye of the fish has to be used under the
water. Our eyes are not fitted for seeing under water as
our lens is too flat. In the case of the trout the lens is
nearly spherical and is forced back towards the retina. Rays
from the water will not be bent on entering the lens, which
THE SMELT 309
has about the same specific gravity as water, but will be se-
verely bent as they leave it. This accounts for the small dis- |
tance between the lens and the retina.
The smelts belong to the bony fishes and are related to the
trout. They are preéminently inhabitants of the northern
temperate zone, since all but one of the ten genera occur only
there. They are small marine fishes, and although a few are
inhabitants of the deep sea, most live near the shore, and in the
spring ascend rivers to spawn. Some of them have become cut
off from descending to the sea, and live permanently, as “ land-
locked’ forms, in fresh water. Such “ land-locked ” indi-
viduals are of smaller size than the marine ones. The food of
smelts, like that of other salmons, is chiefly animal, consisting
of smaller fishes or insects, small crustaceans, and mollusks.
Smelt are of considerable economic importance, since they
share with other members of the salmon family a delicately
flavored flesh. Our Atlantic form (Osmerus! mordax?), which
ranges from Delaware Bay northward, is caught most abun-
dantly in Maine. The total Atlantic smelt fishery is valued at
$125,000. Smelt eggs are artificially hatched and planted in
rivers previously uninhabited by them. Smelt are said to
return to these rivers after spending the winter in the sea.
The family Salmonide, which in its widest sense includes
the smelts,? comprises some of our most important food fishes.
It is distinguished from other families of spineless finned fishes
by having both ventral (v.f, in Fig. 284) and adipose fins (df,
Fig. 284) present. The head is naked, but the body is scaly
and rounded.
1 osmerus, odorous ; the Greek name is the equivalent of the English ‘‘smelt.”’
2 Biting.
3 By recent authors the smelts are assigned to a distinct family, the Argen-
tinide.
310 ZOOLOGY
Besides the smelt there are, in this family, numerous impor-
tant species. The salmon proper? are restricted to the north
temperate and arctic regions, and live either in the sea, migrat-
ing to fresh water to spawn, or exclusively in brooks and
lakes. The migrations of salmon from the sea up the rivers
are remarkable. Hundreds of miles are sometimes journeyed,
rapids swum, and falls leaped, for the purpose of laying eggs
in some remote lake. At the end of their journey the eggs
are laid and male and female parents die. On the Atlantic
coast the Penobscot River has the most important run of
salmon. The Pacific salmon pass up the Sacramento and
Columbia rivers, and up many rivers of British Columbia and
Alaska. In these rivers the fish are caught as they ascend to
breed. Such is the greediness and lack of foresight of the
canning fisheries on the Columbia River that very few salmon
are permitted to pass the nets of the canning factories, and
consequently the apparently inexhaustible supply of this fish
has been immensely reduced and threatened with destruc-
tion, but it will probably be preserved by the assistance of
artificial hatching.
The trout, of which there is a number of kinds on both
continents, is commercially much less important than the
salmon proper. Asa result of overfishing, and the pollution
of streams by factories and sewage, this fish is disappearing
from Eastern waters.
The whitefish, of which we possess many species, is exclu-
sively an inhabitant of fresh water? and is derived chiefly from
the Great Lakes. Its teeth are almost completely absent, or
very small; it feeds almost exclusively upon small arthropods
and mollusks. It is of very great commercial importance,
1 Fig. 284. 2 Pig, 28
g.
oO
THE SMELT 311
its fisheries being valued at nearly three million dollars a
year.
Fie. 288. — Coregonus, the lake whitefish. Much reduced. From Goode.
Leaving now the salmon, we may briefly consider some of
the other more important families of bony fishes.
Fig. 289. — Morone americana, the white perch. The fish is searching for
food along the bottom of the aquarium, an instinct which it shows in
nature also. About one-third nat. size. Photo. of living animal by Dr.
R. W. Shufeldt, from ‘‘Bull. U. 8. Fish Com.,”’ 1899.
312 ZOOLOGY
The darters are spiny-rayed fishes of small size, from four
to seventeen centimetres long, brightly colored, and with well-
developed pectoral fins. They live in clear streams, half
concealed under stones, and are most abundant in the Missis-
sippi drainage basin.
pi 4 oe ae A et 3
Fic. 290. — Eupomatis gibbosus, the common sunfish. Two-thirds nat.
size. Photo. of living animal by Dr. R. W. Shufeldt, ‘‘Bull. U. 8S. Fish
Com.,”’ 1899.
The perches are a widespread family, represented in this
country chiefly by the common yellow perch of the East, the
“wall-eyed pike” of the Great Lake region, and the white
perch of the Atlantic coast (Fig. 289). These fish have an
oblong, compressed body covered with small scales; they are
highly rapacious, and are believed to be destructive to the
young of other species of fish. They are esteemed as food,
although not to the extent of annihilation.
THE SMELT 313
The sunfishes! have a perch-like form, but have only one
dorsal fin instead of two. They live in fresh water, have
rapacious habits, are brilliantly colored,
and build nests in the sand, which the
male watches over and defends with
courage. Some species living in the
Great Lakes are known as black bass, or
rock bass. The small species, with the
brilliant red edge to the operculum, is
called pumpkinseed.
The toadfishes (Fig. 291) are repre-
sented in our faunas by a common
species which lives under stones in har-
bors and attaches its eggs to the under
side of stones. It is a vigorous fighter.
The sculpin (Fig. 292) is closely re- bog
lated to the toadfish. Like the latter, Fic. 291.— Batrachus tau,
it has a broad head and nearly scaleless a Me ean Sn
body. The pectoral fins are large, and size. Photo. by W. H.
the two dorsal fins extend along the ee
greater part of the back. Allied to the foregoing is the rock
eel (Fig. 293), which is sometimes brought up in the seine from
a depth of 8 to 10 fathoms.
Fic. 292. — The little sculpin, Acanthocottus. Two-thirds nat. size.
Photo. by W. H.C. P.
1 Fig. 290.
314 ZOOLOGY
The silversides are especially abundant along our Atlantic
coast. They have an elongated, somewhat compressed body,
Fic. 293. — Pholis, the rock eel. Right side. Nat. size. Photo.
and a broad, bright silvery band on the sides, against a green-
ish general body color. The dorsal spines are slender. The
Fic. 294. — Gasterosteus pungitius, the nine-spined stickleback ; male (above)
and female near the nest in rushes. The female is about to deposit its
eggs in the nest.
THE SMELT 3815
fish swim near shore, in dense schools. One species on the
California coast is known as a “smelt,’’ and is a good food fish.
The sticklebacks are small, elongated fishes, having an
extremely slender tail and a large mouth. The dorsal fin
Fic. 295. — Gasterosteus bispinosus, the two-spined stickleback. Above,
nest with eggs, and male entering. Below, male depositing its milt on
the eggs.
Figs. 294 and 295 are reproductions of water-color paintings in the Mu-
seum of Comparative Zoology at Harvard College.
is preceded by two or more large, isolated spines. The fishes
live in either fresh or brackish water. In some of the species
the male builds an elaborate nest from bits of aquatic plants,
firmly united by a special sticky secretion. The nest, which
316
ZOOLOGY
is built among the plants of the stream, consists of a short
cylinder, through the horizontal cavity of which the fish can
lie while it deposits its eggs. The male guards the single nest,
Fic. 296. — Gadus morrhua, the codfish. About one-seventh nat. size.
After Storer.
and is polygamous, @.e. fertilizes in the one nest the eggs from
various females (Figs.
Fic. 297.— Outline of one
of the flatfishes, seen
from the upper side,
reduced. From ‘‘Cam-
bridge Nat. Hist.”
294, 295).
The codfishes, among the most im-
portant of food fish, have ventral fins,
without spines, and jointed fin-rays,
well-developed tail fin, and barbel on
chin. Our common codfish (Fig. 296)
occurs over the whole of the North
Atlantic; but the most important fish-
ing localities are the banks near New-
foundland, especially Grand Bank.
The flatfishes are peculiar among
fishes in that they have the habit in the
adult stage of lying on one side. In
consequence the under eye migrates to
the upper side, so that both eyes come
to le on the same side of the body.
The mouth also tends to become unsym-
THE SMELT 317
metrical. The flatfish, consequently, illustrates well the prin-
ciples of self-adjustment to a peculiar environment (Fig. 297).
The catfishes have four to eight long barbels around the
mouth, and have no scales on the body (Fig. 298). They
are most common in South America, but there are a large
number of species in the United States, mostly found in the
Mississippi Valley and the Great Lakes, inhabiting deep or
sluggish waters, and living in the mud. The common New
Fic. 298. — Ameiurus nebulosus, the catfish. About one-half nat. size. Photo.
of living animal by Dr. R. W. Shufeldt, ‘‘ Bull. U. S. Fish Com.,”’ 1899.
England species is Ameturus catus. It was with reference to
our common New England species, the bullhead or horn-pout,!
that Thoreau wrote that they are ‘a bloodthirsty and bully-
ing race of rangers, inhabiting the river-bottoms, with ever a
lance at rest and ready to do battle with their nearest neigh-
bor.” The stiff, jagged rays of the pectoral fins can make
severe wounds. The great catfish of the Mississippi River
may weigh up to ninety kilograms, and, like most other
species of catfish, is much prized as food.
The suckers are characteristic North American fish
abundant in every creek, and consequently known to every
1Fig. 298.
318 ZOOLOGY
lover of woods and brooks. The lips are thick, and drawn
down at the corners.1 They are rather sluggish fishes, feed
on small aquatic insects, and suck up mud. They are not
generally esteemed as food, inasmuch as their flesh is coarse
oe
NS a
Fia. 299. — The brook sucker. After Goode.
and very full of bones. In the Mississippi Valley, however,
they are so abundant and large that they are of some commer-
cial importance.
The term “ minnow ” is applied to two distinct families of
Fig. 300. — Fundulus heteroclitus, a killifish or shore minnow. Nat. size.
small fish. One of these is also known as “ killifish.”” The
killifsh have a broad head covered with scales, and have well-
developed teeth in the mouth. They occur in schools in
shallow water along the shore, and ascend streams to their
source. They are carnivorous, and feed at the surface. In
one species from the Southern coast, the male is only about
1 Fig. 299.
THE SMELT 319
two centimetres long, and is the smallest known vertebrate.
Our commonest species on the shore or in brackish water
is Fundulus! (Fig. 300). The minnows of the other family
have a narrow head without scales, and with few teeth in the
mouth. They occur exclusively in fresh water, and are known
as ‘‘shiners.” The “ goldfish ” is related to this group.
The pike and pickerel (Esox *) are roughly cylindrical fishes,
with large mouth, elongated, depressed jaws, and strong,
Fig. 301. — Lucius luctus, the pike. About one-fifth nat. size. Photo. of
living animal by Dr. R. W. Shufeldt, ‘‘Bull. U. 8S. Fish Com.,’’ 1899.
hooked teeth. They are large and voracious fresh-water
fishes, confined, with the exception of a single species, to the
United States. The “ muskallunge” of the Great Lakes
reaches a length of two metres. It is, fortunately, some-
what rare, otherwise there would be few other inhabitants
of our large streams.
The shad is a representative of a family — the herring fam-
ily — which has played an important part in the civilization
of Europe. The Emperor Charles V. said that the herring
brought greater wealth to the Netherlands than did America
1 fundus, bottom.
2 {gox, a fish living in the Rhine, mentioned by Pliny.
320 ZOOLOGY
to Spain. Our common shad! ranges from Newfound-
land to Florida With the Pacific salmon and cod it is
commercially one of our most important fishes, for the catch
of Atlantic shad for 1902 was valued at nearly one million
dollars. The Pacific coast has been successfully stocked with
shad from the Atlantic. The Atlantic shad, like the salmon,
migrate up streams to deposit their eggs. The alewives have
the same habit. The herring, on the contrary, spawn in the
sea, As the common name, allied to the German Heer, an
Fic. 302. — Alosa sapidissima, the shad. After Goode.
army, implies, they travel in great schools. The menhaden,
which also occur in great schools, have of late years been de-
stroyed in vast numbers to make fertilizers.
The eels are easily distinguished by their serpent-like form,
the absence of ventral fins, the long dorsal fin, and the rudi-
mentary or absent scales. These fish occur all along our coast,
and ascend streams. During the day they lie hidden in mud,
and at night they feed, their principal prey being small aquatic
animals, the young of other fish, and shrimps and crayfishes
during the molting period. On account of the narrowness of
1 Alosa sapidissima; Alosa, from Saxon allis, old name of the European
shad ; sapidissima, most delicious.
2 Fig. 302.
THE SMELT 821
the gill-opening, they may live for some time out of water in
amoist place. The reproduction of the eel was long a mystery.
All sorts of creatures have in past times been supposed to pro-
duce them, ranging from the gods to water beetles. They
have even been thought to be generated from slime. We now
know, however, that there are both male and female indi-
viduals; that the males live chiefly, but not exclusively, in the
Fic. 303. — Siphostoma fuscum, the pipe-fish. Nat. size. Photo.
sea; that reproduction occurs chiefly in the sea; and that the
young females come from the sea and pass up the rivers during
the spring.
The pipe-fishes and their allies! include a number of aber-
rant forms. Some of these are greatly elongated, like the pipe-
fish proper (Fig. 303) ; others are shorter and stouter, like the
“sea-horse.” All have a prolonged snout, and usually a
long, slender tail. The body is encased in bony plates, and
the male is often provided with a brood-pouch, in which the
developing young are carried.
1 Lophobranchii.
322 ZOOLOGY
Having considered the bony fishes in detail, we may take
up the other classes of fishes.
The lamprey eels, or Cyclostomi, are the only parasitic
vertebrates. In the adult stage they either live attached to
Fic. 304. — Petromyzon, thelamprey. One-fourth nat. size. After Goode.
the outside of other fishes, sucking their blood, or else they
may penetrate into the body cavity. They do not bite, be-
cause they have no lower jaw, and are known as “ round-
mouthed ” eels.!. Lampreys are found in the seas and in the
rivers of the temperate zones. They occur on our Eastern
coast and ascend rivers; others live in the lakes of New York,
Fig. 305. —Acipenser, the sturgeon. One-sixteenth nat. size. After
Goode.
in the Great Lakes, and in the Mississippi Valley. In Europe
they are much esteemed as food.
The sharks and rays (Selachians) include all inhabitants
of the sea. They may be distinguished from the bony fishes
by the rough skin, beset with spines, and by a skeleton that
is made not of bone, but of cartilage. We have a number
Vig. 304.
oO
THE SMELT 323
of sharks on our Northeastern coast, of which the dog-fishes
and the sand-shark are the commonest (Fig. 283). They are
all carnivorous animals and powerful swimmers. They feed
on the larger crustaceans and fish.
The living Ganoidei are a remnant of a very extensive group
which existed in geological times. North America is especially
Fia. 306. — Lepidosteus, the garpike. One-cighth nat. size. After Tenney.
rich in existing representatives of this group, as of several
other old groups, such as the turtles, tailed amphibians, and
the king-crab. Of the five families of ganoids, four are repre-
sented in this country. In the following four paragraphs a
type of each of the native families is considered.
The sturgeons have five rows of hony scales on the trunk
and four barbels on the head.!. They occur both in the sea
Fig. 307. — Amia calva, the bowfin. One-sixth nat. size. From Leunis.
and in the Great Lakes and the rivers of the Central States.
Although of large size, they feed for the most part on small
aquatic animals, such as worms, insect larvee, and small fish.
The flesh of some species is much used as food; the eggs taken
from the ovaries (roe) are pressed into a delicacy known as
“ caviar.”
1 Fig. 305.
From Dean, after Ginther.
Reduced.
308. — Ceratodus forstert.
Fia.
ZOOLOGY
The spoonbill, which has an elon-
gated, flattened snout and is almost
without scales, is a large fish found
in the Mississippi River. It is also
called “ paddle-fish ” or “ duck-bill
catfish.” It becomes two metres
long, and seeks small animals in the
mud, which it stirs up with its snout.
The garpikes are known by their
long snout (Fig. 306). They are
completely clad in an enamel coat
of mail. They are of sluggish
habits, but voracious, and their
flesh is valueless as food. One
species is found in China, the others
in the rivers of North America.
The bowfin (Amia !) occurs in the
rivers and lakes of the United
States. Ithasashort body, a blunt
head, and a long dorsal fin (Fig.
307). It is the sole survivor of a
formerly large family.
The Dipnoi? include only three
rare foreign forms, which seem to
form a transition between fishes and
the higher groups, for some of them
have lungs in addition to. gills.
From some such lunged fishes must
the amphibia have arisen (Fig. 308).
1 Ancient name of a fish.
2 dis, twice ; pnoe, breath.
CHAPTER XXIII
THE FROG:—A STUDY OF THE ORIGIN OF LAND
LIFE
Tr is certain that the primitive animals lived in water because
all the lowest forms that we know to-day are aquatic and dry
up at once if left in the air. Only some of the higher and
more specialized forms have been able to live on dry land.
Such are the insects, spiders, certain parasitic forms, and the
higher vertebrates. There are a few scattered, terrestrial rep-
resentatives of other groups, such as the earthworms, certain
Crustacea (the wood-lice), and land snails. Animals that are
fitted to live in water find that they are not well adapted to
the land because of the great differences in the two habitats.
In the first place, water animals usually have only a thin skin.
This would not protect the body from loss of water in the air.
Consequently, only the thicker skinned aquatic animals can
become terrestrial. Second, such thick-skinned aquatic
animals must have gills for breathing. These thin-walled
structures cannot exist in dry air. Breathing organs of land
animals must be placed deep in the body so that the air is
moistened by the body before it reaches them. Again the
weight of the body is supported in the water by its buoyancy,
so that the appendages are placed laterally and function as
oars. But on the land the body must be supported by the
appendages on the solid substratum, consequently the appen-
dages are placed below the body. Finally, since all those
825
326 ZOOLOGY
animals that depend upon currents of water to bring them
food have a mode of feeding that is incompatible with living
in the air, they have given rise to no terrestrial species.
The newt well illustrates the changes of form and structure
that an aquatic animal must undergo in adapting itself to the
land. The young newts, as they hatch from the eggs lying in
the water, are thin-skinned animals with delicate, bushy gills
extending out from the
side of the head. The
legs are very small, or
absent, and locomotion
is by a large fin on the
tail. By the move-
ment of this fin the
animal is propelled
through the water very
Fic. 309.— A female newt (Desmognathus much as a fisherman
fuscus) guarding its eggs in a hole by the side geylls a boat. By the
of water. Nat. size. After Wilder.
time the newt has left
the water and has become adjusted to the moist air of the
damp ground on which it lives, the outer layers of its skin
have become somewhat horny and the bushy gills have become
lost (Fig. 309). Respiration now takes place in the throat, or
in other cases in pockets formed from the throat and known
as the lungs. Four legs directed downward support the body
above the ground, and the tail-fin withers away, so that only a
rounded tail remains.
The transformation that the individual newt undergoes in
its lifetime is an epitome of the evolution of many terrestrial
forms. Thus, in the tropics, certain shore crabs have come to
live in the upper part of the beach and eventually in the forests
THE FROG 827
and even on the trees. Their gills have withered away, and the
gill cavities now function as lungs. The hard shell, which
served as a coat of mail to ward off attacks of enemies in the
sea, serves the land crabs to prevent the loss of water. Again,
the ancestors of the wood-lice are common in streams, and even
in this situation are already provided over the whole body
with a thick skin called the cuticula. The possession of this
cuticula has permitted the development of land life in this
group. The gills, which are thin-walled plates in the aquatic
forms, become hollowed out to form lungs. In the case of
snails the thick skin, which is useful in secreting the shell of the
aquatic forms, has permitted some of its possessors to live on
land. Certain representatives of the group, namely, the slugs,
have lost the shell without suffering any disadvantage, because
they have a very thick skin. Even with the thick skin, how-
ever, slugs do not risk a very dry situation, and if forced to
remain long in dry air they varnish themselves over with a
water-tight layer of mucus. In the slugs, as we have already
seen, the gill-chamber has been transformed into a lung-cham-
ber by the degeneration of the gills and the diminution of the
gill-opening so that the influx of air may be reduced or in-
creased as it is dry or moist.
Why have any aquatic organisms given rise to terrestrial
descendants, in spite of the fact that there is room in the
sea for all, and food is almost inexhaustible? The probable
answer to this question is that some species whose structure
permitted land life found it advantageous to leave the water
from time to time to escape from enemies. In the new field
they obtained an abundance of oxygen and food, so they pro-
longed their stay there until, finally, they became better
adapted to the land than to the sea.
328 ZOOLOGY
The first animals to come to the land were probably the
earthworms, many of whose aquatic allies live in ponds that
are apt to dry up during the summer. The aquatic worms are
preserved from annihilation only by burying themselves in
the muddy, damp bottom. One of the next groups to give
rise to terrestrial forms was that of the Arthropods, some of the
representatives of which still retain in their bodies evidences
of their aquatic ancestry. Thus in the terrestrial Peripatus
CO itd
eal Nusa Tt
host.
3
ee
; pas
Fie. 310.— Peripatus, the air-breathing wormlike animal that bridges the
gap between Myriapods and worms.
(Fig. 310) the air-breathing organs have not yet developed, and
the appendages are placed laterally instead of ventrally. From
some such primitive form the plant-eating insects arose, and
on account of the almost limitless supply of vegetation devel-
oped mightily. Then came the carnivorous forms, like the
spiders and their allies, to prey on their herbivorous forerun-
ners.
Among the vertebrates the primitive forms lived in the
water, but in the group Amphibia, which includes the newts,
salamanders, frogs, and toads, there are forms that show the
transition from aquatic to terrestrial life. Most of them
begin life as aquatic animals and end it as terrestrial.
The Amphibia comprise about a thousand species which are
distributed in three great groups. Those forms that retain
their tails permanently, even when they come to land, are
known as Urode'la. They are confined in their distribution
to the Northern Hemisphere, excepting two or three species
THE FROG 829
that extend their range along the Andes south of the Equator.
North America is especially rich both in species and individ-
uals of Urodela. Those which lose the tail in the adult stage,
like the frogs, are called the Anu'ra. These are found in all
parts of the world, especially in South America and Australia.
A third group (Gym'nophiona), which is found only in the tropics,
contains animals that have a worm-like body, live in the ground,
and have more or less rudimentary eyes. It will be seen that
the Amphibia are found chiefly in tropical and subtropical
countries, although a large number thrive in colder parts of the
temperate zone.
As an example to illustrate the structure of Amphibia we
may take the frog.
General Form of the Body. — The frog is not a typical am-
phibian, since it has lost its tail, so that only head and trunk re-
main, and the anal opening lies at the very hind end of the
body. The appendages have become long and slender as
compared with those of the fish, and five distinct toes are
present on each foot. The whole body is covered with a
delicate skin devoid of scales such as fishes have, or other
outgrowths ,and coverings of the skin such as are found in
birds and mammals. The skin contains abundant glands,
however, the secretions of which may be poured over the
skin to protect it from drying up.
The Skeleton of the frog consists of an axial and an appen-
dicular part (Fig. 311). The vertebral column consists of a few
simple vertebree, to each of which a pair of short ribs is fused.
The skeleton of the rudimentary tail is represented by a long,
bony rod.t. The skull is simple as compared with that of the
fish, partly because of the absence of gills and partly because
1 Urostyle, UST., Fig. 311.
AST
Fic. 311.— The skeleton of the frog (Rana temporaria)
The left half of the shoulder girdle and the left fore and hind lees are removed
also the membrane bones on the left side of the skull
A. Skeleton seen from above
. Cartilagenous parts are
dotted. Names of bones that are first formed in cartilage are in GOTHIC capitals,
those formed directly in the skin are in ITALIC capitals. a.c.hy, anterior horn
of hyoid bone; acth, depression to receive femur (fe.); AST, ‘‘astragalus’’; b.hy,
base of hyoid; c,“
calean,”’ bone of a spur; CAL, ‘‘caleaneum”’ of the ankle;
THE FROG 331
of areduction and fusion of parts. The teeth, instead of being
scattered over the mouth, are found chiefly on the jaws, but
there are also a few small patches of
teeth on the roof of the mouth.
The shoulder girdle forms a complete
ring extending from the shoulder blade
(S.SCP), which les on the ribs, to the
breastbone below. To this are at-
tached the upper armbones (HU) of
the relatively short fore legs. The lower
arm is supported by a united radius and
ulna. The pelvic girdle is so long as to
give great elasticity to the attachment
of the skeleton of the long and powerful
hind legs, which are used in Jumping
(FE and TI. Fl).
Organs of Nutrition.— The food of
frogs is very varied, consisting of
Fig. 312. — Three stages
(from above downward)
tadpoles, etc. These are caught inthe in the movement of the
i : tongue of a frog in catch-
roomy mouth, often with the aid of the ing an insect. From
tongue, which is attached in front and “Cambridge Nat. Hist.”
free behind, so that the hind end may be flopped out some dis-
tance in front of the mouth to strike an insect (Fig. 312).
worms, mollusks, insects, small fishes,
EX.OC, exoccipital, connecting with vertebral column; FE, femur; fon,
openings in skull; FR.PA, fronto-parietal; HU, humerus; IL, ileum;
MX, maxilla; olf.cp, olfactory capsule; ot.pr, otic process; p.c.hy, pos-
terior horn of hyoid; PAX, premaxilla; PR.OT, pro-otic bone (ear) ;
RAUL, radio-ulna; SP.ETH, sphenethmoid; SQ, squamosal; S$.SCP,
suprascapula; sus, bone suspending lower jaw from skull; TI.Fl, tibio-
fibula; ¢r.pr, transverse process; UST, urostyle. vV.1, cervical verte-
bra; V.9, sacrol vertebra; VO, vomer; J-V, digits. B. The fourth verte-
bra, anterior face; a.zyg, anterior linking process; cn, centrum; Im,
lamina; n.sp, neural spine; pd, pedicel; tr.pr, transverse process. After
Howes, from Parker and Haswell.
832 ZOOLOGY
Beyond the mouth a short gullet leads to the large stomach.
Next, the food passes into the upper digestive portion of the
we ts *
vs.sem oy
aS, z.
FrpaPel gl ens eg Ling ring al
of fl. ‘ bl nas (zys| Sie pte fdfust | ur | wy!
|
a.
ee
etal
Fig. 313. — Diagram of viscera of a male frog, Rana temporaria, seen from the left
side. SKELETAL System: Skull: FR.PA, fronto-parictal ‘of cranium; PILX,
premaxilla; SPH.ETH, sphenethmoid; M.MCK, cartilage base of lower jaw;
b.hy, tongue-bone (hyoid) ; ve.t, teeth on vomer bone. Vertebral Column: en.5,
centrum of third vertebra; n.a.1, neural arch of first vertebra; UST, urostyle.
Girdles and Appendages: ep.cor, epicoracoid; IL, ileum; IS, ischium; 0.ST,
omo- and epi-sternum; pu, pubis. ALIMENTARY SysTeEM: tng, tonguc; eus.t,
Eustachian tube (remnant of gill-slit); g/, glottis; gud, gullet; st, stomach; du,
duodenum; Jr, liver; b.d, bile duct; pn, pancreas; s.int, small intestine; ret,
rectum; cl, cloaca; an, anus. CIRCULATORY SysTEM: c.art, conus arteriosus;
lau, left auricle; ped, pericardium; s.v, sinus venosus; v, ventricle; cp.ad,
fat body; d.ly.s, dorsal lymph sinus; spl, spleen; v.ly.s, ventral lymph sinus.
RESPIRATORY System: /./ng, left lung; r.dmg, right lung; p.na, posterior ‘nares.
UrRoGENITAL System: kd, kidney; wr, ureter opening into the cloaca, el, at
ur’; bl, urinary bladder opening at bl’ into the cloaca; ts, testis; vs.sem, seminsl
vesicle. NErvowus System: crb.h, cerebral hemisphere ; cblm, cerebellum ; sp.c
spinal cord; olf, olfactory lobe of brain; opt./, optic lobe of brain. From Park i
and Haswell.
intestine, known as the duodenum, where the secretions of the
liver and the pancreas are poured (Fig. 313). This is followed
by a long, absorbing portion, and this, in turn, by the rectum,
which receives also the excretory and reproductive products,
and consequently functions as a “ cloaca.”
THE FROG 333
Organs of Respiration. — Although the young frog (tadpole)
uses gills for absorbing the oxygen dissolved in water, the adult
breathes also air. Even the adult doubtless absorbs the
oxygen of the water through the thin skin, and perhaps also
through the lining of the pharynx; but the main organ of
respiration is the pair of lungs (ring and ling). The lungs
are sacs whose inner surface is divided by partitions into air-
cells which greatly increase the respiratory surface. Through
the thin walls of the air-cells there flows a constant stream of
blood, gaining oxygen from the air in the lungs.
Organs of Circulation.— The impure blood from the body
collects in a single vessel, and then enters a chamber of the
heart called the right auricle. Thence it passes through an
opening, guarded by valves, to a chamber that has thick mus-
cular walls, and is called the ventricle. When the ventricle
contracts, the blood is prevented by the valves from returning
to the auricles, and passes out of the ventricle into a great
arterial trunk, or “conus” (Fig. 314). Alongside of the
right auricle, but completely separated from it by a par-
tition, is the left auricle. This contains richly oxygenated
blood freshly received from the lungs. The left auricle con-
tracts at the same time with the right, and pours its blood into
the same ventricle. It would seem inevitable that the pure
and impure blood should completely mingle, but this is pre-
vented by the prompt contraction of the ventricle, assisted by
a rather complicated mechanism. The conus lies on the right
side of the ventricle, so that it is nearer to the stream of impure
blood emerging from the right auricle, and is first filled by it.
The first outlets from the conus that this impure blood meets
are the arteries that go to the lungs, and so, with the assistance
of certain valves in the conus, the impure blood flows to the
lungs. As the ventricle continues to empty itself, a mixed
3384 ZOOLOGY
blood emerges, and, slipping over the entrance to the now filled
pulmonary arteries, goes on to the dorsal aorta and the organs
Fic. 314. — The heart of the frog with the cavities laid open. Blood
enters from the venous sinus into the right auricle, r.qu, at s.au.ap. The
right auricle is completely separated from the left (law) by a partition
(spt.aur). Both auricles open by the same aperture, guarded by two
valves (au.v.v) into the ventricle, xf. The left auricle receives the pul-
monary veins at pul.v. The exit of blood from the ventricle is guarded
by valves at v, and its further path directed by a valve at lv, into the
right and left pulmonary arteries, pul.cu.fr, and c,c,c', into the arteries
going to the general trunk, syst.dr and b, 6’, and into the arteries going
to the head, carr, with its carotid artery (car.a) and so-called gland
(car.gl) ; and with its tongue branch (/g.a).
of the trunk ; finally the purest blood, which is the last to leave
the ventricle, passes on to the last pair of vessels, which go to
the brain, where it is most needed. The fact that the trunk
THE FROG DDO
receives mixed blood results first in a relatively low body tem-
perature and, second, in slow chemical changes in the body —
a sluggish life.
Organs of Excretion and Reproduction. — The two kidneys
(Fig. 313, kd) lie in the dorsal part of the body cavity. They
Fie. 315.— A urode, Salamandra maculosa, of Europe, showing exter-
nal ringed condition of the body. After Cuvier.
consist of a mass of tubules closely intertwined with
blood-vessels that yield their waste products to the
tubules from which they pass by the ureters to the
s cloaca.
} The male germ glands (ts) lie at the anterior end
i of the kidneys and their products pass through cer-
tain tubules of the kidney and so, by way of the
urcters, to the cloaca. Thus certain of the excretory tubules
serve in the frog, as in annelids, to carry the germ cells to the
exterior.
The ovaries of the frog are large sacs covering the kidneys.
The ripe eggs fall from the ovary into the body cavity, are
picked up by the oviducts which open into the body cavity,
336 ZOOLOGY
and are carried through them to the cloaca, receiving on
their journey the jelly, which swells up enormously when the
eges enter the water at the time they are laid and while the
sperm is making its way to the eggs.
A i
+
cerebellum Typ
=<
,
al
—medulla Le. A
Re
ON"
Fie. 316. — The brain of the frog viewed from above (A) and below (B).
I, olfactory nerve going to olfactory lobe (ol. lobe). II, optic nerve going to
Tropt, the optic tract of the brain. J17, 1V, Vi, 1X, X, XI, XIT @),
other nerves to brain. Z.H, mid brain; Jnf, infundibulum. Med, the
medulla with its first nerve at 7. From Wiedersheim, ‘‘Comp. Anat.”
The muscular system of the frog is reduced on account of its
shortened body. In the tailed amphibians the ringed condi-
tion of the body musculature is still evident (Fig. 315), but
in the frog this appears only in the straight abdominal muscles.
'
“AJOINOG [VoIBoOooT “XN yoday oy} Wor ‘wnuenbe ue ur Suray ‘uasg ‘Joo-pnu sy, —‘2TE “Ol
oD
338 ZOOLOGY
eG
The muscles of the breast and appendages offer special com-
plications.
The nervous system shows an advance over that of fishes.
The brain has two large lobes in front (olfactory lobes,
ol.lobe), but the front part of the brain proper (cerebrum) and
Fic. 318.— Mud-puppy (Necturus), photographed while living in an aqua-
rium. From Report N. Y. Zoological Society.
the cerebellum are poorly developed. The spinal cord is
shortened and modified on account of the shortening of the
trunk.
Sense-organs. — The sense of smell is chiefly located in the
nasal sacs, which open anteriorly to the exterior and posteriorly
into the mouth. The eye is essentially like that of other verte-
brates. The ear also consists of a central chamber and three
semicircular canals. There is a large external membrane, and
THE FROG 339
its vibrations are conveyed to the inner ear by a single rod
instead of the flexible chain present in man.
Families of Urodela.— Of the American Urodela,! the
mud-eel, or Siren, of the Southern States has external
gills and persistent gill-slits. This species becomes sixty
centimetres long and snake-like, has lost its hind legs, and
is of a dark lead color (Fig. 317). It is needlessly feared by
the negro rice cultivators, who slaughter it in great numbers.
Fig. 318 a.— Typhlomolge, a blind, necturus-like salamander from the
caves of Texas. Photo. from life. After W. W. Norman, from ‘The
American Naturalist.’
The mud-puppy (Necturus), frequently known also as water-
dog, is found from the Hudson River to the Mississippi Valley,
and is very abundant in the Great Lakes. Its external gills
are very large, and red with the blood flowing in them. It
feeds on small water animals. In April or May it lays eggs
about the size of a pea. A curiously modified form of Nec-
turus occurs in caves of North America (Fig: 318). An-
other member of this family is the cave ‘
Austria.
‘olm” of western
The Congo snake (Amphiumide) is found in the Carolinas
and Gulf States. This black, snake-like urodele is about a
metre long, and lives in bayous and muddy ditches (Fig. 319).
It has the entirely undeserved reputation of being injurious.
1 oura, tail; delos, conspicuous.
340 ZOOLOGY
The hellbender (Cryptobranchidz ') inhabits the Ohio Valley
and the South.’ It loses its gills before it becomes adult and
the gills-slits close. It is a very voracious scavenger of the
water, bites the hook fiercely, and is noted for its great te-
nacity of life under unfavorable conditions. The only other
Fic. 319. — The ‘Congo snake’? (Amphiuma means). From the Report
N. Y. Zoological Society.
living representative of this family is the Japanese giant sala-
mander, which becomes three metres long.
The salamanders (Amblystomide *) include some twenty-five
species belonging to five genera, four of which occur in north-
ern and eastern Asia, and the fifth, Amblystoma, is confined
to the United States and Mexico, except for one species that
occurs in Siam. In this family the external gills are absorbed
1 kryptos, hidden ; branchion, gill. 2 Fig. 320.
3 From amblys, blunt ; stoma, mouth.
TUE FROG 341
in early life. The common species of New England and the
Central States is known as the Spotted Salamander. It is
Fic. 320. — Cryptobranchus, the ‘“‘hellbender.’’ Reduced. From ‘‘Standard
Natural History.”
about 15 centimetres long, and black, with a series of yellow
spots on each side of the back. It lays eggs in springs or ponds
during April; the dark gray eggs are contained in great masses
of jelly which are attached to sticks at or near the surface of the
Fic. 321. — The larva of Amblystoma tigrinum. the Axolotl stage of the
tiger salamander. From Mivart.
342 ZOOLOGY
C
water. The larve of the more southern species often reach
a size considerably larger than the adult, and breed before the
gills are absorbed. In a Mexican species the larval state is
never passed. The larva of Amblystoma (Fig. 321) was for-
merly described, indeed, as a distinct species under the name
of Axolotl.
Fic. 322. — The red-backed salamander (Plethodon) : A, dorsal view ;
B, lateral view. Nat. size. From hfe.
The newts! (Plethodontide ? and Desmognathide *) include
a number of small Urodeles, having a close general resem-
blance and similar habits.
Plethodon, of the eastern United States, is lead-colored above,
very often with a broad, red dorsal band (Fig. 322). It is found
under logs, and is very active. Spelerpes is lemon-yellow and
white below, and Desmognathus is brown above, with gray or
1 Newts may be captured by sweeping with a net the muddy bottoms of
small, spring-fed pools. They can be kept for months in an aquarium, where
they should be fed thrice a week with earthworms or freshly chopped beef.
2 plethos, abundance ; odontos, tooth.
3 desmos, bond; gnathos, jaw.
THE FROG 343
purplish spots on the sides. Both Spelerpes and Desmognathus
live in and about running brooks, under stones and fallen logs.
Their eggs are attached to the under surface of submerged stones.
The adults are easy to keep in confinement in a moist fernery.
They may be obtained out of doors all the year round, excepting
during the time of deep snow.
Metamorphosis. — As we have seen, all Amphibia have gills
while young, but some lose them before maturity while others
retain them permanently. Those species which retain the
gills pass their whole life in water; the others may live on the
land. The loss of gills is associated with the assumption
of a land life. In the Amblystoma we have species which are
curiously intermediate between the two classes in that they
may retain their gills, tail-fins, and other structures adapted
to aquatic life,! even to the time of reproduction ; or they may
lose their gills and tail-fins. The first result follows if they are
prevented from coming on land; the second, if they are
forced to leave the water. The capacity of the Mexican
Axolotl for either becoming an adult or remaining a larva was
first shown by some experiments of the German naturalist
Weismann and a pupil of his. It will be seen that, when forced
to live in the water, Axolotl retains permanently a larval con-
dition ; and one would never know that in this larval condition
the animal is not adult were it not for the accident of its some-
times becoming adult. It is quite possible that all of the
Urodela which retain their gills throughout life may formerly
have had a gill-less adult stage which is now lost.
Early Development of Urodela. — The eggs of Urodela are
deposited in a gelatinous mass in water, and are attached to
submerged plants, or to other objects in the water, either singly
1Compare Fig. 321.
344 ZOOLOGY
or in masses, according to the species. The eggs contain
much yolk; consequently the cleavage is partial, and the em-
bryo seems to develop on a small part only of the yolk, and for
Fic. 8. Fic. 9. Fic. 13, Fic. 14. Tic. 15,
Fic. 323. — Developmental stages of Spelerpes bilineatus. Figs. 1-5, neural
groove beginning to form; Figs. 6, 7, neural groove closed; Figs. 8, 9,
head beginning to form; Figs. 10-12, tail formed, yolk absorbing; Fig. 13,
embryo capable of moving in egg membrane; Fig. 14, embryo just able
toswim; Fig. 15, three days after hatching. The letters indicate the suc-
cessive stages. After H. H. Wilder, from ‘‘The American Naturalist.”
some time after hatching the yolk mass hangs as a lump on the
under side of the embryo. Very early a deep groove, bounded
by a pair of folds, arises on the edge. This groove is large in
THE FROG 345
front (Fig. 323 6). It forms the beginning of the brain and
spinal cord. The feathery gills and the beginnings of the ap-
pendages next sprout out, while the trunk continues to elon-
gate and assume the form of a young salamander (Fig. 323 h).
Fig. 324. — Pipa americana. Female with young in pits on its back.
Families of Anura. — Of the Anura there are eight or ten
times as many species as there are of the Urodela. They are
distributed into nearly a score of families. Of these a few of
the more interesting deserve to be mentioned.
The South American Pipa (Pipide) is noteworthy because
of the habit which the female has of brooding its young in
pits of the skin on its back (Figs. 324, 325).
348 ZOOLOGY
in two long, parallel strings of albumen, which lie coiled at the
bottoms of ponds, hatch out in May, and metamorphose about
a month later.
The frogs (Ranidie) are almost confined to the Northern
Hemisphere and the East Indies. In the northern United
Fie. 328. — Green frog, Rana clamitans. Nat. size. Photo. of living animal
by W. FoCeP.
States there are some eight species, of which the com-
monest are: the leopard-frog, of green color, with irregular
black blotches edged with whitish; the pickerel-frog, light
brown, with two rows of oblong square brown blotches on the
back ; the wood-frog, living in damp woods, pale reddish brown)
with a brown band on the side of the head; the green frog, of
uniform bright green to brown color, with numerous small
dark spots, and with glandular folds (Fg. 328); and the bull-
frog, of great size, green, with small, faint spots on the
back.
CHAPTER XXIV
THE LIZARD: A STUDY OF DRYNESS LOVERS
In spreading over the land, animals have come into situations
where rain falls only for a small part of the year. In such
places not only is the ground usually dry, but vegetation is
sparse. Nevertheless, certain animals have come permanently
to occupy even such desert situations, and, indeed, entire
genera or families prefer desert habitats. They are the lovers
of dryness. The animals most common in our own deserts
are certain hard-shelled, black beetles, lizards of many kinds,!
the little sphermophiles, looking like slender chipmunks, with
now and then a rattlesnake. All of these animals and many
others that live and feed on the ground burrow into the soil.
There they remain during the heat of the day, coming forth
at night to feed and seek their mates. These desert animals
must go for weeks or even months without drinking water,
such moisture as they can get being obtained from roots
and green parts of succulent cacti. Almost always the skin of
such animals is hard, preventing the loss of internal waters by
evaporation. Indeed the whole body of these animals seems
to be very dry, and they need only a slight amount of water to
live. Even in ordinarily moist climates there is a great deal
of difference between animals in respect to their need and love
of moisture. While many land animals are found in moist
woods and under damp logs, or by the edges of lakes and
1 Fig. 329.
349
300 ZOOLOGY
swamps, others frequent dry country roads, sandy beaches,
and the driest hilltops. Certain land-snails live by preference
in sandy places and even in deserts. The tiger-beetles and
some flies are characteristic of dry situations. One or two
species of sowbugs are capable of living away from mois-
ture, although their ancestors so recently left the water. Cer-
Fic. 329. — Home of lizards (scene in the Nevada desert). They rest on
the stones, dart lke streaks of light across the desert floor and into the
“bunch grass.”
tain birds shun the marshy places which their allies prefer.
Field plovers and the Eskimo curlew belong to the water-
fowl, but they live in the dry uplands. Animals that thus
inhabit dry situations are there by preference because of their
nature. They would find life in marshes not only distasteful,
but probably incompatible with existence.
The reptiles, which are on the whole best represented in the
THE LIZARD 351
desert, are vertebrates in whose skin horny or bony patches
are formed. They constantly breathe by means of lungs, and
lay large eggs provided with a tough, leathery, or calcareous
SF
y Snr
Sa
RSQ
Fie. 330. — Skeleton of a turtle (Cistudo, of Europe), seen from below, the
plastron having been removed and placed at one side. C, rib-plate;
Co, corocoid, a part of the shoulder girdle; F, fibula; Fe, femur;
A, humerus; Jl, ihum; Js, ischium; Pu, pubis; Pro, pro-coracoid ;
R, radius; Sc, scapula; 7, tibia; U, ulna; e, ‘‘entoplastron’’ or inner
plate of plastron; Hp, epiplastron or upper plate; M, marginal plates;
Nu, nuchal plate; Py, pygal plates. From Zittel.
shell. There are about thirty-five hundred species of living rep-
tiles, which are grouped into four principal orders as follows : —
(1) Turtles, or Chelonia, (2) Lizards, or Sauria, (3) Serpents,
or Ophidia, (4) Alligators, or Crocodilina.
302 ZOOLOGY
Asan example of the structure of a reptile, we may consider
the anatomy of the turtle.
General form of body.— The turtle is depressed and
rounded, and the trunk carries an upper and a lower plate,
affording protection to the entire body.
Skeleton. — The vertebrz are few, in correspondence with
the shortened body, and are immovable upon each other (Fig.
330). The spines of the vertebre are flattened out to form
the median row of bony
plates, and the ribs are
flattened to form the
“costal” plates. These,
with certain plates at
the margin, form the
“earapace” of the
turtle. The bony cara-
Fic. 331.— Skull of a turtle (Chelone) viewed , :
from the left side. The bones shown are Dace 1s covered by horny
named from in front backward: Mav, max- plates which are derived
illary; F, frontal; J, jugal; Pt, post- “
frontal; Qj, quadrato-jugal; Q, quadrate ; from the skin, and only
Sq, squamosal; Par, parietal; S.o, supra-
tr Dar roughly agree with th
occipital. From ‘Cambridge Nat. Hist.” roughly Agree with the
bony plates lying below
them. The breast-bone and ventral ribs are replaced by
the “plastron,” which is made up of four paired and one
median plate. The skull is massive, and the bones of the side
of the head form a broad arch, enveloping and protecting, but
separated by a space from, the brain-case proper (Fig. 331).
The shoulder and pelvic girdles are fused with the shell, but
the skeleton of the appendages is typical, though often show-
ing special adaptations for swimming.
The organs of nutrition. — The food of turtles is extremely
varied, according to their habitats. Land tortoises eat toad-
THE LIZARD 303
stools, fruits, and other vegetable matter. Water turtles eat
worms, insects, frogs, and fishes. Some sea-turtles, like our
green turtle, eat various alg; others, like the tortoise-shell
turtle, are carnivorous, living on fish and mollusks. The jaws
are toothless, but are provided with a sharp cutting edge. The
stomach and intestines are
simple. The cloaca is large.
Organs of circulation.— The
general features of the circula-
tion are similar to those for
birds described in the next
chapter. But the heart, while
showing an advance over am-
she r : Fia. 332. — Diagram of the heart of a
phibians, is far from showing turtle. Systemic blood from the
the perfection of development "#ht auricle (R.A), passes by the
; ‘ course, «, through the opening at y
found in birds and mammals. __ in the incomplete septum, a, into the
chamber, Cp; thence, on contraction
of the ventricle to the pulmonary
received hy the right auricle artery (P.A) by the pathz. Blood
from the lungs passes from the left
auricle (L.A) through the passage w
The ventricle is incompletely (guarded hy the valve, v), into the
ies ( : : larger chamber of the ventricle. On
divided into a right and a left contraction, the opening y being
es e ie i automatically closed, the blood goes
chamber by oe perfor ated Dats by s and? to the left and right
tition (Fig. 332, a). When the aortas, respectively, and so on to
: he body. After Huxley.
auricles contract, the blood Weeden eee
Venous blood from the body is
and poured into the ventricle.
from the right auricle passes to the right side of the
ventricle, called the pulmonary space (Cp), and the blood
from the left auricle (pure and bright because having just come
from the lungs) fills the rest of the ventricle. When the ven-
tricle contracts, the imperfect partition (a), cutting off the
pulmonary space, becomes drawn tight across the ventricle.
The blood in the pulmonary space goes to the lungs to become
2a
354 ZOOLOGY
purified, and the pure blood in the ventricle, mingled with
some venous blood, goes to the aortas (RAo, LAo), and so
on to the trunk and head. Thus, in the turtles, the body
receives a little impure blood, and this fact results in keeping
down the temperature of the body.
The organs of respiration are a pair of large lungs. These
show a great advance over those of the frog, since they are not
mere sacs, but contain many lobules. As the body is encased in
an inflexible shell, the
I” Lot WH MH LH 3K R
lungs cannot be filled by
raising the ribs, as is the
case with us, and so the
turtle seems to depend
ly i largely upon the move-
Fic. 333. — Side view of the brainof aturtle ments of its capacious
(Emys). J, olfactory nerve; IJ, optic
nerve; Lol, lobe of smell; VH, cerebral
hemispheres; MH, optie lobes; Tro, from the lungs. Certain
“optic tract’’; HH, cerebellum; NA, ee:
medulla; R, spinal cord; Inf, ‘infundi- water tortoises have
,
throat to force air into or
bulum ”’ terminating in the ‘‘ hypophysis.’
reat sacs opening from
From Wiedersheim, ‘‘Comp. Anat.” 8 I 2
the cloaca, whose walls
are filled with blood-vessels, and which may be alternately
filled with and emptied of water through the cloacal opening.
The oxygen of the fresh water is absorbed by the blood-vessels
in the wall of the sac. Thus these sacs are like gill chambers
in some lower animals, and enable the turtles to breathe
even while submerged. However, this device is only a tempo-
rary expedient and cannot long replace respiration by the lungs.
The organs of excretion and reproduction. — The kidneys
are small and round, in marked contrast to those of amphibi-
ans, of which, indeed, they represent only the posterior por-
tion. They are, on the other hand, like the kidneys of the
oo
or
an
THE LIZARD
higher vertebrates. The testes and ovaries lie dorsal, near the
kidneys, and discharge their products by special tubes (not
through the excretory tubules) into the cloaca. The eggs are
provided with a hard egg-shell and, in most pond and river
species, are laid in the spring in sandy soil at a depth of 30 to
80 centimetres.
The muscular system of turtles is (in correspondence with
the round, bone-encased body) much reduced, except in the
neck and appendages, which are capable of varied and extraor-
dinarily rapid movements.
The nervous system shows, at least so far as the brain goes,
a decided advance over amphibians. The lobes of smell are
reduced in size, and the cerebral hemispheres are well devel-
oped (Fig. 333). Also the cerebellum attains a fair size, indi-
cating increasing power of correlated movements.
The sense-organs are well developed. Turtles are very
sensitive to touch, even on the shell. They discriminate
between various sorts of closely related plants, showing a well-
developed sense of taste and smell. The ear shows no great
advance over that of Amphibia. The eye is protected by a
ring of bony plates in the sclerotic coat. In addition to two
eyelids there is a membrane — the nictating membrane — that
can be rapidly drawn across the front of the eyeball; this we
shall see also in birds. It probably serves to cleanse the
front of the eye and perhaps to regulate the amount of
light entering the eye. Although not present in turtles, men-
tion must be here made of a third eye looking out from the
middle of the skull, and called the pineal eye. This eye is
functional in some lizards (Fig. 334). In our own brains there
is arudimentary organ having the same relative position, and
which has long been known as the pineal gland. This organ
356 ZOOLOGY
was once regarded by a philosopher as the seat of the soul,
on the ground that the soul is a unit and that the pineal gland
Fig. 334. — Section of the pineal eye of a lizard (Hatteria): c, cornea;
i, lens; h, cavity of eyeball; 7, 7’, retina; z, cells in stalk; st, stalk;
g, blood-vessels. After Spencer.
is unpaired. We now know that it is the rudiment of a once
functional eve.
The lizards (Sauria) constitute a large order characteristic
of the tropical and subtropical countries, and reaching the
maximum of its development in South America, while in the
TUE LIZARD 357
northern continents it is relatively poorly represented. Most
lizards have an elongated body, four legs, eyelids, and a breast-
bone or sternum. Lizards are, as a rule, carnivorous, and since
they destroy insects injurious to vegetation they may be
considered as beneficial to man.
Most of our lizards belong to the family Iguan’ide,! a
family that is most abundant in the Western Hemisphere.
They are known by the thick tongue, by a large scale in the
Fic. 335. — Phrynosoma, the horned toad. Photo. by E. R. D.
middle of the head in front of the eyes, and by the fact that all
four legs are well developed. The genus Anolis, known as the
American chameleon, contains eighty tropical species. Our
species lives in pine woods from the latitude of Tennessee
south to the Gulf and the island of Cuba. Its graceful form
and bright colors make it one of the most beautiful of lizards.
It lives on trees, eats insects, is not timid, can live well in con-
finement, and, like the chameleon of Europe, has the power of
changing its colors from bright green to dirty brown. Besides
Anolis, we have various other lizards of the family Iguanide.
The horned toad of the Southwest, which has a broad, flattened
1 Native name.
308 ZOOLOGY
body and long spines on the head, and lives in dry, sandy
places, is a familiar object.t In the South Central and South-
ern States lives the elongated “ swift,” of varying color, often
with black, irregular cross bands above, with iridescent colors
on the throat of the male, and with large, strongly keeled scales
Fic. 336. — Lacerta viridis, the green lizard of Europe. After Brehm.
and aslender tail. The largest of the Iguanide is the “leguan”
of the West Indies and South America, which gains a length
of 1.75 metres, or over five feet.
The family of water-lizards, or Varan’idz,? contains the
largest known lizards. The Nile varanus attains a length of
nearly two metres. It lives in the rivers of Africa, feeds on
small crustaceans, birds, birds’ eggs, frogs, fish, and occasion-
1 Fig. 335. 2 Latinized from the Arabic word waran, lizard.
THE LIZARD 359
ally also on young crocodiles and crocodile eggs. The an-
cient Egyptians regarded these crocodile-like lizards as the
greatest enemies of the crocodile.
The common lizards (Lacertide!) of middle and southern
Europe are agile, harmless creatures, often of bright colors,
and are commonly and favorably known. The more abun-
Fic. 337. — Heloderma, the Gila monster. About two-fifths nat. size.
From Brehm.
dant are the “ green lizard” (Fig. 336), the “ sand-lizard,”
and the “ wall-lizard ” of the Latin countries.
The Gila monster (Helodermidz) is the largest lizard of
the United States. It inhabits New Mexico, Arizona, and
the country southward. The lizard is colored brown, with
reddish spots and numerous yellowish punctations (Fig. 337).
It is nocturnal in its habits, and its bite is very poisonous,
although rarely fatal to man.
1 From lacerta, lizard.
360 ZOOLOGY
The family of slow-worms includes the famous glass-snake,
or joint-snake, of the South. This snake-like lizard has no
legs, or only rudiments of the hinder pair. It is noted for the
ease with which it breaks in two when struck or lifted by the
tail. This result is due to the fact that, as in certain other
lizards, the vertebre of the tail are unossified along the middle
plane, so that they separate at this point upon the slightest
blow. The muscles of this species seem also to be arranged
Fic. 338. — Chameleo, the chameleon. From Leunis.
so as to facilitate separation. In Europe there is a lizard of
this family, the so-called “blindworm” (having, however,
well-developed eyes), which is found in retired localities, from
which it comes out, especially in the evening, to capture earth-
worms and slugs.
The Chameleon, famed in literature, comes from Africa.
Its change of color depends upon the possession of several
layers of different color in the skin, which can be separately
expanded or contracted as required, in consequence of which
sometimes one, sometimes another, color comes to predomi-
nate. It captures insects, a habit which is facilitated by its
power of protruding the tongue to over half the length of its
THE LIZARD 361
body and bringing the sticky end in contact with its prey.
The protrusions and retractions of the tongue take place with
marvellous rapidity (Fig. 338).
While in point of size the lizards of geologically recent times
are inconsiderable, those of former epochs were huge. These
Fie. 339. — Hadrosaurus. From reconstruction model. Osborn, ‘Rept.
Amer. Mus. Nat. Hist.”’
former or fossil lizards were most characteristic of the middle
life era or the Mesozoic age. They belong to three main
groups; namely, swimming, walking or wading,! and flying
lizards. The swimming lizards were sometimes over 10 metres
long, and had feet modified as paddles. The land lizards
were elongated, three-toed, carnivorous reptiles, with hollow
leg bones like birds. In the flying lizards a strong, compact
body was provided with hollow, air-filled bones, and locomo-
1 Fig. 339,
3862 ZOOLOGY
tion was effected by a huge membranous expanse stretched
between the elongated posterior finger, the trunk, and the
hind legs. The spread of the wing was about three feet.
The turtles, or Chelo’nia,! form an order distinct from the
lizards. They are characterized by a depressed form, a bony
case, and toothless jaws. Like other reptiles, they are most
abundant in tropical countries, since the high external tem-
Fie. 340. — Hawkbill-turtle. Much reduced. From Brehm.
perature compensates in a way for the insufficiency of the
mechanism for maintaining from the inside a high blood
temperature. Turtles are abundant in Africa, and are much
commoner in North America than in Europe. Three principal
families of Chelonia may be distinguished. A short account of
each follows.
The family of marine turtles includes certain turtles that
live in all oceans, and may acquire a weight of as much as one
thousand pounds. The green turtle, used in making soup,
1 Cheldne, turtle.
THE LIZARD 363
occurs on the Atlantic coast as far north as Long Island.
From the hawkbill turtle (Fig. 340) comes the tortoise-shell
used in certain ornaments. In the “leatherback”’ the shields
are incompletely ossified.
The family of soft-shelled turtles includes certain turtles
that live in rivers or ponds of the Mississippi Valley and the
Gulf drainage basin (Fig. 341). They
have a flat, rounded shell, the feet are
broadly webbed, and the neck is long.
Although the ancestors of turtles were
without the hard shell, it seems prob-
able from the whole structure of the
upper and lower plates that the soft-
shelled turtles are not ancestral, but of
recent origin, and have recently lost
the hard shell of their ancestors.
The family of fresh-water and land ft a
tortoises is known as Testudinide.’ “CAS y Dy
Our snapping-turtle is distributed Fie. 341.— Trionyx, three-
from Canada to equatorial South cae Saag ee.
America. It feeds on fish, and lays From Leunis.
from forty to fifty eggs, which it buries at a depth of
about a metre (Fig. 342). The alligator snapper of the Gulf
States attains the length of a metre, and is regarded as
the “most ferocious and, for its size, the strongest of
reptiles.” The box-tortoises occupy the northeastern and
central parts of North America. They are well known by
the fact that the body is short and high, the plastron is pro-
vided with a movable hinge, and the carapace is colored
black and yellow.’
1 From testa, a shell, 2 Fig. 343.
364 ZOOLOGY
Fig. 342. — A snapping-turtle in the act of digging a nest.
Other common tortoises of the eastern United States are the musk-
turtle, told by a strong odor of musk; the painted turtle, of green-
ish black color and with marginal plates marked with bright red;
Fie. 343. — Terrapene carolina, the box-tortoise.
Photo. of living animal
by W. H.C. P,
THE LIZARD 365
the speckled tortoise, black with round orange spots; and the wood
tortoise, with keeled shell, and plates marked with concentric strie.
The order of snakes, or Ophi’dia,! is characterized by the
elongated body without appendages, and by the absence of
eyelids and sternum. Like other reptiles, the snakes are chiefly
tropical, but inhabit also the temperate zones. They feed
on living animals. Hidden in the muscles of certain kinds of
Fic. 344. — Euteenia, garter-snake, dorsal view. Photo. by E. R. D.
snakes, rudimentary appendages are found, so we may conclude
that the ancestors of the snakes had legs. It is because snakes
are without legs that they travel so well through thickly
matted vegetation.
The family Colubride? includes the great majority of our
common non-venomous snakes, such as the garter-snake,?
water snake, black snake, milk snake, and spreading adder.
Allied are the boas of South America and the pythons of India,
which attain a length of six metres ormore. Not being poison-
1 ophis, serpent. 2 colubra, serpent. 3 Fig. 344,
366 ZOOLOGY
ous, their bite is not dangerous, but they attack large birds and
even medium-sized mammals, and crush them to death in the
folds of their body.
The family Elapide includes the large, venomous serpents
of the East, the cobra of the East Indies, and the asp of the
Fie. 345. — Elaps corallina, a harlequin snake of South America allied to
the bead-snake of the South. From ‘‘Standard Natural History,” after
Brehm.
Egyptians. The bite of these serpents is quickly fatal to man.
To this family belongs also the bead-snake of our Southern
States, which is, however, harmless (Fig. 345).
The Crotalide' include the rattlesnakes, characteristic of
America? Of this family the most dangerous is the water
moccasin, or black moccasin, which inhabits the Southern
1 krotalon, clapper. 2 Figs. 346, 347.
THE LIZARD oO
Fic. 346. — Crotalus, the rattlesnake. Photographed as the snake was
about to strike. Taken in Wyoming and kindly lent by H. W. Menke.
Fig. 347. — The rattlesnake. The recoil after striking. Photographed in
Wyoming and kindly lent by H. W. Menke.
Note in both figures the elevated rattle, toward the right.
368 ZOOLOGY
States, and gives no warning noise as does the rattlesnake.
The copperhead of the eastern half of the United States is also
dangerous, but is mostly confined to wooded, mountainous
regions. The rattlesnake was once common over the whole
Fic. 348. — Florida crocodile. (Courtesy of the New York Zoological
Park.)
of the Northern States as far west as the Rocky Mountains,
but it is now nearly exterminated in well-settled districts.
Related to these are the venomous vipers of Europe.
The order of crocodiles, or Crocodilina, contains only
some twenty living species, distributed in three genera.
The gavial is the crocodile of the Ganges River. It captures
even large mammals and man. The crocodile in the strict
sense is found in the Nile and other African rivers, in certain
THE LIZARD 369
countries on the western border of the Pacific, and in north-
ern South America, Central America, and the Antilles. Of the
alligators, which have a different arrangement of the dentition
from the crocodiles, there are seven slightly differing species,
all of which are South American, excepting a Chinese species
and the alligator of our Southern States. The latter feeds on
fish, and attacks larger animals (Fig. 348).
CHAPTER XXV
THE ENGLISH SPARROW: A STUDY OF BIRDS AND
MIGRATIONS
Most animals, unlike most plants, are free to travel about in
search of food and mates. Thus every morning in winter the
crows can be seen flying from their rookery in the forest to
distant fields where some grain still remains. At low tide
along the seashore many of them come to pick up clams. At
night they all fly back again to their rookery. When a family
has been raised, the young move away from their birthplace
to seek feeding-grounds, mates, and homes of their own.
Usually this dispersal is so gradual that it is not observed ;
but in certain mammals the young of a season may swarm
from their native home and traverse the country like an army.
This is the case with the widely known lemmings of Scandi-
navia. The importance of their march has been much exag-
gerated, for the migration has been noticed only a few times.
The numbers involved in these migrations, however, were
great. The lemmings travelled far; some did not stop even
when they reached the sea, but plunged into it and were
drowned. Their behavior well illustrates the blindness of the
impulse that drives them from home.
Even man migrates when his native country becomes over-
crowded and there are attractive prospects in other lands.
History records the migrations in ancient times of men from
central Asia into Europe, and one may witness any day at the
370
THE ENGLISH SPARROW 371
port of New York the incoming of hundreds of immigrants
allured by the prospects of freedom from military service,
excessive taxation, and oppression in various forms. To-day,
with improved facilities for travelling across continents and
oceans, the human tide moves back and forth more freely than
ever before.
In temperate climates the change of seasons leads certain
animals to migrate towards the equator during the winter and
to return towards the poles in summer. It has been suggested
that the animals were first driven southward by the glacier, a
vast ice-cap that reached in North America from the pole south-
ward to a line extending from New York City to southern Ohio,
thence to near Chicago and on, southwestward, over the Great
Plains to the Rocky Mountain region. When the glacier re-
treated northward again, the animals that had been forced
south made their way back to the homes of their ancestors.
But many of them returned to the south again on the ap-
proach of each winter’s cold. For example, the Bison, which
formerly lived in countless thousands on the Great Plains,
migrated south with the sun, and thus kept in verdant pas-
tures, and similarly to-day scores of species of birds migrate
in the spring and autumn.
The Migration of Birds.— In respect to their migratory
habits all birds are divided into four classes. The examples
that follow are all taken from the latitude of New York City
and Chicago.
1. Residents. These do not migrate, or migrate so short a
distance that those individuals that nest in the northern part
of the range do not move below the southern limit of the
summer range of the species. Examples: the blue jay and
song sparrow.
vo
we)
r
12 ZOOLOGY
2. Winter residents. This class includes those species that
summer to the north and winter only less far north. Exam-
ples: white-throated sparrow and junco or snowbird.
3. Summer residents of any place comprise those species
that nest at the place and winter southward. Examples:
song-thrush, bobolink.
4. Transients. These are species that pause at a place only
while passing from their nesting-place in the North to their
winter home in the South, or which tarry a few days on their
northward journey. Examples: great blue heron, fox-
sparrow, black-poll warbler.
Migration Routes. — The nesting area of any of the migra-
tory species has the form of a band extending east and west a
certain distance along the continent. From this zone during the
fall migrating period the birds move southward along the
meridians, and as they do so the lines of migration gradually
converge, corresponding to the narrowing of the continent.
Consequently, there is a crowding along certain lines, such as
the seashore and river-courses. Thus the birds that follow
down the streams of the Middle West become concentrated into
a narrow migration route when they all reach the lowlands of
the Mississippi River. Some species pass south of the southern
boundary of the United States, and a number even reach the
mainland of South America. Thus the redstart, one of the
commonest of our “ wood-warblers,” reaches Colombia,
Venezuela, British Guiana, and Ecuador. In passing from
southeastern United States to South America, birds take
various routes. Some go by the Antilles, and others fly
across the Gulf of Mexico to Yueatan. The Antillan
route has two main paths, one by the Bahamas and one
by Cuba.
THE ENGLISH SPARROW 373
To get a conerete idea of the migration of a particular species let
us consider in detail the movements of the redstart. This species
breeds from the Gulf of St. Lawrence to British Columbia. Its north-
ern limit in the summer is northern Canada, its southern is North
Carolina. It winters in the Greater and Lesser Antilles and along the
northern shore of South America. About March 20 the redstarts
reach southern Florida, having come from Cuba. The van of the
migrating hosts arrive, on the average, successively at, Raleigh, North
Carolina, April 10; Washington, District of Columbia, April 23; New
York City, May 4; and Montreal, May 16. They move westward
from Florida as well as north. They reach St. Louis, April 17;
Chicago, May 8; Manitoba, May 14, and Athabasca, May 23.
Kansas City is reached about May 5, and British Columbia early
in June. By the middle of August the Canadian birds begin to
migrate southward, the last bemg seen at Athabasca, August 14;
Manitoba, September 20; Chicago, October 5; New Orleans, Octo-
ber 27, and southern Florida, November 4. Every year this broad
red veil of bird life floats slowly northward, in April and May, and is
drawn back to the tropics in September and October. Other species
of birds move similarly, but with great variation in speed and distri-
bution in their summer range.
The peculiar charm of the study of bird migration is due to
the fact that the return of the birds after a long winter heralds
the coming of spring. We hail with delight the return of the
blackbird and robin. The successive weeks show a constantly
increasing number of new arrivals. At the latitude of New
York and Chicago the pheehbe, field-sparrow, chipping-sparrow,
barn-swallow, chimney-swift, cat-bird, wood-thrush, hum-
ming-bird, king-bird, orioles, and wood-warblers follow in quick
succession. The height of the spring migration period is
reached in the early part of May.
Of the species that do not migrate there is no better example
374 ZOOLOGY
than the English sparrow, which is common in all our large
cities and in many farming districts. The term ‘ English ”
sparrow is somewhat of a misnomer, for at the time it was
introduced into our country this bird ranged over all Europe,
where it is known as the house-sparrow. The history of the
spread of this bird shows us in a vivid way what are the suc-
cessful qualities among birds. Originally this sparrow was
confined to middle Europe, and probably made its way into
Germany at the time of the Romans. It has since swept all
over Europe, including the British Isles, and has penetrated
even into Siberia. It has crossed the Mediterranean and is
found along the Senegal River, and, probably through human
agency, has penetrated to the Cape of Good Hope. It has
been transplanted voluntarily by man to North America, Aus-
tralia, and Java. It seems to occupy among birds the place
taken among mammals by the rats. Crafty, pugnacious,
obtrusive, thieving, dirty, it has become a nuisance wherever
it has penetrated. But just these pushing qualities, com-
bined with small size, great hardiness, a universal diet, and
immense fecundity, have enabled it to make its way against
all competitors. Its introduction into America can only
be regarded as a deplorable blunder.
Spread of English Sparrows in America. — The first impor-
tations of the house-sparrow (Passer domesticus) to North
America were made at Brooklyn, New York, in 1850 and 1852.
The second importation survived and multiplied. Subsequent
importations were made to Maine, Rhode Island, and Pennsyl-
vania, so that by 1870 the sparrow was firmly established in
the eastern United States. From this time on the sparrow
spread at a rate unparalleled by any native bird. Bw 1886
it had spread as far west as Kansas, and had established colo-
THE ENGLISH SPARROW 375
nies at Salt Lake City, San Francisco, and other outlying
regions; and throughout this territory it occurred in great
abundance. Since then it has penetrated west to the Rocky
Mountains, and south to Texas. This extraordinary spread
has been due to several causes. As already suggested, the
bird can adapt itself to various climatic conditions and its
fecundity is very great. Thus in our Southern cities there
are from five to six broods a year, and from four to six young
in each brood. Assuming that twenty-four young, half of them
females, are produced by a pair each year, and that all the
females breed when one year old, and successively for ten years,
and that there are no deaths, then in the tenth year 136 billion
individuals will have been produced from the original pair.
To the realization of the possible maximum of reproduction
there are, however, many checks, especially the destruction
of birds by accidents, disease, and beasts and birds of prey.
Food of English Sparrow. — The house-sparrow was intro-
duced for the purpose of destroying or holding in check the
“canker-worm” and the various other caterpillars which
destroy our fruit, forest, and shade trees. There is much doubt,
however, whether the house-sparrow is at all efficient in the way
of destroying insect pests, while it is quite certain that it fights
with and drives away our native insect-eating birds. More
important still, it destroys large quantities of grain in the field
as well as many kinds of garden produce, so that, on the whole,
the English sparrow must be reckoned destructive to agri-
culture. Of late years it has come into our Southern markets
as a substitute for the rice-bird, and it is to be hoped that there
will be a widespread demand for it in the market.
Increase of Exotic Species. — The extraordinary spread of
the English sparrow after importation to this country is not
376 ZOOLOGY
wholly explained by its large fecundity ; for although equally
reproductive in Europe it increases less rapidly there than
here. Also it is not due to any peculiarity of our country, for
the bird is a similar pest in Australia. Similar facts concern-
ing the spread of other animals lead us to conclude that it is
the new country which permits the rapid spread and conse-
quent destructiveness. Thus, when the cabbage-butterfly
(Pieris rape) was brought to this country, it spread with such
rapidity that, starting in 1860 at Quebec, it has now spread all
over the United States as far as the Rocky Mountains. Again,
the grapevine insect pest, Phylloxera, a native of this country,
but not particularly destructive here, has been accidentally
transported to France, and there it has wrought great havoc
in the vineyards. Another instance, this time of an aquatic
animal, shows the same result: the periwinkle, Littorina
littoria,! now the commonest snail on the seashore north of New
York, has migrated down the shore from Halifax since 1868.
This old species in the new country has almost driven out the
other shore mollusks, to such an extraordinary degree has it
multiplied. Now why should animals in a new country develop
with such unusual rapidity? It is because, coming into a new
country, they have left behind them their natural enemies, and
there has not yet been time for them to acquire new ones.
Eventually new enemies are gained, or their old ones over-
take them, and then the numbers of the exotie form become
reduced ; a new equilibrium becomes established.
As an example of the structure of a bird, and for comparison
with the anatomy of the English sparrow, the common pigeon
may be taken.
General Form of the Body. — If the smaller (or “ contour ’’)
1 See page 216.
oo
THE ENGLISU SPARROW
Fig. 349. — The pigeon viewed from the left side with most of the body-
feathers removed. FEATHERS SySTEM: ad. dg. rmx, remex (flight) from the
base of the fingers; al.sp, false wing; ch.rmg, remiges on the ‘‘cubit”’
or forearm; hu.pt, feather tract of the humerus; lg, ligament of the
flights; md.dg.rmg, remiges of the mid-digit; mtcp.rmg, remiges of the
metacarpal region; pr.dg.rmg, remiges of the tip of the finger; pr.pigm,
wing web (patagium) in front of arm; pr.ptgm, patagium behind arm;
ret, one of the tail feathers (rectrices) and the saes from which they have
been removed (ret’) ; sp.pt, feather tracts of the spine; v.apt, featherless
space of the belly. Other references: an, anus; au.ap, ear opening;
cr, cere; dg, 1, 2, 3, fingers; dg, 1, 2, 3, toes; na, nostril; net.m, nictitat-
ing membrane; o.gl, oil gland; ts.mtts, tarsus. From Parker and
Haswell.
378 ZOOLOGY
feathers of the body be removed from one side of a pigeon
(Fig. 349), it will be seen to consist of a head, trunk, and, behind
the vent, a rudimentary tail. In front the trunk is drawn out
Fic. 350. — Feathers of the common pigeon. A, quill feather, basal portion ;
cal, the quill; inf.wmb, lower depression; for admission of blood-vessel
and nerve; sup.umb, upper depression; rch, shaft. B, hair-like
feathers, ‘‘filoplumes.” CC, nestling down. From Bronn’s ‘ Tiesreich.”’
into a long neck connecting with the head. The length of the
neck gives great freedom of movement to the bead, a move-
ment useful not only in flight and in picking grain from
the ground, but also in enabling the bird to reach every
part of the plumage. There are two pairs of appendages, of
which the anterior is greatly modified, being without fingers,
THE ENGLISH SPARROW 3879
and serving to carry the great flight feathers. The hinder
appendages, used as legs, bear four toes, whose great spread
serves to increase the base of support for the relatively large
body.
Body Covering. — The feathers are of two general sorts,
those which form a relatively close covering over the body
of the bird and serve to maintain its high temperature, and the
great quill feathers which are the main organs of flight. Those
which are borne on the fore limbs serve to propel the bird
through the air, whereas those which arise from the tail may,
by their change in position, control the direction of flight.
The earliest feathers of the young pigeon are called ‘ down ”’
feathers, and consist of a cylindrical base which breaks up into
many branches above the skin (Fig. 350C). Among the main
body-feathers of the adult there are found hair-like feathers
which break up into several branches at the tip (Fig. 350 B).
These feathers serve as connecting links to show the real
relations between feathers and hair. The remaining feathers
of the adult plumage are, however, much more complicated
(Fig. 350 4). They consist of a central shaft which passes
into the quill below the level of the skin. Outside the skin,
however, the shaft bears on each side a row of “ barbs,”
which, taken all together, make up the “ web ”’ of the feather.
The barbs cling together so that the web acts as a unit, and as
the web is concave toward the downward stroke and convex
toward the upward stroke, the air is held better in the down
stroke, and this is therefore the more effective in lifting the
bird than the upward stroke is in depressing it. When a single
barb is removed from the web, it will be seen to bear two rows
of microscopic organs which are the interlocking apparatus
(Fig. 351). The organs on that side of the barb facing the tip
580 ZOOLOGY
are called distal barbules, and are provided with hooks, whereas
the organs facing the base of the feather are called proximal
barbules, and bear flanges. The hooks of the one barb inter-
lock with the flanges of the next following barb, and thus all
the barbs are held together in one firm web.
Skeleton. — The bones of birds are exceedingly light, many
of them being hollowed out and filled with sacs connected with
the lungs and containing heated air. This hot air greatly
Fria. 351. — Structure of a feather. Two barbs are represented cut across.
Each bears to the left three ‘‘distal barbules’? armed with hooks which
engage in the flanges of the ‘proximal barbules”’ lying to the right of the
neighboring barb. After Pycraft.
increases the buoyancy of the bird in the air. The avxial
skeleton differs from that of most other vertebrates in the
great length of the neck region, the compactness and rigidity
of the trunk, and the shortness of the tail (Fig. 352). The
latter ends in a square bone which consists of a lot of rudimen-
tary vertebrie fused together. This piece corresponds to most
of the long tails of reptiles, and in some fossil birds (Archeopte-
rix, see also Fig. 388) the vertebra of the tip of the tail are still
distinct. The skull is very compact and light, and the limits of
the different bones of which it is composed are hard to make out
except in young specimens (Fig. 353). The lower jaw is sup-
ported from the skull, as in the lower vertebrates, by a special
THE ENGLISH SPARROW 381
hinge called the “ quadrate”’ bone. Neither upper nor lower
jaw bear teeth in living birds, but fossil birds are known which
bear teeth. One of the most notable features of the skull of
birds is the remarkable length of both the upper and lower
car
Fia. 352. — Bones of the trunk of the pigeon: th.v./, first and th.v.5, last
vertebra of the thorax; s.scr, sacrum; cd.v, caudal vertebrx, ending in
the tail piece, pyg.st. The ribs are short on the neck (cv.r); on the
thorax they consist of two parts, the vertebral (vr.r), and sternal (s¢.r)
ribs, of which the former bears the uncinate process (unc) ; scp, scapula;
cor, corocoid; fur, wishbone or furcula; acr.cor, process of the corocoid;
gl.cv, place of union of the humerus; sf, sternum, and its keel, car. The
pelvis includes: the ilium, 7, ischium, 7s, and pubis, pu.acthb, acetabu-
lum for reception of the head of the femur; a.tr, for attachment of the
ligaments of the femur; is.for, foramen of ischium; obt.n, obturator
notch. From Parker and Haswell.
jaws, which are drawn out to constitute the beak. Another
feature is the enormous cavity reserved for the eye.
Surrounding the viscera are five pairs of ribs which connect
below with the huge breastbone or sternum, a bone remarkable
for its deep keel. This keel serves for the attachment of the
breast muscles, by means of which the powerful downward
382 ZOOLOGY
stroke of the wing is performed. The skeleton of the wing is
connected with that of the trunk by two bones, one of which
Fig. 353. — Skull of a young pigeon in three views: A, dorsal; B, ventral;
and C, lateral. With the aid of the skull of a young pigeon or chicken
one can find the bones which bear the names indicated: a/.s, alisphenoid ;
an, angular, and ar, articular of the lower jaw; bo, basioccipital; d,
dentary (but bearing no teeth in modern birds); e0, exoccipital; eu,
opening of Eustachian tube; f.m, great foramen of skull; fr, frontal;
v.0.8, interorbital septum; ju, jugal; dc, lachrymal; 7/b.s, lamboidal
suture; m.eth, mesethmoid; mer, maxilla; rexr.p, maxillopalatine
process; na, na’, na'’, nasal; o.c, occipital condyle; or. fr, orbital plate
of frontal; pa, parietal; pa.s, parasphenoid; pl, palatine; p.ma, pre-
maxilla; pt, pterygoid; qu, quadrate; s.an, supraangular; s.o, supra-
occipital; sg, squamosat; (y, tympanic cavity; IJIJ-NXJI, opening for
cerebral nerves. From Parker's ‘‘ Zootomy.”
THE ENGLISH SPARROW 383
runs up to the vertebre and the other down to the breastbone.
The two halves of the girdle thus formed are kept apart
by a bone that serves as a spring, the so-called wishbone
(Fig. 352, fur). While the shoulder girdle is thus character-
ized by a high degree of elasticity as befits its important work
of supporting the strokes of the wing, the pelvic girdle, on the
other hand, consists of a pair of bones rigidly fastened to the
immovable sacral vertebre.
The skeleton of the wing consists of a single bone in the
upper arm, two bones in the forearm, and rudiments of three
fingersin the hand. The skeleton of the leg consists of a single
bone (femur) in the upper leg, two bones (tibia and fibula)
in the lower leg, a kneepan (or patella) at the joint between
the upper and lower leg, and a foot consisting of four digits
which are grown together in what corresponds to the sole of
the foot in man (the shank of the bird’s leg), but are separate
in the toes.
Organs of nutrition in the pigeon are much more com-
plex than in the lower classes of vertebrates (Fig. 354). From
the toothless mouth, with its long tongue, the long gullet leads
through the neck to enlarge into a capacious crop lying just
in front of the wishbone. Here the food, which consists
chiefly of grain, is thoroughly soaked and softened. Thence
it passes by a continuation of the gullet to the stomach, which,
as in most birds, consists of two parts; the first, which is
glandular; the second, or gizzard, which is muscular. In the
first part the grain is further softened and treated by the se-
cretions of the glands; in the second it is mechanically treated,
being crushed and ground by aid of small stones that have been
swallowed by the bird. From the gizzard leads the intestine.
In its anterior part the digestive processes are active, and it
ZOOLOGY
384
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THE ENGLISH SPARROW 385
is into this region that the principal digestive fluids (those from
the liver and pancreas) are poured. The great middle portion
of the intestine, together with a pair of blind sacs (ceca)
opening into it, serves for the absorption of the digested sub-
stances and, finally, the indigestible remnants are collected
in the rectum, whence they pass, through a cloaca, to the
external vent. The cloaca receives also the excretory products.
Organs of Respiration. — These also reach an extraordinary
complication in birds. From the larynx, which, as in man, is
supported by cartilages but is not, in birds, the vocal organ,
a long windpipe passes to the two lungs. Where the wind-
pipe begins to subdivide to form the bronchi of the lungs, there
is found the vocal organ of birds —the syrinx (Fig. 355) ;
nothing like it is found in any other class of vertebrates, and
it gains a very complex structure in the singing-birds. As it
would take a long time to describe the mechanism of the
syrinx, this will not be attempted; suffice it to say that the
sound is produced by the vibration of a membrane which is
stretched part way across the windpipe.
The respiratory organs proper are of two kinds — the lungs
and the air-sacs. The lungs (Fig. 355) are relatively small
organs and are not mere bags, as in the lower orders of verte-
brates, but spongy masses rich in blood-vessels. Through this
sponge-work the pure inspired air rushes on its way to the air-
sacs which lie beyond. Consequently the blood of the lungs
is bathed by a current of fresh air, and this insures that it shall
receive a maximum of oxygen and this, in turn, results in the
bird maintaining a high body temperature, 103° F. (40° C.), in-
stead of 98° F. (37° C.), asin mammals. The air-sacs of birds
correspond, in a way, with the little terminal sacs of the bron-
chi in ourselves, but some of these have become immensely
2c
386 ZOOLOGY
enlarged and occupy great spaces of the body and even com-
municate with the cavities of the bones.
These air-sacs serve
not only to diminish the specific gravity of the body, but also
the tidal air.
as reservoirs to receive
bp"
Fic. 355. — The lungs of the pigeon, together
with the lower end of the trachea, viewed from
the ventral side: ¢r, trachea with the syrinx
(sy) at its lower end where the two bronchii (br)
branch off, eventually dividing into branches,
br’, br’. The pulmonary artery enters at
p.a, and the vein leaves at p.v. With the
lungs, various air sacs are connected at a.in,
the anterior thoracic; at p.in, the posterior
thoracic; at p, the abdominal; at sh.b, the
interclavicular, and at sp.b, the cervical. From
Parker's ‘‘ Zootomy.”
pure blood from the tissues is received
From these reservoirs
some of the air is no
doubt absorbed by
the blood and other
fluids of the body;
the
are periodically
but reservoirs
emptied through the
air-tube, as are the
terminal sacs in our
own lungs.
Organs and Func-
tions of Circula-
tion. — The heart is
completely
into a right and a
divided
left side, as in man.
Each side has a re-
ceiving chamber or
auricle, and a dis-
charging chamber or
The im-
by the right auricle,
ventricle.
passes to the right ventricle, and thence is pumped into
a paired pulmonary artery, of which one branch goes to
each lung, where it breaks up into capillaries.
The re-
collected, oxygenated blood is returned to the left auricle,
1 Fig. 354,
THE ENGLISH SPARROW 387
enters the left ventricle, whence it is pumped to the tissues.
The great artery that carries blood from the left ventricle
is called the aorta. It quickly divides into a right and a
left branch, from each of which an artery goes to the head
with its brain and sense-organs, and to the wings and their
great muscles. The right branch of the aorta passes up around
the throat and reaches the vertebral column and runs under
this (as the dorsal aorta) to the tail. It gives off blood-vessels
to the food-canal and its glands, to the legs, to the kidneys, and
other organs. The blood which is thus carried by the arteries
to various organs of the body breaks up in each of them into
capillaries and is finally collected into veins which eventually
empty, as stated above, into the right auricle. While passing
through the capillaries, the blood gives up its oxygen and re-
ceives from the organs carbon dioxide and other waste products
of activity lying in these organs.
The organs of excretion consist of a pair of bodies of compact
form like those of reptiles and mammals, and in striking con-
trast to the elongated, segmented kidneys of Amphibia. This
kidney, indeed, represents only the hinder end of the kidney
of Amphibia. It is richly supplied with blood that carries ex-
cretory products which, passing from the blood-vessels, enter
little tubes. These tubules eventually empty into a central
basin which, in each kidney, connects by a larger tube with
the cloaca and the exterior (Fig. 354).
The Organs and Functions of Reproduction. — In the female
the ovary and oviduct of the right side has atrophied ; only
that of the left side persists. The eggs grow, in the oviduct,
to an enormous extent by the addition of yellow food matter
—the yolk. As a yolk passes down the oviduct a layer of
albumin or ‘
‘white ’’ is poured around it; next a thin mem-
388 ZOOLOGY
brane, and lastly a hard, white shell. Two of these eggs are laid,
one after the other, in successive days, and then incubated by
the parents, who by sitting on them maintain them at the tem-
perature of the body, so that the egg develops. After fourteen
days the young pigeon hatches and is fed and brooded by the
parents for a time longer until it is able to care for itself.
The muscular system is best developed in connection with
the function of flight. Every one who has eaten a chicken or
Fic. 356. — The brain of the pigeon, left side: olf, olfactory lobe; ch,
cerebral hemispheres; pn, pineal body; cb, cerebellum with a side lobe
at f; ot, optic tract; mo, medulla oblongata; J-NJJ, cranial nerves;
spJ, spinal nerve. From Parker's ‘t Zootomy.”’
turkey knows of the great “ breast ’’ muscles. These consti-
tute ‘ white” meat in the turkey because they are relatively
bloodless, being little used for flying; but in pigeons, which
fly readily, the breast muscles are full of blood and are dark.
The great breast muscles depress the wing, the reaction to
which keeps the bird in the air. The other muscles of the
body are less important. Those of the neck and tail are well
developed, corresponding to the mobility of these parts, but,
owing to the compact, immobile nature of the trunk proper, the
musculature of that region is very slight.
THE ENGLISH SPARROW 389
The nervous system consists of the brain, spinal cord, and
the sympathetic system. The brain shows a great advance
over reptiles, particularly in the development of the hind
brain, or cerebellum —the centre of codrdination (Fig. 356).
Since flight demands extreme codrdination, we can under-
stand the large cerebellum of birds.
Fic. 357.— Median section through the eye of the pigeon: cn, cornea;
ir, iris; J, lens; cl.pr, lens muscles; pet, pecten; opt.nr, optic nerve;
rt, retina; ch, choroid coat; scl, sclerotic coat. After Vogt and Yung,
from Parker and Haswell’s ‘‘ Zoology.”
Sense-organs. — As befits such active animals, pigeons, like
birds in general, have well-developed sense-organs. Organs of
smell, lying at the base of the beak, and those of hearing, having
much the same structure as in man, are present. But the
most perfect organ is the eye which has relatively a large size.
It differs from that of man in its lenticular (compressed) form,
well adapted to the vision of distant objects. A peculiar organ
390 ZOOLOGY
lies in the aqueous humor in front of the entrance of the optic
nerve — it has the form of a comb (whence called pecten) and
is deeply pigmented, but its function is quite unknown (Fig.
357).
The class of Birds, or Aves, as they are technically called,
is divided into eleven orders as follows: —
1. The running birds: Birds incapable of flight because
their wings are rudimentary, e.g. Ostriches.
2. The swimming birds. These are the web-toed birds like
the loons, gulls and terns, petrels, pelicans, ducks, geese, and
swans.
3. The shore birds. These possess long, stilt-like shanks
with slight web; such are the flamingoes, herons, storks,
cranes, snipes, and plovers.
4. The ground birds, including the turkeys, grouse, fowl, and
quail.
5. The pigeons, perchers on rocks, with all four toes on the
same level.
6. The birds of prey, with hooked beak and claws (talons),
including the vultures, hawks, and owls.
7. The talkers, with beak shorter than high, including the
parrots, paroquets, etc.
8. The cuckoos and kingfishers.
9. The woodpeckers, with long beaks fitted for drilling into
bark.
10. The long-winged birds, or humming-birds, swifts, and
goat-suckers, of varied form, for the humming-birds have
slender bills, but the other groups have short bills and large
mouths. The wings are generally long and pointed.
11. The perchers, including most of the common migratory
birds.
THE ENGLISH SPARROW 391
The order of runners (Cursores) includes the African ostrich,
the American ostriches, or rheas, the cassowaries of the East
Indies, and certain wingless birds of New Zealand (Apteryx !),
Fia. 358. — Apteryx australis, with egg. From a specimen in the Royal
College of Surgeons, London. From Parker and Haswell, ‘‘Text-book of
Zoology.”
These are regarded as the most lowly developed of the birds;
the vanes of their feathers are not united, but separate to form
a sort of hair-like covering to the body. The African ostrich
is the largest living bird. It wanders in families or flocks in
the deserts of Africa, and feeds on grass, grain, and small
1 Fig, 358.
392 ZOOLOGY
animals. It also swallows undigestible matters, such as stones,
which probably aid it in triturating its food. The nest consists
of a hollow scooped out of the earth, into which about thirty
eges are laid. Ostrich feathers are used for ornament, and so
important is the commerce in these articles that ostriches are
‘iy
FOX
Fic. 359. — Common tern (Sterna hirundo).
extensively farmed in South Africa, southern California, and
Arizona. The feathers are cut off and not pulled out, so that
the operation of gathering the feathers is a painless one for the
bird, but attended with some risk to the operator.
The swimmers, or Natatores, comprise the ducks and geese,
the pelicans, the petrels, the gulls and terns, and the divers.
Of the geese, the wild goose, or Canada goose, is most commonly
seen in its migrations. Of the native ducks we have many
kinds, almost all rapidly disappearing before the “ sportsman.”
The pelicans are large fish-eating birds, with a huge bag-like
THE ENGLISH SPARROW 393
lower bill. In this country the white pelican is not un-
common. The large-winged petrels follow in the wake of
coastal vessels. The terns, which are slender birds with a
straight bill,! were once abundant along our coast, but have
been decimated to “ ornament” bonnets. The gulls, which
Fic. 360. — Spotted sandpiper (Actitis macularia).
are heavier than the terns, and have hooked bills, are still abun-
dant along the seashore and Great Lakes. Finally, the loons
are large birds, powerful fliers and swimmers, which are found
in the lakes of the Northern Hemisphere. They are quick
divers, and can swim under water for a considerable distance.
The waders (Grallatores) include a great number of shore
birds known as plovers, sandpipers, snipes, rails, cranes, herons,
and storks. The plovers walk and fly along shore, picking up
1 Fig. 359.
394 ZOOLOGY
worms, mollusks, and amphibians; the golden plover is a well-
known game bird. The snipes are found in meadows or, less
commonly, in woods. One of the most common is the spotted
sandpiper, also called ‘“ tip-up ” from its rocking movements
(Fig. 360). It is seen walking around the margins of ponds and
rivers. Woodcock and large snipe are found in moist places.
Among the herons, our great blue heron attains a length of
Fic. 361. — Ruffed grouse (Bonasa umbellus).
four feet, and is a notable resident of swampy regions, while
the egrets have been practically exterminated to meet the de-
mands of milliners.
The order of scratchers (Gallinee) includes a number of ter-
restial birds of large size, especially the grouse or partridges,
the pheasants and common fowl, the guinea-fowl, and the tur-
keys. On account of their large size and well-flavored flesh,
they are much used as human food. The grouse of America
include the familiar “ bob-white,” or quail, which is being
THE ENGLISH SPARROW 399
rapidly reduced in numbers in populous regions; the Canada
grouse, which does not occur south of New York; the ruffed
grouse of the Eastern States;! and the prairie chicken of the
Great Plains, which has
also become almost exter-
minated. In Europe the
large “capercaillie”’? and
the blackcock are favorite
game birds. The pheas-
ants are characteristic of
southern Asia and China ;
they comprise some of the
most brilliantly colored
and greatly ornamented
of birds, such as the
peacock and the golden
pheasant. Here also be-
long our barnyard fowl
derived from a wild spe-
cies, Gallus bankiva, in-
habiting northern India,
the East Indies, and the
Philippines. The guinea-
fowl is a native of Africa,
where it goes in large Fic. 362.— Passenger pigeon (Hctopistes
flocks and is difficult of PugT tents)
approach. The turkeys are North American birds. The
wild turkey formerly occurred over all the United States
and Mexico. It was first taken to Europe in 1524, was domes-
ticated there, and now occupies much of its former habitat as
1 Fig. 361.
396 ZOOLOGY
a domesticated fowl. From this brief view we see that the
family of Gallinacei is, for man at least, the most important
family of food-birds.
The order Columbine includes the pigeons and _ allies,
characteristic of the Eastern Hemisphere. The most inter-
esting species of the group — the dodo and the solitaire, for-
merly inhabitants of the islands of Mauritius and Rodrigues,
respectively — have become extinct within historic times
through the settlement of these islands by whitemen. These
birds had rudimentary wings and tail. Their nearest living
ally seems to be the “
The pigeons proper are represented in North America by three
wild species (Fig. 362). The domesticated pigeon, Columba
livia, is a native of southern Europe or western Asia.
manu-mea’”’! of the Samoan Islands.
The birds of prey (Raptores) include eagles, hawks, and
falcons; the vultures; condors; and owls. These birds feed
chiefly on birds and mammals, which they capture alive in
their claws or beaks; a few live on carrion. They occur in all
parts of the globe. The bald eagle, used as a symbol of the
republic, is the commonest of our eagles. Among our hawks,
the sparrow-hawk, which is only about the size of the robin,
is one of our most abundant; others are the sharp-shinned
hawk, which kills birds almost exclusively and is especially
destructive to poultry,? and Cooper’s hawk, which is also de-
structive to birds. These two hawks have practically no
redeeming qualities, except the fact that they prey upon the
English sparrow. The vultures are represented in our fauna
by the turkey-buzzard which, like other members of the family,
feeds on carrion. The condor is the largest of the American
Raptores. It preys even upon live sheep and calves. The
1 Redbird, 2 Fig. 363.
THE ENGLISH SPARROW 397
owls, which live in dark holes and feed upon small mammals
at night, are found over most of the globe. Our commonest
species is the reddish gray screech owl.2 The great horned
Fic. 363. — Sharp-shinned hawk (Ac- Fic. 364. — Screech owl (Megascops
cipiter velox). asto).
owl is an inhabitant of wooded tracts, and is destructive to
poultry and small mammals. The snowy owl is one of the
handsomest of all owls, and is frequently seen stuffed in
houses in Europe as well as in North America.
The parrots and cockatoos (Psittaci) are sometimes called
2 Fig. 364.
598 ZOOLOGY
“climbers.” In the cockatoos the feathers of the head are
elevated to form acrest. In the parrots there is no such crest ;
in one subdivision the tail is long; inasecond, very short. The
representatives of this family are found almost exclusively in
the tropics, in Brazil, the Moluccas, and in Australia. In gen-
Fie. 365. — Conurus carolinensis, the Carolina paroquet. One-fifth nat.
size. After Wilson.
eral, these birds have a loud voice, and certain species may be
trained to articulate words and combine them into sentences.
There is only one parrot native to the United States — the
Carolina paroquet (Fig. 365). This formerly occurred north
to the Ohio River, but it has been within recent years practi-
cally exterminated by plumage hunters.
THE ENGLISU SPARROW 399
The toucans and cuckoos on the one hand and the king-
fishers on the other are grouped into the order Coccyges. The
toucans are characterized by an enormous bill, whichin extreme
cases is as long as the rest of the bird. It would be extremely
Fie. 366. — Belted kingfisher (Ceryle alcyon).
heavy were it not filled with air spaces of great extent. These
birds inhabit Brazil. The great bills are of use in feeding on
fruits. Filling the place in the Old World of the toucans of the
New are the hornbills of Africa and Asia, which are likewise
frugivorous. The cuckoos are typically represented by the Old-
world cuckoos. Like our own cow-bird, they have the peculiar
400 ZOOLOGY
habit of laying their eggs in the nests of other birds, espe-
cially insectivorous birds, where they are brooded and the young
are fed by the foster-
mother. Our native
cuckoo, however, broods
its own eggs, and is a
useful insectivorous bird.
The kingfishers are also
placed in this group.
They are especially an
Old-world family, but
one genus (Ceryle) has
found its way into the
Americas. These birds
feed chiefly on fish, and
they have gained a com-
pact, oily plumage to
prevent them from get-
ting wet when they
plunge for their prey.
Our species is known as
the belted kingfisher
(Fig. 366).
The woodpeckers, or
Fic. 367. — Flicker (Colaptes auratis).
Pici, include for the
most part arboreal birds which feed chiefly on insects,
and have loud, harsh cries. The common idea that they
are sap-suckers and destructive to trees seems to be true
only of one of our species — the yellow-bellied wood-
pecker. The heavy, long bill enables woodpeckers to
peck holes in trees for wood-eating insects, and the long,
THE ENGLISH SPARROW 401
barbed, protrusible tongue aids in removing the prey. Our
commonest woodpeckers are the golden-winged woodpecker,
or flicker,! the red-headed woodpecker, the hairy woodpecker,
and the downy woodpecker. An interesting question con-
cerning the golden-winged woodpeckers of the East and South-
west is whether they
hybridize where _ their
areas of distribution over-
lap.
The “long-wings ” in-
clude the humming-birds,
swifts, and goat-suckers.
The humming-birds are
mostly small species,
limited to our hemisphere,
and characteristic of the
tropics. They fill the
same place among the
birds that hawk-moths do
among insects, in so far as
they are fitted to visit Fic. 368. — Ruby-throated humming-bird
trumpet-shaped flowers. RS recs SONORA
They do not feed solely upon nectar, but devour in-
sects also. They are usually brilliantly colored, and fly
with great swiftness, nest in trees, and lay only two white
eges. One species, the ruby-throated humming-bird, reaches
New England and Canada (Fig. 368).
The swifts have a broad gape, and no bristles at the base of
the bill. They have habits much like swallows, and are found
especially in the warm parts of the world. Most species of this
1 Fig. 367.
2D
402 ZOOLOGY
family have salivary glands, whose secretions aid in cementing
the nest. Our common representative of this group is the
chimney-swift, or chimney-swallow.! Certain Chinese species
make nests entirely of the mucilaginous secretion of the sali-
vary glands; these constitute the edible birds’-nests of the
Chinese. The goat-suckers include night-flying birds, with
exceedingly broad gape and insectivorous habits. The night-
Fig. 369. — Nest of chimney-swift. Photo. looking down chimney, by
D. and 8.
hawk of North America, and the whippoorwill, named for its
characteristic night cry, are familiar examples.
The order of perchers, or Passeres, is the most important for
us because of the abundance of species and individuals included
init, and because of the intimacy that many of them have cul-
tivated with man. The representatives of the order that live
in the United States are arranged into about fifteen families,
concerning each of which a brief account follows:
The flycatchers (or Tyrannidie) are an exclusively American
family, feeding on insects. The best-known representatives are
| Fig. 369.
THE ENGLISH SPARROW 403
the courageous kingbird (Fig. 370), the wood pewee (Fig. 371),
and the water-loving phcebe.
Fic. 371. — Nest of pewee. Photo. by D. and 8.
404 ZOOLOGY
The larks are a family chiefly of Old-world birds of dull
color, building a rough nest on the ground, and feeding on seeds
and insects. The skylark of Europe is renowned as a songster.
Fie. 372. — Blue jay (Cyanocitta cristata).
In this country we have one representative of the family, the
horned lark, found also in Europe.
The crows (Corvidie) and their allies are all of them birds
of large size and omnivorous, but prefer animal food. The
crow, the raven of the West and of Europe, and the blue jay
THE ENGLISH SPARROW 405
(Fig. 372) are the commonest North American species of this
family.
The blackbird family (Icteridz) includes numerous species
with different habits. These are also confined to America, and
Fic. 373. — Purple grackle (Quiscalus quiscula).
are especially abundant in the tropics. They feed, for the
most part, on seeds. The commonest representatives are the
crow blackbird,! of large size and iridescent plumage; the
Baltimore oriole, which weaves a hanging nest; the orchard
1 Fig. 373.
406 ZOOLOGY
oriole, with less orange than the preceding ; the large meadow-
lark, brownish above and yellow below ; the red-winged black-
bird; the cow-bird, which builds no nest, but lays its eggs in
Fig. 374. — The American crossbill (Loria curvirostra).
the nests of various small birds; and the ‘“ bobolink,” as it
is called in the North, whose song is the merriest of all birds.
In the South, whither the bobolink migrates in the winter, it is
a great pest in the rice-fields, and is known as the “ rice-bird.”
It is slaughtered there as a game bird.
The sparrows (Fringillidze), to which family the English
sparrow belongs, constitute a large group comprising over
THE ENGLISH SPARROW 407
five hundred species, found in all parts of the world, ex-
cepting, until recently, Australia. In the United States
it is the largest family of birds, comprising in most. places
about one-seventh of the species. Among common or
striking native Fringillide may be mentioned the crossbills,!
yellowbird, vesper-sparrow, white-throated sparrow, tree-
Fie. 375. — Chipping-sparrow (Spizella socialis).
sparrow, chipping-sparrow,? snowbird, song-sparrow, fox-
sparrow, chewink, cardinal grosbeak, rose-breasted grosbeak,
and indigo-bird. Most of these birds are known to every
country boy.
The tanagers are exclusively American and belong especially
to the tropics. They live in the woods, and feed on berries and
fruits. The northernmost member of the family is the scarlet
tanager of the eastern United States (Fig. 376).
The swallows are found over the world. They are powerful
fliers, and are insectivorous. Formerly all of them bred in
1 Fig. 374. 2 Fig. 375.
408 ZOOLOGY
Fic. 377. — Barn-swallow (Chelidon erythrogaster).
THE ENGLISIT SPARROW 409
boughs, and hollow trees, cliffs, and some species still retain
these habits. The best-known species are the bank-swallows,
which, living in colonies, form
numerous holes in railroad cuts
and sand-banks in general; the
white-bellied swallow, abundant
about water; and the barn-swal-
low (Fig. 377), with a chestnut
belly, which builds its nest in the
rafters of our barns (Fig. 378.)
The waxwings are found over Ftc. 378. — Nests of barn-swal-
the Northern Hemisphere. They PoP vee eens
are migratory, go in flocks, feed on insects and fruits, and
chatter rather than sing. Our commonest species is called
“ eedar-bird ” (Fig. 379).
The shrikes are of world-wide distribution. They are
vigorous, pugnacious birds, which have the habit of impaling
grasshoppers and other small animals upon thorns, and leav-
ing them there. In Germany there is a tradition that the
shrike daily impales nine victims, and it is hence commonly
called Newntodter, or “ ninekiller.”” The impaling seems to be
done chiefly in the winter time, and apparently has for its pur-
pose the storing of food against possible famine. Among birds
frequently destroyed by them is the English sparrow, and it has
been suggested that the shrikes should be encouraged to live in
parks of cities infested by sparrow pests; but unfortunately the
shrikes do not confine themselves to this intruder. We have
two species of shrikes, a northern (Fig. 380) and a southern.
The vireos or greenlets are bright, handsome, and exclusively
American birds. The commonest species are the red-eyed
vireo (Fig. 381) and the yellow-throated vireo.
410 ZOOLOGY
The family of wood-warblers is the peculiar glory of
America. It contains numerous small, mostly brilliantly col-
ored birds, which migrate. Although a few of them — like the
redstart, the Maryland yellowthroat (Fig. 382), the redpoll
Huo
Fig. 379. — Cedar waxwing (Ampelis cedrorum).
warbler, the chestnut-sided warbler, and the vellow warbler
are abundant, few of the thirty-five or forty Eastern species can
be said to be commonly known except to careful observers of
birds ; for during the migrations they hide in thickets, and are
extremely shy.
The wrens are characteristic of South America, but some have
THE ENGLISH SPARROW 411
Fic. 381. — Red-ceyed vireo (Vireo olivaceus).
412 ZOOLOGY
spread into North America and northern Europe. Our house
wren, which is a near relative of the European house wren,
is an active little brown bird, witha sharply bent-up tail. In
this same family belong the mocking-hirds, the centre of whose
Fic. 382. — Maryland yellowthroat (Geothlypis trichas).
distribution is Central America, the West Indies, and the south-
ern United States. The large brown thrasher and the catbird
are familiar over the country. The mocking-bird does not
1 Fig. 383,
THE ENGLISH SPARROW 413
get far north into New England. It is regarded by many as
superior to the nightingale as a singer.
The family of titmice includes also the nuthatches. The tits
are chiefly Old-world birds, but we have a common represen-
tative in the black-
capped chickadee, well
known from its cheerful
whistle. In this family
belong the nuthatches
which run over tree-
trunks, head up or down,
indiscriminately (Fig.
384).
The little brown
creeper which travels
over the bark of trees
much as the nuthatches
do and uses its tail-
feathers as props against
the tree-trunk (Fig. 385)
belongs to an_ allied
family.
The family of thrushes
includes several common
American birds, —the robin, abundant about houses during
the summer, but for the most part migrating south from New
England during the winter; the wood or song thrush,! one of
our finest songsters; the bluebird, one of the earliest of our
migrants, with “the sky on its back and the earth on its
breast.”
Fic. 383. — House wren (Troglodytes aédon).
1 Fig. 386,
414 ZOOLOGY
Bird flight. — The difficulties which must be overcome in
order to fit birds for flight are, first, that of sustaining the heavy
body in a medium of such low specific gravity as the air; and,
secondly, that of progression in this medium. To diminish the
difficulty of sustaining the body, the specific gravity is reduced
C4
we!
Fic. 384. — White-breasted nuthatch (Sitta Fig. 385. — Brown creeper
carolinensis). (Cerithia familiaris).
to a minimum by great air spaces in the body, which exist even
in the hollow bones. The body is kept from being overturned
in the air by the position of the wings, which are placed high up
on the trunk, while the digestive organs, breastbone, and breast
muscles are placed low. To aid locomotion, the general form
of the body is made conical, so as to offer little resistance to the
air, while, by varying the position of the head, wings, and tail,
THE ENGLISH SPARROW 415
the centre of gravity is quickly shifted. In starting to fly, the
bird gains an initial velocity, if on the ground, by springing into
the air, or if on a tree, by combining the velocity due to gravity
with a pushing from the limb; but aquatic birds strike the
Fig. 386. — Wood-thrush (Turdus mustelinus).
surface of the water with their wings. The best fliers have
relatively large, pointed wings. Three methods of flight are
employed by birds when once in the air: (a) stroking the air
with the wing; (b) gliding or skimming ; and (c) sailing or soar-
ing. Some birds can use all three methods, and all good fliers
use the first two. In the stroke the wing moves downward and
forward, backward and upward, so that the tip of the wing
416 ZOOLOGY
describes a © ; and since the bones of the wing — its most
rigid part —are at its front edge, the hinder edge tends to
lag behind the front edge, so that the wing as a whole hits the
air in a plane which is not perpendicular but oblique to the
direction of impact. Consequently on both the up and the
down stroke one component pushes backward and tends to
drive the bird forward (Fig. 387). In gliding, the wings are
spread, but are not flapped; progression depends upon an
acquired velocity, as in
aeroplanes, or upon the
wind. In soaring, the
wings remain motion-
less, and the bird does
not lose its velocity nor
Fig. 387. — Diagram showing resolution of ciate
forces (A) on down and on up strokes of the tend to fall. The w ay
wing; the component B, in both cases exerts jy which the bird is
a backward pressure that drives the bird : ae
forward; while the component C’ keeps the supported and carried
bird up. along is uncertain. It
seems to depend upon certain favorable currents in the air.
Birds, like insects, have the closest economic relations with
man. A few of them, chiefly belonging to the orders of swim-
mers and grouse, are very important as human food; but
most of them concern man on account of their feeding habits,
which are either favorable to man, as when noxious insects are
destroyed, or injurious, as when grain-fields are ravaged or
other birds are preyed upon. Unquestionably the vast ma-
jority of birds are commercially advantageous to man. The
Raptores are only partially so, for they feed entirely upon
animal food, chiefly birds and small (usually destructive)
mammals. The bobolink and the American crow, to be sure,
together annually destroy millions of dollars’ worth of grain,
THE ENGLISH SPARROW 417
yet during the breeding season they both feed much upon
insects. Outside of the group Raptores, there are few, if any,
completely noxious birds, and even many of the hawks are
efficient destroyers of insects. Legislation directed toward
the destruction of any kind of birds, excepting the English
sparrow, the Cooper’s and sharp-shinned hawks, and perhaps
the crow, is quite as apt to do harm as good.
Bird Protection. — Travellers in certain parts of Europe,
where the poverty and ignorance of the people have led them
to prey upon birds, have remarked on the desolation of a bird-
less country. The natural enemies of insects being destroyed,
there is no adequate check to the destruction of vegetation by
insects, and the beauty of a forest landscape is missing. North
America has been richly provided with a native bird fauna; but
within the last few years it has become plain that most of our
species are undergoing reduction, and many are near extermi-
nation. Careful inquiries recently made indicate that during
the past fifteen years the number of our common song-birds
has been reduced one-half, and the number of certain birds
prized as food or ornament has been reduced to one-fourth. At
the present rate, extermination of many species will occur dur-
ing the lives of most of us. The causes of this destruction of
birds are numerous. The most efficient cause is the shotgun
in the hands of boys and thoughtless men and of those who
gather bird skins to meet the demand for bonnet “ ornaments.”
Very great destruction is also caused by egg-collectors, who
annually gather scores of thousands of eggs, often of rare birds.
The disastrous results of killing birds need only to be appre-
ciated in order to put a stop to this destructiveness. No
species, once exterminated, can ever be replaced, and the world
cannot afford to lose any of the objects of beauty and utility.
25
418 ZOOLOGY
Extinct Birds. — The destruction of species of birds goes on
fast enough without the more efficient aid of man. We know
of species which have become extinct within recent times
through the introduction of new enemies among them. Such
Fig. 388. — Hesperornis regalis. The restored skeleton. After Marsh.
was the fate of the dodo and of the great auk of Labrador.
The remains of species which lived in very remote periods
have been preserved to us in the rocks. The oldest known
fossil bird, Archzeopteryx, of the Jurassic age, has a long tail
like a lizard; but feathers, which are only modified scales,
THE ENGLISH SPARROW 419
were present even in this oldest known bird. In the Creta-
ceous rock deposits of the Great Plains there have been found
fossil birds with teeth set in sockets or grooves, precisely as
they are to-day in reptiles (Fig. 388). These remains show
us in the clearest manner that birds have been derived from
reptiles or both from a common source. Indeed, the two
groups are closely related anatomically, and are often united
under the name Sauropsida, or lizard-like animals.
CHAPTER XXVI
THE MOUSE: A STUDY OF THE EVOLUTION OF
DOMESTIC ANIMALS
Man loves company, not only of his own kind but also that of
other animals, and many other animals similarly enjoy society.
The dog is one of these. In the wild state it goes in packs and
when alone gladly attaches itself to man. Such a mutual,
social instinct was probably the earliest impulse to associations
between man and other animals such as dogs and cats. More-
over, man found that certain other animals, which might not
share his fireside, could nevertheless be trained to stay about
his tent or hut, where they could be utilized for food, for
clothing, or for burden-bearing. Thus man came to domesti-
cate cattle, goats, sheep, and horses. A list of the more fa-
miliar domesticated animals is as follows:
Hairy animals (Mammalia): cat, dog, rabbits, guinea-pig,
mouse and rats, pig, horse (including the ass), cattle, llama,
camels, sheep, goats, and elephants.
Birds: canary bird and various finches, paraquets, poultry,
pheasants, ducks and geese, guinea-fowl, turkey, and ostrich.
Fishes: goldfish. Insects: bee, silkworm.
Some of these domestic animals deserve a fuller description.
The cat is a solitary animal with a strong homing instinct.
There are several domestic races, such as long-haired, short-
haired, and tailless (or Manx). In each of these races there
white, black, tortoise-shell, tiger, and
420
are various color types,
THE MOUSE 421
1. The Manx or tuailless cat. 2. The Siamese cat.
3. Short-haired cats. Black 4. A white long-haired Angora
and white, and tiger marked. cat.
Fic. 389. — A group of domestic cats, illustrating the results of domes-
tication.
439 ZOOLOGY
maltese. Cats are carnivorous. Since they are sly, noiseless
of tread, and quick of movement, they are the most effi-
cient check upon the multiplication of house mice and rats
(Fig. 389).
The dog belongs to a species that hunts in the wild state
in bands or packs. It becomes attached to man, and readily
removes with him to live in a new locality. Numerous races
are recognized, varying in size and proportions of parts. The
mastiffs and great Danes are breeds of large size, while the
Japanese bulldogs and the toy spaniels are very small. The
hair of dogs, like that of cats, is either long or short. It may
be either straight, or curled as in the setters. In color it is
white, black, red, and piebald, that is to say, a mixture of
all three colors. Races of dogs differ in their mental as well
as their physical attributes. Some dogs, like the collies, are
gentle, while others, notably the bulldog, are very pugnacious.
The dog was probably one of the first animals to be domesti-
cated by man, although economically less useful to him than
other races later acquired (Fig. 390).
Cattle are easily maintained in confinement, and furnish
milk, meat, and hides. They originated from some unknown
Asiatic species and have been domesticated for over 6000 years.
The races differ in size and in the quality and quantity of milk.
The large Holstein produces the greatest amount of milk, while
the small Jersey produces milk which contains a large percen-
tage of butter-making fat, and the Hereford and Angus breeds
produce large animals for beef.
Horses were domesticated for purposes of transportation
and general work. It is believed that two species have been
combined to make our common carriage horse. One is the
small Siberian pony that was early brought into central and
a
ee.
§
i
Fic. 390. — Types of races of domestic dogs: a, rough-coated St. Bernard ;
b, old English sheep dogs; c,d, small pet dogs; e, English setter;
f, bull dog.
424 ZOOLOGY
western Europe; the other is the large, more gracefully molded
Arabian horse. The horse of the ancient Gauls was so small
that it was rarely used for horseback riding, but only for draw-
ing chariots. Later it was much improved by crossing with
the Roman horses, which had much Arabian blood. Horses
range in size from great truck and draft horses of the Per-
cheron type to the little Shetland pony. In color they are
white, black, chestnut, and red, or bay, or the colors may be
mottled and dappled. The gait of the horse also varies from
running to pacing and trotting.
Sheep and goats have been domesticated both for their flesh
and for their wool or hair. Goat’s milk is especially prized
in hospitals as an excellent food for young children and invalids,
and from it cheese is made. The different races of sheep are
characterized by various qualities. Thus, while most breeds
are hornless, the Dorsets are horned. The merinos have very
abundant wool, which is of good quality as well. The South-
downs have black faces and feet and are prized for the qual-
ity of their mutton. Of the goats, the two principal domesti-
cated varieties are the short-haired and the long-haired, or
Angora. The hair of the latter (mohair) is used in the manu-
facture of a cloth to cover furniture and buttons, and is em-
ployed for other purposes where great resistance to wear is
essential.
Domestic rabbits depart little from the wild type although
they have long been kept in captivity and bred for food and for
their hair which is used in the manufacture of felt. Both long-
and short-haired varieties are known. The ears of some varie-
ties are short, while others have ears so long (lop-ears) that
they drag upon the ground. Guinea-pigs occur in races that
vary in color and length of ears.
THE MOUSE 425
Of the domesticated birds the poultry are the most impor-
tant. Under the term “poultry”’ are included the common fowl
of the barnyard, ducks, geese, turkeys, guinea-fowl, and pea-
cocks. The common fowl is one of the main sources of animal
food in the United States. The annual value of eggs produced
and poultry sold is estimated to amount to about half a billion
dollars. A hen may lay eight times her weight in eggs in a
single year at an average total valuation of $3 for the year.
The principal kinds of fowls are the game breeds,’ which are
most like the wild fowl of the jungle; the Mediterranean breeds,?
which are prolific layers, but do not, as a rule, incubate their
eges; and the Asiatic fowls,’? which are valuable for their great
size and because they make excellent mothers. Combinations
of these three groups have been made in profusion. Fowls
have been kept under domestication in China for over 2000
years. They are not mentioned in the Old Testament, and
hence probably reached Syria only shortly before our era
began.
Pigeons have been derived from a blue, wild, rock pigeon
having two black bars on the wings. From this ancestral
form over a score of well-marked varieties have been produced
by the fanciers. The pouters, fantails, and the tumblers are
familiar examples. Not only are pigeons interesting to bird
lovers, but they have considerable economic value, since the
young birds, known as squabs, are highly esteemed as food
because of their gamy flavor.
Of the fishes only the goldfish can be regarded as domesti-
cated. It has been cultivated by the Chinese and Japanese in
a great variety of colors and with extraordinary modifications
of the fins.
. 1 Fig. 391,c. 2Fig. 391,a. Fig. 391, d.
if
as
Fic. 391. — Types of domestic fowl : a, rose-comb white leghorn; b, barred Plymouth
Rock; c, English game bantams; d, dark Brahmas, male and female; e, seabright
bantams.
THE MOUSE 427
Among insects bees have been domesticated from early
times. The habits of the tame bees differ little from those in
the wild state. In place of a hollow tree a box is provided
which is so arranged that an excess of honey may be withdrawn
without jeopardizing the life of the colony. The different races
of domesticated bees differ much in color and in amiability.
Perhaps of greater economic importance than bees are the silk
moths, which manufacture silk threads in the construction of
their cocoons. By proper treatment in hot water the threads
are unwound from the cocoon. A number of these fine threads
are spun together into stouter threads suitable for use in the
manufacture of silk cloths.
This review of domestic animals shows that species that are
under the care of man are much more variable than wild species.
Why is this? Because man controls the breeding of domesti-
cated animals. He carefully observes the young produced
each year, and selects those that best conform to his ideal, or
which possess some striking peculiarity which may be of eco-
nomic importance. Any such peculiarity of an individual will
be transmitted to its offspring. Thus a race may be improved
or a new one founded. In the formation of perfected races,
two processes are involved. First, an individual must appear
with some new, some peculiar characteristic. Second, there
must be a selection, a preservation, of the most perfect de-
scendants of this individual. By such means the race is im-
proved. Charles Darwin,’ to whom is due the present accept-
ance by naturalists of the theory of evolution, came to the
conclusion that nature works with species in the same way that
man does. Of the vast number of individuals produced in
each generation in the wild state only a few survive, and these,
1 Tig. 392,
428 ZOOLOGY
in the long run, will be the most perfectly fitted to their environ-
ment. Darwin, however, did not sufficiently appreciate the
process in nature that corresponds to the breeder’s preserva-
tion of a new peculiarity. The Dutch naturalist De Vries
has shown that in nature peculiarities, mutations, frequently
suddenly occur and these may
constitute the beginnings of new
species. These two processes,
the occurrence of variations and
the inheritance of them, are
sufficient to bring about those
great changes in organisms which
constitute evolution.
As a concrete illustration of
the evolution of a domestic race,
the fancy mice may he taken.
Fancy mice have been derived
from the house mouse. The
house mouse is of an ashy gray
color. When its hairs are care-
fully examined, it will be found that they are black at the base
and reddish yellow near the tip. Wild mice, like all other ani-
mals belonging to the class of mammals (including man), some-
Fic. 392. — Charles Darwin.
times produce individuals without pigment in the skin, hair, and
even the eyes. Such individuals are called albinos, and the
peculiarity is designated as albinism. Albino or white mice with
pink eyes have this peculiarity, that when bred together they
produce only white mice. But when a white mouse is bred with
a house mouse, none of the offspring are white. However, when
the gray descendants of white and house mice are bred together,
one-fourth of their offspring will be white. This statement
THE MOUSE 429
holds true not only for the inheritance of the color of mice but
of most other animals. Indeed, many other characteristics
of both plants and animals are inherited in these same propor-
tions. The reason for this law is as follows: when the parents
differ greatly in that one has and the other lacks a character-
istic, the differences in the parents do not blend in the offspring,
but all of the offspring show the characteristic. This pres-
ence of a characteristic is said to be “dominant” over its
absence. The absence of the character — the recessive condi-
tion —is, however, not lost but exists in the reproductive cells
of the offspring; half of the reproductive cells possess the
characteristic and half lack it. Now if two individuals with
an equal number of germ cells of the dominant and the recessive
types are crossed, their germ cells meet in pairs, and it can be
shown that, in the long run, the following four combinations
of the two types are equally apt to occur. In the following
formula the letter d stands for the dominant condition, the
letter r for the recessive, the sign ¢ for the germ cells from
the male parent, and the sign ? for the germ cells from the
female parent.
$édedSderéeéreadsérer.
Whenever the combination contains the dominant character,
the body of the fully grown offspring will show only the domi-
nant character. It is easy to see that three-fourths of the
offspring will be dominant, and one-fourth recessive. The fore-
going law and its explanation were discovered forty years ago
by a monk, Gregor Mendel, in his monastery garden in Aus-
tria.'. The law is important because it enables us to predict
what proportion of the grandchildren will show the domi-
nant character of their grandparents or its absence. Men-
1 Fig. 393.
430 ZOOLOGY
del’s law thus affords a sort of explanation of why a child
often resembles a grandparent rather than a parent. For a
recessive condition that appears in only one grandparent
on each side cannot appear in the following generation, but
only in the grandchildren.
In addition to albinos breeders have obtained mice without
the black pigment in the hair; the result is a golden yellow.
By reducing the yellow at the
tips of the hair, the color be-
comes chocolate. When the red
and yellow are both absent from
the tips, a black race is produced.
In addition, some mice move in
circles, producing the race known
as waltzing mice.
Mice are of interest not only
on account of the evolution of the
fancy races, but also on account
of the rapidity with which they
as well as their allies, the rats,
Fic: 803) —\Gieror Johann have spread over the world. The
Mendel. house mouse was originally lim-
ited in its distribution to Asia. It made its way into
Europe. By hiding in the cargoes of vessels, it has made
its way over the whole world. America originally had not
a single representative of the genus Mus to which rats
and mice belong. Both rats and mice were imported to
America by the early explorers. Of the rats the roof rat
seems to have been imported by the early Spanish discoverers
to the Southern States, where it still persists. It originated
in Egypt. The second was the black rat, believed to have
THE MOUSE 43
been imported to America about 1544. It has existed from
time immemorial in Europe; it has a mild disposition, and
from it the white rats we keep as pets have been derived.
The brown, or Norway, rat has been the latest importation.
The history of its migrations has been written. Probably
originating in central Asia, it crossed the Volga in great troops
in 1727, occupied Russia in 1730, France in 1750, and Denmark
about 1810. Before the advance of this powerful and aggres-
sive foe, the black rat of Europe gave way and became well-
nigh exterminated, although of late it is said to be reasserting
itself in Germany. The brown rat was introduced into Amer-
ica in 1775, has spread over the whole country, reaching the
Pacific coast about 1855 and, as in Europe, has nearly exter-
minated the black rat except in inland towns remote from rail-
roads.
The habits of rats and mice are well known. They inhabit
our buildings, gnaw our doors and furniture, destroy our pro-
visions, kill poultry, and aid in spreading disease. They shun
the light, living in holes during the day, run with great agility,
and are capable of making long leaps. Owing to their instinct
to go into holes, they are easily trapped by a funnel-shaped
opening leading into a closed box. Despite the ease of trapping
and their destruction by cats, they maintain themselves by
virtue of a great fecundity, for, if no deaths occur, more than
a hundred young may, in one year, descend from a single pair.
The food of mice is very varied. They naturally thrive
best on a vegetable diet ; oats especially are recommended for
tame mice, and hard-shelled nuts are useful because the mice
keep their teeth sharp by gnawing the sheils. If the teeth
are not kept worn off, they soon become inconveniently long,
owing to the fact that they grow continuously throughout
432 ZOOLOGY
life, and are not formed, once for all, like our teeth. In addition
to plant materials, rats and mice eat a certain amount of ani-
mal food.
Rats and mice belong to the class Mammalia! characterized
by having milk glands for the nourishment of the young.
Most mammals have also hair, although in the case of por-
poises and whales the hair is nearly or quite absent.
Fic. 394.— The rabbit. Lateral view of skeleton enclosed in outline of
body. From Parker and Haswell.
The structure of the mammalia may be illustrated by a
study of the rabbit.
General Form of the Body. — The body consists of head,
trunk, and tail, the latter in a rudimentary condition (Fig. 394).
The head is connected to the trunk by a relatively narrow neck
to insure mobility. Its large size results from the fact that it
bears the strong teeth, brain, sense organs, and their supporting
and protecting skull. Nearly the entire body is covered with
hairs which develop in the skin. At the base of each hair is
usually a gland that secretes an oily substance — sebaceous
1 From mammals, belonging to the breast.
THE MOUSE 433
gland. Along the under side of the body, best developed in
the female, are two rows of milk glands. Each milk gland
is an aggregation of sebaceous glands whose secretion is modi-
fied to furnish a nutritive fluid for the young mammal.
Two pairs of appendages are present, the hinder pair func-
tioning the more vigorously in locomotion. The entire hand or
foot does not lie flat on the ground as the sole of the human foot
does, but the wrist and heel are slightly elevated, while in the
horse the wrist and heel are elevated far from the ground, since
it stands on the tip of a single finger. In the rabbit the hand
has five digits, but the foot shows a reduction to four.
Skeleton. — The vertebral column of the rabbit, as of other
mammals, is divisible into five regions: (1) The neck, or
cervical vertebrze ; (2) the chest, or thoracic vertebre ; (3) the
waist, or lumbar vertebre ; (4) the pelvic, or sacral vertebre ;
(5) the tail, or caudal vertebra. Of the neck vertebre there
are seven, as in all other mammals whether the neck is short,
as in the whale, or long, as in the giraffe; but the number of
the other vertebree is variable. Each vertebra bears a spine
and processes for the attachment of muscles and ligaments.
The thoracic vertebre bear ribs. The anterior ribs abut
ventrally upon a long rod, the breastbone, or sternum. The
skull is heavier than that of the bird; the huge bone for the
lower jaw — the quadrate —is a part of the brain case or
cranium. A separate cheek-bone protects the eye cavity
below.
The shoulder girdle consists on each side of two bones, forming
a V, which embraces between its arms half of the thorax, and
the skeleton of the appendages is fastened to the apex of the V.
The dorsal arm of the V is the shoulder-blade (scapula) ; this
is broad, and has a high ridge for the attachment of the muscles
2F
454 ZOOLOGY
of the arm. The ventral arm of the V runs down to the sternum,
which affords it a firm support — this is the collar-bone. The
skeleton of the fore limb consists of the same parts as that of
man. They permit of a large amount of bending and rotation
of the appendages. The pelvic girdle forms a complete ring
surrounding the viscera of the posterior part of the abdomen.
It consists on each side of three pieces, fused into one in the
adult, which radiate from a centre as spokes from a hub, where
the skeleton of the leg impinges. One of these pieces passes
dorso-anteriorly and is fastened to the sacrum; it is called the
ileum ; the other two pass ventrally, each to unite with its fellow
of the opposite side in the mid-ventral line. Indeed, all four
bones are tied together here. The anterior pair of these bones
is called the pubis, the posterior pair the ischium — being the
bone which supports us when we sit. The rigidity and size
of the pelvis is necessary because it has to support the whole
body when the animal sits up on its hind legs. The skeleton
of the hind limbs of the rabbit differs little from that of man
except in having only four toes instead of five.
Organs and Function of Digestion. — The teeth show an
advance over those of reptiles in reduction of number, in
specialization of form, and in being each lodged in a special
socket. The number of dentitions has become reduced to two,
the milk teeth and the permanent teeth, in contrast to the croc-
odiles, where the dentitions are changed throughout life. In
the permanent dentition the front pair of teeth are called cut-
ting teeth, or incisors. In rabbits the two middle incisors of the
upper jaw continue to grow throughout life and, as the front
edge only has a thick layer of hard enamel, the teeth keep a
sharp, chisel-shaped edge very useful for cutting. The per-
sistent growth of the teeth keeps them from wearing off com-
THE MOUSE 435
pletely as a result of persistent use in gnawing hard vegetable
fibre. The rabbit has no canine teeth, as in man and carniv-
orous animals, where they are used for tearing flesh; and an
Fic. 395. — Ventral view of skull of rabbit. Bones named are as follows:
p.max, premaxilla; pal.p.mazx, palatine process of premaxilla; mac,
maxilla; pal.mar, palatine plate of maxilla; pal, palatine bone; vo,
vomer; b.sph, basisphenoid; b.oc, basioccipital; s.oc, supraoccipital ;
zyg.max, zygotic process of maxilla; ju, jugular; ty.bul, tympanic bulla;
aud.me, external ear opening; par.oc, paroccipital process. From Par-
ker and Haswell.
empty space in the jaw is followed by a series of chewing teeth,
or molars (Fig. 395).
The food passes first into the mouth cavity, where, by the
help of the tongue, it is ground by the molars and at the same
time moistened and acted on chemically by the secretions of the
salivary glands. Then the food passes through a gullet to the
436 ZOOLOGY
stomach, where it is well churned and subjected to pepsin and
hydrochloric acid. Thence the food goes to the first part of the
small intestines (duodenum), where it is treated to the action
of the bile and the pancreatic juice. The food, now digested,
passes slowly down the long, small intestine, which is richly
supplied with lymph and blood-vessels, into which the food
passes to be carried away to the tissues. Further absorption
takes place in the large intestine, and finally the unabsorbed
remains collect in the rectum.
Organs of Circulation. — The circulation in general resembles
that of birds. The heart is divided into two separate halves,
each with its auricle and ventricle. The right auricle receives
a pair of large veins from the fore limbs and head and a single
vein coming from the posterior part of the body. The blood
thus collected in the right auricle passes to the right ventricle,
and thence is pumped to the right and left lungs. From the
lungs it returns to the left auricle, to be pumped by the left
ventricle into the aorta. The aorta gives off arteries to the
fore limbs and head, and then passes on the left (instead of the
right, as in birds) of the gullet to form the dorsal artery, which
supplies the hinder part of the body and the viscera. While the
blood from the tail, hind legs, germ glands, and kidneys goes
directly back to the heart, the blood from the food-canal flows
first to the liver to deliver its load of food there, and then passes
on to the right auricle.
Organs of Respiration. — The air that enters through the
nostrils crosses the back of the mouth and enters into the upper
part of the windpipe or larynx, through a slit that is guarded
from the entrance of food by a fold —the epiglottis. The
wall of the larynx contains certain large cartilages which sup-
port and control the vocal cords; these are represented in
THE MOUSE 437
man by the ‘ Adam’s apple.” The wall of the windpipe
(trachea) contains small rings of cartilage which serve to sup-
port it and prevent its collapse on exhalation of the breath.
Below, the trachea divides into two tubes (bronchi), one of
which goes to each lung. Here it divides repeatedly, and
finally the smallest branches open into a thin-walled air vesi-
cle called a lobule of the lung. The wall of the lobule is cov-
ered with a network of blood capillaries, and here oxygen
passes from the air to the blood.
Organs of Excretion. — The kidneys are a pair of oval, bean-
shaped bodies lying close to the dorsal wall of the abdominal
cavity. As in the pigeon, the kidney is a mass of tubules each
associated with a capillary network where the waste products
pass from the blood to the cavity of the tubules, whence they
are collected in the central cavity of the kidney, and thence
conducted by the ureters to a single urinary bladder, which is
periodically emptied.
Organs of Reproduction. — The male and female germ glands
— testes and ovary — are small organs lying in young animals
in the dorsal part of the abdominal cavity. The products are
carried by special tubes to the exterior — the sperm ducts
and the oviducts. The eggs are of small size and not sur-
rounded with albuminous and limy covering, as in birds, nor is
there much food yolk. The reason for the difference is that,
whereas the eggs of birds, developing independently of the
mother, must be supplied with a protective covering and a
supply of food-stuff, the egg of the rabbit is not only fertilized
in but develops in the oviduct, is protected by the maternal
body, and is supplied with food from the maternal blood-
vessels. Only after the embryonic rabbit has become well
developed, has gained its coat of hair, and is almost ready to
438 ZOOLOGY
run about, is it expelled from the oviduct (born) to live its
separate existence.
Muscular System. — The muscles of mammals are developed
in close relation with the skeleton. On the head, besides a thin
sheet of skin muscles, the largest development is that of the
jaws. On the trunk is a general skin musculature and a pow-
erful dorsal musculature used! in jumping. Then there is a
rudimentary set of muscles uniting the ribs, and a muscular
fb. hb.
i ii Deh. NA Vay Sit ai
Fie. 396.— Brain of the rabbit seen from the right side: h.o, olfactory
lobe; fb, cerebrum; A.b, cerebellum and its median lobe, ¢)’; md,
medulla oblongata; p.c, the “‘pons”’ or bridge of transverse fibres; i—rv7,
cranial nerves. After Wiedersheim.
membrane (or diaphragm) completely dividing the body cavity
into an anterior and a posterior portion. Both the rib muscles
and diaphragm are used in breathing. The musculature of
the appendages is the most powerful, but so complex as to
be beyond the limits of such a book as this.
Nervous System. — The central nervous system consists,
as In the pigeon, of a brain and spinal cord. The chief advance
in the brain is shown by the enlarged cerebrum, showing traces
of the foldings of its surface which become more marked in the
higher mammals and are associated with intelligence.
THE MOUSE 439
Sense-organs. — In addition to certain diffuse senses, such
as touch and heat and cold, the rabbit has complex organs of
taste and smell, hearing and sight. The organs of taste and
smell lie in the delicate lining of the mouth and nose—as small,
diffuse sense cells. The ear is essentially like that of man, and
differs from that of birds in the greater development of the
cochlea, which, in the rabbit, forms a close spiral of two and
one-half turns. The eye lacks the pecten, and is more nearly
fia. 397. — The duckhill, Ornithorhynchus anatinus. After Vogt and Specht.
spherical in shape. There are two eyelids; and the nictating
membrane, so prominent in birds, is rudimentary.
Mammals are divided into three main groups. The division
depends upon the condition in which the young are born.
The lowest group is called monotremes. The milk glands are
in alow state of development, and eggs are laid in the shell, as
in reptiles and birds. There are two principal types, — the
“ Duckbill” (Fig. 397), with aquatic habits, and the “ Spiny
Ant-eaters”’ (Echidna, Fig. 398), inhabiting rocky places.
Both types are confined to Australia and neighboring islands.
440 ZOOLOGY
In many ways this group seems to connect the mammalia with
reptiles.
The second group is known as Marsupalia, because the
mothers are provided with a marsupium,' or pouch, in which
the young are carried. The young are born very imperfectly
developed. Immediately after birth they are placed in the
Fic. 398.— The spiny ant-eater, Echidna aculeata. After Vogt and Specht.
marsupium, where they become attached to the mammary
glands which lie within the pouch. In this situation the young
complete their development. All marsupials are confined to
Australia and adjacent islands, excepting the family of opos-
sums (Fig. 399), found only in the Americas. There is thus
a great discontinuity in the distribution of marsupials. This
is accounted for by the evidence that formerly the whole world
contained marsupials, so that those living to-day are the sepa-
rated remnants of that once universal race. The opossums are
1 marsupium, a pouch.
THE MOUSE 441
most numerous in the tropics, but the Virginian opossum
ranges north to New York.
The third division of the Mammalia includes all of its re-
maining orders. These orders will be briefly considered in the
following paragraphs.
The sloths and allies constitute a group that either have
no teeth or imperfect ones. Here are associated with the
Fic. 399.—The opossum, Didelphys virginiana. After Vogt and Specht.
sloths the hairy ant-eaters, armadillos, scaly ant-eaters, and
African ant-eaters. The three first-named families inhabit
South America; the two latter, Asia and Africa. Here
again, the discontinuity of the group indicates, what fossils
prove, that the Edentata! (as this group is named) have
been killed off from the connecting continents. The sloths
have cutting teeth, live in trees, and eat leaves (Fig. 400).
le, without ; dens, dentis, tooth.
442 ZOOLOGY
The armadillos are protected by strong plates developed in
the skin; they are chiefly nocturnal and omnivorous animals,
and burrow rapidly. The other three families feed on ants and
Fie. 400.— Two-toed sloth, Cholespus. After Vogt and Specht.
termites, usually lack complete teeth, and either live in trees
or burrow in the ground.
The whales and allies (Cetacea '!) have taken to an aquatic
life, for it is certain that their ancestors were land animals.
The sea-cows (manatees °), found in rivers in various parts of
1 cetus, whale. 2 From a native name.
THE MOUSE 443
the world, seem ! to show a transition to the marine forms, such
as the dolphins, the toothed whales (Fig. 401), and the tooth-
less or whalebone whales. The largest of these whales —
the Greenland whale — reaches an extreme length of twenty-
two to twenty-four metres, and a weight of over 100,000 kilo-
grammes. It is, indeed, the largest living animal. Although
whales in general are partly adapted to an aquatic life, they
still retain the essential mammalian qualities. They breathe
air which passes to the lungs and is expelled again through the
nostrils, which are placed high up on the head. The “ blow-
ing” of the whale is the forcible expiration of moisture-laden
air, which becomes visible by condensation, just as our own
breath does on a cold day. The young are necessarily born in
the water, but the breeding habits are poorly known. The
various Cetacea have diverse feeding habits. All are preda-
ceous. The toothed whales feed on larger animals, the whale-
bone whales on floating fish, crustaceans, medusz, and squids ;
1 The relation to Cetacea is not close.
444 ZOOLOGY
their whalebone is, indeed, merely a strainer to let the water
pass out of the mouth while the solid masses are retained.
The order of hoofed mammals includes a large number of
animals, almost all of which are closely related and have never
more than four functional toes, excepting in the allied groups of
Fig. 402.—Stone’s Alaskan black sheep. Photo. of a group in the Field
Columbian Museum.
elephants and certain small animals allied to the “ coney ” of
Scripture, where there are typically five. Of the true hoofed
mammals we distinguish the even-toed and the odd-toed, which
we may consider further.
The even-toed hoofed mammals include the hippopotamus
and other pigs and the peccaries, the camels and Hamas, the
deer, the giraffes, and the antelopes, sheep (Fig. 402), and oxen.
THE MOUSE 445
Excepting the pigs, most of these feed exclusively on plants.
The giraffes and antelopes are characteristic of Africa; but
the “mountain goat” of our highest ranges may be placed
with the antelopes, as may also the chamois of Europe. The
prong-horn of our southwestern plains is remarkable in having
hollow horns like the antelopes, which are, however, shed like
those of the deer.
The odd-toed hoofed mammals include the horses, tapirs,
and rhinoceroses. The horses are remarkable in that they
all the other
digits being rudimentary or absent. While fossil remains of
horses are found in all continents, the living species have come
stand upon the toenail of the middle digit
from Asia and Africa. The African species are striped (zebras).
The tapirs are found living to-day only in South America
and southeastern Asia. They frequent the depths of forests
near watercourses, and feed on leaves and shoots of shrubbery.
The rhinoceroses of Africa, of India, of Java, and of the Malay
Archipelago, are quite distinct. All are large, stupid, and fero-
cious when attacked, feed on herbage, and wallow in pools.
The elephants are distinguished by their long trunks, great
incisors (tusks), and huge, complex grinding teeth. The
Indian and African types are quite distinct. Elephants are
intelligent, tractable, and capable of doing much work for
man. Their diet is vegetable, consisting especially of the
leaves and young branches of forest trees, which they gather
with their proboscis.
The moles and shrews are small mammals and chiefly ter-
restrial. One of our common families includes the moles which
burrow in the ground, have smail eyes and broad, shovel-
shaped fore feet, used for digging their tunnels. They feed
chiefly on earthworms. The other common family is that of
446 ZOOLOGY
the shrews, which are mouse-like, live chiefly on the surface
and in the woods, and feed on insects and small crustaceans.
The flesh-eaters (Carnivora ') include both land and marine
forms. To the first group (Fig. 403) belong the cats (including
tigers, lions, leopards, lynx, etc.); the civet-cats, mongoose,
etc.; the hyenas; the dogs (including jackals, wolves, and
foxes); the bears; the raccoons; and the great fur-bearers, —
Fria. 403. — The cheetah, or hunting leopard, Felis jubata. Photo. of a
group in the Field Columbian Museum.
martens, minks, weasels, badgers and otters, and skunks.
Marine Carnivora comprise the seals (Fig. 404), walruses,
and sea-lions, the more valuable of which are disappearing
as a result of man’s lack of foresight. Altogether, the Car-
nivora comprise the most agile, the most intelligent, the most
dreadful, and some of the commercially most important of
fellow-animals.
The gnawing mammals include our types, the mouse and the
rabbit, and also the squirrels and marmots, beavers, jumping
mice and gophers, and poreupines. The order contains no
learo, carnis, flesh; vorare, to devour.
THE MOUSE 447
very large animals, as befits a group of burrowers— true con-
tact lovers. The typical squirrels are, however, arboreal, and
run over trees and from tree to tree; nevertheless, even they,
by preference, make their nests in holes of trees. Our common-
est squirrels are the gray, the little red, the striped or chip-
munks, and the spermophiles of the Western States. On the
whole, excepting perhaps the red squirrel, they are useful ani-
mals and deserve to be protected rather than slaughtered.
It is shameful to see grown men shoot the harmless and com-
Fic. 404. — The harbor seal, Phoca vitulina. From Parker and Haswell,
“Manual of Zoology.”
panionable gray squirrel —one of the friendliest of the wild
animals. Closely related to the squirrel are the prairie dogs
and woodchucks, of which the former make extensive villages
in the Great Plains regions, and the latter lives in solitary
burrows throughout our northeastern States. The beavers
are now almost exterminated. They were the leading engi-
neers among animals, building dams across streams in order to
make deep ponds for their protection. Near the middle of the
pond a great house of mud and sticks was reared; the inner
chamber lay above the level of the pond, but the entrance to it
was under water. The pocket gophers (Fig. 405) are invet-
448 ZOOLOGY
erate tunnellers; their cheek pouches enable them to carry an
extra supply of seeds and vegetables. The porcupine of our
Fia. 405. -— Geomys tuza, the Georgia gopher. One-half nat. size. After
V. Bailey.
northern country is remarkable for its modified hairs, which
form spines, many of which are hollow quills. These are for-
midable organs of defence. Finally, the hares and rabbits are
characterized by their great ears, short tails, and swift flight ;
Fic. 406. — An insectivorous bat, Synotus. After Vogt and Specht.
in these respects the hares have developed further than the
rabbits.
The bats (Fig. 406) are extraordinarily modified mammals
THE MOUSE 449
which, like the birds, seem to have penetrated into the air to
prey on the flying insects. Not all bats are insectivorous,
however, for certain Old-world bats feed on fruits. Our
commonest species are the little brown bats (with a nearly
Fig. 407. — Simia satyrus, the orang-utan, mn breadfruit tree. From a
photograph of a group in the Field Columbian Museum.
furless wing), and the red bats (with patches of fur on the wing
membrane).
The Primates! are of interest because we ourselves are
placed in this category, together with certain other animals
that have attained a less lofty station. The lowest Primates
1 primus, the first.
2G
450 ZOOLOGY
are the lemurs, found chiefly in Madagascar. These have an
arboreal habit, and feed on fruits, leaves, and small birds and
insects. Next higher come the American marmosets, the
howling monkeys, and the flat-nosed, prehensile-tailed Amer-
ican apes; still higher are the small-nosed, nonprehensile-
tailed apes, including the baboons, mandrills, and macaques.
Finally, come the tailless, manlike apes, found exclusively in
the Old World —the gibbons, orangs (Fig. 407), chimpanzee,
and the gorilla. The two latter are nearest to man, but one
cannot say which is the nearer. For, while the chimpanzee
approaches man more closely in facial appearance and in
intelligence, the gorilla is more manlike in the size and com-
plexity of the brain and in its habit of walking on the ground.
There is no reason to doubt that man’s species came off from
the anthropoid apes; the discovery in Java of a fossil form
(Pithecanthropus erectus) intermediate between man and the
manlike apes is a strong additional piece of evidence.
This differentiation of man’s species probably began in late
Tertiary times.
CHAPTER XXVII
THE DEVELOPMENT OF THE FROG’S EGG
ALL living matter has the capacity of increasing itself under
proper conditions to an almost unlimited extent, the food which
animals devour being the material out of which the new living
substance is made. This living substance exists in isolated
particles, or masses, which we call individual animals or plants.
The animal or plant has also at any stage a definite form which
is not exactly alike in any two individuals, but is roughly alike
within the “ species.”” Now the number of individuals of any
species ' tends constantly to diminish through death. It is
actually maintained by reproduction, by a piece of the parent
individual being cut off to form a new individual. This piece
may be at first almost shapeless or approximately spherical.
But as it grows larger it assumes more and more the form and
complex structure of the adult. This process of growing into
the adult form is development. In most of the more familiar
cases development begins with an approximately spherical egg.
In the case of the frog, the egg is between one and two mil-
limetres in diameter. The eggs, which are numerous, are laid
in a common jelly, and during development float near the sur-
face of the water in which they are laid. The first visible
changes are furrows running across the surface of the egg, as
a result of which the egg becomes divided into small areas
which correspond to a division of the whole egg into “ cells.”
This stage of development is called cleavage.2 Toward the end
1 See also Chapter XVIII. 2 Fig, 408 A-F,
451
452 ZOOLOGY
of the cleavage stage the white or volk side of the egg becomes
enveloped by the black dividing cells, excepting for a small
white plug edged by a sharp groove. This is where cells have
G H \
Fic. 408. — Cleavage of frog’s egg, A-G; H, beginning of gastrulation;
I, the white plug. From Morgan, ‘‘ Development of the Frog’s Egg.”
THE DEVELOPMENT OF THE FROGS EGG 455
rolled in to form the beginnings of the food canal (Fig. 407 H).
Next, on the future dorsal side of the embryo, two ridges arise
with a furrow between them; they are the beginnings of the
brain and spinal cord (Fig. 409). When the furrow is closed
by the ridges folding over it, the central nerve tube is formed
and begins to sink into the body. Later the trunk elongates,
nerves and muscles are formed, gills sprout out, and the tad-
pole is formed (Fig. 410).
Fic. 409. — Two stages in the development of the frog while the brain and
spinal cord are arising. From Morgan, ‘Development of the Frog’s
Egg.”
Effect of Heat and Light on Development. — Eggs devel-
oping in normal environments in nature arrive at nearly the
same end-result, even when the environments are not identical.
We gain, in consequence, an impression that development
proceeds unaffected by any changes in the outside world.
But thisis not true. For one thing, the rate at which the devel-
opment of frogs’ eggs proceeds depends closely upon the tem-
perature of the water. They develop most rapidly at about
30-32° C. If the temperature is elevated above this point,
the rate of development is retarded, and finally ceases at about
40°C. So, likewise, as the temperature is lowered, the devel-
opment is retarded, until at the temperature of freezing water
454 ZOOLOGY
it ceases (Fig. 411). If the temperature is too high, develop-
ment may be abnormal, so that a monstrosity is produced.
Light has a less striking effect on the development of the
frog. If light is excluded from the developing eggs, they will
develop more slowly. The acceleration of development by
rather high temperature and by daylight is probably due
to a chemical effect of these agents. It indicates that devel-
opment is a complex chemical process.
Healing and Regeneration. — If the egg of a frog be pricked
slightly, there will be a loss of substance, and the resulting
oe gg EES Beara =
Fic. 410. — Young tadpole of the frog. From Morgan, ‘Development
of the Frog's Egg.”’
embryo will be at first abnormal. Later, however, this abnor-
mality will become smoothed over by appropriate develop-
ment. So, also, if the tail of the developing larva is mutilated,
the wound will heal and the missing parts will be re-formed.
This capacity of the living organism to restore the normal
form after mutilation is seen also inman. For if some of the
skin be cut away, orevenif parts of internal organs are removed
the wounds will not merely heal, but the lost part will regen-
erate. The remarkable thing is that in regeneration almost
exactly that is produced which was lost. Both regeneration
and healing in the adult are a survival of the same capacity for
development which we see in the egg.
THE DEVELOPMENT OF TIE FROGS EGG 455
Postembryonic Development of the Frog. — After reaching
a certain stage of development, the embryo frog, called tadpole,
MEAN. FEMPERATURE
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Fie. 411. — A chart showing the correlation between the stage of develop-
ment of the frog on successive days and the temperature at which it has
developed. From Higgenbottom.
begins to develop legs. The hind legs first appear, afterward
the fore legs sprout out, and finally the tail begins to wither
away, until the form of the four-legged tailless frog (anuran)
is fully developed. In the leopard frog, as in the toad, this
456 ZOOLOGY
change of form (metamorphosis) is completed during the first
summer, but in case of the bullfrog and green frog the tadpole
passes through the winter in the immature state, and does not
complete its metamorphosis until the second summer. Conse-
quently, it is not uncommon to find quantities of large tadpoles
in ponds at the time the ice breaks up in the spring.
Since Amblystoma and Necturus do not lose their tails,
the metamorphosis which they undergo is less profound than
that of the frog. In Amblystoma, as stated in Chapter XVILI.,
the gills and the fin on the tail of the tadpole are lost in the
metamorphosis. Necturus, on the contrary, retains gills and
tail-fin, so that its acquisition of legs is almost the sole indi-
cation of metamorphcsis.
General Laws of Development. — Development consists
of an unfolding of potentialities wrapped up in the germ; an
awakening in orderly succession of processes lying dormant
there. But the causes which control development, the causes
which determine when this process and that shall awaken, are
still too obscure for us to attempt to picture them in detail.
This much is certain, that the causes of development from the
egg are the same as those of budding of leaves on a tree, the
regeneration of the parts of a Hydra, or the healing of a cut in
our skin. In the case of most of the higher plants and animals,
the ripe egg will not develop until it is “ fertilized,” that is,
until a gerra from another individual has fused with the ripe
egg. But the ripe egg of many of the lower plants and animals
requires no fertilization for development, and the meaning of
the fertilization process is quite obscure.
The developing eggs of all the higher animals pass through
much the same sort of early stages. The egg “ cleaves ” into
a number of cleavage spheres, each of which is destined to give
THE DEVELOPMENT OF THE FROGS EGG 457
rise to a particular part of the organism. By repeated division,
a mass of small cells, constituting the morula stage, is formed.
Usually a cavity arises in the middle of the morula, and into this
some of the surface cells are pushed to form an internal sac —
the food canal. This is necessarily an early step, as all food
is taken into the interior of the body. The process by which
external cells are pushed in is known as gastrulation. Very
early the body is seen to be composed mostly of layers, or
membranes and cavities. It is by the folding and union
and breaking through of these membranes that most of the
organs of the adult arise. Development of the individual is,
on the whole, accompanied by increase in complexity. The
evolution of animals in the animal kingdom is likewise, on the
whole, accompanied by increase in complexity of organization.
Thus both the embryonic development of the individual and
the evolution of the species proceed from simple to complex,
and since they start from about the same point and reach the
same goal, we are not surprised to find that the individual de-
velopment of any species often goes through stages markedly
like the stages in the evolution of the species. The parallelism
of development and evolution was early noticed, and is often
called ‘Von Baer’s law,” after a naturalist who lived in the
middle of the nineteenth century and very clearly formulated
this parallelism.
CHAPTER XXVIII
A BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY
A SCIENCE is the recorded body of facts and general ideas on
some subject-matter, especially after they have been arranged
under general laws. Zoology as a science, therefore, had its
beginning when a man wrote out for public use some observa-
tions he had made on animals, while unwritten observations
constitute personal knowledge or at best “ folklore.” The
development of the science is traced by books, by special re-
ports, and by the proceedings of scientific societies, which
have appeared in ever increasing volume since the invention
of printing.
Who first definitely recorded observations on animals it
would be hard to say. Nascent man evolved in the company
of other animals, and the dog was doubtless one of his earliest
companions. Primitive language, in so far as it contains the
names of animals, gives the first record of his observations, and
these names show his appreciation of the fact that there are
different kinds of animals. Later arise the oral traditions or
folklore, with their animal stories, fables, superstitions con-
nected with animals, and even a mass of fairly accurate obser-
vation. As time goes on, observation is sharpened, language
is enriched with a constantly increasing number of names of
animals and, eventually, as students and philosophers appear,
critical studies are made on animals. Such studies, we find,
were first made by the Greeks. While there were not lacking
458
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 459
those who thought about and even dissected animals as early
as the sixth century before Christ, yet so relatively vast were
the observations and records make by Aristotle (334-322 B.c.)
that he is commonly accepted as the father of zoology. Living
near the mild waters of the Mediterranean Sea, which swarm
with living beings, he was led to make studies on marine as
well as terrestrial organisms. He made observations on snails,
muscles, hermit crabs, sea-urchins, tunicates, and sea-anemones.
His studies on nesting habits,
care of young, and general eco-
nomics of bees and wasps are
extensive and valuable. While
his observations lacked the
thoroughness which is expected
in modern zoological work, and
his generalizations seem crude
in view of established facts, yet
we can only admire his ideal of
making independent observa-
: : : : Fie. 412.— Aristotle. From Locy,
tions and his aim of finding a “Biology and its Makers,” New
general law in nature, the law York, Henry Holt and Company.
of fitness or “ adaptation.” He clearly saw also the principles
of division of labor, and that the process of development in an
organism is a progress from the simple and general to the
complex and special. If Aristotle did not enter to any im-
portant extent into the speculations of the Greeks as to the
origin and evolution of the universe, it is clear that he conceived
a progressive development of the animal kingdom out of the
simplest beings.
After Aristotle there was a decline in the intellectual life of
Greece, and with the spread of Roman influence and ideas in
460 ZOOLOGY
which politics and the social organization dominated, science
slumbered. The intellectual centre was transferred to Alex-
andria and here medicine, with its stimulus to careful stuclies
in human anatomy and physiology, flourished. The most
famous of the anatomists who studied at Alexandria was Galen
(second century of our era), who
made numerous dissections on man,
monkeys, ruminants, rats, and even
many kinds of birds, snakes, and fish
His anatomy was for eleven or twelve
centuries the most esteemed work on
the subject, being by some apparently
regarded as more reliable than nature
itself. During the Middle Ages of
Europe, the age of constant strife,
central and northern Europe gradually
i CS "| acquired the culture of thesouth. At
ie GCALENVS,
2 this time all science languished, but
Be 2599 dst ig : : = :
with the Renaissance, whose opening
Fie. 413.— Galen. From
Locy, “Biology and its May be put at the discovery of
Makers,” New York, America, we note the first stirrings of
Henry Helt and Company.
areturn to nature. The epoch from
1500 to the present time may be divided into four periods, as
follows: the Encyclopedic period, 1500 to 1650; the System-
atic period, 1650 to 1800; the Morphological period, 1800 to
1890; the Dynamic period, 1890 to the present.
The eneyclopiedic period is opened by Gesner (born in Zu-
rich, 1516), who had the aim of collecting all facts concerning
animals, of examining them critically, and of writing a compen-
dium that would show the position of the science and obviate
the necessity of consulting the older authors. His book was
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 461
the great zoological text-book of
the new era, as Pliny’s was of
the Roman era. Gesner’s text-
book appeared between 1551 and
1558 in four huge quarto volumes
bound in parchment. He never
completed this work, which is
not strange, since he busied him-
self with many other great un-
dertakings. He was the first to
establish a museum and a botani-
Fie. 414. — Gesner. From Locy,
cal garden. _Gesner’s work was “Biology and its Makers,’’ New
imitated and extended some
York, Henry Holt and Company.
years later by Aldrovandi (b. 1522 in Bologna, d. 1605).
Such works, which had many successors, characterized the
Fie. 415. — Andreas Vesalius.
From Foster, ‘‘Lectures on the
History of Physiology,”’ by per-
mission,
encyclopedic period.
But the encyclopedic period
was one of original scientific in-
vestigation as well as of codifica-
tion. The bonds of authority
which held naturalists to the
writings of Aristotle and Galen
were at last broken by Vesalius
(b. 1512, d. 1564). Born into a
noted family of physicians, Vesa-
lus early showed a strong taste
for anatomy, and was well edu-
cated at different universities.
He applied himself to careful per-
sonal dissections of the human
body, and in 1543 published his
462 ZOOLOGY
d
memorable work, ‘‘ Structure of the Human Body.” This great
work in anatomy created a revolution in the science, and
scholars flocked to him at Bologna, Pisa, and Louvain. From
among these arose nearly all the prominent anatomists of the
latter part of the sixteenth century, many of whom extended
their anatomical studies to the lower animals. Indeed, the
scientific activity
started by Vesalius
has continued un-
broken to the present
time, and has re-
sulted in the zoologi-
cal sub-sciences of
comparative an-
atomy and physi-
ology.
In consequence of
the construction of
encyclopedic works
on zoology, a search
Fic. 416. — John Ray. From Ray Society was made for new
ee species in order to
make the books as complete as possible. New countries were
visited for the purpose of collecting new animals, the seashore
and ponds were fished, and even the new world opened by the
compound microscope at the beginning of the seventeenth cen-
tury was utilized. The increase of species made necessary the
invention of names for them. Gradually the necessity of recog-
nizing subdivisions of the primitive groups of quadrupeds,
birds, etc., became apparent, and this necessity led to the sys-
tematic period. This period is opened by the English natural-
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 463
ist, John Ray. He saw the importance of recognizing in ani-
mals categories of successively diminishing rank in the various
classes of the animal kingdom. But it was left to Linnzeus
(b. in Sweden 1707, d. 1778) to perfect the system by estab-
lishing categories. The animal kingdom was divided by him
into classes, the classes into orders, each order into genera, and
each genus into species. He in-
vented the binomial nomencla-
ture that is still in use for both
plants and animals. The first
name is a sort of surname and
indicates the genus; the second
name gives the particular species.
Thus, Felts catus is the particular
name of the cat, Felis leo of the
lion, Felis tigris of the tiger, and
so on. Finally, Linneus intro-
duced the method of brief de-
scription of the characteristic Fic. 417.— Marcellus Malpighi.
5 . From Locy, ‘Biology and its
points of each group in place of — yyaxers,” New York, Henry Holt
the wordy, ill-ordered descrip- and Company.
tions of his predecessors. The brilliancy of Linnzeus’s work
attracted many investigators, and the interest in collecting and
classifying species remains to this day. Such work, although
often fascinating, is not the highest type of scientific work.
The foundations of modern morphological or anatomical
zoology were laid in part by men whose original interest was
medical and in part by a new school of naturalists who studied
the structure and behavior of the lower animals. As early as
the middle of the seventeenth century we find Malpighi, pro-
fessor of medicine at Bologna, publishing his investigations
464 ZOOLOGY
upon the internal anatomy of the silk-moth, which afforded
not only an extended but also the first insight into insect
anatomy. The Dutchman Swammerdam (b. 1637, d. 1680)
made even wider studies in the same field. His observations
were published in a book entitled “ Bible of Nature.”
The newly discovered and
gradually much improved com-
pound microscope lured many to
Jj/)| a study of the structure and be-
| havior of microscopic species
and permitted the beginning of
new sciences dealing with the
tissues of organs (histology) and
with the cell (cytology). The
first to employ the compound
microscope to serious work in
zoology were the Italian Mal-
pighi and the Dutchman
Fe Ti aaa een Leeuwenhoek. The work of
From Loey, “Biology and its Malpighi upon insects has al-
Makers,’ New York, Henry
Holt and Company.
ready been referred to. Not less
important are his histological
studies on higher animals. He first saw and described the
circulation of the capillaries, observing it in the lung of the frog.
He first gave a detailed account of the series of stages in the
development of the chick, and was thus one of the founders of
embryology. He studied thoroughly the structure of various
tissues of the higher animals, and may be said to be the founder
of histology.
Unlike Malpighi, who used the microscope as an incidental
aid to his researches, Leeuwenhoek used the microscope to study
BRIEF HISTORY OF THE SCIENVE OF ZOOLOGY 465
small things just because they were small. He first saw the red
corpuscles, the cross striations of muscle fibres, the tubules in
teeth, the dry cells of the outer skin. He first studied under
the microscope numerous small animals, such as fleas, flies,
various small beetles, and the compound eyes of insects. He
discovered the parthenogenesis of the plant lice and the bud-
ding of Hydra. Also he dis-
covered the rotifers and various
Protozoa. It is rare that an
opportunity arises to study, by
the aid of a new invention, a
wholly new world of organ-
isms without leaving home,
and Leeuwenhoek took full
advantage of his unique
opportunity.
The end of the seventeenth
and the beginning of the eigh-
teenth century was a period of
: x ‘ rane i Fie. 418. — Leeuwenhoek. From
immense scientific activity in Locy, ‘Biology and its Makers,”
many directions. Numerous New York, Henry Holt and
Company.
learned societies or academies
were started in England, Germany, France, Italy, Austria, and
Russia, and their publications served as repositories for the
new discoveries. In consequence of the great collections of
animals and plants that were being made, museums were
founded, frequently by the academies, to care for them and
to encourage further collecting. Zoological gardens were es-
tablished to keep alive the new and strange animals that ex-
plorers brought back from newly discovered lands. All of
these things must have stimulated the love of nature innate
24H
466 ZOOLOGY
in normal young people, and were responsible for the creation
of many zoological investigators.
As the eighteenth century drew to a close, a more philo-
sophical tendency appeared in zoology — particularly in the
French school. Buffon (1707-1788) began a great popular
encyclopedic work on the nat-
ural history of animals, but it
was never completed by him.
The work was finished by other
hands. It is, however, on his
theoretical opinions, particularly
his recognition of the evolution
of species, and his protest
against Linneus’s view of im-
mutability, that Buffon’s great-
est claim to recognition rests.
But it is Lamarck (1744-1829)
who has made most famous this
French school of philosophical
Fie. 419.— Lamarck. From
“Lamarek, his Life and his
Work,” by permission of the are not immutable, but alter
publishers, Messrs. Longmans,
Green, and Company.
zoologists. He held that species
under changing environment,
and that there has been an up-
ward progression in the animal kingdom. He argued that
changes in environment bring about changes in habits, and that
new habits involve the use of new parts, resulting in modifying
them. Such modifications are inherited, and thus are perpet-
uated as new specific characters. Rudimentary structures like
the eyes of moles or cave animals result from this use. Webbed
fect of birds, on the other hand, result from stretching the web
by extending the toes to swim more effectively. The neck of
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 467
the giraffe became elongated from the constant effort to reach
the foliage higher up on the trees. Use and disuse, effort and
habit, lie at the basis of Lamarck’s theory of progressive evolu-
tion.
The French school contributed not only to general theory
but also to the solid facts of zoology. Lamarck described hun-
dreds of new species of invert-
ebrates, and proposed a sub-
division of invertebrates which
was amarked advance over any-
thing that had hitherto existed.
In fact the division of animals
into Vertebrata and Inverte-
brata was Lamarck’s own sug-
gestion. But the fame of
Lamarck as a student and de-
scriber of animals was over-
shadowed by his colleague and
opponent, Cuvier (1769-1832).
As the greatest comparative
a Pi ; Fic. 420.— George Cuvier. From
anatomist of his age, he at- Locy, ‘Biology and its Makers,”
tracted to Paris many pupils. | New York, Henry Holt and Com-
His anatomical studies em- 07”
braced ccelenterates, mollusks, arthropods, and vertebrates,
and he recognized that fossil forms belong as truly to the do-
minion of zoology as do those that have not been so long dead.
In his two great comprehensive works, “‘ The Animal IXtingdom
classified on the Basis of Organization’ and ‘‘ Lessons in Com-
parative Anatomy,” he introduced for the first time internal
as well as external anatomy as the proper basis for classification.
He also established the theory of distinct types of animal struc-
468 ZOOLOGY
ture which were independent and parallel and did not all fall
into one series leading from Protozoa toman. Cuvier opposed
the theory of evolution, and so great was his influence in France
that the ideas of Lamarck were neglected and almost forgotten
in the supremacy of the view of the immutability of species.
The science of embryology had its beginnings in Aristotle’s
studies on the hen’s egg, and in the revival of biological studies in
the seventeenth century there were not wanting those who, like
Malpighi, made some superficial studies on developing chicks;
but it was not until the middle of the eighteenth century that
serious embryological studies were made. At this time there
was raging a discussion as to thenature of development. On
the one hand it was maintained that in the egg lay the embryo
as we see it when the chick is hatched, only it is of very small
size. Development consists in the growing of the different
parts until they become visible. On the other hand, it was
asserted that the sperm-cell contains the young creature and
that it finds in the egg food for growth. One day a teacher in
Germany remarked to a brilliant pupil, Caspar Friedrich Wolff;
that many things of value would be got from a careful study
of the development of the hen’s egg. Wolff set to work and
succeeded in proving that the egg is at first without the organs
of the adult, and that these are gradually formed in it. These
conclusions, based on careful study, were combated by Haller,
the eminent physiologist, and on account of his great authority
he crushed, for a time, the truth; but at the beginning of the
nineteenth century new studies were made by Carl Ernst von
Baer, who confirmed Wolff’s observations, and in 1832 estab-
lished embryology as a separate science. During the re-
mainder of the century embryology almost overshadowed the
other sub-sciences of zoology. In England were Huxley and
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 469
Balfour and their numerous pupils. In Germany, Russia,
and France the workers were even more abundant, and
America includes as its share the work of Agassiz and of men
still active.
Cytology. — When thin sections of plant tissues were first
looked at with a microscope, they were seen to be made up of
spaces surrounded by thick walls, and these were called “ cells.”
Similar cells were seen in animal tissues also. But it was not
until 1838-1839 that the botanist Schleiden and the zoologist
Schwann raised these isolated facts to a theory by declaring
that the whole body of organisms is made up of such cells and
their products. It was, however, left to Schultze to bring out
the more fundamental idea that the body is made up of a living
substance — protoplasm — which is divided for physiological
purposes into more elementary parts called cells. Later it was
discovered that the activity of each cell is controlled by a central
body, or nucleus, and for the last three or four decades the
behavior of the nucleus in cell division and in heredity has
been the object of extensive investigation.
The Evolution Theory. — We have seen how the Greeks
regarded the evolution of the organic world as a part of cosmic
philosophy. Through a narrow interpretation of the Mosaic
account of creation, the Christian church was led away from
those broad views, and in this attitude it was supported by Lin-
nzeus and others. We have seen that a French school of evolu-
tion arose, but its explanation of the method of evolution was
not acceptable, and the school was crushed by the authority of
Cuvier. In England there were not wanting those who accepted
or promulgated the theory with a very slight basis of fact.
It was the great service of Charles Darwin to offer such a
theory, accompanied by proofs so numerous and presented in a
470 ZOOLOGY
fashion so judicial as to win acceptance by all. Charles Dar-
win was born in Shrewsbury, England, in 1809; his uncle,
Erasmus Darwin, had written a theory of evolution in metric
form. After having studied in Edinburgh and Cambridge,
Charles Darwin, at the age of 22, accompanied the ship
Beagle on a five years’ scientific
expedition around the world.
On this trip he made studies on
the distribution of animals in
space and time, and published
a fascinating book on them.
These studies led him, on his
return, to collect facts which
might bear on the origin of
species. In 1859 Darwin pub-
lished his book entitled ‘ The
Origin of Species through Nat-
ural Selection.” Besides the
ies, aes = tageneae Wes: general argument for evolution,
he proposes the special hypothe-
sis of selection to account for it. In every species many
more individuals are produced in each generation than
can survive. In this weeding-out process those individuals
that in any way peculiarly fit the conditions of life will
be more apt to survive than the less fit; thus the fact of
adaptation is accounted for, and, whenever the environment
changes, a change in the species tends to occur. Darwin was
inclined to believe that the changes in successive generations
would be always slight, but the experiments and observations
of the Dutchman De Vries (‘The Mutation Theory ”’ 1901-
1903) make it seem probable that the progressive steps are
BRIEF HISTORY OF THE SCIENCE OF ZOOLOGY 471
usually new characters which breed true from their start.
We find ourselves thus in the twentieth century with the
theory of evolution generally accepted, but with the method
of evolution incompletely worked out. There thus remains
plenty of work on this theory to be done in the future.
Zoological expeditions. — We have seen that the work of the
encyclopzedists led men to add to the number of known species
by exploring new countries. The great systematic works of
Linneus and the others had a similar effect. One of the
greatest of the early expeditions was undertaken by Pallas
(b. at Berlin 1741, d. 1811), who travelled through Siberia
and as far south as the Caspian Sea. He also investigated the
fauna of eastern and southern Russia in Europe, and published
the results of his studies in extensive books.
During the early part of the nineteenth century a great
interest was revived in the study of marine animals, and
many expeditions were sent around the world. Of these the
Challenger Expedition is the most noteworthy. Its results
are published in fifty fine quarto volumes. In this country
the expedition under Wilkes, which opened Japan to Western
civilization, and those of Alexander Agassiz in the Blake
and the Albatross are the most noteworthy. Despite all of
this activity, much of the land and of the sea remains to be
explored.
APPENDIX I
A LIST OF BOOKS DEALING CHIEFLY WITH
ECOLOGICAL AND SYSTEMATIC ZOOLOGY
OF AMERICAN ANIMALS
A. GENERAL SYNOPTIC WORKS:
Leunis, J.— Synopsis der Thierkunde. Dritte Auflage von H.
Ludwig. 2Bande. Hannover. 1883-86.
This is the nearest approach to a systematic manual, taking the place
in Zoology which Gray’s and Coulter’s Manuals do in Botany. It deals
chiefly with European species, and has not been translated.
Thomson, J. A. — Outlines of Zoology. 3d edition, with 332 illus-
trations. New York: D. Appleton & Co. 1899. 819 pp.
An excellent condensed compendium; in which, however, the struc-
tural side predominates.
Riverside [formerly Standard] Natural History, edited by J. S. Kings-
ley. 6 vols., large Svo. Boston and New York: Houghton,
Mifflin & Co. Price $30.
The most important large compendium written by American authors,
somewhat after the plan of Brehm’s Thierleben.
Cambridge Natural History, edited by S. F. Harmer and A. E.
Shipley. New York: The Macmillan Company. 1894-1908.
An English work of surpassing merit.
Klassen und Ordnungen des Thierreiches, edited (originally) by
Bronn. Leipzig u. Heidelberg: C. F. Winter.
An extensive and thorough work. Although the whole work is not
yet completed, some of the volumes are out of date. The most recent
and important are the volumes on Protozoa, Porifera, Coelenterata,
Vermes, Echinodermata, Crustacea, Mollusca, Reptilia, and Birds.
473
474 APPENDIX
Das Tierreich. Eine Zusammenstellung und Kennzeichnung der
rezenten Tierformen. General redacteur: F. E. Schulze.
Berlin; R. Friedlander und Sohn. 1896—
A systematic account of every known species, with keys for their
determination. An ambitious enterprise which will hardly be finished
during one generation.
B. WORKS RELATING TO ANIMALS OF A
PARTICULAR HABITAT
Verrill, A. E. (and S. I. Smith). — Report upon the Invertebrate
Animals of Vineyard Sound and the Adjacent Waters, in Report
(of U. S. Fish Commission) on the Condition of the Sea Fisheries
of the South Coast of New England in 1871 and 1872. (1873.)
pp. 295-778.
An indispensable accompaniment of the zoologist at the Eastern sea-
shore; separate copies can be purchased of dealers in scientific books.
Emerton, J. H. — Life on the Seashore. [For sale by Bradlee Whid-
den, Boston.]
Mayer, A. G. — Seashore Life. New York Zoological Society.
C. GENERAL WORKS ON HABITS, ECOLOGY, AND
DISTRIBUTION
Verworn, M. — General Physiology. An Outline of the Science of
Life. New York: The Macmillan Company. 1899. 615 pp.
Price $4.00.
Morgan, C. L. — Animal Life and Intelligence. New York: Ed-
ward Arnold. 1891. 503 pp.
Morgan, C. L. — Habit and Instinet. New York: Edward Arnold.
1896. 351 pp.
The two best books on the topics considered.
Lubbock, J. — On the Senses, Instinct, and Intelligence of Animals,
with special reference to Insects. International Scientific
Series, Vol. LXIV. New York: D. Appleton & Co. 1888.
APPENDIX 475
Poulton, E. B. — The Colors of Animals. The International Scien-
tific Series, Vel. LXVII. New York: D. Appleton &Co. 1890.
Semper, K. — Animal Life as affected by the Natural Conditions of
existence. International Scientific Series, XXX. New York:
D. Appleton & Co. 1881.
Even to-day the best book on Animal Ecology.
Wallace, A. R.— Tropical Nature. London and New York:
Maemillan & Co. 1895.
Wallace, A. R. — Geographical Distribution of Animals. 2 vols.
London: Macmillan & Co. 1879.
Beddard, F. E. — Text-book of Zoogeography. Cambridge (Eng.)
Scientific Series. 1895.
D. WORKS DEALING CHIEFLY WITH ANATOMY AND
EMBRYOLOGY
Parker, T. J., and W. A. Haswell. — Text-book of Zoology. 2 vols.
Many illustrations. New York: The Macmillan Co. 1897.
Parker, T. J., and W. A. Haswell. — Manual of Zoology. Adapted
for use of American Schools and Colleges. 563 pp. 327 figs.
New York: The Macmillan Co. 1900.
Rolleston, G., and W. H. Jackson.— Forms of Animal Life. 1888.
Lang, A. — Text-book of Comparative Anatomy. Translated by
Bernard. 2vols. New York: The Macmillan Co. 1896.
Brooks, W. K. — Handbook of Invertebrate Zoology. For labora-
tories and seaside work. Boston: 8S. E. Cassino. 1882. [May
be purchased of Bradlee Whidden, Boston. ]
Korschelt, E., and K. Heider. — Text-hook of the Embryology of
Invertebrates. 3 vols. New York: The Macmillan Co.
1899.
Balfour, F. M.— A Treatise on Comparative Embryology. In 2
vols. London: Macmillan & Co. 1880-81.
Although decidedly out of date, yet gives the best general discussion
in English of the subject.
Hertwig, O. — Text-book of the Embryology of Man and Mammals.
Translated by E. L. Mark. New York: Macmillan, 1892.
476 APPENDIX
Wilson, E. B. — The Cell in Development and Inheritance. New
York: The Macmillan Co. 1900.
E. WORKS ON SPECIAL GROUPS
I. INSECTS IN GENERAL
The Cambridge Natural History. Vols. V and VI. Macmillan.
1895 and 1899. [Especially ecological.]
Comstock, J. H. and A. B. — Manual for Study of Insects. Com-
stock Publishing Co. 1899. Price $3.75. [Excellent syste-
matic treatise.]
Comstock, J. H.—Insect Life. D. Appleton. 1897. Price
$2.25.
Folsom, J. W.— Entomology with Special Reference to its Bio-
logical and Economic Aspects. Blakiston. 1906. [Excellent
in its field.]
Smith, J. B.— Economic Entomology. Lippincott. 1896. Price
$2.50.
Packard, A. S.— Fifth Report of United States Entomological
Commission, U.8. Dept. of Agriculture. Washington: Govern-
ment Printing Office. 1890. [Extensive treatise.]
Miall, E. C. — Natural History of Aquatic Insects. Macmillan.
1895. Price $1.75.
Needham, J. G., and C. Betten. — Aquatic Insects in the Adiron-
dacks. University of State of New York, Albany. 1901.
Price $0.45.
Needham, J. G., and others. — Aquatic Insects of New York
State. University of State of New York, Albany. 1903.
Price $0.80.
Needham, J. G., K. J. Morton, O. A. Johannsen. — Mayflies and
Midges of New York. University of State of New York,
Albany. 1905. Price $0.80.
Needham, J. G. — Report of Entomologie Field Station conducted
at Old Forge, N.Y. University of State of New York, Albany.
1908.
Lubbock, J. — Origin and Metamorphoses of Insects. Macmillan.
1895,
APPENDIX AT7
Howard, L. O. — The Insect Book. Doubleday, Page & Co. 1901.
Smith, J. B. — Insects of New Jersey. (Franklin Dye, Secretary,
Trenton, N.J.) [Excellent local list.]
Banks, N.— List of Works on North American Entomology.
Washington : Government Printing Office. 1910.
Riley, C. V. — Directions for Collecting and Preserving Insects.
Smithsonian Institution, Washington. 1892. Price $0.25.
II. ORTHOPTERA, NEUROPTERA, HEMIPTERA, ETC.
Guthrie, J. E.—Collembola of Minnesota. Geological and Natural
History Survey of Minnesota. 1903.
Scudder, S. H. — Guide to the Genera and Classification of the
North American Orthoptera found north of Mexico. Cam-
bridge, Mass. 1897.
Lugger, O.— Orthoptera of Minnesota. State Experiment Station.
1898.
Morse, A. P.— Researches on North America Acridiidae. Car-
negie Institute of Washington. 1904.
Miall, L. G., and A. Denny.— Structure and Life History of the
Cockroach. London: Loweil, Reeves & Co. 1886.
Calvert, P. P. — Catalogue of the Odonata (Dragon Flies) of the
vicinity of Philadelphia. Transactions Entomological Society,
Philadelphia. Price $1.00.
Williamson, E. B. — Dragonflies of Indiana. 24th Annual Report
Department Geological and Natural Resources, Indiana. 1899.
Hagen, H. — Synopsis of Neuroptera of North America. Smith-
sonian Collections. 1861.
Banks, N. — Catalogue of Neuropteroid Insects of United States.
Secretary, American Entomological Society, Philadelphia. 1907.
Summers, H. E.— True Bugs, or Heteroptera, of Tennessee.
Bulletin Tennessee Agricultural Experiment Station. 1891.
III. LEPIDOPTERA AND HYMENOPTERA
French, G. H. — Butterflies Eastern United States. Lippincott,
Philadelphia, 1886.
478 APPENDIX
Scudder, S. H.— Butterflies of Eastern United States and Canada,
3 vols. Cambridge, Mass. Privately printed. 1889.
Scudder, S. H. — Brief Guide to Commoner Butterflies of Northern
United States and Canada. Holt. 1893. Price $1.25.
Edwards, W. H.— Butterflies of North America. Houghton,
Mifflin & Co.
Holland, W. J. — Butterfly Book. Doubleday, Page & Co. 1898.
Holland, W. J. — Moth Book. Doubleday, Page & Co. 1903.
Knobel, E. — Day Butterflies and Dusk Fliers of New England ;
how to find and know them (1895); also Night Moths of
New England; how to determine them readily. Boston:
Bradlee Whidden. 1895.
Wright, W. G.— Butterflies of West Coast of United States,
San Francisco. 1905.
Cresson. E. T. — Synopsis of Families and Genera of the Hymenop-
tera, North of Mexico. Secretary, American Entomological
Society, Philadelphia. 1887. Price $3.00.
Lubbock, J. — Ants, Bees, and Wasps. D. Appleton. 1882.
Wheeler, W. M.— Ants, their Structure, Development, and Be.
havior. Macmillan. 1910.
IV. COLEOPTERA
Le Conte, J. L., and G. H. Horn. Classification of the Coleoptera
of North America. Secretary, American Entomological Society.
1883. Price $2.50.
Ulke, H. — List of Beetles of the District of Columbia, Proceedings
United States Natural Museum, 25, pp. 57. Government
Printing Office. 1902.
Knobel, E. — Beetles of New England; a guide to know them
readily. Boston: Bradlee Whidden. 1895.
V. DIPTERA
Williston, S. W.— Manual of North American Diptera. 3d ed.
New Haven. 1908.
Giles, G. M.— A Handbook of Gnats or Mosquitoes. London:
John Bale Sons & Danielsson. 1902.
APPENDIX 479
Howard, L. O. — Mosquitoes. Doubleday, Page & Co. 1901.
Knobel, E.— Beetles of New England. Boston: Bradlee Whidden,
1895.
VI. MYRIAPODA
Bollman, C. H.— Myriapoda of North America, Bulletin 46,
United States National Museum. Government Printing Office.
1893.
Wood, H. C., Jr. — Myriapoda of North America. Transactions
American Philosophical Society, 13. 1865.
VII. ARACHNIDA
Emerton, J. H.— Common Spiders of the United States. Ginn.
1902.
Comstock, J. H.— Classification of North American Spiders. Com-
stock Publishing Co. 1993.
McCook, H. C.
3 vols., 4to. Secretary, Academy Natural Science, Philadelphia.
1889-93.
Peckham, G. W. and E. G.—North American Spiders of the
Family Attide. Transactions Wisconsin Academy of Science,
Vol. 7. 1888.
Kraepelin, K.—Scorpiones und Pedipalpi. Das Tierreich, 8S. Lief-
erung. Berlin: R. Friedlander. 1899.
Banks, N. — Synopsis of the Phalangida, American Naturalist, Vol.
XXXV. 1901.
Banks, N.—A Treatise on the Acarina or Mites. Proceedings of
United States National Museum, 28. United States Govern-
ment Printing Office. 1904.
American Spiders and their Spinning Work.
VIII. CRUSTACEA
Rathbun, R. — Natural History of Economie Crustaceans. Bulle-
tin U. S. Fish Commission for 1889. Government Printing
Office. 1893.
Huxley, G. H. — The Crayfish: an Introduction to the Study of
Zoology. D. Appleton. 1880.
480 APPENDIX
Hay, W. P.— Synopsis of Astacide of North America. American
Naturalist, Vol. XX XIII. 1899.
IX. MALACOSTRACA AND GEOGRAPHICAL
DISTRIBUTION
Stebbing, T. R. R. — A History of Crustacea, Recent Malacostraca.
D. Appleton. 1893.
Faxon, W.— Revision of the Astacide. Memoirs Museum Comp.
Zool., Cambridge, Mass., Vol. X. 1885.
Herrick, F. H. — American Lobster, Bulletin U. S. Fish Commis-
sion, Vol. XV. 1896.
Kingsley, J. S. — Synopses of Caridea and Astacoid and Thalas-
sinoid Crustacea. American Naturalist, Vol. XX XIII. 1899.
Rathbun, M. J. —Synopses of Crabs, American Naturalist, Vol.
XXXIV. 1900.
Wallace, A. R. — Geographical Distribution of Animals. 2 vols.
Macmillan. 1876.
Heilprin, A. — Geographical and Geological Distribution of Ani-
mals. D. Appleton. 1887.
X. ENTOMOSTRACA
Richardson, H. — Monograph on the Isopods of North America,
Government Printing Office. 1905.
Holmes, S. J. —Synopsis of Amphipoda. American Naturalist,
Vol. XXXVII. 1903.
Wheeler, W. M.—Free-swimming Copepods of the Woods Hole
region. Government Printing Office. 1900.
Marsh, C. D.— Revision of the New York Species of Cyclops.
Transactions Wisconsin Academy. 1910.
Hay, W. P. — Ostracoda of North America, American Naturalist,
Vol. XXXIIT. 1899.
XI. WORMS
Cambridge Natural History. Vol. II. Macmillan. 1896.
Delage, Y., and E. Hérouard.— Les Vermidiens, in Traité de
Zoologie coneréte, Tome V. Schleicher fréres. 1897.
APPENDIX 481
XII. OLIGOCHATA, LEECHES, BRYOZOA, AND
BRACHIOPODA
Michaelsen, W.— Oligochexta, in Das Tierreich, 10 Lief. Berlin:
R. Friedlinder & Sohn. 1900.
Darwin, C. — Formation of Vegetable Mold through the Action
of Worms. D. Appleton. 1881.
Moore, J. P. — Hirudinea of [linois, Bulletin Illinois State Labora-
tory of Natural History, Vol. V. 1901.
Davenport, C. B. — Fresh-water Bryozoa. American Naturalist,
Vol. XXXII. 1899.
XIII. POLYCHZHTA AND LOWER WORMS
Verrill, A. E.— New England Annelida. Transactions Connecticut
Academy, Vol. IV. 1880.
Andrews, E. A.— Report on Annelida Polycheta of Beaufort.
Proceedings U. 8. National Museum, Vol. XIV. Government
Printing Office. 1891.
Johnson, H. P.— Preliminary Account of Marine Annelids of
Pacific Coast. Proceedings California Academy of Sciences,
Vol. I. 1897.
Pratt, H. S. — Synopsis of the Trematodes. American Naturalist,
Nos. 404, 432. 1900, 1902.
Coe, W. R. — Synopsis of the Nemerteans. American Naturalist,
No. 463. 1905.
Montgomery, T. H.—Synopsis of the Gordiacea. American
Naturalist, Vol. 33. 1899.
Ward, H. B. — Parasitic Worms of Man and the Domestic Ani-
mals, in Report for 1894 of Nebraska State Board of Agricul-
ture. 1895.
XIV. MOLLUSCA
Cooke, A. H. — Mollusea in Cambridge Natural History. Mac-
millan. 1896.
Tryon, Gen., Jr. — Structural and Systematic Conchology. S. R.
Roberts. 1882, 1884. Price $6.00.
21
482 APPENDIX
Gould, A. A. — Report on Invertebrata of Massachusetts. 2d ed.
Binney. 1870. [Mollusca and Tunicata.]
Apgar, A. C. — Molluses of the Atlantic Coast of the United States.
A.C. Apgar, 511 E. State St., Trenton. 1891. [Compact, ex-
cellent keys.]
Dall, W. H. — Shell-bearing Marine Molluses and Brachiopods of
the Southeast Coast of United States. Government Printing
Office. 1903. [Numerous figures.]
Baker, F. C. — Mollusca of Chicago Area. Chicago Academy of
Science. 1898-1902.
Ingersoll, E., and J. A. Ryder. — Natural History of Economie Mol-
luses of the United States, in Bull. U. S. Fish Commission for
1889. Government Printing Office. 1893.
XV. GASTROPODS AND CEPHALOPODS, AND ANIMAL
BEHAVIOR
Simpson, G. B. — Anatomy and Physiology of Polygyra albolabris
and Limax maximus, ete. New York State Educational Depart-
ment. 1901. Price $0.25.
Verrill, A. E. — Report on the Cephalopods of the Northeastern
Coast of America. Report of U.S. Fish Commission for 1879.
Government Printing Office. 1882.
Thorndike, E. L. Animal Intelligence, in Psychological Review,
No. 8. Macmillan. 1898.
Jennings, H. S. — Contributions to the Study of the Behavior of
Lower Organisms. Carnegie Institution of Washington. 1904.
Walter, H. E. — Behavior of the Pond Snail. Cold Spring Harbor
Monographs, VI. 1906.
See also Section C.
XVI. LAMELLIBRANCHS AND RIVER FAUNAS
Drew, G. A. — Habits, Anatomy, and Embryology of the Proto-
branchia [Yoldia, Nucula]. Anatomischer Anzeiger. G. Fischer,
Jena. 1899.
Drew, G. A. — Habits and Movements of the Razor Clam. Bio-
logical Bulletin, Vol. XII. 1907.
APPENDIX 483
Kellogg, J. L. — Observations on the Life History of the Common
Clam, Mya arenaria. Bulletin of U. 8S. Fish Commission for
1899. Government Printing Office. 1900.
Simpson, G. B. — Anatomy and Physiology of Anodonta fluvia-
tilus. 35th Annual Report N.Y. State Museum of Natural
History. 1884.
C. A. Kofoid. — Plankton of the Illinois River, 1894-1899. Bulle-
tin Illinois State Laboratory of Natural History, Vol. VI, 1903 ;
Vol. VIII., 1908.
XVII and XVIII. ECHINODERMS
Agassiz, A.— North American Starfishes. Memoirs Museum Com-
par. Zoology, Vol. V. 1877.
Azassiz, A. — Revision of the Echini, Illustrated Catalogue of Mu-
seum Compar. Zoology, Vol. VII. 1872-73.
Clark, H. L. — Synopsis of the Holothuroidea of North America,
American Naturalist, Vol. XXXV. 1901.
Brooks, W. K.— Handbook of Invertebrate Zoology. Boston :
Cassino. 1882. [Excellent chapter on the development of
Echinoderms. ]
XIX. CCELENTERATES
Trembley, A. — Mémoires pour servir & l’histoire d’un genre de
polypes d’eau douce & bras en forme de cornes. Leyden. 1744.
[Remarkable first study of Hydra.]
Agassiz, L. — Acalephs, Ctenophore, Discophore, Hydroide, in
Contributions to the Natural History of the United States.
1860, 1862.
Hargitt, C. W. — Synopsis of the Hydromeduse of North America,
American Naturalist, Vol. XXXV. 1901.
Parker, G. H.—Synopsis of the Actinaria of North America,
American Naturalist, Vol. XXXIV. 1900.
Hyatt, A. — Guides for Science Teaching: JII, Commercial and
Other Sponges. Heath & Co., Boston. 1893.
Potts, E. — Synopsis of American Fresh-water Sponges, Proceed-
ings Academy of Natural Science of Philadelphia. 1887.
484 APPENDIX
XX. PROTOZOA
Calkins, G. N. — Protozoa. Macmillan.
Briitschli, O. — Protozoa, in Bronn’s Tierreich. 1889.
Leidy, J. — Fresh-water Rhizopods of North America. Govern-
ment Printing Office. 1879.
Conn, H. W.— Protozoa of Fresh Water of Connecticut. Bulle-
tin Geological and Natural History Survey of Connecticut.
1905.
XXI. VERTEBRATES
Jordan, D. S.— Manual of the Vertebrates of the Northern U. S.
Chicago: McClurg.
Kingsley, J. S. — Text-book of Vertebrate Zoology. Holt. 1899.
Parker, T. J.,and W. A. Haswell. — Text-book of Zoology, Vol. II.
Maemillan. 1897.
XXII. FISHES
Jordan, D. S., and B. W. Evermann. — The Fishes of North and
Middle America, Bulletin U. 8S. National Museum, No. 47.
Government Printing Office. 1898. [Very valuable; with
much biological data and keys.]
Goode, G. B.— American Fishes. New York: Standard Book Co.
1888.
XXIII. AMPHIBIA
Mivart, S. and G. — The Common Frog. Maemillan. 1881.
Dickerson, Mary E. — Frog Book. Doubleday, Page & Co.
Sherwood, W. L. — Frogs and Toads in Vicinity of New York.
Proe. Linn. Soe. of N. Y., No. 10. 1898.
Gage, S. H. — Life History of Newt. American Naturalist, Decem-
ber, 1891.
Ritter, W. E. — Life History of Habits of the Pacific Coast Newt.
Proceedings California Academy of Science, Vol. I. 1897.
Wilder, H. H. — Desmognathus fusca and Spelerpes bilineatus,
American Naturalist, Vol. XX XIII. 1899.
Kirkland, A. H. — Habits, Food and Economie Value of the Ameri-
ean Toad. Hatch Experiment Bulletin No. 46. Amherst,
Mass. 1897.
APPENDIX 485
XXIV. REPTILIA
Agassiz, L. — North American Testudinata and Embryology of the
Turtle, in Contributions to the Natural History of the U.S.
Little, Brown & Co. 1857.
XXV. BIRDS
Newton, A., and Hans Gadow. — Dictionary of Birds. A. & C.
Black, Edinburgh. 1893-96.
Cowes, E. — Key to North American Birds. 1896.
Ridgeway, R. — Manual of North American Birds. Lippincott.
1896.
Chapman, F. M. — Bird Life. D. Appleton. 1897.
Parkhurst, H. E. — How to name the Birds. C. Seribner.
Wright, Mabel O., and E. Cones. Macmillan. 1898.
Walter, H. E. and A. H. — Wild Birds in City Parks.
Besides these there are dozens of good books on American birds
and guides to their study ; see any good hook-store.
XXVI. MAMMALIA AND DOMESTIC ANIMALS
Flower, W. H., and R. Lydekker. — Introduction to the Study of
Mammals, Living and Extinct. A. & C. Black. 1891.
Lydekker, R. — Geographical History of Mammals. Macmillan.
1886.
Mivart, S. and G. — The Cat. Seribners. 1881.
Darwin, C.— The Variation of Animals and Plants under Do-
mestication. 2ded. D. Appleton. 1870.
Bateson, W. — Mendel’s Principles of Heredity. Macmillan. 1909.
XXVII. DEVELOPMENT OF THE FROG’S EGG
Morgan, T. H.— Development of the Frog’s Egg. Macmillan.
1897.
XXVIII. HISTORY OF ZOOLOGY
Locy, W. A. — Biology and its Makers. Holt. 1908.
APPENDIX II
SYNOPSIS OF THE ANIMAL KINGDOM
GROUPS OF ANIMALS ARRANGED APPROXIMATELY
IN AN ASCENDING SERIES; WITH REFERENCES TO
EVERY FAMILY MENTIONED IN THE MAIN TEXT;
AND WITH DEFINITIONS OF THE CLASSES AND
ORDERS
Nore. — Owing to the method employed in the text of proceeding from a
type to the allied groups, the systematic relations of the organisms considered
are often obscured. This synopsis is intended to make these relations clearer.
It can also be used as a systematic index of the book. Moreover, the student
can use it in reviewing his knowledge of the tert, and as a key for the deter-
mination of the class in which a specimen falls. The teacher can employ it as
a guide to collecting illustrative material; for every family mentioned should,
as far as possible, be illustrated by specimens or good figures.
In the synopsis group-names printed in full-face are phyla; in
LARGE CAPITALS, classes; in Smatu CapitTats, orders; in
italics, families. Subphyla, subclasses, and suborders are indicated
by bracketing. Thus [CILIATA] is a subclass. Numbers in
parentheses refer to pages of the text.
PROTOZOA
Animals composed of a single cell; or, if of several cells, these are
of one kind.
RHIZOPODA. Protozoa with retractile pseudopodia: Amceha
(284).
SPOROZOA. Protozoa without appendages; internal parasites
(285).
FLAGELLATA. Protozoa without cilia, but with one or more
flagella (286).
486
APPENDIX 487
INFUSORIA. Protozoa with cilia or sucking tentacles (286).
[CILIATA]. Locomotor, with cilia: Ho.orricua (Parame-
cium, 287); Hererorricua (287); Prrirricua: Vorticella (288).
{[SUCTORIA]. Sessile, with sucking tentacles (288).
C@LENTERATA
Animals of radial structure whose digestive cavity is lined by the
body-wall (262).
[SPONGIARIA]
Ceelenterata whose body-wall is perforated by incurrent pores
(262).
[CNIDARIA]
Ceelenterata whose body-wall is not perforated by incurrent pores,
and which have nettling organs of some sort (264).
HYDROZOA. Cnidaria whose body is composed of more than
two rays and contains a simple cavity. Hypromepusa#, attached
Hydrozoa in hydroid stage; medusa simple: Hydroide (265);
Hydrocorallide (267); Tubularide (267); Campanularide (267) ;
Trachomeduse (Zygodactyla, 271). SripHonopHora, a free swim-
ming colony of Hydrozoa (271).
SCYPHOZOA. Cnidaria with many radii, and with radial parti-
tions in cavity of body (273).
CTENOPHORA. Cnidaria with only two radii, and rows of
cilia-plates (275).
SCOLECIDA
Animals of worm-like form, with bilateral, unsegmented hody.
PLATYHELMINTHES. Bilaterally symmetrical, soft-bodied
animals, without true segmentation of the body; flattened in a
dorso-ventral direction, and having body-cavity filled with a loose
meshwork of cells. Tursevvarta, free-living flatworms whose body
is covered by cilia; alimentary tract with only one opening to the
exterior: Planaria (191). Tremaropba, parasitic, without cilia in
the adult; the mouth leads into a forked food-canal without anus:
Distomum (193). Crsropa, elongated tape-like intestinal parasites,
488 APPENDIX
without mouth or food-canal: Tzenia (195). NEMERTINI, body more
or less flattened; food-canal with mouth and anus; a separate pro-
trusible proboscis (190).
NEMATHELMINTHES. Bilateral, unsegmented, round-
worms; usually with alimentary tract, mouth, and anus: Ascaris
(191).
ROTIFERA. Small aquatic Scolecida, with ciliated band
around mouth, and a special organ for attachment, the foot; wheel-
animalcules.
BRYOZOA. Scolecida in which the ciliated band is carried out
on a series of tentacles surrounding the mouth; form colonies by
budding. ENpoprocta, Bryozoa with head and stalk, and crown
of tentacles surrounding both mouth and anus (177). Ecroprocta,
with anus outside tentacular corona (177).
BRACHIOPODA. — Shelled, with long, tentaculiferous arms;
lamp-shells (180).
MOLLUSCA !
Animals with unsegmented body and without jointed appen-
dages. Usually with a shell and with a muscular organ of locomo-
tion, the foot.
LAMELLIBRANCHIATA. Mollusca with nearly symmet-
rical er leaf-like gills, and a shell composed of two valves.
Ledide (236); Arcide (234); Mylilide eee Aviculide (235);
Pectinida ee Ostreid@ (236); Unionidae (228); Cycladide (230) ;
Maclride (231); Veneride (232); Myide (231); Solenide (231);
Pholadide (230); Teredid@ (230).
tASTROPODA. Mollusca with head, feelers, and eyes, an un-
paired foot, and a shell that is univalve when present. AmPpHI-
NEuRA, with strict bilateral symmetry, no externally visible gills,
and usually a shell composed of eight pieces: Chiton (220). Proso-
BRANCHIATA, With gills in front, shelled and operculate: Acmaide
(219); Patellide (219); Fissurellide (219); Naticide (217); Ca-
lyptraide (Crepidula, 218); Littorinida (216); Muricide (Urosal-
pinx, 218); Fasciolariide (Fulgur, 217). OpistTHoBRANCHIATA,
' This classification, unlike that of the text, follows Cooke in his ‘“ Mol-
lusca.”’
APPENDIX 489
with gills behind heart; if shelled, without operculum; olidiide
(220). Putmonara, breathing by means of lungs, no opereulum :
Auriculide (214); Limn@wide (214); Limacide (211); Helicide
(213); Pupide (214).
CEPHALOPODA. Mollusca with large head, mouth sur-
rounded by a circle of arms, and funnel-shaped foot. Argonaulide
(221); Spirulide (221); Loliginide (221); Naulilide (221).
ECHINODERMATA
Animals of a prevailingly radial structure, with intestinal wall dis-
tinct from body-wall and with calcareous plates in the skin (192).
CRINOIDEA. Sessile Echinodermata, having a cup-shaped
body (258).
ASTEROIDEA. Star-shaped Echinodermata, with a furrow
along the under side of the arms (251).
OPHIUROIDEA. Star-shaped Echinodermata, with ungrooved
arms (253).
ECHINOIDEA. With armless, globular, or cake-shaped body
(254).
HOLOTHUROIDEA. Worm-like, with tentacles around mouth
(256).
ANNELIDA
Bilateral, segmented worms without jointed legs.
POLYCHATA. Annelida possessing parapodia on one or more
segments, and with many bristles on parapodia. Erranrta, free-
swimming Polycheta: Autolytus (187), Lepidonotus (187), Nereis
(185). Sepentaria, Polycheta which live in tubes composed of
mud, sand, or lime: Amphitrite (189), Polycirrus (189), Cistenides
(189), Clymenella (188), Serpula (189).
OLIGOCH-ETA. Annelida without parapodia and with few
sete; living in fresh water or in the ground. Limicou», aquatic:
Nais (173); Dero (172); Tubifex (172). Trrricou®, earth-inhab-
iting: Allolobophora, Lumbricus (169).
GEPHYREA. Annelida having sessile habits and consequently
without external segmentation in the adult, sete sometimes present.
Phascolosoma (176), Echiurus (177).
490 APPENDIX
HIRUDINEA. Annelida with short rings or none at all and with
a ventral sucker; ‘‘bloodsuckers.’’ Clepsine (175) ; Nephelis (175).
ARTHROPODA
Symmetrical, segmented animals, with jointed appendages.
CRUSTACEA. Typically, aquatic and gill-bearing Arthropoda.
Two pairs of antenne, except in Gigantostraca.
(ENTOMOSTRACA]. Crustacea with varied number of
pairs of appendages; usually of small size. BraNcHuiopopa, man-
dibles without palps, numerous legs (156). TrrtLosira, fossil (160).
CuLapocera, mandibles palpless, few legs (157). Ostrracopa, palp
on mandible, only two pairs of legs (157). Coprpopa, elongated
Crustacea, with only one pair of maxille; females with external
ovisacs (158). Cuirripepia, attached Crustacea (barnacles, 158).
[MALACOSTRACA]. Crustacea with nineteen pairs of ap-
pendages. Ampuipopa (146). Isopopa (145). Sromaropopa (144).
PopopaTHaumatTa: [Macrural], large-tailed Podophthalmata : Cari-
dide (138); Astacide (131); Thalassinidew (138); Paguride (188) ;
Hippide (140). [Bracuyura], crabs: Oxyrhyncha (140); Cyclo-
metopa (141); Catometopa (143).
(GIGANTOSTRACA]. Crustacea with five pairs of appen-
dages on cephalo-thorax, abdomen without feet ; body ends in a long
telson, Limulus (146).
ARACHNOIDEA. Air-breathing Arthropoda without antenne.
AcarRINA, mites (117). Pycnoconipa, sea-spiders (119). ARE-
NEINA, spiders: Saltigrade (110); Citigrade (109); Laterigrade
(109); Tubitelarie (105); Retitelarie (106); Orbitelarie (106);
Territelarie (105). PHataneina, harvest-men (117). ArtTHrRo-
GASTRA, scorpions (116).
TRACHEATA. Air-breathing Arthropoda, with one pair of
antenne.
(PROTRACHEATA]. Tracheata with worm-like body.
Each segment of the trunk bears a short, stout appendage. Peri-
patus (101).
[MYRIAPODA]. Tracheata with distinct head and abdo-
men, all the segments of the abdomen bearing appendages. Cu1-
APPENDIX 491
LOPODA, centipedes: Scutigeride (98); Lithobiide (98); Scolopen-
dride (99); Geophilide (100). DipLopopa, millipedes: Julide (100) ;
Polydésmide (100). SympuyLa: Scolopendrella (101), Pauropus
(101).
[HEXAPODA]. Tracheata with only three pairs of legs, con-
fined to thorax. Orruoprera, Hexapoda with two pairs of wings,
masticating mouth-parts, incomplete metamorphosis: Forficulide
(17); Blatttde (17); Mantide (17); Phasmide (18); Acridide (13);
Locustide (19); Grillide (20). Neuroptrera, Hexapoda with two
pairs of net-veined wings; biting mouth-parts, metamorphosis com-
plete or incomplete: Odonata (24); Hphemeride (24); Termitide
(26); Sialide, Corydalis (28). Hrmiprera, Hexapoda with two
pairs of wings or none, sucking and piercing mouth-parts, incom-
plete metamorphosis. [Hrrrroprrera], upper wings leathery:
Redwiide (23); Pentatomide (22). [Homorrmra], wings alike:
Cicada (23); [here, also, plant lice and animal lice]. Diprera:
Hexapoda with (typically) one pair wings; piercing and sucking
mouth-parts; complete metamorphosis. [ApHANIPTERA], fleas (88).
{(Pupipara]: Hippoboscide. [BracHycrra], true flies: Muscidae
(80); stride (81); Syrphide (82); Asilide (82); Tabanide (82);
Simuliide (83). [Nematocgrra], gnats: Cecidomyide (83); Culicide
(84); Tipulide (87). CoLtnoprEra, Hexapoda whose fore wings are
modified into wing covers; hind wings folded when not in use: Coc-
cinellide (73); Chrysomelide (72); Cerambycide (72); Curculionide
(71); Scolyttde (71); Lampyride (70); Elateride (70); Buprestide
(70); Lamellicornia (69); Lucanide (68); Dermestide (68); Sil-
phide (67); Staphylinide (66); Hydrophilide (65); Gyrinide (65);
Dytiscide (65); Carabide (64); Cicindelide (63). LeprpoprEera,
Hexapoda with two pairs of scale-covered wings, sucking mouth-parts,
complete metamorphosis: Tineide (47); Tortricide (47); Geometride
(47); Noctuwide (45); Bombycide (42); Arcttide (42); Xylotropide
(42); Sphingide (47); Papilionide (40). Hymenoprrra, Hexapoda
with two pairs of membranous wings; biting and licking mouth-
parts; complete metamorphosis: [PHytTopHaaal], plant-eating (59).
[ENTOMOPHAGA] insect parasites (58). [AcuLEATA] stinging: Formi-
cide (52); Fossoria (52); Vespide (51); Apide (49).
492 APPENDIX
CHORDATA
Animals which possess, at some time of life, throat slits and a
dorsal supporting rod or chorda.
[HEMICHORDA]
Animals of worm-like form, showing gill-slits like fishes. Balano-
glossus (293).
[TUNICATA]
Usually sessile Chordata, often forming colonies (290).
[VERTEBRATA-ACRANIA]
Free-living fish-like Chordata, but without skull, paired fins, or
heart, and with colorless blood. Amphioxus (294).
(VERTEBRATA-CRANIATA]
Free-living Chordata, with skull and complex brain, and red
blood.
CYCLOSTOMI. Eel-like vertebrates without lower jaw, and
living a parasitic life (322).
PISCES. Aquatic vertebrates with gills, without lungs, and
with paired fins instead of legs. SpLacuu, skeleton cartilaginous, no
operculum, spiral valve (322). Ganorpe1, skeleton either cartilagi-
nous or bony, spiral valve and operculum present : sturgeons (323) ;
spoon-bill (324); garpike (324); bowfin (324). TrLeosrer, skele-
ton bony, no spiral valve. [AcanTHopTeER!], dorsal, anal, and ven-
tral fins with spines, pharyngeal bones distinet: perches (312);
darters (311); sunfishes (313); toadfishes (313); seulpins (313);
silversides (314); sticklebacks (815). [PHaryNcoGNnarui], fins with
spines, pharyngeal bones united. [ANacanTuini], fins without
spines, ventral fins far forward: codfishes (310); flatfishes (316).
[Puysostomyi], fins without spines, ventral fin placed far backward :
smelts (309); trouts (310); whitefishes (316); catfishes (317);
suckers (317); minnows (318); pikes (319); shads (319); eels
APPENDLY 493
(320). [PLecroenarui], intermaxillaries and maxillaries united.
{[LopHosrancut], body covered with bony plates: pipefishes (321).
Dipnor, lung-fishes (324).
AMPHIBIA (= Batrachia). Vertebrata having no lateral fins
(but instead, legs); functional external gills during a part of their
life. Uropsva. Amphibia which retain the tail permanently:
Strenide (255); Proteida (339); Amphiumidw (339); Crypto-
branchide (339); Amblystomida (340); Plethodontide (342); Des-
mognathide (342). ANura, Amphibia which lose the tail in the
adult stage: Pipide (345); Hylide (345); Bufonide (347); Ranide
(347). Gymnopuiona, Amphibia which have no limbs nor tails;
body worm-like (329).
REPTILIA. Vertebrata which breathe exclusively by lungs
and whose skin contains horny epidermal scales or bony plates.
CHELONIA, trunk enclosed ina bony case: Chelonide (362); Trio-
nychide (363); Testudinide (363). Sauria, shoulder-girdle and
sternum present, usually with eyelids: Chamealeonide (360); Iguan-
ide (857); Varanide (358); Lacertide (359); Helodermide (359) ;
Anguide (360). Oputpia, footless scaled reptiles with no shoulder-
girdle, sternum, nor movable eyelids: Colubride (365); Elapide
(366); Crotalide (366). Crocopitina, large reptiles, with longitu-
dinal vent (368).
AVES. Feathered Vertebrates. Cursorres, Aves with keelless
sternum (391). NavratTores, swimming birds (392). Granua-
ToRES, wading birds (393). Gatun, large ground birds with
strong, perching feet and flat nails (394). Co LumBin», short cloven
feet and compressed nails (396). Coccyagrs, birds with powerful
beak and feet adapted for climbing (399). Pict, woodpeckers (400).
Macrocuires, long-winged birds, without cere or scales on meta-
tarsus (401). Passrres, birds whose metatarsus is covered with
lamine or scales, usually with singing apparatus: Tyrannide (402) ;
Alaudide (404); Corvide (404); Icteride (405); Fringillide (406) ;
Tanagride (407); Hirudinide (408); Ampclide (409); Laniide
(409); Vireonide (409); Mniotilide (410); Troglodyltide (410);
Certhiide (413); Paride (413); Turdide (413). Raprorss, birds
with cere, hooked bill, and strong, hooked claws (396). Psrrract,
birds with cere, high, hooked beak, and fleshy tongue (parrots, 397).
494 APPENDIX
MAMMALIA. Vertebrates which nourish the young by means
of milk, and are usually covered with hair. Monorremata, ovipa-
rous mammals (439). Marsupauia, provided with a marsupium
(440). Epernrara, teeth either absent, rudimentary, or without
enamel (441). CrTracea, marine hairless mammals, hind limbs
absent (442). Unauxuata, hoofed mammals: even-toed ungulates
(444); odd-toed ungulates (445); elephants (445). Ropgntia,
canines absent, incisors grow continuously through life (446.) Car-
NIVORA, canines large (446). Insectivora, small, terrestrial, car-
nivorous mammals, with small canines (445). CHEIROPTERA,
mammals with flying membrane between elongated digits (448).
PRIMATES, with hands (449).
INDEX
A
Abdomen, 3, 120.
Abnormalities in Crustacea, 151.
Aboral, 238.
‘Academies established, 465.
Acarina, 117.
Acartia, 158.
Acmea, 219.
Admiral, 40.
Agassiz, Alexander, 471.
Agassiz, Louis, 469.
Agricultural ant of Texas,
Air-bladder, 305.
Albino mice, 430.
Aldrovandi, 461.
Alternation of generation, 269.
Alligator Snapper, 363.
Alligators, 351, 369.
Amblyopsis, 94.
Amblystoma, 343, 456.
Amblystomide, 340.
Ameiurus catus, 317.
Amia, 323, 324.
Ammonites, 222.
Amceba, 284.
Amphibia, 328;
343.
55.
Amphioxus 294.
Amphipoda, 145.
Amphitrite, 188.
Amphiumide, 339.
Anatomical Zoology, 463.
metamorphosis of,
167; organs of nutrition, 163;
phy: siolozy of, 161; respiration in,
164; reproductiv e organs of, 166;
sense-organs of, 167.
Anodonta, 228.
Odes 86.
Anophthalmus, 95.
Ant-eater, 441.
Antelopes, 444, 445.
Antenne, 4, 13, 31
Anterior, 2.
Ant-lions, 28.
Ants, 52; armies, 55; colonies, 53,
5; language, 54; leaf-cutting, 56.
Anura, 329, 344.
Apes, 450.
Aphids, 24.
Aphrodite,
Apidee, 49.
Aplysia, 212.
Appendages, 3;
of Annelids,
of Crustacea,
mammals, 434.
Apteryx, 391.
Aquatic pulmonates, 214.
Arabian horse, 424.
Arachnida, 114.
Araneina, 104.
Arbacia, 256.
Arca pexata, 234.
Archeopteryx, 418.
186.
of Amphibia, 331;
163; of birds, 382;
120; insects, 3;
Anatomy, 2; of Amphibia, 329; of | Arcidew, 230, 234.
Annelids, 161; of birds, 376; of | Arctiide, 42.
Crustacea, 120; Echinoderms, 238; | Argiope, 107.
insects, 1; mammals, 432; Mol-| Argonauta, 221.
lusea, 199; turtle, 352. Arion, 212.
Ancestry of Vertebrates, 289, 296.
Angle-wings, 40.
Animal architecture, 102.
Animal behavior, A study of, 208.
Animalcula, 282.
Annelids, 161,
161;
excretory organs of, 166;
form of body, 161;
172:
anatomy of,
circulatory system of, 164;
general
musculature of,
Aristotle, 459.
Arks, 234.
Armadillo, 441.
Army-worm, 45.
Arthrobranch, 123.
Arthropods, 114.
Ascaris, 191.
Asiphonata, 227.
Assassin-bug, 22.
495
496
Astacus, 130; food, 13
distribution, 130;
Asteris
INDEX
35
geograph
ical |
organs of, 123.
Atoll, 27
Attached animals, a study of, 260.
Attidee, 110.
Auriculidee, 214.
Autolytus, 187.
Aviculidee, 230, 235.
B
Baboon, 450.
Bacteria, 76.
Badger, 446.
Balanogk yssus, 293.
Balfour, 469.
Baltimore pee 405.
Bark-borers, 71.
Barnacles, ,
Be: aker animals, DETs
Bears, 446.
Beaver, 446.
Bedbug, 23.
Bees, 49; domestication of, 427;
honey, 50; social, 49; swarming,
50.
Beetles, 60; development of, 62;
economic importance of, 74, 75;
food of, 61; geographical range of,
ee habitats of, 61; larval habits
Hehiwon animal, 2
Bell-anime alcule,
Bell-hydroids, 2
Bilateral sy mmetry,
Binomial nomenclatur
Birds, 420;
ticated, 425;
oF
flight of, 414; mig
migration routes of,
of,
system
of, 389;
prey, 396;
sense-organs of,
370; teeth of, 419.
Bivalve Entomostraca,
Bivalves, 227.
Blackbirds, 405.
Black-flies, $3.
Black rat, 430
Black snake, 36!
Black Sw: ee -tail, 40.
Blattida
Blind cray fash, 92, 97.
classes of, :
extinction of, 418;
290.
e, 463.
); don
ration of, 3
Bho
383-3)
tion of,
4
study
157.
1es-
371;
muse cul ar
‘ nervous
organs of,
protec
389;
Lis
of,
Blindworm, 360.
Blister beetle, 75.
(See also Circulation.)
Blood-vessels, 2.
Bluebird, 413.
Blue crab, 142; economic importance
of, 146.
Bobolink, 406.
Boll-worm, 45.
Bombus, 49.
Bombycicke,
Bombyx, 42.
Bony fishe S,
39, 42.
2.
w
Boring Mollusea, 230,
Bot-fly, 8
Cate oo
Bougainvillia, 269.
Bowfin, 324.
Box-tortoise, 363.
Brachiopoda, 180.
Brachycera, SO.
Brachyura, 140.
Brain coral, 275.
308.
160.
Brain, divisions of,
Branchiopod, 156
eubee star, 253.
Brook sue kers, oleh.
Brown creeper, 413.
Brown rat, 431.
Brown-tail moth, 47.
Bruchids, 62.
Bryozoa, 177;
Buck beetle, 72
Budding in corals, 277.
Buffalo-bug, 61, 63.
Buffalo-gnat, SS.
Buffon, 466.
Bufonids, 347.
Bugula, 178.
Bullfrog, 348.
Bullhead, 317.
Bumblebees, 49.
Bupestide, 70.
Burrowing habits, 168.
Buthus, 116.
of estuaries, 225.
Butterfy, 29; broods of, 34; devel-
opment of. habits and food. of,
polymorphism,
35;
32; mimicry, 35;
34; protective resemblance,
types of, 40; wings of, 33.
Byssus, 229.
Cc
Cabbage butterflies, 34, 40.
Callinectes, 142.
Calosoma, 64.
Cambarus, 132, 143.
Camels, 444.
Campanularide, 267.
Camponotus, 53.
Canada grouse, 395.
Cancer, 142.
Canker-worm, 47.
Capillaries, circulation in, 464.
Carabide, 64, 95.
Carapace, 363; of lobster, 123.
Carboniferous age, 12.
Carchesium, 287.
Cardinal Grosbeak, 407.
Carnivora, 446.
Carnivorous, 17.
Carolina paroquet, 398.
Carpenter ant, 53.
Carrion beetles, 67.
Case-bearers, 48.
Cassowary, 391.
Cat, 420, 446.
Caterpillar, 30, 31.
Catfish, 317.
Catocala, 35, 45.
Cattle, 422.
Caudina, 258, 259.
Cave beetles, 95.
Cave crickets, 95.
Cecropia moth, 44.
Cedar waxwing, 410.
Cells, 469.
Centipedes, 97.
Cephalopoda, 198, 220.
Cephalothorax, 104.
Cerambycide, 62, 72.
Ceryle, 400.
Cetacea, 442.
Ceuthophilus, 95.
Cheetie, 163.
Cheetopod, 163.
Chameleon, 357, 360.
Cheetah, 446.
Chelicerze, 105.
Chelonia, 351, 362.
Chestnut-sided warbler, 410.
Chewink, 407.
Chickadee, 413.
Chigger, 119.
Chilopoda, 97.
Chimney swift, 402.
Chimpanzee, 450.
Chinch-bugs, 22.
Chipping-sparrow, 407.
Chitin, 201.
Chiton, 220.
Cholera, 281.
Cholcepus, 442.
Chorda, 289, 294.
2k
INDEX 497
Chordates, 289; relationship to in-
vertebrates, 290.
Chrysomelidie, 72.
Chrysops, 83.
Cicada, 23.
Cicindelidee, 63.
Cilia, 276, 286.
Ciona, 293.
Circulation, organs of, in Annelids,
164; in birds, 386; insects, 7; in
fish, 307; in frog, 333; in lobster,
124; in mammals, 436; in turtles,
353:
Cirri, 189.
Cistenides, 189.
Citheronia, 44.
Civet-cats, 446.
Cladocera, 157.
Clams, fresh-water, 227; marine, 231.
Cleavage, 456; of frog’s egg, 451.
Clepsine, 175.
Click-beetles, 70.
Chsiocampa, 45.
Clothes-moth, 32, 48.
Clymenella, 188.
Cnidaria, 275.
Cobra, 366.
Cobweb spiders, 106.
Coccinellide, 73.
Coceyges, 399.
Cockatoos, 397.
Cockroaches, 17.
Cocoon, ¢ of spider, 109.
Codfish, 316.
Codling-moth, 47.
Coelenterata, 262.
Colaptes, 400.
Coleoptera, 60.
Colonies, in ants, 53; in bees, 49; in
enidaria, 277; wasp, 51.
Colorado potato-beetle, 73.
Colubride, 365.
Columbine, 396.
Condor, 396.
Congo snake, 339.
Contact lovers, 447.
Contour feathers, 376.
Conurus, 398.
Cooper's hawk, 396.
Copepoda, 158.
Copperhead, 368.
Coppers, 41.
Copris, 69. '
Coral, brain, 275; formation of
colonies of, 277; organ-pipe, 267;
reefs, 276.
Cordylophora, 265.
Coregonus, 311.
498 INDEX
Corvidee, 404. Deer, 444.
Cotton-worm, 45. Dermestide, 68.
Cow-bird, 406. Dero, 172.
Crab, burrowing, 142; spider, 109;
swimming, 142.
Crab-spiders, 109.
Crane, 393.
Crane-flies, 87.
Crayfish, 128; distribution, 130.
Creeper, 413.
Crepidula, 218.
Cribella, 252.
Cricket, 1, 20; cave, 20; external
structure, 3; general form, 2;
mole, 21.
Cricket- er assheDpers 20.
Crinoids, ‘
Crocodiles, 351, “368.
Crop, of birds, 383;
of Mollusea, 202.
Crossbill, 406.
Crotalide, 366.
Croton bug, 17.
Crow, 404.
Crow blackbird, 405.
Crustacea, 134, 281; abnormalities
in, 151; anatomy of, 120; phys-
jiology of, 120; regeneration of
lost parts of, 149.
Cryptobranchide, 339.
Ctenophora, 275.
Cuckoos, 399.
Cucumaria, 258.
Culicide, 84.
Curculionide, 71.
Currant-worm, 59.
Cursores, 391.
Cuticula, 3, 4, 30.
Cuttlefish, 220.
Cut-worm, 46.
of cricket, 6;
Cuvier, 467, 469.
Cyclas, 230.
Cy clops, 15 rate of reproduction,
158.
Cyclostomi, 322.
Cynthia moth, 43.
Cytology, 469.
D
Daddy-long-legs, 117.
Danaide, 37.
Daphnia, 134, 153, 157.
Darters, 312.
Darwin, Charles, 469, 470.
Darwin, Erasmus, 470.
Darwinism, 37, 470.
Decapods, economic importance of,
145.
Desmognathide, 342.
Desmognathus, 326, 342.
Development, beetle, 62; crayfish,
148; effect of heat on, 453; of
light on, 453; frog’s egg, 451;
fly, 78; general laws of, 456;
grasshopper, 15; Lepidoptera, 29;
lobster, 146; mammals, 437;
postembryonic, of frog, 455; star-
fishes, 247; Urodela, 343.
Devonian age, 12.
De Vries, 428, 470.
Diapheromera, 19.
Didelphys, 441.
Digestion (see Nutrition).
Digger wasps, 52.
Dimorphism, sexual, 113.
Diplopoda, 100.
Dipnoi, 303, 324.
Diptera, 76-89.
Discontinuous genera, 132.
Disease-producing animals, 76.
Distomum, 196.
Diver-beetle, 65.
Division of labor, physiological, in
Cnidaria, 278; in Crustacea, 151.
Dodo, 396, 418.
Dog, 422, 446.
Dolphins, 443.
Domestic animals, evolution of, 420.
Dominant characters, 429.
Dorsal, 2.
Downy woodpec ker, 401.
Dragon- flies
Dryness-lovers, 349.
Duckbill, 439.
Duckbill catfish, 324.
Dytiscidee, 61, 65.
E
Eagle, 396.
Earthworm, 168; economics of, 171;
food of, 170; regeneration in, 170;
source of diseases, 172.
Earwig, 17.
Echidna, 439.
Echinoderms, 238 ;
musculature — of,
system of, 245; organs of circula-
tion, 243; excretion, 244; repro-
duction, 244; respiration, Dao 's
phy siology of, 238; sense-organs
of, 245; water- vascular system cf,
240.
anatomy of, 238;
244; nervous
INDEX
Echinoids, 254.
Echiurus, 177.
Ecology, beetles, 60; birds, 416;
butterflies, 32; grasshopper, 13.
Economies of, beetles, 61; birds, 416;
earthworms, 171; fishes, 298 ; grass
hopper, 13; Lepidoptera, 39; oys
: parasitic worms, 195; smelts,
309! slugs, 211; spider webs, 112.
Ectoderm, 262.
Ectoprocta, 179.
Edentata, 441.
Edible crab, 141.
Eel, 320; lamprey,
Effect of heat and light on the devel-
opment of the egg, 453.
Egg, fertilization of, 247, 307, 335,
437.
Egrets, extermination of, 394.
Elupide, 366.
Elateride, 70.
Elephants, 445.
Elytra, 60, 66.
Embryology, definition of, 247;
history of, 468; study of, 246.
Encyclopedic zoology, 462.
Endoprocta, 177
Enemies of the lobster, 136.
English sparrow, 370; body covering,
379; food of, 375; form of body,
376; spread of, in America, 374.
Engraver beetle, 71.
Ensis, 231.
Entoderm, 262.
Entomostraca, 134, 153, 281; bi-
valve, 157; distribution of, 155;
volume of, 153.
Eolis, 220.
Ephemeride, 24.
Euglena, ae
Eupagurus, 139.
Even-toed hoote d mammals, 444.
Evolution, of domestic animals,
of species, 466; theory of, 469.
420;
Excretion (see Excretory organs).
Excretory ducts, 2.
Excretory organs, annelids, 166; |
birds, 387; cricket, 75 fish, 307; |
frog, 334; lizards, 354; lobster,
125; mammals, 437.
Exhalent opening, 291.
Exotic species, increase of, 375.
Extinct birds, 418.
Eyespot, 295.
F
Fairy shrimp, 156.
Falcon, 396.
499
Fertilization, 9.
Femur, 5.
Fiddler-crahs, 143.
Filaria, 86.
Fireflies, 61, 70.
Fish, 420; armored, 303; bony, 302;
cartilaginous, 302; cl ification
of, 302; culture of, 301; domes-
ticated, 425; general form of body,
303; musculature of, 308; ner-
vous system of, 308; organs of
circulation, 307; excretion, 307;
nutrition, 305; reproduction, 307;
respiration in, 307; study of the
food of, 153; sense-organs of, 308°
use of, by man,
Fisheries, value of,
Tissurella, 219
Flagellata, 286.
Flatfish, 316.
Flatworm, 191.
Flea, 88.
Flesh-eaters, 446.
Flight of birds, 414.
Flower-flies, $2.
)
299,
Fly, 76; ae ssenerate, 87; develop-
ment, 7 pennant import: ince of,
Ss, SO = hae mimicry in, 52
parasitic, Aa:
Flycatchers, 402.
Food-canal, 294.
Food of beetles, 61; butterflies, 32;
earthworm, 170; fishes, 153; flies,
78; fresh-water mussels, 228;
ner¢
375 5:
lobster, 12
hydra, 2
431; sparrow,
186; mice,
whale, 443.
Food supply, a study of, 298.
Forficulid, 17.
Form of body, frog, 329;
432; turtle, 352.
Formicide, 52.
Fossil brachiopods, 180;
cephalopods, 222;
man, 450.
Fowl, domestic,
Fox, 446.
Fox-sparrow, 407.
Fresh-water hydroids, 265;
228; sponges, origin
turtles, 363.
Fringillidee, 406.
Fringing reefs,
Fritillar 40.
Frog, 325, 347; general form of body,
329; muscular system of,
nervous tem of, > organ
circulation, 333; exeretion,
mammalia,
birds,
lizards,
418;
361;
425, 426.
mussels,
Of 225:
277.
n
d00
reproduction,
sen
329,
nutrition, 331;
re spiration, 333 ;
skeleton of,
mace s egg, deve toe nt of, 451.
Fulgur, 217.
Fundulus, 319.
G
Gadus, 316.
oe the anatomist, 460.
100.
Galley-worm,
Gall-gnats, 83.
Gall-wasp, 58.
Galline, 394.
Galls, S4.
Gallus, 395.
Ganglia, 9.
Ganoidei, 323.
Ganoids, 303.
Garpikes, : 324.
Garter Saaake ;
rasteropoda, 210.
10
Cuusteropods, form of body,
organs of respiration, 202.
asterosteus, 315.
astrolith, 137.
astrulation, 457.
425.
G
G
G
Geese,
Gelasimus, 143.
Genera, discontinuous, 133.
Generations, alternation of,
Geographical distribution
fish, 128.
Geometride,
Geomys, 445.
Geophilus, 100.
Gephyrea, 176.
Germ-cell, 8, 246.
Germ theory of disease, 283.
Gesner, 460.
Gibbon, 450.
of
47.
Gila monster, 359.
Gills, 2 of lobs 123.
Gill-slits, 294, 295, 289
Giraffe, 444, 445.
Glass-snake, 360.
Glochidium, 229.
Cilossina, SI.
Glow-worm, 71.
Cat, 83.
Gnawing mammals, 446.
Goats, 424.
Goat-suckers, 401.
Goldfish, 319.
Gopher, 446.
Gorilla, 450.
Crallatores,
393.
Organs
269.
INDEX
334;
of,
198 ;
cray-
| Grapta, 40.
| Grasshopper, 11; allies of,
cricket, 20; long-horned, 19.
Gray-veined White Butterfly, 34
Great auk, 418.
Great northern shrike, 411.
16;
Green frog, 348.
Green turtle, 362.
Gregarious, 13 3.
Ground- bee tles, 64.
Grouse, 395
Gryllide, 20.
Gryllotalpa, 21.
Guinea-fowl, 395.
Guinea- -pigs, domesticated, 424.
Gull,
Ceres 329.
Gypsy moth, 46.
Gyrinidie, 65.
yee
Habitat: aerial, 12,371; cave, 92-97 ;
di urkness, 90, 91; desert, 349;
or, 223: lt river,
shore, 2 260;
ab: terre sstrial, 168.
Hemal, 297.
Hair-streaks, 41.
Hairy ant-eater, 441.
Hairy antelope, 401.
Hard-shelled clams, 232.
Hare, 448.
Harvester ant, 55.
Harvestmen, 117.
Hawk, 396.
Hawk-bill turtle, 363.
Hawk-moths, 41.
Head, 3.
Healing,
Heart
Heat,
45-4.
(see Circulation).
effect on development of egg,
453.
Helix, 213; variability of, 214.
Hellbender, 341.
Helodermic
Hemiptera, 22.
Hemocyanin, 204.
Hen clams, 231.
Hermaphrodite, 160.
Hermit-crabs, 138.
Heron, 393.
Hesperornis, 418.
Hessian-fly, 83.
Heteroptera,
Heterotrichia,
Hexapoda, 12.
| Hippide, 140.
287.
INDEX 501
Hippopotanius, 444,
History of Science of Zoology, 458.
Holothurians, 240, 244, 256,
Holotrichia, 2
Homarus, disntbinion of, 134.
Homoptera, 22, 23.
Honey bees, 50.
Hoofed mammals, 444.
Horn-fly, 88.
Horn-pout, 317.
Horned Corydalis, 28.
Horned toad, 357.
Hornet, | isn
House wren, 412.
Humming-birds, 401.
Huxley, 468.
Hydra, 260, 262, 264, 275;
of estuaries, 225;
279.
Hydrachnids, 117.
Hydractinia, 266.
Hydranth, 267, 271, 278.
Hy drocorallidse, 267.
Hydroids, bell, 267;
265; tubularian, 267.
Hydromeduse, 271.
Hydrophilide, 65.
Hydrozoa, 271.
Hyenas, 446.
Hylide, 345.
Hymenoptera, 48; boring, 48; plant-
eating, 59; stinging, 48.
Ichneumon, 58.
Icteride, 405.
Iguanidse, 357.
Imago, 24, 32, 337
Increase of exotie species, 375.
Indigo bird, 407.
Infusoria, 282, 286.
Inhalent ope nings, 291.
Insects, disse ae ho of disease,
domesticate ad, 42
Intelligence of te. 53
Intestine of cricket, 6
Isabella caterpillar, 42.
Tsopoda, 145.
Isoptera, 26.
Jackals, 446.
Jay, 404.
Jellyfish, 270;
) 2 discovery
of budding in, to -like aninials
regeneration in,
fresh-water,
of Diptera, 75.
of fresh water, 266;
life-history of, 268.
Jigger, 119.
Joint-snake, 360.
Julus, 100.
Jumping spiders, 110; mice, 446.
June-bugs, 69.
Kk
Kallima, 36.
Katydids, 19.
Kidney tubules, 295.
Killer whale, 443.
Killifish, 318.
Kingbird, 403.
Kingfishers, 400.
Kitchen-middens, 237.
L
Labium, 4.
Lacertide, 359.
Lachnosterna, 63.
Ladybird beetle, 73.
Lady-crab, 142.
Lamarck, 466, 467.
Lamellibranchs, 198.
Lamellicorn bectles, 68
Lamprey eels, 302, ¢
Lamp-shells, 180.
Lampyride, 70.
Land life, origin of, 325.
Land-locked fishes, 309.
Land tortoises, 363.
Language of ants, 54.
Lantern of Aristotle, 242.
Larks, 404.
cea, 291.
Larvee, of amphibia, 342; of Coleop-
tera, 62; of Diptera, 78; of
Lepidoptera, 32; of lobster, 148.
Larval stage, 30.
Lash animalcules, 286.
Laws of development, 456.
Leaf-cutting ants, 56.
Leaf-eating bectles, 72; lamellicorns,
69.
Leaf-hopper, 24.
Leaf-insects, 18.
Leaf-miner, 47.
Leaf-roller, 47
Learned societies, establishment of,
465.
Ledidie, 230, 236.
Leeches, 174.
Leeuwenhoek, 464.
Lemur, 450.
502
Leopard, 446.
Leopard frog, 348.
Lepidonotus, 186.
Lepidoptera, 29;
gene oral dev lopment, 29.
Limpet, 219.
Limulus, 146.
Line-weave
Linnzus, 463, 466.
Liobunum, 115.
Lions, 446.
Lithobius, 90, 97, 98
Littorina, 216;
217, 379; palliata, 217;
Liver of frog,
pigeon, 5
Liver-fluke,
93.
Lizards, 349, 35
359; dryness
Lk amas,
Lobster, 1: 20;
development of, 146;
of, 134; economic importance
145; enemies of, 136; i
125; molting of, 136;
of, 125; nervous system of,
nutrition in, 122; protection of, 1
reproductive organs, 5
sense-organs of, 126.
Locomotion, of bird, 415 ; i
Locust borer, 74.
9
tion in, 122;
Locustidie,
Locusts, 15
Loligo, 221.
Long-horned beetles,
grasshoppers, 19.
Long-winged birds, 401.
Louse-flies,
Tosi 109.
Lynx, 446.
Macaques, 450.
Macrura, 140.
INDEX
Mactra, 232.
Mactridie, 230, 231.
Madreporite, 240.
Maggots, S80.
Malacostraca, 134, 144.
Malaria, 251, 285; causes of, 85.
Malpighi, 463, 464, 46s.
Mammalia, 420, 432, 441.
Mammals, even-toed, hoofed, 444;
form of body of, 432; function of
digestion, 434; gnawing, 446;
hoofed, 444; muscular system of,
438; nervous system of, 435;
odd-toed, hoofed, 445; organs of
circulation, 436; digestion, 454;
excretion, 437; reproduction, 437 ;
respiration, 436; sense organs of,
439; skeleton of, 433; structure
of, 482.
Manatees, 442.
Mandrills, 450.
Mantide, 17.
Mantis shrimp, 144.
Mantle of Mollusca, 198, 199, 210.
Manx cat, 420.
Marmosct, 450.
Marmot, 446.
Marsupialia, 440.
Martens, 446.
Maryland yellow-throat, 410.
Maxillee, 4.
May flies, 24, 26.
Meadow grasshopper, 20.
Meadow-lark, 406.
Meal-beetles, 61.
Mealy bugs, 24.
Me suring worms, 35, 47.
Meduse, 259.
Melampus, 214.
Membranes, 1.
Mendel, 429.
Mendel’s law, 429.
Metallic wood-borers, 70.
3; Amphibia, 343,
456; Coleoptera, 6 Diptera, 80;
Echinodermata, ae Lepidoptera,
31; Tunicata, 292
Metridium,
Mice, domestic: ation of, 428; food of,
431; habits of, 431; rapid distri-
bution of, 430.
Microhydra, 266.
Migration routes, of birds, 372; of
redstart, 373; study of, 370.
Milk-snake, 5.
Millipedes, 97, 100.
Mimicry, 35, 37, 82.
Minks, 446.
a
INDEX
Minnows, 318.
Mites, 117.
Moccasin snake, 366.
Mocking-bird, 412.
Mole, 445.
Mole-crabs, 140.
Mole-cricket, 21
Mollusca, 210; anatomy of, 198; mus-
culature of, 206; nervous system
of, 206; organs of circulation, 203;
excretion, 204; nutrition, 200;
reproduction, 204; physiology of,
198; sense-organs of, 206.
Molt, 16; of lobsters, 136.
Monarch, 37, 40.
Mongoose, 446.
Monkeys, 450.
Monotremes, 439.
Morone, 311.
Morphological Zoology, 463.
Morula, 457.
Mosquitoes,
Moth, 29.
Mother-of-pearl, 236.
Mourning-cloak, 40.
Mouse, 420, 446.
Mud-eel, 338.
Mud-puppy, 339.
Mud-snail, 218.
Mud-wasps, 52.
Mus, 430.
Muscide, 80.
Muscles, 2.
Musculature, of annelids, 167;
388; cricket, 9;
84.
birds,
echinoderms, 244 ;
fish, 308; frog, 335; gasteropods,
206; lobster, 125; mammals, 438 ;
turtles, 355.
Muskallunge, 319.
Musk-turtle, 364.
Mussels, 234; pearl, 235.
Mutation theory, 470.
Mutations, 42S.
Mya arenaria, 231
Myide, 230, 231
Myriapoda, 92, 97.
Mytilide, 230, 234.
N
Nais, 173.
Nassa, 218.
Natatores, 392.
Natica, 217.
Natural selection, 37.
Nautilus, pearly, 221.
Necturus, 339, 456.
Nematocera, 82.
503
Nemertini, 190.
Nephelis, 175.
Nereis, 162, 164, 182;
Nerve, 2; chord, 289.
food of, 186
Nervous system, of birds, 389;
cricket, 9; echinoderms, 245;
fish, 308; frog, 336; lobster, 126;
mammals, 439; mollusca, 206;
lizard, 3
Nest, of barn swallow, 409; of chim-
ney swift, 402; of pewee, 403.
Nettle animals, 264.
Neuroptera, 27.
Newt, 326, 342; transformation,
326.
Nighthawk, 402.
Noctuids, 45.
Norway rat, migrations of, 431.
Nucleus, 288, 469.
Nuthatch, 413.
Nutrition, functions and organs of, 5;
in echinoderms, 241; fish, 305;
frog, 331; lobster, 122; lizard,
352; mammals, 434.
Nymphs, 40.
Oo
Obelia, 267, 278.
Odd- toed, hoofed mammals, 445.
Odonata, 25.
Oligochetse, 172;
Omnivorous, 17.
Oniscus, 145.
Operculum, annelids, 190; fishes, 304.
Ophidia, 351, 365.
Ophiuoridea, 253.
Opisthobranchs, 212
Opossum, 441.
Oral, 238.
Orang-utan, 449, 450.
Orb-weavers, 106.
Orb-web, structure, 107.
Orbitelariee, 106.
Orca, 443.
Orchard oriole, 405.
Origin of land life, 325.
Organ-pipe coral, 267.
Organs, of circulation, in echinoderms,
terrestrial, 174.
, 220.
243; fish, 307; frog, 333; Mol-
lusea, 203; lizard, 353; excretion,
in birds, 387; echinoderms, 244;
fish, 307; Mollusca, 204; lizard,
354; lobster, 122; nutrition, in
birds, 383; echinoderms, 241;
fish, 305; Mollusca, 200; lizard,
352; respiration, in birds, 385;
echinoderms, 242; zastéropods,
504
202; lizard, 354; reproduction, in
birds, 387; fish, 307; Mollusca,
204; lizard, 354.
Ornithorhynchus, 439.
Orthoptera, 3
Osmerus, 5
Ostracoda, 157.
Ostrea, 237
Ostreidie, 230, 236.
Ostrich, 461.
Otocyst of lobster, 127.
Otter, 446.
Ovipositor, 9, 57
Owlet moths, 45.
Owls, 396.
Oxen, 444.
Os -crab, 143.
Oyster-drill, 218.
Oysters, 236.
P
Paddle-fish, 324.
Paguridse, 1: 38.
Painted turtle, 364.
Palsemonetes, 138.
Pallene, 119.
Palm-erab, 140.
Pandorus, 41.
Panopeus, 142.
Papilio, 40; ajax, 34; asterias, 40;
turnus, 40.
Paramacium, 280, 283, 284, 286.
Parapodia, 18s.
Parasitic Hymenoptera, 57
281; vertebrates, 322
economic importance of,
Parrot, 397.
Parthenogenctic, 158.
Partridges, 394.
€ nger pigeon, 395.
Pe
> worms,
195.
Pate la, 219.
Pauropus, 101.
Pearl-fishing, 235.
Pearl mu
Pecten, H.
Pectinidee, 230,
Pedicellina, 177.
Pedipalps, 105.
Pelican, 393.
Pelopxus, 52.
Perch, 312.
Perchers, 402.
Peripatus, 101.
236.
| Phy:
| Plastron,
| Pleuron,
INDEX
Petrel, 393.
Petromyzon, 322.
Pewee, 403.
Phalangidea, 117.
Pharynx, 295.
Phascolosoma, 176.
Phasmide, 18.
Pheasants, 394.
Phoca, 447.
Phahe, 40:
Pholadid:
Photuri ‘
Phrynosoma, 3¢
Phylum, 289.
Physa, 215.
salia, 271,
Physiological
Crustacea, 151.
Physiology of annelids,
tacea, 120; Insecta,
198.
Pici, 400.
Pickerel, 319.
Pieris, 40.
Pigeons, domesticated, 425.
Pigs, 444, 445.
Pike, 319.
Pine. ayoren!
ae aon of labor in
161; Crus-
1; Mollusea,
ee
Pineal gle ind,
| Se
| Pipe -fish
Pipide, 345.
Pithee ecu 450.
Planaria, 191, 194.
Planor bk
215.
; protista, | Plant- eating Hymenoptera, 59.
| Plant-lice, 24.
363.
Plethodon, 342.
Plethodontide, 342.
Pleurobranch, 123.
123%,
Plovers, 393.
Plumatella, 17S.
Podobranch, 123.
Pogonomyrmex, 55.
, Poisonous spiders, 113.
Polistes, 51.
Polycheta, circulatory system in,
164; respiration in, 164; seden-
tary, 188.
189.
100.
3b.
Polycirrus,
Polydesmus,
Polymorphism,
Polyp, 273, 275.
Polyphemus moth, 43.
Pond snail, 214.
Porcupine, 446,
44s.
| Portuguese man-of-war, 271.
INDEN
Postembryonic
frog, 455.
Posterior, 2.
Potato beetle, 61.
Potato ‘worm,’ 41.
Poultry, domesticated, 425.
Prairie dog, 447.
Prawns, 138.
Praying mantises, 17.
Primates, pe
Proboscis, 32, 293.
Prong-horn, 445.
Promethia moth, 43.
Protection of birds, 417 ;
Protective resemblance,
Protista, 280; cause of dis
parasitic, 281,
Protophyta, 280.
Protoplasm, 1, 469.
development of the
lobster, 135.
Boy Oly ob:
ases, 281;
Protozoa, 280; discovery of, 282,
465; origin of, 282; reproduction
in, 282.
Psittaci, 397.
Pulmonata 210, 213; aquatic, 214.
Pumpkin-seed sunfish, 313.
Pupa, 31, 32, 214.
Purple grackle, 405.
Q
Quadrate, 304.
Quail, 395.
Quedius, 95.
Queen bee, 50.
R
Rabbits, 424, 446, 448.
Raccoons, 446.
Radii of echinoderms, 239.
Radula, 201.
Rail, 393.
Ranide, 347.
Raptores, 396.
Rat, distribution of, 430; habits of,
431; systematic position of, 432.
Rattlesnakes, 366, 367.
Ray, John, 462.
Rays, 322.
Razor-clams, 231.
Recessive, 429.
Red-eyed vireo, 409.
Red-headed woodpecker, 401.
Redstart, 410; migration of, 373.
Red-winged blackbird, 406.
Reefs, barrier, 277; coral,
fringing, 277.
Regeneration, 454 ;
DHE
earthworms, 170;
505
lost
hemer-
flatworms, 191; hydra,
parts in Crustacea, 149;
teans, 190.
Reproduction by transverse — divi-
sion, 173; in the cricket, %;
in me immals, 387; in Protozoa,
283.
Reproductive ducts, 2.
Reproductive organs,
166; of birds, 387; of
dermis, 244; of fish, 307;
334; of lobster, 125; of
mals, 437; of lizard, 354.
Reptiles, 350.
Respiration, in annelids, 164 ;
279;
of annelids,
echino-
of frog,
mam-
cricket,
6; fish, 305; lobster, 122; organs
of, in frog, 332; mammals, 456;
lizard, 354.
Rhea, 391.
Rhinoceros, 445.
Rhizopods, '
Rice-bird, 406.
Riv er faunas, origin of, 225;
Oy
River mollusks, 225
Robber-flies, 82.
Robin, 413.
Rock eel, 314.
Rodentia, 447.
Roof rat, 430
Rose-breasted grosbeak, 407.
Rose-bug, 70.
Rotifers, discovery of, 465.
Round worms, 191.
Ruby-throated humming-bird, 401.
Running beetles, 62.
Running birds, 391.
Running spiders, 109.
study of,
5
Salamander, 93, 340.
Salmon, 304, 310.
Salmonidee, 309.
Sand-dollars, 2.
Sandpipers, 393.
Sandworm, 185.
Sauria, 351, 356.
Sawflies, 59.
Scale, 29.
Scale-bugs, 24.
Scaled- -worms, 187.
Scallop, 235.
Scaly ant-eater,
Searabide, 69.
Scarlet tanager, 408.
Schleiden, 469.
441.
Schultze, 469.
506
Schwann, 469.
Scolopendra, 99.
Scolopendrella, 101.
Scolytidxe, 71.
Scorpions, 116.
Scratchers, 394.
Screech owl, 397.
Sculpin, 313.
Scutigera, 98.
Scyphozoa, 27:
Sea-anemones,
Sea-cows, 442.
Sea-cucumber, 258.
Sea-lilies, 258.
Sea-lion, 446.
Sea-mouse, 186, 187.
Sea-spiders, 119
Sea-urchins, S
Sea walnuts,
Seal, 446.
Searcher, 64.
Segmentation, of body
162.
Segmented animals, 290.
Selachians, 322.
INDEX
of annelids,
Sense-organs of — annelids, 167;
birds, 389; crickets,
oderms, 245: fish, 308;
lobster,
; Mollusea, 2
hee
mals, 4
Serpent, *
Serpent-st ars, 253.
Serpula, 18
Sertularia, 268, 278.
Sexton beetles, 67.
Sexual dimorphism, 113.
10; echin-
frog, 338;
126; mam-
06.
Shad, 319; fishing, value of, 320.
Sharks, 322,
Sharp- shinned hawk, 397.
Shell, rudimentary, in cephalopods,
221.
Sheep, 424, 444.
Sheep-tic k, Ss.
Short-horned Diptera, 80.
Short-horned grasshoppers, 13.
Short-winged beetles, 66.
Shrews, 445.
Shrikes, 409.
Shrimps, 138; burrowing, 138.
39, 42; cultu
Silphide,
Silverside ‘Ss, 314.
Simia, 449.
Siphonata, 227.
Siphonophore, 271.
Siren, 338.
Skeleton, 1;
lizard, 352; mammals,
birds, 380;
re of, 43.
frog, 329;
433.
Skunk, 446.
Skylark, 404.
Sloth, 441.
Slow-worms, 360.
Slug, 208, 210; apparent absence of
shell of, 211; economical impor-
tance of, 211: food of, 211; habi-
tat of, 211.
Smallest organisms, a study of, 280.
Smelt, 298, 309; economic impor-
tance of, 309.
Snail, 198; form of body, 198; mus-
culature of, 206.
Snake, 365.
Snapping-turtle, 364.
Snipe, 394.
Snowbird, 407.
Snowy owl, 397.
Social bees, 49.
Social life of ants, 55.
Soft-shelled clams, oo, gaat
Soft-shelled turtle, 363.
Solenide, 230, 231.
Somites, 3, 4.
Song-sparrow, 407.
Song thrush, 413.
Sow-bugs, 145.
Spanish fly, 75.
Sparrow, 406; English, 370.
Sparrow “hawk, 396,
Spelerpes, 93, 344.
Sphingide, 41.
Spider, 102, 104; cave, 96; position
of in zoological system, 114; webs,
economic importance of, 112.
Spider-crabs, 140.
Spinnerets, 104.
Spinning instinct, uses of, 110;
methods of, in spiders, 112.
Spiny ant-eater, 439.
Spiracles, 3; of cricket, 6.
Sponges, 262.
Spontaneous generation, theorv of,
989.
Spoonbill, 324.
Spore animalcules,
Sporozoa, 285;
285.
Spotted sandpiper, 393.
Spreading adder, 365
Spread of English sparrow in Amer-
ica, 374.
Spring azures, 34, 41.
Spring-tails, 92, 96.
Squash- bugs, 22:
Squids, 220.
Squirrel, 446, 447.
Stag-beetles, 68.
of malaria,
INDEX 507
Staggers of sheep, 82. Tibia, 5.
Staphylinide, 66. Ticks, 117.
Starfish, 246; abnormalities of, 251;
development, 247; distribution,
251; habitat, 251; serpent-stars,
253; study of embryology, 246;
systematic position of, 251.
Stegomyia, 86.
Stentor, 287.
Sterna, 392.
Stickleback, 315.
Sting of scorpions, 116.
Stink-bugs 2
Stolons, 279.
Stomach of crickets, 6.
Stomapoda, 144.
Storks, 393.
Strongylocentrotus, 256.
Sturgeons, 323.
Stylactis, 266.
Subterrestrial organisms, 168.
Suckers, 317.
Suctoria, 288.
Sunfish, 313.
Swallow, 407.
Swallow-tails, 40.
Swammerdam, 464.
Swarming of bees, 50.
Swifts, 401.
Swimming birds, 392.
Sycon, 263.
Synapta, 259.
Syrphide, 82.
Tabanus, 83.
Teenia, 197.
Talorchestia, 146.
Tanagers, 407.
Tapeworm, 195, 197.
Tapirs, 445.
Tarantula, 113.
Tarsus, 5.
Teeth, amphibia, 331; birds, 419;
echinoderms, 242; fish, 304, 305;
mammals, 435.
Tentacles, 271.
Tent-caterpillar, 44-46.
Teredide, 230.
. Termites, 26, 52.
Tern, 392.
Testudinide, 363.
Thalassinide, 138.
Theclas, 41.
Theory of evolution, 469.
Thomisus, 112.
Thorax, 3.
Thrushes, 413,
Tiger, 446.
Tiger-beetles, 61, 63.
Tiger-moths, 42.
Tiger swallow-tails, 40.
Tineids, 47.
Tipulide, 87.
Titmice, 413.
Toad, 347.
Toadfish, 313.
Tomato worm, 35, 41.
Tortricids, 47.
Toucans, 399.
Trachea, 13, 80; of cricket, 6.
Tree-hopper, 24.
Tree-sparrow, 407.
Tree-toad, 345.
Trichina, 191.
Trilobite, 160.
Trionyx, 363.
Trochilus, 401.
Troglodytes, 413.
Trout, 310.
True bugs, 22.
Trunk, 3.
Tsetse-fly, 80.
Tube-weavers, 105.
Tubifex, 172.
Tubularian hydroids, 267.
Tubularide, 267.
Tumble-bugs, 69.
Tunicates, 290.
Tunnel-weavers, 105.
Turdus, 415.
Turkey, 395.
Turkey-buzzard, 396.
Turtles, 351, 362; general form of
body, 352; marine, 362; muscular
system of, 355; nervous system
of, 355; organs of circulation, 353 ;
excretion, 354; nutrition, 352; re-
production, 354; respiration, 354;
sense-organs, 355; skeleton, 352.
Tussock moth, 46.
Twin-spotted sphinx, 41.
Tyrannid, 402.
U
Unionide, 228.
Unios, 228; development of, 229;
economic value of, 229; spawning
season, 229.
Urodela, 328,
ment of, 343.
Urosalpinx, 218.
Uses of spinning instinct, 110,
338; early develop-
008
y
Varanide, 358.
Variability of Helix, 214.
Veneridwe, 230, 232.
Ventral, 2.
Venus, D3:
Vertebr: ates s, 302; ancestry of, 289,
296.
Vesalius, 461.
Vespa, 51.
Ves arrow, 407.
Viceroy, 37, 40.
Vinegar eel, 191.
Vireos, 409.
Volvox, 286.
Von Bac
Vorticella, 28s.
Vultures, 396
Ww
Waders, 393.
Walking-stick, 18.
Walrus, 446.
Wampum, 234.
Wandering spiders,
Warbler, 410.
Wasps, 51.
Water-boatman, 22.
Water-flea, 157.
Water-lizard, 358.
Water scavenger- beetle, 65.
Water- scorpion,
Water snake, 365
Water-striders, 22.
Water-vascular system
derms, 240.
Waste products, 7
Waxwings, 409,
Ve
109.
in echino-
Jeevils,
‘Whales,
W hippoorwill, 402.
Whirligig beetles, 65.
£95. 443.
INDEX
| White ant, 26
| White
sh, 310.
White-throated sparrow,
Wigglers, 85.
Wing, butterfly, 33.
Wing-cells, 5.
Wing-veins, 5.
Wingless birds,
17;
Wireworms,
Wolf, 446.
Wolff, 468.
Wolf spiders, 109.
Woodcock, 394.
Wood-feeders, 42.
Wood-lice, 145.
Woodpeckers, 400.
Wood-warbler, 410.
Wool-bectle, 6s.
Worker bee, 50.
Worm, earth, 169-172;
190-195; ringed, 161;
sealed, 187; stomach,
195.
Wren, 410.
407.
391; cockroaches,
70.
parasitic,
sand, 185;
191; tape,
xX
Xylotropids, 42.
Y
Yellow fever, 251.
Yellow warbler, 410.
Yoldia, 235.
Z
Zebra, 445.
Zebra swallow-tail, 34.
Zooids, 271, 279, 291.
Zoological expeditions, 471;
465.
Zoology, 458;
gardens,
anatom-
463;
phil =
foundation of,
ical, 463; morphological,
history of science of, 458;
sophical, 466.
Zygodactyla, 271.
HIGH SCHOOL COURSE
IN LATIN COMPOSITION
BY
CHARLES McCOY BAKER
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AND
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