MAMMALS
SUGGESTIONS.—A tame rabbit, a house cat, or a pet squirrel may be
taken to the school and observed by the class. Domestic animals may be
observed at home and on the street. A study of the teeth will give a
key to the life of the animal, and the teacher should collect a few
mammalian skulls as opportunities offer. The pupils should be required
to identify them by means of the chart of skulls (p. 194). If some
enthusiastic students fond of anatomy should dissect small mammals,
the specimens should be killed with chloroform, and the directions for
dissection usual in laboratory works on this subject may be followed.
There is a brief guide on page 223. The following outline for the
study of a live mammal will apply almost as well to the rabbit or the
squirrel as to the cat.
=The Cat.=—The house cat (_Felis domestica_) is probably descended from
the Nubian cat (_Felis maniculata_, Fig. 333) found in Africa. The wild
species is about half as large again as the domestic cat, grayish brown
with darker stripes; the tail has dark rings. The lynx, or wild cat of
America (_Lynx rufus_), is quite different. Compare the figures (333,
335) and state three obvious differences. To which American species is
the house cat closer akin, the lynx (Fig. 335) or the ocelot (Fig. 334)?
The domestic cat is found among all nations of the world. What is
concluded, as to its nearest relatives, from the fact that the Indians
had no cats when America was discovered? It was considered sacred by the
ancient Egyptians, and after death its body was embalmed.
The =body of the cat= is very flexible. It may be divided into five
regions, head, neck, trunk, tail, and limbs. Its eyes have the same
parts as the eyes of other mammals. Which part of its eye is most
peculiar? (Fig. 333.) What part is lacking that is present in birds? How
are the eyes especially adapted for seeing at night? Does the pupil in
the light extend up or down or across the iris? Does it ever become
round?
[Illustration:
FIG. 333.—WILD CAT OF AFRICA (_Felis maniculata_), × ⅛.
]
What is the shape and the position of the _ears_? Are they large or
small compared with those of most mammals? They are fitted best for
catching sound from what direction? What is thus indicated in regard to
the cat’s habits? (Compare with ears of rabbit.) Touch the _whiskers_ of
the cat. What result? Was it voluntary or involuntary motion? Are the
_nostrils_ relatively large or small compared with those of a cow? Of
man?
Is the _neck_ long or short? Animals that have long fore legs usually
have what kind of neck? Those with short legs? Why? How many _toes_ on a
fore foot? Hind foot? Why is this arrangement better than the reverse?
Some mammals are sole walkers (_plantigrade_), some are toe walkers
(_digitigrade_). To which kind does the cat belong? Does it walk on the
ends of the toes? Does it walk with all the joints of the toes on the
ground? Where is the _heel_ of the cat? (Fig. 334.) The _wrist_? To make
sure of the location of the wrist, begin above: find the shoulder blade,
the upper arm (one or two bones?), the lower arm (one or two bones?),
the wrist, the palm, and the fingers (Fig. 337). Is the heel bone
prominent or small?
[Illustration:
FIG. 334.—OCELOT (_Felis pardalis_), of Texas and Mexico. × ⅑.
]
In what direction does the _knee_ of the cat point? The heel? The elbow?
The wrist? Compare the front and the hind _leg_ in length; straightness;
heaviness; number and position of toes; sharpness of the _claws_. What
makes the _dog’s claws_ duller than a cat’s? What differences in habit
go with this? Judging from the toe that has become useless on the fore
foot of the cat, which toe is lacking in the hind foot? Is it the cat’s
thumb or little finger that does not touch the ground? (Fig. 337.)
Locate on your own hand the parts corresponding to the pads on the
forefoot of a cat. Of what use are soft pads on a cat’s foot?
Some animals have short, soft =fur= and long, coarse over hair. Does the
cat have both? Is the cat’s fur soft or coarse? Does the fur have a
colour near the skin different from that at the tip? Why is hair better
suited as a covering for the cat than feathers would be? Scales? Where
are long, stiff bristles found on the cat? Their length suggests that
they would be of what use to a cat in going through narrow places? Why
is it necessary for a cat to be noiseless in its movements?
[Illustration:
FIG. 335.—LYNX (_Lynx rufus_). The “Bob-tailed cat” (North America).
]
Observe the =movements of the cat=.—Why cannot a cat come down a tall
tree head foremost? Did you ever see a cat catch a bird? How does a cat
approach its prey? Name a jumping insect that has long hind legs; an
amphibian; several mammals (Figs. 362, 374). Does a cat ever trot?
Gallop? Does a cat chase its prey? When does the cat move with its heel
on the ground? The claws of a cat are withdrawn by means of a tendon
(see Fig. 338). Does a cat seize its prey with its mouth or with its
feet.?
How does a cat make the purring sound? (Do the lips move? The sides?)
How does a cat drink? Do a cat and dog drink exactly the same way? Is
the cat’s tongue rough or smooth? How is the tongue used in getting the
flesh off close to the bone? Can a cat clean a bone entirely of meat?
[Illustration:
FIG. 336.—JAGUAR, of tropical America.
]
In what state of development is a newly born kitten? With what does the
cat _nourish its young_? Name ten animals of various kinds whose young
are similarly nourished. What is this class of animals called? Why does
a cat bend its back when it is frightened or angry? Does _a cat or a dog
eat_ a greater variety of food? Which refuses to eat an animal found
dead? Will either bury food for future use? Which is sometimes
troublesome on account of digging holes in the garden? Explain this
instinct. Which lived a solitary life when wild? Which had a definite
haunt, or home? Why are dogs more sociable than cats? A dog is more
devoted to his master. Why? A cat is more devoted to its home, and will
return if carried away. Why? Why does a dog turn around before lying
down? (Consider its original environment.)
[Illustration:
FIG. 337.—SKELETON OF CAT.
]
=The Skeleton= (Fig. 337).—Compare the _spinal column_ of a cat in form
and flexibility with the spinal column of a fish, a snake, and a bird.
The _skull_ is joined to the spinal column by two knobs (or _condyls_),
which fit into sockets in the first vertebra. Compare the jaws with
those of a bird and a reptile. There is a prominent ridge in the temple
to which the powerful chewing muscles are attached. There is also a
ridge at the back of the head where the muscles which support the head
are attached (Fig. 348).
[Illustration:
FIG. 338.—CLAW OF CAT (1) retracted by ligament, and (2) drawn down by
muscle attached to lower tendon.
]
Count the _ribs_. Are there more or fewer than in man? The breastbone is
in a number of parts, joined, like the vertebræ, by cartilages. Compare
it with a bird’s sternum; why the difference? The shoulder girdle, by
which the front legs are attached to the trunk, is hardly to be called a
girdle, as the collar bones (clavicles) are rudimentary. (They often
escape notice during dissection, being hidden by muscles.) The shoulder
blades, the other bones of this girdle, are large, but relatively not so
broad toward the dorsal edge as human shoulder blades. The clavicles are
tiny because they are useless. Why does the cat not need as movable a
shoulder as a man? The pelvic, or hip girdle, to which the hind legs are
attached, is a rigid girdle, completed above by the spinal column, to
which it is immovably joined. Thus the powerful hind legs are joined to
the most rigid portion of the trunk.
=Mammals.=—The cat belongs to the _class Mammalia_ or mammals. The
characteristics of the class are that the young are not hatched from
eggs, but _are born alive, and nourished with milk_ (hence have lips),
and the _skin is covered with hair_. The milk glands are situated
ventrally. The position of the class in the animal kingdom was shown
when the cow was classified (p. 9). Their care for the young, their
intelligence, and their ability to survive when in competition with
other animals, causes the mammals to be considered the highest class in
the animal kingdom.
According to these tests, what class of vertebrates should _rank next to
mammals_? Compare the heart, the lungs, the blood, and the parental
devotion of these two highest classes of animals.
[Illustration:
FIG. 339.—SKELETON OF LION (cat family).
]
=The first mammals=, which were somewhat like small opossums, appeared
millions of years ago, when the world was inhabited by giant reptiles.
These reptiles occupied the water, the land, and the air, and their
great strength and ferocity would have prevented the mammals from
multiplying (for at first they were small and weak), but the mammals
carried their young in a pouch until able to care for themselves, while
the reptiles laid eggs and left them uncared for. The first mammals used
reptilian eggs for food, though they could not contend with the great
reptiles. Because birds and mammals are better parents than reptiles,
they have conquered the earth, and the reptiles have been forced into
subordination, and have become smaller and timid.
[Illustration:
FIG. 340.—WALRUS (_Trichechus rosmarus_).
]
=Classification of Mammals=.—Which two have the closest _resemblances_
in the following lists: Horse, cow, deer. Why? Cat, cow, bear. Why?
Monkey, man, sheep. Why? Rat, monkey, squirrel. Why? Giraffe, leopard,
camel. Why? Walrus, cat, cow. Why? Check the five mammals in the
following lists that form a group _resembling one another most closely_:
Lion, bear, pig, dog, squirrel, cat, camel, tiger, man. State your
reasons. Giraffe, leopard, deer, cow, rat, camel, hyena, horse, monkey.
State reasons.
[Illustration:
FIG. 341.—WEASEL, in summer; in Canada in winter it is all white but
tip of tail.
]
[Illustration:
FIG. 342.—FOOT OF BEAR (_Plantigrade_).
]
=Teeth and toes= are the basis for subdividing the class mammalia into
orders. Although the breathing, the circulation, and the internal organs
and processes are similar in all mammals, the external organs vary
greatly because of the varying environments of different species. The
internal structure enables us to place animals together which are
essentially alike; _e.g._ the whale and man are both mammals, since they
resemble in breathing, circulation, and multiplication of young. The
external organs guide us in separating the class into orders. The teeth
vary according to the food eaten. The feet vary according to use in
obtaining food or escaping from enemies. This will explain the
difference in the length of legs of lion and horse, and of the forms of
the teeth in cat and cow. Make a careful study of the teeth and the
limbs as shown in the figures and in all specimens accessible. Write out
the dental formulas as indicated at the top of page 194. The numerals
above the line show the number of upper teeth, those below the line show
the number of lower teeth, in one half of the jaw. They are designated
as follows: _I_, incisors; _C_, canine; _M_, molars. Multiplying by two
gives the total number. Which skulls in the chart have the largest
canines? Why? The smallest, or none at all? Why? Compare the molars of
the cow, the hog, and the dog. Explain their differences. In which
skulls are some of the molars lacking? Rudimentary? Why are the teeth
that do not touch usually much smaller than those that do?
[Illustration:
FIG. 343.—POLAR BEAR (_Ursus maritimus_).
]
KEY, OR TABLE,
FOR CLASSIFYING
MAMMALS (_class
Mammalia_) INTO
ORDERS
│ ORDERS │
=A_{1} Imperfect Mammals=, young hatched │
or prematurely born │
│B_{1} Jaws a birdlike beak, _Mon’otremes_
│ egg-laying
│B_{2} Jaws not beaklike, young _Marsu’pials_
│ carried in pouch
=A_{2} Perfect Mammals=, young not │
hatched, nor prematurely born │
B_{1} │C_{1} Front part of both jaws _Eden’tates_
_Digits │ lack teeth
with │
claws_ │
│C_{2} Teeth with sharp points _Insect’ivors_
„ │ for piercing shells of
│ insects
│C_{3} Canines very long, _Car’nivors_
„ │ molars suited for
│ tearing
„ │C_{4} Canines lacking, _Rodents_
│ incisors very large
B_{2} │C_{1} Head large; carnivorous _Ceta’ceans_
_Digits │
not │
distinct_│
„ │C_{2} Head small; herbivorous _Sire’neans_
B_{3} │C_{1} Five toes, nose _Proboscid’eans_
_Digits │ prolonged into a snout
with │
nails or │
hoofs_ │
„ │C_{2} Toes odd number, less _E’quines_ │_Ungulates_
│ than five │
│C_{3} Toes even number, upper _Ru’minants_ │
„ │ front teeth lacking, │ „
│ chew the cud │
│C_{4} Toes even number, upper _Swine_ │
„ │ front teeth present, │ „
│ not cud-chewers │
„ │C_{5} All limbs having hands _Quad’rumans_
„ │C_{6} Two limbs having hands _Bi’mans_
=Exercise in Classification=.—Copy the following list, and by
reference to figures write the name of its order after each mammal:—
Ape (Figs. 405, 406)
Rabbit (Fig. 345)
Dog (Figs. 356, 408)
Hog (Figs. 357, 393)
Bat (Figs. 347, 370)
Cat (Figs. 337, 348)
Armadillo (Figs. 349, 365)
Cow (Figs. 344, 386)
Walrus (Fig. 340)
Monkey (Figs. 352, 401)
Horse (Figs. 355, 395)
Ant-eater (Figs. 354, 364)
Antelope (Fig. 391)
Mole (Figs. 367, 368)
Beaver (Figs. 372, 373)
Duckbill (Fig. 359)
Tapir (Fig. 384)
Dolphin (Figs. 379, 397)
Use chart of skulls and Figs. 381, 382, 395–400 in working out this
exercise.
Man’s dental formula is (_M_ ⁵⁄₅, _C_ ¹⁄₁, _I_ ²⁄₂)^2 = 32.
In like manner fill out formulas below:—
Cow (_M_—_C_—_I_—)^2 = 32
Rabbit (_M_—_C_—_I_—)^2 = 28
Walrus (_M_—_C_—_I_—)^2 = 34
Bat (_M_—_C_—_I_—)^2 = 34
Cat (_M_—_C_—_I_—)^2 = 30
Armadillo (_M_—_C_—_I_—)^2 = 28
Horse (_M_—_C_—_I_—)^2 = 40
Whale (_M_—_C_—_I_—)^2 = 0
Am. Monkey (_M_—_C_—_I_—)^2 = 36
Sloth (_M_—_C_—_I_—)^2 = 18
Ant-eater (_M_—_C_—_I_—)^2 = 0
Dog (_M_—_C_—_I_—)^2 = 42
Hog (_M_—_C_—_I_—)^2 = 44
Sheep (_M_—_C_—_I_—)^2 = 32
[Illustration:
FIG. 344.—Skull and front of lower jaw of COW.
]
[Illustration:
FIG. 345.—RABBIT. _A_, _B_, incisors; _C_, molars
]
[Illustration:
FIG. 346.—WALRUS (see Fig. 341).
]
[Illustration:
FIG. 347.—BAT.
]
[Illustration:
FIG. 348.—CAT.
]
[Illustration:
FIG. 349.—ARMADILLO.
]
[Illustration:
FIG. 350.—HORSE (front of jaw).
]
[Illustration:
FIG. 351.—GREENLAND WHALE.
]
[Illustration:
FIG. 352.—AMERICAN MONKEY.
]
[Illustration:
FIG. 353.—SLOTH (Fig. 363).
]
[Illustration:
FIG. 354.—ANT-EATER (Fig. 364).
]
[Illustration:
FIG. 355.—HORSE.
]
[Illustration:
FIG. 356.—DOG. Upper (_A_) and lower (_B_) jaw.
]
[Illustration:
FIG. 357.—HOG.
]
[Illustration:
FIG. 358.—SHEEP.
]
[Illustration:
FIG. 359.—DUCKBILL (_Ornithorhynchus paradoxus_).
]
The =lowest order of mammals= contains only two species, the duckbill
and the porcupine ant-eater, both living in the Australian region. Do
you judge that the _duckbill_ of Tasmania (Fig. 359) lives chiefly in
water or on land? Why? Is it probably active or slow in movement? It
dabbles in mud and slime for worms and mussels, etc. How is it fitted
for doing this? Which feet are markedly webbed? How far does the web
extend? The web can be folded back when not in use. It lays two eggs in
a nest of grass at the end of a burrow. Trace resemblances and
differences between this animal and birds.
[Illustration:
FIG. 360.—SPINY ANT-EATER (_Echidna aculeata_). View of under surface
to show pouch. (After Haacke.)
]
The _porcupine ant-eater_ has numerous quill-like spines (Fig. 360)
interspersed with its hairs. (Use?) Describe its claws. It has a long
prehensile tongue. It rolls into a ball when attacked. Compare its jaws
with a bird’s bill. It lays one egg, which is carried in a fold of the
skin until hatched. Since it is pouched it could be classed with the
pouched mammals (next order), but it is egg-laying. Suppose the two
animals in this order did not nourish their young with milk after
hatching, would they most resemble mammals, birds, or reptiles?
Write the name of this _order_. —— (See Table, p. 193.) _Why_ do you
place them in this order (——)? (See p. 193.) The name of the order comes
from two Greek words meaning “one opening,” because the ducts from the
bladder and egg glands unite with the large intestine and form a cloaca.
What other classes of vertebrates are similar in this?
[Illustration:
FIG. 361.—OPOSSUM (_Didelphys Virginianus_).
]
=Pouched Mammals.=—These animals, like the last, are numerous in the
Australian region, but are also found in South America, thus indicating
that a bridge of land once connected the two regions. The _opossum_ is
the only species which has penetrated to North America (Fig. 361). Are
its jaws slender or short? What kinship is thus suggested? As shown by
its grinning, its lips are not well developed. Does this mean a low or a
well-developed mammal? Where does it have a thumb? (Fig. 361.) Does the
thumb have a nail? Is the tail hairy or bare? Why? Do you think it
prefers the ground or the trees? State two reasons for your answer. It
hides in a cave or bank or hollow tree all day, and seeks food at night.
Can it run fast on the ground? It feigns death when captured, and
watches for a chance for stealthy escape.
[Illustration:
FIG. 362.—GIANT KANGAROO.
]
The _kangaroo_ (Fig. 362), like the opossum, gives birth to imperfectly
developed young. (Kinship with what classes is thus indicated?) After
birth, the young (about three fourths of an inch long) are carried in a
ventral pouch and suckled for seven or eight months. They begin to reach
down and nibble grass before leaving the pouch. Compare fore legs with
hind legs, front half of body with hind half. Describe tail. What is it
used for when kangaroo is at rest? In jumping, would it be useful for
propelling and also for balancing the body? Describe hind and fore feet.
_Order_ ——. _Why?_ ________. See key, page 193.
=Imperfectly Toothed Mammals.=—These animals live chiefly in South
America (sloth, armadillo, giant ant-eater) and Africa (pangolin). The
sloth (Fig. 363) eats leaves. Its movements are remarkably slow, and a
vegetable growth resembling moss often gives its hair a green colour.
(What advantage?) How many toes has it? How are its nails suited to its
manner of living? Does it save exertion by hanging from the branches of
trees instead of walking upon them?
[Illustration:
FIG. 363.—SLOTH of South America.
]
[Illustration:
FIG. 364.—GIANT ANT-EATER of South America. (See Fig. 354.) Find
evidences that the edentates are a degenerate order. Describe
another ant-eater (Fig. 360).
]
[Illustration:
FIG. 365.—NINE-BANDED ARMADILLO of Texas and Mexico. (_Dasypus
novemcinctus._) It is increasing in numbers; it is very useful, as
it digs up and destroys insects. (See Fig. 347.)
]
Judging from the figures (363, 364, 365), are the members of this order
better suited for attack, active resistance, passive resistance, or
concealment when contending with other animals? The ant-eater’s claws
(Fig. 364) on the fore feet seem to be a hindrance in walking; for what
are they useful? Why are its jaws so slender? What is probably the use
of the enormous bushy tail? The nine-banded armadillo (Fig. 365) lives
in Mexico and Texas. It is omnivorous. To escape its enemies, it burrows
into the ground with surprising rapidity. If unable to escape when
pursued, its hard, stout tail and head are turned under to protect the
lower side of the body where there are no scales. The three-banded
species (Fig. 366) lives in Argentina. Compare the ears and tail of the
two species; give reasons for differences. Why are the eyes so small?
The claws so large? _Order_______. _Why?_ ______.
[Illustration:
FIG. 366.—THREE-BANDED ARMADILLO (_Tolypeutes tricinctus_).
]
=Insect Eaters.=—The soft interior and crusty covering of insects makes
it unnecessary for animals that prey upon them to have flat-topped teeth
for grinding them to powder, or long cusps for tearing them to pieces.
The teeth of insect eaters, even the molars (Fig. 368), have many sharp
tubercles, or points, for holding insects and piercing the crusty outer
skeleton and reducing it to bits. As most insects dig in the ground or
fly in the air, we are not surprised to learn that some insect-eating
mammals (the bats) fly and others (the moles) burrow. Are the members of
this order friends or competitors of man?
[Illustration:
FIG. 367.—THE MOLE.
]
[Illustration:
FIG. 368.—SKELETON OF MOLE. (Shoulder blade is turned upward.)
]
Why does _the mole_ have very small eyes? Small ears? Compare the shape
of the body of a mole and a rat. What difference? Why? Compare the front
and the hind legs of a mole. Why are the hind legs so small and weak?
Bearing in mind that the body must be arranged for digging and using
narrow tunnels, study the skeleton (Fig. 368) in respect to the
following: Bones of arm (length and shape), fingers, claws, shoulder
bones, breastbone (why with ridge like a bird?), vertebræ (why are the
first two so large?), skull (shape). There are no eye sockets, but there
is a snout gristle; for the long, sensitive snout must serve in place of
the small and almost useless eyes hidden deep in the fur. Is the fur
sleek or rough? Why? Close or thin? It serves to keep the mole clean.
The muscles of neck, breast, and shoulders are very strong. Why? The
mole eats earthworms as well as insects. It injures plants by breaking
and drying out their roots. Experiments show that the Western mole will
eat moist grain, though it prefers insects. If a mole is caught, repeat
the experiment, making a careful record of the food placed within its
reach.
[Illustration:
FIG. 369.—SKELETON OF BAT.
]
As with the mole, the skeletal adaptations of _the bat_ are most
remarkable in the hand. How many fingers? (Fig. 369.) How many nails on
the hand? Use of nail when at rest? When creeping? (Fig. 369.) Instead
of feathers, the flying organs are made of a pair of extended folds of
the skin supported by elongated bones, which form a framework like the
ribs of an umbrella or a fan. How many digits are prolonged? Does the
fold of the skin extend to the hind legs? The tail? Are the finger bones
or the palm bones more prolonged to form the wing skeleton?
[Illustration:
FIG. 370.—VAMPIRE (_Phyllostoma spectrum_) of South America. × ⅙.
]
The skin of the wing is rich in blood vessels and nerves, and serves, by
its sensitiveness to the slightest current of air, to guide the bat in
the thickest darkness. Would you judge that the bat has sharp sight?
Acute hearing?
The moles do not _hibernate_; the bats do. Give the reason for the
difference. If bats are aroused out of a trance-like condition in
winter, they may die of starvation. Why? The mother bat carries the
young about with her, since, unlike birds, she has no nest. How are the
young nourished? _Order_ ________. _Why?_ ________. (Key, p. 193.)
[Illustration:
FIG. 371.—POUCHED GOPHER (_Geomys bursarius_) × ¼, a large, burrowing
field rat, with cheek pouches for carrying grain.
]
[Illustration:
FIG. 372.—Hind foot _a_, fore foot _b_, tail _c_, of BEAVER.
]
[Illustration:
FIG. 373.—BEAVER.
]
=The Gnawing Mammals.=—These animals form the most numerous order of
mammals. They _lack canine_ teeth. Inference? The incisors are four in
number in all species except the rabbits, which have six (see Fig. 345).
They are readily recognized by their _large incisors_. These teeth grow
throughout life, and if they are not constantly worn away by gnawing
upon hard food, they become inconveniently long, and may prevent closing
of the mouth and cause starvation. The hard enamel is all on the front
surface, the dentine in the rear being softer; hence the incisors
sharpen themselves by use to a chisel-like edge. The molars are set
close together and have their upper surfaces level with each other. The
ridges on them run crosswise so as to form a continuous filelike surface
for reducing the food still finer after it has been gnawed off (Fig.
345). The lower jaw fits into grooves in place of sockets. This allows
the jaw to work back and forth instead of sidewise. The rabbits and some
squirrels have a hare lip; _i.e._ the upper lip is split. What advantage
is this in eating? In England the species that burrow are called
rabbits; those that do not are called hares.
[Illustration:
FIG. 374.—POSITION OF LIMBS IN RABBIT.
]
Name six enemies of rabbits. Why does a rabbit usually sit motionless
unless approached very close? Do you usually see one before it dashes
off? A rabbit has from three to five litters of from three to six young
each year. Squirrels have fewer and smaller litters. Why must the rabbit
multiply more rapidly than the squirrel in order to survive? English
rabbits have increased in Australia until they are a plague. Sheep
raising is interfered with by the loss of grass. The Australians now
ship them to England in cold storage for food. Rabbits and most rodents
lead a watchful, timid, and alert life. An exception is the porcupine,
which, because of the defence of its barbed quills, is dull and
sluggish.
The common rodents are:—
squirrels
rabbits
rats
mice
beavers
muskrats
porcupines
guinea pig
pouched gopher
prairie dog
prairie squirrel
chipmunk
ground hog
field mouse
Which of the above rodents are commercially important? Which are
injurious to an important degree? Which have long tails? Why? Short
tails? Why? Long ears? Why? Short ears? Why? Which are aquatic? Which
dig or burrow? Which are largely nocturnal in habits? Which are
arboreal? Which are protected by coloration? Which escape by running? By
seeking holes?
[Illustration:
FIG. 375.—FLYING SQUIRREL (_Pteromys volucella_). × ¼.
]
=Economic Importance.=—Rabbits and squirrels destroy the eggs and young
of birds. Are rabbits useful? Do they destroy useful food? The use of
beaver and muskrat skins as furs will probably soon lead to their
extinction. Millions of rabbits’ skins are used annually, the hair being
made into felt hats. There are also millions of squirrel skins used in
the fur trade. The hairs of the tail are made into fine paint brushes.
The skins of common rats are used for the thumbs of kid gloves. _Order_
________. _Why?_ ________.
=Elephants.=—Elephants, strange to say, have several noteworthy
resemblances to rodents. Like them, elephants have no canine teeth;
their molar teeth are few, and marked by transverse ridges and the
incisors present are prominently developed (Figs. 376, 377). Instead of
four incisors, however, they have only two, the enormous tusks, for
there are no incisors in the lower jaw. Elephants and rodents both
subsist upon plant food. Both have peaceful dispositions, but one order
has found safety and ability to survive by attaining enormous size and
strength; the other (_e.g._ rats, squirrels) has found safety in small
size. Explain.
[Illustration:
FIG. 376.—HEAD OF AFRICAN ELEPHANT.
]
Suppose you were to observe an elephant for the first time, without
knowing any of its habits. How would you know that it does not eat meat?
That it does eat plant food? That it can defend itself? Why would you
make the mistake of thinking that it is very clumsy and stupid? Why is
its skin naked? Thick? Why must its legs be so straight? Why must it
have either a very long neck or a substitute for one? (Fig. 376.) Are
the eyes large or small? The ears? The brain cavity? What anatomical
feature correlates with the long proboscis? Is the proboscis a new organ
not found in other animals, or is it a specialization of one or more old
ones? Reasons? What senses are especially active in the proboscis? How
is it used in drinking? In grasping? What evidence that it is a
development of the nose? The upper lip?
[Illustration:
FIG. 377.—MOLAR TOOTH OF AFRICAN ELEPHANT.
]
The tusks are of use in uprooting trees for their foliage and in digging
soft roots for food. Can the elephant graze? Why, or why not? There is a
finger-like projection on the end of the snout which is useful in
delicate manipulations. The feet have pads to prevent jarring; the nails
are short and hardly touch the ground. _Order_ ________. _Why?_
________. Key, page 193.
=Whales, Porpoises, Dolphins.=—As the absurd mistake is sometimes made
of confusing _whales_ with fish, the pupil may compare them in the
following respects: eggs, nourishment of young, fins, skin, eyes, size,
breathing, temperature, skeleton (Figs. 209, 379, and 397).
[Illustration:
FIG. 378.—HARPOONING GREENLAND WHALE (see Fig. 351).
]
_Porpoises and dolphins_, which are smaller species of whales, live near
the shore and eat fish. Explain the expression “blow like a porpoise.”
They do not exceed five or eight feet in length, while the deep-sea
whales are from thirty to seventy-five feet in length, being by far the
largest animals in the world. The size of the elephant is limited by the
weight that the bones and muscles support and move. The whale’s size is
not so limited.
The _whale_ bears one young (rarely twins) at a time. The mother
carefully attends the young for a long time. The _blubber_, or thick
layer of fat beneath the skin, serves to retain heat and to keep the
body up to the usual temperature of mammals in spite of the cold water.
It also serves, along with the _immense lungs_, to give lightness to the
body. Why does a whale need large lungs? The _tail of a whale_ is
horizontal instead of vertical, that it may steer upward rapidly from
the depths when needing to breathe. The _teeth_ of some whales do not
cut the gum, but are reabsorbed and are replaced by horny plates of
“whalebone,” which act as strainers. Give evidence from the flippers,
lungs, and other organs, that the whale is descended from a land mammal
(Fig. 397). Compare the whale with a typical land mammal, as the dog,
and enumerate the specializations of the whale for living in water. What
change took place in the general form of the body? It is believed that
on account of scarcity of food the land ancestors of the whale, hundreds
of thousands of years ago, took to living upon fish, etc., and,
gradually becoming swimmers and divers, lost the power of locomotion on
land. _Order_____. _Why?_____.
[Illustration:
FIG. 379.—DOLPHIN.
]
Elephants are rapidly becoming extinct because of the value of their
ivory tusks. Whales also furnish valuable products, but they will
probably exist much longer. Why?
[Illustration:
FIG. 380.—MANATEE, or sea cow; it lives near the shore and eats
seaweed. (Florida to Brazil.)
]
The =manatees and dugongs= (sea cows) are a closely related order living
upon water plants, and hence living close to shore and in the mouths of
rivers. _Order_____. _Why?_ ____.
=Hoofed Mammals.=—All the animals in this order walk on the tips of
their toes, which have been adapted to this use by the claws having
developed into _hoofs_. The order is subdivided into the _odd-toed_
(such as the horse with one toe and the rhinoceros with three) and the
_even-toed_ (as the ox with two toes and the pig with four). All the
even-toed forms except the pig and hippopotamus chew the cud and are
given the name of _ruminants_.
[Illustration:
FIG. 381.—Left leg of man, left hind leg of dog and horse; homologous
parts lettered alike.
]
=Horse and Man Compared.=—To which finger and toe on man’s hand and foot
does a horse’s foot correspond? (Figs. 381, 383, 399.) Has the horse
kneecaps? Is its heel bone large or small? Is the fetlock on toe,
instep, or ankle? Does the part of a horse’s hind leg that is most
elongated correspond to the thigh, calf, or foot in man? On the fore
leg, is the elongated part the upper arm, forearm, or hand? (Figs. 395,
399.) Does the most elongated part of the fore foot correspond to the
finger, the palm, or the wrist? (Fig. 382.) On the hind foot is it toe,
instep, or ankle? Is the fore fetlock on the finger, the palm, or the
wrist? (Figs. 382, 385, 399.) Is the hock at the toe, the instep, the
heel, or the knee?
=Specializations of the Mammals.=—The early mammals, of which the
present marsupials are believed to be typical, had five toes provided
with claws. They were not very rapid in motion nor dangerous in fight,
and probably ate both animal and vegetable food.
[Illustration:
FIG. 382.—SKELETONS OF FEET OF MAMMALS.
_P_, horse; _D_, dolphin; _E_, elephant; _A_, monkey; _T_, tiger; _O_,
aurochs;
_F_, sloth; _M_, mole.
=Question=: Explain how each is adapted to its specialized function.
]
[Illustration:
FIG. 383.—Feet of the ancestors of the horse.
]
According to the usual rule, they tended to increase faster than the
food supply, and there were continual contests for food. Those whose
claws and teeth were sharper drove the others from the food, or preyed
upon them. Thus the specialization into the bold flesh eating beasts of
prey and the timid vegetable feeders began. Which of the flesh eaters
has already been studied at length? The insectivora escaped their
enemies and found food by learning to burrow or fly. The rodents
accomplished the same result either by acquiring great agility in
climbing, or by living in holes, or by running. The proboscidians
acquired enormous size and strength. The hoofed animals found safety in
flight.
[Illustration:
FIG. 384.—TAPIR OF SOUTH AMERICA (_Tapirus americanus_). × ¹⁄₂₅.
=Questions=: How does it resemble an elephant? (Fig. 376.) A horse?
(p. 210.)
]
[Illustration:
FIG. 385.—HORSE, descended from a small wild species still found in
Western Asia.
]
=Ungulates=, as the horse, need no other protection than their great
speed, which is due to lengthening the bones of the legs and rising upon
the very tip of the largest toe, which, to support the weight, developed
an enormous toe-nail called a hoof. The cattle, not having developed
such speed as the horse, usually have horns for defence. If a calf or
cow bellows with distress, all the cattle in the neighbourhood rush to
the rescue. This unselfish instinct to help others was an aid to the
survival of wild cattle living in regions infested with beasts of prey.
Which of Æsop’s fables is based upon this instinct? The habit of rapid
grazing and the correlated habit of chewing the cud were also of great
value, as it enabled cattle to obtain grass hurriedly and to retire to a
safe place to chew it. Rudiments of the upper incisors are present in
the jaw of the calf, showing the descent from animals which had a
complete set of teeth. The rudiments are absorbed and the upper jaw of
the cow lacks incisors entirely, as they would be useless because of the
cow’s habit of seizing the grass with her rough tongue and cutting it
with the lower incisors as the head is jerked forward. This is a more
rapid way of eating than by biting. Which leaves the grass shorter after
grazing, a cow or a horse? Why? Grass is very slow of digestion, and the
ungulates have an alimentary canal twenty to thirty times the length of
the body. Thorough chewing is necessary for such coarse food, and the
ungulates which chew the cud (ruminants) are able, by leisurely and
thorough chewing, to make the best use of the woody fibre (cellulose)
which is the chief substance in their food.
[Illustration:
FIG. 386.—SKELETON OF COW. Compare with horse (Fig. 395) as to legs,
toes, tail, mane, dewlap, ears, body.
]
=Ruminants= have four divisions to the stomach. Their food is first
swallowed into the roomy _paunch_ in which, as in the crop of a bird,
the bulky food is temporarily stored. It is not digested at all in the
paunch, but after being moistened, portions of it pass successively into
the _honeycomb_, which forms it into balls to be belched up and ground
by the large molars as the animal lies with eyes half closed under the
shade of a tree. It is then swallowed a second time and is acted upon in
the third division (or _manyplies_) and the fourth division (or _reed_).
Next it passes into the intestine. Why is the paunch the largest
compartment? In the figure do you recognize the paunch by its size? The
honeycomb by its lining? Why is it round? The last two of the four
divisions may be known by their direct connection with the intestine.
[Illustration:
FIG. 387.—Food traced through stomachs of cow. (Follow arrows.)
]
[Illustration:
FIG. 388.—Section of cow’s stomachs. Identify each. (See text.)
]
[Illustration:
FIG. 389.—OKAPI. This will probably prove to be the last large mammal
to be discovered by civilized man. It was found in the forests of
the Kongo in 1900.
=Questions=: It shows affinities (find them) with giraffe, deer, and
zebra. It is a ruminant ungulate (explain meaning—see text).
]
The true _gastric juice_ is secreted only in the fourth stomach. Since
the cud or unchewed food is belched up in balls from the round
“honeycomb,” and since a ball of hair is sometimes found in the stomach
of ruminants, some ignorant people make the absurd mistake of calling
the ball of hair the cud. This ball accumulates in the paunch because of
the friendly custom cows have of combing each other’s hair with their
rough tongues, the hair sometimes being swallowed. Explain the saying
that if a cow stops chewing the cud she will die.
[Illustration:
FIG. 390.—AFRICAN CAMEL (_Camelus dromedarius_).
]
[Illustration:
FIG. 391.—PRONG-HORNED ANTELOPE (_Antelocarpa Americana_).
]
Does a cow’s lower jaw move sidewise or back and forth? Do the ridges on
the molars run sidewise or lengthwise? Is a cow’s horn hollow? Does it
have a bony core? (Fig. 344.)
The permanent hollow horns of the cow and the solid deciduous horns of
the deer are typical of the two kinds of horns possessed by ruminants.
The prong-horned antelope (Fig. 391) of the United States, however, is
an intermediate form, as its horns are hollow, but are shed each year.
The hollow horns are a modification of hair. Do solid or hollow horns
branch? Which are possessed by both sexes? Which are pointed? Which are
better suited for fighting? Why would the deer have less need to fight
than the cattle? Deer are polygamous, and the males use their horns
mostly for fighting one another. The sharp hoofs of deer are also
dangerous weapons. The white-tail deer (probably the same species as the
Virginian red deer) is the most widely distributed of the American deer.
It keeps to the lowlands, while the black-tailed deer prefers a hilly
country. The moose, like the deer, browses on twigs and leaves. The elk,
like cattle, eats grass.
[Illustration:
FIG. 392.—ROCKY MOUNTAIN SHEEP (_Ovis montana_). × ¹⁄₂₄.
]
The native sheep of America is the big horn, or Rocky Mountain sheep
(Fig. 392). The belief is false that they alight upon their horns when
jumping down precipices. They post sentinels and are very wary. There is
also a native goat, a white species, living high on the Rocky Mountains
near the snow. They are rather stupid animals. The bison once roamed in
herds of countless thousands, but, with the exception of a few protected
in parks, it is now extinct. Its shaggy hide was useful to man in
winter, so it has been well-nigh destroyed. For gain man is led to
exterminate elephants, seals, rodents, armadillos, whales, birds, deer,
mussels, lobsters, forests, etc.
[Illustration:
FIG. 393.—PECCARY (_Dicotyles torquatus_) of Texas and Mexico. × ¹⁄₁₂.
]
Our only native hog is the peccary, found in Texas (Fig. 393). In
contrast with the heavy domestic hog, it is slender and active. It is
fearless, and its great tusks are dangerous weapons. The swine are the
only ungulates that are not strictly vegetable feeders. The habit of
fattening in summer was useful to wild hogs, since snow hid most of
their food in winter. The habit has been preserved under domestication.
Are the small toes of the hog useless? Are the “dew claws” of cattle
useless? Will they probably become larger or smaller? _Order?_
[Illustration:
FIG. 394.—BIRD.
]
[Illustration:
FIG. 395.—HORSE.
]
[Illustration:
FIG. 396.—OX.
]
[Illustration:
FIG. 397.—DOLPHIN.
]
[Illustration:
FIG. 398.—FISH.
]
[Illustration:
FIG. 399.—MAN.
]
[Illustration:
FIG. 400.—CHIMPANZEE. (See Fig. 406.)
]
=Illustrated Study of Vertebrate Skeletons=: Taking man’s skeleton as
complete, which of these seven skeletons is most incomplete?
Regarding the fish skeleton as the original vertebrate skeleton, how
has it been modified for (1) walking, (2) walking on two legs, (3)
flying?
Which skeleton is probably a degenerate reversion to original type?
(p. 209.)
How is the horse specialized for speed?
Do all have tail vertebræ, or vertebræ beyond the hip bones? Does each
have shoulder blades?
Compare (1) fore limbs, (2) hind limbs, (3) jaws of the seven
skeletons. Which has relatively the shortest jaws? Why? What seems to
be the typical number of ribs? limbs? digits?
Does flipper of a dolphin have same bones as arm of a man?
How many thumbs has a chimpanzee? Which is more specialized, the foot
of a man or that of a chimpanzee? Is the foot of a man or that of a
chimpanzee better suited for supporting weight? How does its
construction fit it for this?
Which has a better hand, a man or a chimpanzee? What is the difference
in their arms? Does difference in structure correspond to difference
in use?
Which of the seven skeletons bears the most complex breastbone?
Which skeleton bears no neck (or cervical) vertebræ? Which bears only
one?
Are all the classes of vertebrates represented in this chart? (p.
125.)
[Illustration:
FIG. 401.—SACRED MONKEY OF INDIA (_Semnopithecus entellus_). × ¹⁄₁₂.
]
[Illustration:
FIG. 402.—LEMUR (_Lemur Mongoz_). × ⅒. Which digit bears a claw?
]
=Monkeys, Apes, and Man.=—Study the figures (399, 400); compare apes and
man and explain each of the differences in the following list: (1) feet,
three differences; (2) arms; (3) brain case; (4) jaws; (5) canine teeth;
(6) backbone; (7) distance between the eyes.
_A hand_, unlike a foot, has one of the digits, called a thumb, placed
opposite the other four digits that it may be used in grasping.
Two-handed man and four-handed apes and monkeys are usually placed in
one order, the _Primates_, or in two orders (see table, page 193). The
lowest members of this order are the _lemurs_ of the old world. Because
of their hands and feet being true grasping organs, they are placed
among the primates, notwithstanding the long muzzle and expressionless,
foxlike face. (Fig. 402.) Next in order are the _tailed monkeys_, while
the _tailless apes_ are the highest next to man.
[Illustration:
FIG. 403.—BROAD-NOSED MONKEY. × ⅒. America.
]
[Illustration:
FIG. 404.—NARROW-NOSED MONKEY. × ¹⁄₁₂. Old World.
]
[Illustration:
FIG. 405.—GORILLA. (Size of a man.)
]
The _primates of the New World_ are all monkeys with long tails and
broad noses. They are found from Paraguay to Mexico. The _monkeys and
apes of the Old World_ have a _thin partition_ between the nostrils, and
are thus distinguished from the monkeys of the New World, which have a
_thicker partition_ and have a broader nose. (Figs. 403, 404.) The
monkeys of America all have _six molar teeth_ in each half jaw (Fig.
352); the monkeys and apes of the Old World have thirty-two teeth, which
agree both in number and arrangement with those of man.
[Illustration:
FIG. 406.—CHIMPANZEE.
]
Which of the primates figured in this book appear to have the arm longer
than the leg? Which have the eyes directed forward instead of sideways,
as with cats or dogs?
Nearly all the primates are _forest dwellers_, and inhabit warm
countries, where the boughs of trees are never covered with ice or snow.
Their _ability in climbing_ serves greatly to protect them from beasts
of prey. Many apes and monkeys are able to assume the upright position
in walking, but they touch the ground with their knuckles every few
steps to aid in preserving the balance.
The _Simians_ are the highest family of primates below man, and include
the gorilla, chimpanzee, orang, and gibbon. Some of the simians weave
together branches in the treetops to form a rude nest, and all are very
affectionate and devoted to their young. How are apes most readily
distinguished from monkeys? (Figs. 401, 406.)
[Illustration:
FIG. 407.—ANATOMY OF RABBIT.
]
_a_, incisor teeth;
_b_, _b′_, _b″_, salivary glands;
_k_, larynx;
_l_, windpipe;
_c_, gullet;
_d_, diaphragm (possessed only by mammals);
_e_, stomach;
_g_, small intestine;
_h_, _h′_, large intestine;
_f_, junction of small and large intestine;
_g_, _g′_, cæcum, or blind sac from _f_ (corresponds to the shrunken
rudimentary vermiform appendix in man);
_m_, carotid arteries;
_n_, heart;
_o_, aorta;
_p_, lungs;
_q_, end of sternum;
_r_, spleen;
_s_, kidney;
_t_, ureters (from kidney to bladder _v_).
2. brain of rabbit:
_a_, olfactory nerves;
_b_, cerebrum;
_c_, midbrain;
_d_, cerebellum.
Table for Review
══════════════════════╤══════╤══════╤══════╤══════╤══════╤══════╤══════
│ FISH │ FROG │TURTLE│ BIRD │ CAT │HORSE │ MAN
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Names of limbs │ │ │ │ │ │ │
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Acutest sense │ │ │ │ │ │ │
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Digits on fore and │ │ │ │ │ │ │
hind limb │ │ │ │ │ │ │
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Locomotion │ │ │ │ │ │ │
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Kind of food │ │ │ │ │ │ │
──────────────────────┼──────┼──────┼──────┼──────┼──────┼──────┼──────
Care of young │ │ │ │ │ │ │
══════════════════════╧══════╧══════╧══════╧══════╧══════╧══════╧══════
[Illustration]
St. Bernard German Pointer Newfoundland
mastiff
Eskimo English Bulldog Shepherd
bloodhound
Poodle Greyhound Spitz
Dachshund
FIG. 408.—ARTIFICIAL SELECTION. Its effects in
causing varieties in one species. Which of
the dogs is specialized for speed? Driving
cattle? Stopping cattle? Trailing by scent?
Finding game? Drawing vehicles? Going into
holes? House pet? Cold weather? In Mexico
there is a hairless dog specialized for hot
climates. The widely differing environments
under various forms of domestication cause
“sports” which breeders are quick to take
advantage of when wishing to develop new
varieties. Professor De Vries by cultivating
American evening primroses in Europe has
shown that a sudden change of environment
may cause not only varieties but new species
to arise.
INDEX
Aboral surface, 35.
Acephala, 107.
Adaptation to environment, 148, 185, 201, 205, 207.
Ambulacral, 36.
Amœba, 10.
Anodon, 98.
Antelope, 215.
Antennæ, 68, 87.
Ant-eater, giant, 199;
spiny, 196.
Ant lion, 91.
Ape, 220.
Aptera, 82.
Apteryx, 174.
Aquarium, 17.
Argonaut, paper, 107.
Armadillo, 200.
Arthropoda, 9, 125.
Bat, 202.
Batrachia, 126.
Beaver, 204.
Bedbug, 92, 93.
Bee, bumble, 89;
honey, 88.
Beetle, 90, 91.
Big-headed turtle, 149.
Bilateral, 34, 49, 98.
Bill of bird, 151.
Biology defined, 1.
Birds, 150.
Blood, of insects, 78.
Boll weevil, 95, 96.
Boll worm, 95, 96.
Brain, of fish, 118.
Breathing, of bird, 161;
of insect, 76.
Bureau of entomology, 95.
Butterfly, 83.
Cabbage butterfly, 84, 86, 87.
Camel, 214.
Candle, 5.
Carbon dioxide, 24.
Carp, 112, 117, 123.
Cat, 184.
Caterpillar, tent, 84.
Cell, 6, 7.
Celom, 46.
Cephalopod, 106.
Chelonia, 143.
Chimpanzee, 219, 221.
Chirping, 66.
Chitin, 77.
Cilia, 14, 20, 101, 103.
Ciliated chamber, 17.
Circulation, in amœba, 12;
in insect, 77;
in fish, 117.
Clam, hardshell, 104;
softshell, 104.
Class, 9.
Classification, of animals, 8, 125;
of birds, 177;
insects, 82;
mammals, 193.
Click beetle, 91.
Clitellum, 43, 47.
Cloaca, 18.
Clothes moth, 84, 92, 93.
Cockroach, 71.
Cocoon, 84.
Codling moth, 84, 86, 87, 95.
Cœlenterata, 28.
Coleoptera, 82.
Collecting insects, 72.
Colorado beetle, 90, 91.
Coloration, warning, 84, 146;
protective, 34, 37, 49.
Colours of flowers, 85.
Comparative study, 85, 108, 122, 223;
moth and butterfly, 85.
Copper head, 145.
Coral, 31.
Coralline, 31.
Coral snake, 145, 146.
Cricket, 71.
Cross-fertilization, 25.
Cuckoo, 179.
Cuttlefish, 107.
Cypræa, 104.
Cysts, 13.
Darwin, 48, 148.
Devil’s horse, 71.
De Vries, 148, 224.
Digits, 222.
Diptera, 82.
Division of labour, 27, 29.
Dog, 224.
Dolphin, 209.
Doodle bug, 91.
Dorsal, 43.
Dove, 179.
Dragon fly, 93.
Duckbill, 196.
Ear, of bird, 151;
of frog, 131;
of fish, 112.
Earthworm, 42.
Echinoderms, 9, 34, 125.
Economic importance of birds, 167;
insects, 93;
molluscs, 105;
rodents, 206.
Ectoderm, 26, 87.
Ectoplasm, 11, 14.
Egg, of insect, 81.
Endoderm, 26, 27, 37.
Endoplasm, 11, 14.
Energy, in amœba, 12;
organic, 2, 3;
plant, 2, 3, 5.
Environment, 148.
Epidermis, of mussel, 98.
Excretion, 12.
Eye, of bird, 150;
of frog, 30;
of grasshopper, 67, 79;
of fish, 111.
Family, 8.
Fangs, venomous, 145.
Farmers’ bulletins, 95.
Feather, 155.
Fertilization, cross, 85.
Field study, 10, 22, 42, 71, 72, 97, 127, 165, 166, 167, 184.
Fins, 110, 113.
Flagellum, 21, 27.
Flatworm, 49.
Flea, 92, 93.
Flight, of bird, 157, 175;
of moth, 84.
Fly, horse, 81;
house, 92, 93.
Food, of birds, 177.
Food tube, of bird, 163;
of fish, 116;
of insect, 76;
of mussel, 102.
Foraminifera, 15, 18.
Frog, 128.
Function, 1.
Ganglion, 45.
Gasteropod, 108.
Gastrula, 7.
Genus, 8.
Geographical barriers, 148.
Gila monster, 147.
Gills, of mussel, 100;
of fish, 115.
Gnawing mammals, 203.
Gopher, pouched, 204.
Gorilla, 221.
Grantia, 18.
Grasshopper, 70.
Gypsy moth, 95.
Hands, defined, 220.
Heart, insect, 77.
Hemiptera, 82.
Heredity, 147, 153.
Hessian fly, 95.
Horned toad, 140.
House fly, 92, 93.
Human species, 220.
Hydra, 22.
Hydranth, 29.
Hydroid, 28, 29, 30.
Hymenoptera, 82.
Hypostome, 23.
Ichneumon fly, 89.
Imago, 81.
Infusoria, 16.
Inorganic, 1.
Insecticides, 95.
Insects, 73, 75;
biting, 82;
classified, 82;
sucking, 82.
Instinct, 80, 121.
Jacana, Mexican, 178.
Jay, blue, 181.
Jelly fish, 29, 30.
Kangaroo, 198.
Kidneys, of fish, 117;
of insects, 76;
of mussel, 102;
of worm, 45.
Labial palpi, 68, 74, 101.
Labium, 68, 74.
Labrum, 68, 74.
Lady bug, 91.
Lamellibranch, 107.
Lark, meadow, 182;
sky, 179.
Larva, 81.
Lasso cell, 34.
Leg, of bird, 152;
of horse, 210;
of insect, 74.
Lemur, 220.
Lepidoptera, 82, 87.
Louse, 92, 93.
Lungs, of bird, 165.
Madreporite, 35.
Mammal, 184;
classified, 193;
defined, 189.
Manatee, 209.
Mandibles, 68, 74.
Mantis, praying, 3.
Mantle, 99.
Maxillæ, 68, 74.
Maxillary palpi, 68, 74.
May beetle, 90, 91.
May fly, 83.
Measuring worm, 81, 84.
Medusa, 31.
Mesoglea, 26.
Metamorphosis of insect, 80, 81, 82.
Metazoan, 1.
Migration of birds, 171, 173.
Mimicry, 146.
Moccasin, 145.
Mole, 201.
Mollusc, 9, 97, 125.
Moulting, 69, 174.
Monkey, 220.
Morula, 7.
Mosquito, 92, 93, 96.
Moth, 83.
Mother-of-pearl, 99.
Mussel, 96, 103.
Nautilus, chambered, 107.
Nectar, 8.
Nephridium, 45.
Nervous system, of bee, 78;
of mussel, 102.
Nest building, 166, 182.
Neuroptera, 82.
Nostril, of bird, 151;
of fish, 112.
Nucleolus, 6.
Nucleus, 6, 11, 14.
Octopus, 106.
Okapi, 214.
Omnivorous, 47.
One-celled animals, 7.
Opossum, 197.
Oral surface, 35.
Orang, 227.
Order, 9.
Organ, 1.
Organism, 1.
Orthoptera, 82.
Osculum, 18.
Ovary, 25, 37, 117.
Oviduct, 46.
Oxidation, 3, 4, 5.
Oxygen, 4, 5.
Oyster, 104.
Paramecium, 13.
Parasites, 49, 93.
Partridge, 178.
Pearls, 105.
Peccary, 217.
Perch, 109, 110, 123.
Pests, insect, 93.
Pheasant, 174.
Plastron, 141.
Pollen, 85.
Pollen basket, 88.
Polyp, 9, 22, 125.
Portuguese man-o’-war, 28.
Potato bug, 90.
Primates, 220.
Proboscis, of butterfly, 83, 87;
elephant, 207.
Prolegs, 84, 87.
Protection of birds, 171.
Protective resemblance, 34, 146.
Protoplasm, 6, 11.
Protozoa, 7, 9, 11, 125.
Pseudoneuroptera, 82.
Pseudopod, 11.
Quill, 156.
Rabbit, 205, 223.
Radial symmetry, 34, 125.
Rattlesnake, 145.
Rectum, 134.
Regeneration of lost parts, 37.
Reproduction, 12, 15, 20, 25, 37, 46, 120.
Reptiles, 139.
Rhizopoda, 16.
Road runner, 169.
Robin, 183.
Rotifer, 49.
Round worm, 49.
Ruminant, 213.
Salamander, 134, 138, 139.
Sandworm, 49.
San José scale, 95.
Scab in sheep, 95.
Scales, of bird, 161;
fish, 110;
moth, 89.
Scallops, 104.
Scarab, 90, 91.
Sea anemone, 33.
Sea fan, 32.
Sea horse, 124.
Sea urchin, 38.
Senses of insects, 76.
Setæ, 43, 48.
Sexual selection, 174.
Shark, 121.
Silkworm, 84, 86, 95.
Silver scale, 83.
Siphon, 101.
Siphonoptera, 82.
Skeleton, of bird, 152;
cat, 188;
frog, 131;
of fish, 113;
chart of, 218.
Skull, mammalian, 194.
Slipper animalcule, 13.
Sloth, 199.
Slug, 105.
Snail, 105.
Soil, 48.
Sparrow, 182;
English, 170.
Specialization, 20, 27, 66, 210.
Species, 8.
Spermary, 25, 27.
Spicule, 18.
Spider, 94.
Spiracle, 77, 87.
Sponges, 17, 125;
glass, 19;
horny, 19;
limy, 19.
Sports, 148, 224.
Squash bug, 93, 95.
Squid, 106.
Stickleback, 119.
Struggle to live, 147.
Study, comparative, 82, 149, 223.
Sun energy, 2.
Sunlight, 2.
Survival of fittest, 147.
Tadpole, 126, 134.
Tapeworm, 49.
Tarantula, 94.
Teeth, of frog, 130.
Terrapin, 143, 144.
Toad, 137.
Tortoise, 140, 143, 144.
Trap-door spider, 94.
Tube feet, 35.
Tumble bug, 90, 91.
Turtle, 140, 143, 144.
Umbo, 98.
Ungulate, 212.
Vacuole, 11, 12, 14.
Vampire, 203.
Variation, 147.
Variety, 8.
Venomous snakes, 143.
Vent, 42.
Ventral, 43.
Vermes, 9, 125.
Vertebrates, 9, 125.
Vertebrate skeletons, 218.
Viscera, of bird, 163.
Warning sound, 147.
Wasps, digging, 89.
Weevil, 90, 91, 96.
Whale, 208.
Wings, of grasshopper, 67;
of bird, 153, 158.
Woodpecker, 180.
Worms, 42.
Zoology defined, 1.
Zoophytes, 33.
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TRANSCRIBER’S NOTES
Page Changed from Changed to
61 Have you seen crayfish with one Have you seen crayfish with one
claw smaller than the claw smaller than the other?
1. Typos fixed; non-standard spelling and dialect retained.
2. Enclosed italics font in _underscores_.
3. Enclosed bold font in =equals=.
4. The caret (^) serves as a superscript indicator, applicable to
individual characters (like 2^d) and even entire phrases (like
1^{st}).
5. Subscripts are shown using an underscore (_) with curly braces { },
as in H_{2}O.