Study of a Turtle or a Tortoise

Suggestions.—Because of the ease with which a tortoise or a turtle may be caught and their movements and habits studied, it is suggested that one of these be studied as an example of reptiles. Besides a live specimen, a skeleton of one species and the shells of several species should be available.

Fig. 266.—European Pond Turtle (Emys lutaria). (After Brehms.)

The body (of a turtle or a tortoise) is divided distinctly into regions (Fig. [266]). Is there a head? Neck? Trunk? Tail? The trunk is inclosed by the so-called shell, which consists of an upper portion, the carapace, and a lower portion, the plastron. How are the other regions covered? What is the shape of the head? Is the mouth at the front, or on the under side? Where are the nostrils? Are the motions of breathing visible? Is there a beak or snout? Do the jaws contain teeth?

Do the eyes project? Which is thinner and more movable, the upper or the lower lid? Identify the third eyelid (nictitating membrane). It is translucent and comes from, and is drawn into, the inner corner of the eye. It cleanses the eyeball. Frogs and birds have a similar membrane. The circular ear drum is in a depression back of the angle of the mouth. What other animal studied has an external ear drum?

The tortoise has a longer, more flexible neck than any other reptile. Why does it have the greatest need for such a neck? Is the skin over the neck tight or loose? Why?

Do the legs have the three joints or parts found on the limbs of most vertebrates? How is the skin of the legs covered? Do the toes have claws? Compare the front and the hind feet. Does the tortoise slide its body or lift it when walking on hard ground? Lay the animal on its back on a chair or a table at one side of the room in view of the class. Watch its attempts to right itself. Are the motions suited to accomplish the object? Does the tortoise succeed?

What are the prevailing colours of turtles? How does their colouration correspond to their surroundings?

What parts of the tortoise extend at times beyond the shell? Are any of these parts visible when the shell is closed? What movements of the shell take place as it is closed? Is the carapace rigid throughout? Is the plastron?

Fig. 267.—Skeleton of European Tortoise.
C, rib plates; M, marginal plates; B, plastron; H, humerus bone; R, radius; U, ulna; Fe, femur.

The Skeleton (Fig. [267]).—The carapace is covered with thin epidermal plates which belong to the skin. The bony nature of the carapace is seen when the plates are removed, or if its inner surface is viewed (Fig. [267]). It is seen to consist largely of wide ribs (how many?) much flattened and grown together at their edges. The ribs are seen to be rigidly attached to the vertebræ. The rear projections of the vertebræ are flattened into a series of bony plates which take the place of the sharp ridge found along the backs of most vertebrates. Show that the shell of a turtle is not homologous with the shells of mollusks. Does the turtle have shoulder blades and collarbones? Hipbones? Thigh bones? Shin bone (fibia) and splint bone (fibula)? (Fig. [267].)

Fig. 268.—Three-chambered Heart of a Reptile (tortoise).
a, veins; b, f, right and left auricles; cg, ventricle; d, arteries to lungs; e, veins from lungs; i, n, two branches of aorta. Compare with Fig. [269] and coloured Fig. [2].

Do the plates formed by the ribs extend to the edge of the carapace? See Fig. [267]. About how many bony plates form the carapace? The plastron? Do the horny plates outside correspond to the bony plates of the shell? How many axial plates? How many costal (rib) plates? How many border plates? Which plates are largest? Smallest? Do the horny plates overlap like shingles, or meet edge to edge? Is there any mark where they meet on the bony shell? Basing it upon foregoing facts, give a connected and complete description of the structure of the carapace. Compare the skeleton of the turtle with that of the snake, and correlate the differences in structure with differences in habits.

Fig. 269.—Plan of Reptilian Circulation. See arrows.

Draw the tortoise seen from the side or above, with its shell closed, showing the arrangement of the plates.

Fig. 270.—Reptilian Viscera (lizard).
lr, windpipe; h, heart; lu, lungs; lr, liver; ma, stomach; dd, md, intestines; hb, bladder.

Place soft or tender vegetable food, lettuce, mushroom, roots, berries, and water, also meat, in reach of the turtle. What does it prefer? How does it eat? It has no lips; how does it drink?

Study the movements of its eyeballs and eyelids, and the respiratory and other movements already mentioned. State a reason for thinking that no species of land animals exists that lacks the simple power of righting itself when turned on its back.

Tortoise, Turtle, Terrapin.—The turtles belong to the order of reptiles called chelonians. No one can have any difficulty in knowing a member of this order. The subdivision of the order into families is not so easy, however, and the popular attempts to classify chelonians as turtles, tortoises, and terrapins have not been entirely successful. Species with a vaulted shell and imperfectly webbed toes and strictly terrestrial habits are called tortoises. Species with flattened shells and strictly aquatic habits should be called terrapins (e.g. mud terrapin). They have three instead of two joints in the middle toe of each foot. The term turtle may be applied to species which are partly terrestrial and partly aquatic (e.g. snapping turtle (Fig. [271])). Usage, however, is by no means uniform.

Fig. 271.—Snapping Turtle (Chelydra serpentina).

Most reptiles eat animal food; green terrapins and some land tortoises eat vegetable food. Would you judge that carnivorous chelonians catch very active prey?

The fierce snapping turtle, found in ponds and streams, sometimes has a body three feet long. Its head and tail are very large and cannot be withdrawn into the shell. It is carnivorous and has great strength of jaw. It has been known to snap a large stick in two. The box tortoise is yellowish brown with blotches of yellow, and like its close kinsman, the pond turtle of Europe (Fig. [266]), withdraws itself and closes its shell completely. Both lids of the plastron are movable, a peculiarity belonging to these two species. The giant tortoise of the Galapagos Islands, according to Lyddeker, can trot cheerfully along with three full-grown men on its back. “Tortoise shell” used for combs and other articles is obtained from the overlapping scales of the hawkbill turtle, common in the West Indies. The diamond-back terrapin, found along the Atlantic Coast from Massachusetts to Texas, is prized for making soup.

Fig. 272.—A Rattlesnake.

Fig. 273 a.—Head of Viper, showing typical triangular shape of head of venomous snake.

Fig. 273 b.—Side View, showing poison fangs; also tongue (forked, harmless).

Fig. 274.—Viper’s Head, showing poison sac at base of fangs.

Fig. 275.—Skull, showing teeth, fangs, and quadrate bone to which lower jaw is joined. See Fig. [284].

Venomous snakes named in order of virulence: 1. Coral snakes, Elaps, about seventeen red bands bordered with yellow and black (coloured figure 6) (fatal). 2. Rattlesnakes (very deadly). 3. Copperhead (may kill a small animal of the size of a dog). 4. Water moccasin (never fatal). 5. Ground rattler.—Effects: Pulse fast, breathing slow, blood tubes dilated, blood becomes stored in abdominal blood tubes, stupefaction and death from blood being withdrawn from brain. Always two punctures, the closer together the smaller the snake. Remedies: Ligature between wound and heart, lance wound and suck; inject into wound three drops of 1 per cent solution of chromic acid or potassium permanganate. Give strychnine, hypodermically, until strychnine symptoms (twitchings) appear. No one but a physician should give strychnine. Digitalin or caffein acts like strychnine; alcohol has opposite effect.

Fig. 276.—“Glass Snake,” a lizard without legs.

Fig. 277.—Skull of Elaps. See colored Fig. [5].

Fig. 278.—Skull of Lampropeltis.

Protective Coloration and Mimicry.—When an animal imitates the colour or form of its inanimate surroundings it is said to be protectively coloured or formed. Give an instance of protective Coloration or form among lizards; butterflies; grasshoppers; amphibians; echinoderms. When an animal imitates the colour or the form of another animal it is said to mimic the animal. Mimicry usually enables an animal to deceive enemies into mistaking it for an animal which for some reason they avoid. The milkweed butterfly has a taste that is repulsive to birds. The viceroy butterfly is palatable to birds, but it is left untouched because of its close resemblance to the repulsive milkweed butterfly. The harlequin snake (Elaps) of the Gulf states is the most deadly snake of North America (Figs. [277], [278]). It is very strikingly coloured with rings of scarlet, yellow, and black. This is an example of warning coloration. The scarlet snake (Lampropeltis) has bands of scarlet, yellow, and black (coloured Fig. [6]) of the same tints, and it is hardly distinguishable from the harlequin. The scarlet snake is said to mimic the harlequin snake. It also imitates the quiet inoffensive habits of the harlequin snake, which fortunately does not strike except under the greatest provocation. The rattles of the less poisonous but deadly rattlesnake (Fig. [272]) may be classed as an example of warning sound which most animals are quick to heed and thus avoid encounters which might be destructive to either the snake or its enemy.

Coloured Figures 1, 2, 3.—Circulation in Fish, Reptile, Mammal.
In which is blood from heart all impure? Mixed? Both pure and impure?

Fig. 4.—Anatomy of Carp. For description see Fig. [220], page [117].

The Deadly Harlequin Snake is mimicked by the Harmless Scarlet Snake.

Fig. 5.—Harlequin Snake (Elaps).

Fig. 6.—Scarlet Snake (Lampropeltis).

Fig. 279.—Gila Monster (Heloderma suspectum), of Arizona. If poisonous, it is the only instance among lizards. It is heavy-built, orange and black mottled, and about 16 inches long. Compare it with the green lizard (Fig. [280]).

Fig. 280.—Chameleon (Anolis), or green lizard of southern U.S. Far excels European chameleon (Fig. [281]) and all known animals in power of changing colour (green, gray, yellow, bronze, and black).

Survival of the Fittest.—The two facts of most far-reaching importance in the history of animals and plants are: (1) Heredity; animals inherit the characteristics of their parents. (2) Variation; animals are not exactly like their parents. The first fact gives stability, the second makes evolution possible. The climate of the world is slowly changing, and animals must change to adapt themselves to it. A more sudden change of environment (surroundings) of animals occurs because of migration or isolation; these in turn are caused by the crowding of other animals or by the formation or disappearance of geographical barriers, such as deserts, water, mountain chains.

Fig. 281.—Chameleon of Southern Europe.

The young vary in many ways from their parents. Some have a more protective colour or form, sharper claws, swifter movements, etc. The individuals possessing such beneficial variations live longer and leave more offspring, and because of heredity transmit the desirable qualities to some of their young. Variations which are disadvantageous for getting food, defence, etc., cause shorter life and fewer offspring. Thus the fittest survive, the unfit perish; an automatic natural selection occurs.

Fig. 282.—Embryo of a Turtle, showing four gill slits. (Challenger Report.)

Darwin taught that variations are infinitesimal and gradual. Recent experiments and observations seem to show that many variations are by sudden jumps, somewhat resembling so-called “freaks of nature.” As to whether these “sports,” or individuals with new peculiarities, survive, depends upon their fitness for their environment. “Survival of the fittest” results from this natural selection, but the selection occurs between animals of marked, not infinitesimal, differences, as Darwin taught. Darwin’s theory is probably true for species in the usual state of nature; the new theory (of De Vries) is probably true for animals and plants under domestication and during rapid geographical changes.

Table for Review (for notebooks or blackboards).


	Fish	Tadpole	Frog	Turtle	Lizard
Limbs, kind and number
Are claws present? How many?
Covering of body
Teeth, kind of, if present
Which bones found in man are lacking?
Chambers of heart
Respiration
Movements

Fig. 283.—Big-headed Turtle (Platysternum megalocephalum). × ⅓. China.
This and Fig. [282] suggest descent of turtles from a lizardlike form. Figure 282 shows earlier ancestors to have been gill breathers.

CHAPTER XIII
BIRDS

Suggestions.—The domestic pigeon, the fowl, and the English sparrow are most commonly within the reach of students. The last bird has become a pest and is almost the only bird whose destruction is desirable. The female is somewhat uniformly mottled with gray and brown in fine markings. The male has a black throat with the other markings of black, brown, and white, in stronger contrast than the marking of the female. As the different species of birds are essentially alike in structural features, the directions and questions may be used with any bird at hand. When studying feathers, one or more should be provided for each pupil in the class. The feet and the bills of birds should be kept for study.

Does the body of the bird like the toad and the turtle, have a head, a trunk, a tail, and two pairs of limbs? Do the fore and hind limbs differ from each other more or less than the limbs of other backboned animals? Does any other vertebrate use them for purposes as widely different?

Eye.—Does the eyeball have parts corresponding to the eyeball of a fish or a frog; viz., cornea, iris, pupil? Which is more movable, the upper or the lower eyelid? Are there any lashes? The bird (like what other animal?) has a third eyelid, or nictitating membrane. Compare its thickness with that of the other lids. Is it drawn over the eyeball from the inner or the outer corner of the eye? Can you see in the human eye any wrinkle or growth which might be regarded as remains, or vestige, of such a membrane?

How many nostrils? In which mandible are they located? Are they nearer the tip or the base of the mandible? (Fig. [284].) What is their shape? Do the nasal passages go directly down through the mandible or do they go backward? Is the inner nasal opening into the mouth or into the throat?

Fig. 284.—Skull of Domestic Fowl.
q, quadrate (“four-sided”) bone by which lower jaw is attached to skull (wanting in beasts, present in reptiles; see Fig. [277]).

The beak or bill consists of the upper and lower mandibles. The outside of the beak seems to be of what kind of material? Examine the decapitated head of a fowl or of a dissected bird, and find if there is a covering on the bill which can be cut or scraped off. Is the mass of the bill of bony or horny material? With what part of the human head are the mandibles homologous? (Fig. [284].)

Ears.—Do birds have external ears? Is there an external opening leading to the ear? In searching for it, blow or push forward the feathers. If found, notice its location, size, shape, and what surrounds the opening. There is an owl spoken of as the long-eared owl. Are its ears long?

The leg has three divisions: the uppermost is the thigh (called the “second joint” in a fowl); the middle division is the shank (or “drumstick”); and the lowest, which is the slender bone covered with scales, is formed by the union of the ankle and the instep. (The bones of the three divisions are named femur, tibiotarsus, and tarsometatarsus.) The foot consists entirely of toes, the bones of which are called phalanges. Is there a bone in each claw? (See Fig. [285].) Supply the numerals in this sentence: The pigeon has ____ toes, the hind toe having ____ joints; of the three front toes, the inner has ____ joints (count the claw as one joint), the middle has ____ joints, and the outer toe has ____ joints (Fig. [285]). Is the thigh of a bird bare or feathered? The shin? The ankle? Where is the ankle joint of a bird? Do you see the remains of another bone (the splint bone, or fibula) on the shin bone of the shank? (Fig. [285] or 286.) Why would several joints in the ankle be a disadvantage to a bird?

Fig. 285.—Leg Bones of Bird.

Fig. 286.—Skeleton of Bird.
Rh, vertebræ; Cl, clavicle; Co, coracoid; Sc, scapula; St, sternum; H, humerus; R, radius; U, ulna; P, thumb; Fe, femur; T, tibia. See Fig. [394].
Questions: Which is the stiffest portion of the vertebral column? How are the ribs braced against each other? Which is longer, thigh bone or shin? Compare shoulder blade with man’s (Fig. [399]). Which is the extra shoulder bone? Compare tail vertebræ with those of extinct bird, Fig. [290].

The thigh hardly projects beyond the skin of the trunk, as may be noticed in a plucked fowl. The thigh extends forward from the hip joint (Figs. [286], [299]) in order to bring the point of support forward under the centre of weight. Why are long front toes more necessary than long hind toes? As the bird must often bring its head to the ground, the hip joints are near the dorsal surface and the body swings between the two points of support somewhat like a silver ice pitcher on its two pivots. Hence stooping, which makes a man so unsteady, does not cause a bird to lose steadiness.

Fig. 287.—Hand and Wrist of Fowl (after Parker).
DG. 1–3, digits; MC. 1–3, metacarpals; CC. 3, wrist.

The wing has three divisions which correspond to the upper arm, the forearm, and the hand of man (Fig. [286]). When the wing is folded, the three divisions lie close alongside one another. Fold your arm in the same manner. The similarity of the bones of the first and second divisions to the bones of our upper arm and forearm is very obvious (Fig. [286]). Explain. The hand of a bird is furnished with only three digits (Fig. [287]). The three palm bones (metacarpals) are firmly united (Fig. [287]). This gives firmness to the stroke in flying.

Fig. 288.—Hand, Wrist (c), Forearm, and Elbow of Young Chick (after Parker).

That the bird is descended from animals which had the fingers and palm bones less firmly united is shown by comparing the hands of a chick and of an adult fowl (Figs. [287], [288]). The wrist also solidifies with age, the five carpals of the chick being reduced to two in the fowl (Figs. [287], [288]). The thumb or first digit has a covering of skin separate from that of the other digits, as may be seen in a plucked bird. The degenerate hand of the fowl is of course useless as a hand (what serves in its place?) but it is well fitted for firm support of the feathers in flying. The two bones of the forearm are also firmly joined. There are eighteen movable joints in our arm and hand. The bird has only the three joints which enable it to fold its wing. The wrist joint is the joint in the forward angle of the wing.

Fig. 289.—Breastbone And Shoulder Bones of Cassowary.

Fig. 290.—A Fossil Bird (archæopteryx) found in the rocks of a former geological epoch.
Question: Find two resemblances to reptiles in this extinct bird absent from skeletons of extant birds.

Since the fore limbs are taken up with locomotion, the grasping function has been assumed by the jaws. How does their shape adapt them to this use? For the same reason the neck of a bird surpasses the necks of all other animals in what respect? Is the trunk of a bird flexible or inflexible? There is thus a correlation between structure of neck and trunk. Explain. The same correlation is found in which of the reptiles? (Why does rigidity of trunk require flexibility of neck?) Why does the length of neck in birds correlate with the length of legs? Examples? (See Figs. [314], [315], [332].) Exceptions? (Fig. [324].) Why does a swan or a goose have a long neck, though its legs are short?

Fig. 291.—Quill Feather.
D, downy portion.

To make a firm support for the wings the vertebræ of the back are immovably joined, also there are three bones in each shoulder, the collar bone, the shoulder blade, and the coracoid bone (Fig. [286]). The collar bones are united (why?) and form the “wishbone” or “pulling bone.” To furnish surface for the attachment of the large flying muscles there is a prominent ridge or keel on the breastbone (Fig. [286]). It is lacking in most birds which do not fly (Fig. [289]).

The feathers are perhaps the most characteristic feature of birds. The large feathers of the wings and tail are called quill feathers. A quill feather (Fig. [291]) is seen to consist of two parts, the shaft, or supporting axis, and the broad vane or web. What part of the shaft is round? Hollow? Solid? Is the shaft straight? Are the sides of the vane usually equal in width? Can you tell by looking at a quill whether it belongs to the wing or the tail, and which wing or which side of the tail it comes from? Do the quills overlap with the wide side of the vane above or beneath the next feather? Can you cause two parts of the vane to unite again by pressing together the two sides of a split in the vane? Does the web separate at the same place when pulled until it splits again?

Fig. 292.—I, Contour Feather. II, III, Parts of Quill Feather, enlarged.

The hollow part of the shaft of a quill feather is called the quill. The part of the shaft bearing the vane is called the rachis (rā-kis). The vane consists of slender barbs which are branches of the shaft (II, Fig. [292]). As the name indicates (see dictionary), a barb resembles a hair. The barbs in turn bear secondary branches called barbules, and these again have shorter branches called barbicels (III, Fig. [292]). These are sometimes bent in the form of hooklets (Fig. [292], III), and the hooklets of neighbouring barbules interlock, giving firmness to the vane. When two barbules are split apart, and then reunited by stroking the vane between the thumb and the finger, the union may be so strong that a pull upon the vane will cause it to split in a new place next time.

Fig. 293.—A Down Feather, enlarged.

There are four kinds of feathers, (1) the quill feathers, just studied; (2) the contour feathers (I, Fig. [292]), which form the general surface of the body and give it its outlines; (3) the downy feathers (Fig. [293]), abundant on nestlings and found among the contour feathers of the adult but not showing on the surface; (4) the pin feathers, which are hair-like, and which are removed from a plucked bird by singeing. The contour feathers are similar in structure to the quill feathers. They protect the body from blows, overlap so as to shed the rain, and, with the aid of the downy feathers, retain the heat, thus accounting for the high temperature of the bird. The downy feathers are soft and fluffy, as they possess few or no barbicels; sometimes they lack the rachis (Fig. [293]). The pin feathers are delicate horny shafts, greatly resembling hairs, but they may have a tuft of barbs at the ends.

Fig. 294.—Dorsal and Ventral View of Plucked Bird, showing regions where feathers grow.

A feather grows from a small projection (or papilla) found at the bottom of a depression of the skin. The quill is formed by being moulded around the papilla. Do you see any opening at the tip of the quill for blood vessels to enter and nourish the feather? What is in the quill? (Fig. [291].) The rachis? A young contour or quill feather is inclosed in a delicate sheath which is cast off when the feather has been formed. Have you seen the sheath incasing a young feather in a moulting bird?

There are considerable areas or tracts on a bird’s skin without contour feathers. Such bare tracts are found along the ridge of the breast and on the sides of the neck. However, the contour feathers lie so as to overlap and cover the whole body perfectly (Fig. [294]).

Fig. 295.—Wing of Bird.
1, false quills (on thumb); 2, primaries; 3, secondaries; tertiaries (dark) are one above another at right; a, b, coverts.

The shedding of the feathers is called moulting. Feathers, like the leaves of trees, are delicate structures and lose perfect condition with age. Hence the annual renewal of the feathers is an advantage. Most birds shed twice a year, and with many the summer plumage is brighter coloured than the winter plumage. When a feather is shed on one side, the corresponding feather on the other side is always shed with it. (What need for this?) A large oil gland is easily found on the dorsal side of the tail. How does the bird apply the oil to the feathers?

Fig. 296.
A, point dividing primaries from secondaries; B, coverts.

Fig. 297.—Cedar Waxwing, with regions of body marked.
S, forehead; Sc, crown (with crest); Hh, nape; K, throat; Br, breast; Ba, lower parts; R, back; Rt, tail; B, tail coverts; P, shoulder feathers (scapulars); T, wing coverts; HS, primaries; AS, secondaries; Al, thumb feathers.

In describing and classifying birds, it is necessary to know the names of the various external regions of the body and plumage. These may be learned by studying Figs. [295], [296], [297], [298]. The quills on the hand are called primaries, those on the forearm are the secondaries, those on the upper arm are the tertiaries. Those on the tail are called the tail quills. The feathers at the base of the quills are called the coverts. The thumb bears one or more quills called the spurious quills. Is the wing concave on the lower or the upper side? Of what advantage is this when the bird is at rest? When it is flying?

Fig. 298.—Plan of Bird.
s, centre of gravity.

Fig. 299.—Position of Limbs of Pigeon.

Control of Flight.—Did you ever see a bird sitting on a swinging limb? What was its chief means of balancing itself? When flying, what does a bird do to direct its course upward? Downward? Is the body level when it turns to either side? Birds with long, pointed wings excel in what respect? Examples? Birds with great wing surface excel in what kind of flight? Examples. Name a common bird with short wings which has a laboured, whirring flight. Is its tail large or small? Does it avoid obstacles and direct its flight well? Why or why not? When a boat is to be turned to the right, must the rudder be pulled to the right or to the left? (The rudder drags in the water and thus pulls the boat around.) When the bird wishes to go upward, must its tail be turned up or down? How when it wishes to go down? When a buzzard soars for an hour without flapping its wings, does it move at a uniform rate? For what does it use the momentum gained when going with the wind?

Fig. 300.
a, clambering foot of chimney sweep; b, climbing foot of woodpecker; c, perching foot of thrush; d, seizing foot of hawk; e, scratching foot of pheasant; f, stalking foot of kingfisher; g, running foot of ostrich; h, wading foot of heron; i, paddling foot of gull; k, swimming foot of duck; l, steering foot of cormorant; m, diving foot of grebe; n, skimming foot of coot. Question: Does any bird use its foot as a hand? (Fig. [320].)

Flying.—When studying the quill feathers of the wing, you saw that the wider side of the vane is beneath the feather next behind it. During the downward stroke of the wing this side of the vane is pressed by the air against the feather above it and the air cannot pass through the wing. As the wing is raised the vanes separate and the air passes through. The convex upper surface of the wing also prevents the wing from catching air as it is raised. Spread a wing and blow strongly against its lower surface; its upper surface. What effects are noticed?

Study the scales on the leg of a bird (Fig. [300]). Why is the leg scaly rather than feathered from the ankle downward? Which scales are largest? (Fig. [300].) How do the scales on the front and the back differ? What can you say of the scales at the bottom of the foot; at the joints of the toes? Explain. How does the covering of the nails and the bill compare in colour, texture, hardness, and firmness of attachment with the scales of the leg?

Fig. 301.—An Altrical Bird, i.e. poorly developed at hatching. Young pigeon, naked, beak too weak for eating.

Draw an outline of the bird seen from the side. Make drawings of the head and the feet more detailed and on a larger scale.

Fig. 302.—A Precocial Bird (well developed at hatching). Feathered, able to run and to pick up food. Precocity is a sign of instinctive life and low intelligence. A baby is not precocious.
Question: Is pigeon or fowl exposed to more dangers in infancy?

Why does a goose have more feathers suitable for making pillows than has a fowl? In what country did the domestic fowl originate? (Encyclopædia.) Why does a cock crow for dawn? (Consider animal life in jungle.)

Activities of a Bird.—Observe a bird eating. Does it seem to chew or break its food before swallowing? Does it have to lift its head in order to swallow food? To swallow drink? Why is there a difference? After feeding the bird, can you feel the food in the crop, or enlargement of the gullet at the base of the neck? (Fig. [304].)

Feel and look for any movements in breathing. Can you find how often it breathes per minute? Place hand under the bird’s wing. What do you think of its temperature; or better, what temperature is shown by a thermometer held under its wing? Do you see any connection between the breathing rate and the temperature? Test (as with the crayfish) whether a bird can see behind its head. Notice the movements of the nictitating membrane. Does it appear to be transparent?

Watch a bird fly around a closed room and review the questions on Control of Flight.

Bend a bird’s leg and see if it has any effect upon its toes. Notice a bird (especially a large fowl) walk, to see if it bends its toes as the foot is lifted. Pull the rear tendon in a foot cut from a fowl for the kitchen. Does the bird have to use muscular exertion to grasp a stick upon which it sits? Why, or why not? When is this bending of the toes by bending the legs of special advantage to a hawk? To a duck? To a wading bird? Why is a fowl safe from a hawk if it stands close to a tree?

Fig 303.—Head of Woodpecker.
c, tongue; a, b, d, hyoid bone; e, q, windpipe; f, salivary gland.

Do you see any signs of teeth in the bird’s jaws? Why are duck’s “teeth” (so called by children) not teeth? Can the tongue of a bird be pulled forward? (Fig. [303].) What is its shape? If there is opportunity, dissect and study the slender, bony (hyoid) apparatus to which the base of the tongue is attached (Fig. [303]), the opening of the windpipe, or trachea, the slitlike opening of windpipe, which is so narrow as to prevent food falling into the windpipe.

Fig. 304.—Anatomy of Dove × ½.
bk, keel of breastbone; G, g, brain; lr, windpipe; lu, lung; h, heart; sr, gullet; k, crop; dr, glandular stomach; mm, gizzard; d, intestine; n, kidney; hl, ureter; eil, openings of ureter and egg duct into cloaca, kl.

Fig. 305.—Food Tube of Bird.
P, pancreas; C, cæca.
Question: Identify each part by means of Fig. [304].

The Internal Organs, or Viscera (Figs. [304] and [305]).—The viscera (vis’se-ra), as in most vertebrates, include the food tube and its glands; the lungs, the heart, and the larger blood vessels; the kidneys and bladder and the reproductive organs. The lower part, or gullet, is enlarged into a crop. It is largest in grain-eating birds. It is found in the V-shaped depression at the angle of the wishbone, just before the food tube enters the thorax. The food is stored and softened in the crop. From the crop the food passes at intervals into the glandular stomach. Close to this is the muscular stomach, or gizzard. Are the places of entrance and exit on opposite sides of the gizzard, or near together? (Fig. [304].) Is the lining of the gizzard rough or smooth? Why? Is the gizzard tough or weak? Why are small stones in the gizzard? Why do not hawks and other birds of prey need a muscular gizzard? The liver and pancreas empty their secretions into the intestines by several ducts a little way beyond the gizzard. Beyond the mouths of two cæca (Fig. [305]) the many-coiled intestine empties into the straight rectum, which terminates in a widened part called the cloaca. Not only the intestine, but the two ureters of the urinary system and the two genital ducts of the reproductive system all empty into the cloaca (Figs. [304], [305]).

Fig. 306.—Position of Lungs and Air Sacs (Pigeon).
Tr, windpipe; P, lungs; Lm, sac under clavicle with prolongation (Lh) into humerus; La, sacs in abdomen.

The lungs have their rear surfaces attached to the spinal column and ribs (lu, Fig. [304]). They are connected with thin-walled, transparent air sacs which aid in purifying the blood. When inflated with warm air, they probably make the body of the bird more buoyant. For the names, location, and shape of several pairs of air sacs, see Fig. [306]. The connection of the air sacs with hollows in the humerus bones is also shown in the figure. Many of the bones are hollow; this adds to the buoyancy of the bird. The pulmonary artery, as in man, takes dark blood to the lungs to exchange its carbon dioxide for oxygen. Of two animals of the same weight, which expends more energy, the one that flies, or the one that runs the same distance? Does a bird require more oxygen or less, in proportion to its weight, than an animal that lives on the ground? Are the vocal chords of a bird higher or lower in the windpipe than those of a man? (Fig. [307].)

Fig. 307.—Position of Vocal Cords (str) of Mammal and Bird.
Question: Does a fowl ever croak after its head and part of its neck are cut off? Explain.

The heart of a bird, like a man’s heart, has four chambers; hence it keeps the purified blood separate from the impure blood. Since pure blood reaches the organs of a bird, oxidation is more perfect than in the body of any animals yet studied. Birds have higher temperature than any other class of animals whatsoever. Tell how the jaws, the tail, and the wings of the fossil bird Archæopteryx differed from living birds (Fig. [290]).

Suggestions.—In the field work, besides seeking the answers to definite questions, pupils may be required to hand in a record of the places and the times of seeing a certain number of birds (20–40) with the actions and features which made each distinguishable. Also, and more important, each pupil should hand in a record of a careful and thorough outdoor study of one common species (see below) as regards habits, nesting, relation to environment, etc.

Field Study of a Common Species.—(For written report.) Name of species. Haunts. Method of locomotion when not flying. Flying (rate, sailing, accompanying sound if any, soaring).

What is the food? How obtained? Association with birds of its own species. Relation to birds of other species.

Where does it build its nest? Why is such a situation selected? Of what is the nest built? How is the material carried, and how built into the nest? Does the bird’s body fill the nest?

Describe the eggs. Does the male bird ever sit or otherwise assist female before hatching? Does it assist after hatching? How long is taken to lay a sitting of eggs? How long before the birds are hatched? When hatched are they helpless? Blind? Feathered? (Figs. [301], [302].) Do the nestlings require much food? How many times in an hour is food brought? How distributed? Even if the old birds sometimes eat fruit do they take fruit to the young? What do they feed to the young? How long before they leave the nest? Do the parents try to teach them to fly? Do the parents care for them after the nest is left? What songs or calls has the bird?

Fig. 308.—European Tomtit’s Nest.
What are the advantages of its shape?

Fig. 309.—Tailor Bird’s Nest (India).
Instinct for nest building highly perfected.

General Field Study.—(For written report.) Name the best and poorest flyers you know; birds that fly most of the time; birds that seldom fly. Observe birds that pair; live in flocks. Does their sociability vary with the season? Do you ever see birds quarrelling? Fighting? What birds do you observe whipping or driving birds larger than themselves? Which parent do young birds most resemble? Name the purposes for which birds sing. Which senses are very acute? Why? Dull? Why? Can you test your statements by experiment? A partridge usually sits with 18 to 24 eggs in nest. About how long after laying first egg before sitting begins? Do several partridge hens lay in the same nest?

Fig. 310.—House Wren.

Haunts.—Name some birds that are found most often in the following localities: about our homes, in gardens and orchards, fields and meadows, in bushes, in the woods, in secluded woods, around streams of water, in thickets, in pine woods.

Size.—Name birds as large as a robin or larger, nearly as large, half as large, much smaller.

Colours.—Which sex is more brilliant? Of what advantage are bright colours to one sex? Of what advantage are dull colours to the other sex? Which have yellow breasts, red patch on heads, red or chestnut breasts, blue backs, black all over?

Habits.—Name the birds that walk, jump, swim, live in flocks, sing while flying, fly in undulations, in circles, have laboured flight.

Economic Importance of Birds.—Farmers find their most valuable allies in the class aves, as birds are the deadliest enemies of insects and gnawing animals. To the innumerable robbers which devastate our fields and gardens, nature opposes the army of birds. They are less numerous than insects and other robbers, it is true, but they are skilful and zealous in pursuit, keen of eye, quick, active, and remarkably voracious. The purely insectivorous birds are the most useful, but the omnivorous and graminivorous birds do not disdain insects. The perchers and the woodpeckers should be protected most carefully. The night birds of prey (and those of the day to a less degree) are very destructive to field mice, rabbits, and other gnawing animals. Some ignorant farmers complain continually about the harm done by birds. To destroy them is as unwise as it would be to destroy the skin which protects the human body because it has a spot upon it! It cannot be repeated too plainly that to hunt useful birds is a wrong and mischievous act, and it is stupid and barbarous to destroy their nests.

Fig. 311.—Screech Owl (Megascops asio).
Question: Compare posture of body, position of eyes, and size of eyes, with other birds.

Fig. 312.—Goshawk, or chicken hawk.

Injurious birds are few. Of course birds which are the enemies of other birds are enemies of mankind, but examples are scarce (some owls and hawks). Many birds of prey are classed thus by mistake. Sparrow-hawks, for instance, do not eat birds except in rare instances; they feed chiefly upon insects. A sparrow hawk often keeps watch over a field where grasshoppers are plentiful and destroys great numbers of them. When a bird is killed because it is supposed to be injurious, the crop should always be examined, and its contents will often surprise those who are sure it is a harmful bird. The writer once found two frogs, three grasshoppers, and five beetles that had been swallowed by a “chicken hawk” killed by an irate farmer, but no sign of birds having been used for food. Fowls should not be raised in open places, but among trees and bushes, where hawks cannot swoop. Birds which live exclusively upon fish are, of course, opposed to human interests. Pigeons are destructive to grain; eagles feed chiefly upon other birds.

Fig. 313.—Road Runner, or chaparral bird (Tex. to Cal.). What order? (Key, p. [177].)

If the birds eat the grapes, do not kill the birds, but plant more grapes. People with two or three fruit trees or a small garden are the only ones that lose a noticeable amount of food. We cut down the forests from which the birds obtain part of their food. We destroy insect pests at great cost of spraying, etc. The commission the birds charge for such work is very small indeed. (See pages [177]–183.)

Fig. 314.—Wood Duck, male (Aix sponsa). Nests in hollow trees throughout North America. Also called summer duck in South. Why?

The English sparrow is one bird of which no good word may be said. Among birds, it holds the place held by rats among beasts. It is crafty, quarrelsome, thieving, and a nuisance. It was imported in 1852 to eat moths. The results show how ignorant we are of animal life, and how slow we should be to tamper with the arrangements of nature. In Southern cities it produces five or six broods each year with four to six young in each brood. (Notice what it feeds its young.) It fights, competes with and drives away our native useful birds. It also eats grain and preys upon gardens. They have multiplied more in Australia and in North America than in Europe, because they left behind them their native enemies and their new enemies (crows, jays, shrikes, etc.) have not yet developed, to a sufficient extent, the habit of preying upon them. Nature will, perhaps, after a long time, restore the equilibrium destroyed by presumptuous man.

Protection of Birds.—1. Leave as many trees and bushes standing as possible. Plant trees, encourage bushes.

2. Do not keep a cat. A mouse trap is more useful than a cat. A tax should be imposed upon owners of cats.

3. Make a bird house and place it on a pole; remove bark from pole that cats may not climb it; or put a broad band of tin around the pole.

4. Scatter food in winter. In dry regions and in hot weather keep a shallow tin vessel containing water on the roof of an outhouse, or in an out-of-the-way place, for shy birds.

5. Do not wear feathers obtained by the killing of birds. What feathers are not so obtained?

6. Report all violators of laws for protection of birds.

7. Destroy English sparrows.

Fig. 315.—Great Blue Heron. In flight, balancing with legs.

Migration.—Many birds, in fact most birds, migrate to warmer climates to spend the winter. Naturalists were once content to speak of the migration of birds as a wonderful instinct, and made no attempt to explain it. As birds have the warmest covering of all animals, the winter migration is not for the purpose of escaping the cold; it is probably to escape starvation, because in cold countries food is largely hidden by snow in winter. On the other hand, if the birds remained in the warm countries in summer, the food found in northern countries in summer would be unused, while they would have to compete with the numerous tropical birds for food, and they and their eggs would be in danger from snakes, wild cats, and other beasts of prey so numerous in warm climates. These are the best reasons so far given for migration.

Fig. 316.—European Swallows (Hirundo urbica), assembling for autumn flight to South.

The manner and methods of migration have been studied more carefully in Europe than in America. Migration is not a blind, infallible instinct, but the route is learned and taught by the old birds to the young ones; they go in flocks to keep from losing the way (Fig. [316]); the oldest and strongest birds guide the flocks (Fig. [317]). The birds which lose their way are young ones of the last brood, or mothers that turn aside to look for their strayed young. The adult males seldom lose their way unless scattered by a storm. Birds are sometimes caught in storms or join flocks of another species and arrive in countries unsuited for them, and perish. For example, a sea or marsh bird would die of hunger on arriving in a very dry country.

The landmarks of the route are mountains, rivers, valleys, and coast lines. This knowledge is handed down from one generation to another. It includes the location of certain places on the route where food is plentiful and the birds can rest in security. Siebohm and others have studied the routes of migration in the Old World. The route from the nesting places in northern Europe to Africa follows the Rhine, the Lake of Geneva, the Rhone, whence some species follow the Italian and others the Spanish coast line to Africa. Birds choose the lowest mountain passes. The Old World martin travels every year from the North Cape to the Cape of Good Hope and back again! Another route has been traced from Egypt along the coast of Asia Minor, the Black Sea and Ural Mts. to Siberia.

Fig. 317.—Cranes Migrating, with leader at point of V-shaped line.

Field Study of Migration.—Three columns may be filled on the blackboard in an unused corner, several months in spring or fall being taken for the work. First column, birds that stay all the year. Second column, birds that come from the south and are seen in summer only. Third column, birds that come from the north and are seen in winter only. Exact dates of arrival and departure and flight overhead should be recorded in notebooks. Many such records will enable American zoologists to trace the migration routes of our birds.

Fig. 318.—Apteryx, of New Zealand. Size of a hen, wings and tail rudimentary, feathers hair-like.

Moulting.—How do birds arrange their feathers after they have been ruffled? Do they ever bathe in water? In dust? Dust helps to remove old oil. At what season have birds the brightest feathers? Why? Have you ever seen evidence of the moulting of birds? Describe the moulting process (page [120]).

Fig. 319.—Golden, Silver, and Noble Pheasants, males. Order? (Key, p. [177].) Ornaments of males, brightest in season of courtship, are due to sexual selection (Figs. [321]–7–9, [333]).

Fig. 320. Cockatoo.

Fig. 321.—Bird Of Paradise (Asia).

Adaptations for Flying.—Flight is the most difficult and energy-consuming method of moving found among animals, and careful adjustment is necessary. For balancing, the heaviest muscles are placed at the lower and central portion of the body. These are the flying muscles, and in some birds (humming birds) they make half of the entire weight. Teeth are the densest of animal structures; teeth and the strong chewing muscles required would make the head heavy and balancing difficult; hence the chewing apparatus is transferred to the heavy gizzard near the centre of gravity of the body. The bird’s neck is long and excels all other necks in flexibility, but it is very slender (although apparently heavy), being inclosed in a loose, feathered skin. A cone is the best shape to enable the body to penetrate the air, and a small neck would destroy the conical form. The internal organs are compactly arranged and rest in the cavity of the breast bone. The bellowslike air sacs filled with warm air lighten the bird’s weight. The bones are hollow and very thin. The large tail quills are used by the bird only in guiding its flight up and down, or balancing on a limb. The feet also aid a flying bird in balancing. The wing is so constructed as to present to the air a remarkably large surface compared with the small bony support in the wing skeleton. Are tubes ever resorted to by human architects when lightness combined with strength is desired? Which quills in the wing serve to lengthen it? (Fig. [296].) To broaden it? Is flight more difficult for a bird or for a butterfly? Which of them do the flying machines more closely resemble? Can any bird fly for a long time without flapping its wings?

Fig. 322.—Herring Gull. (Order?)

Exercise in the Use of the Key.—Copy this list and write the name of the order to which each of the birds belongs. (Key, page [177].)

Cockatoo (Fig. [320])

Sacred Ibis (Fig. [328])

Screech Owl (Fig. [311])

Nightingale (Fig. [325])

Top-knot Quail (Fig. [329])

Wren (Fig. [310])

Apteryx (Fig. [318])

Lyre bird (Fig. [327])

Road Runner (Fig. [313])

Ostrich (Fig. [332])

Penguin (Fig. [330])

Pheasant (Fig. [319])

Wood Duck (Fig. [314])

Jacana (Fig. [324])

Sea Gull (Fig. [322])

Heron (Fig. [315])

Hawk (Fig. [312])

KEY, OR TABLE, FOR CLASSIFYING BIRDS (Class Aves) INTO ORDERS


					Orders
A₁ Wings not suited for flight, 2 or 3 toes					Runners
A₂ Wings suited for flight (except the penguin)
	B₁ Toes united by a web for swimming, legs short
		C₁ Feet placed far back; wings short, tip not reaching to base of tail (Fig. [300])			Divers
		C₂ Bill flattened, horny plates under margin of upper bill (Fig. [323])			Bill-strainers
		C₃ Wings long and pointed, bill slender			Sea-fliers
		C₄ All four toes webbed, bare sac under throat			Gorgers
	B₂ Toes not united by web for swimming
		C₁ Three front toes, neck and legs long, tibia (shin, or “drumstick”) partly bare			Waders
		C₂ Three front toes, neck and legs not long
			D₁ Claws short and blunt (e, Fig. [300])
				E₁ Feet and beak stout, young feathered, base of hind toe elevated	Scratchers
				E₂ Feet and beak weak, young naked	Messengers
			D₂ Claws long, curved and sharp, bill hooked and sharp		Robbers
			D₃ Claws long, slightly curved, bill nearly straight		Perchers
		C₃ Two front and two hind toes (Fig. [300])
			D₁ Bill straight, feet used for climbing		Foot-climbers
			D¹ Bill hooked, both bill and feet used for climbing		Bill-climbers

The Food of Birds.—Extracts from Bulletin No. 54 (United States Dept. of Agriculture), by F. E. L. Beal.

Fig. 323.—Head of Duck.

The practical value of birds in controlling insect pests should be more generally recognized. It may be an easy matter to exterminate the birds in an orchard or grain field, but it is an extremely difficult one to control the insect pests. It is certain, too, that the value of our native sparrows as weed destroyers is not appreciated. Weed seed forms an important item of the winter food of many of these birds, and it is impossible to estimate the immense numbers of noxious weeds which are thus annually destroyed. If crows or blackbirds are seen in numbers about cornfields, or if woodpeckers are noticed at work in an orchard, it is perhaps not surprising that they are accused of doing harm. Careful investigation, however, often shows that they are actually destroying noxious insects; and also that even those which do harm at one season may compensate for it by eating insect pests at another. Insects are eaten at all times by the majority of land birds. During the breeding season most kinds subsist largely on this food, and rear their young exclusively upon it.

Fig. 324.—Jacana. (Mexico, Southwest Texas, and Florida.)
Questions: What appears to be the use of such long toes? What peculiarity of wing? head?

Partridges.—Speaking of 13 birds which he shot, Dr. Judd says: These 13 had taken weed seed to the extent of 63 per cent of their food. Thirty-eight per cent was ragweed, 2 per cent tick trefoil, partridge pea, and locust seeds, and 23 per cent seeds of miscellaneous weeds. About 14 per cent of the quail’s food for the year consists of animal matter (insects and their allies). Prominent among these are the Colorado potato beetle, the striped squash beetle, the cottonboll-weevil, grasshoppers. As a weed destroyer the quail has few, if any, superiors. Moreover, its habits are such that it is almost constantly on the ground, where it is brought in close contact with both weed seeds and ground-living insects. It is a good ranger, and, if undisturbed, will patrol every day all the fields in its vicinity as it searches for food.

Fig. 325.—Nightingale, × ⅓.

Fig. 326.—Skylark, × ⅓.

Two celebrated European songsters.

Doves.—The food of the dove consists of seeds of weeds, together with some grain. The examination of the contents of 237 stomachs shows that over 99 per cent of the food consists wholly of vegetable matter.

Cuckoos.—An examination of the stomachs of 46 black-billed cuckoos, taken during the summer months, showed the remains of 906 caterpillars, 44 beetles, 96 grasshoppers, 100 sawflies, 30 stink bugs, and 15 spiders. Of the yellow-billed cuckoos, or “rain-crow,” 109 stomachs collected from May to October, inclusive, were examined. The contents consisted of 1,865 caterpillars, 93 beetles, 242 grasshoppers, 37 sawflies, 69 bugs, 6 flies, and 86 spiders.

Fig. 327.—Lyre Bird, male.

Woodpeckers.—Careful observers have noticed that, excepting a single species, these birds rarely leave any conspicuous mark on a healthy tree, except when it is affected by wood-boring larvæ, which are accurately located, dislodged, and devoured by the woodpecker. Of the flickers’ or yellow-hammers’ stomachs examined, three were completely filled with ants. Two of the birds each contained more than 3,000 ants, while the third bird contained fully 5,000. These ants belong to species which live in the ground. It is these insects for which the flicker is reaching when it runs about in the grass. The yellow-bellied woodpecker or sapsucker (Sphyrapicus varius) was shown to be guilty of pecking holes in the bark of various forest trees, and sometimes in that of apple trees, and of drinking the sap when the pits became filled. It has been proved, however, that besides taking the sap the bird captures large numbers of insects which are attracted by the sweet fluid, and that these form a very considerable portion of its diet. The woodpeckers seem the only agents which can successfully cope with certain insect enemies of the forests, and, to some extent, with those of fruit trees also. For this reason, if for no other, they should be protected in every possible way.

Fig. 328.—Sacred Ibis. (Order?)

The night hawk, or “bull bat,” may be seen most often soaring high in air in the afternoon or early evening. It nests upon rocks or bare knolls and flat city roofs. Its food consists of insects taken on the wing; and so greedy is the bird that when food is plentiful, it fills its stomach almost to bursting. Ants (except workers) have wings and fly as they are preparing to propagate. In destroying ants night hawks rank next to, or even with, the woodpeckers, the acknowledged ant-eaters among birds.

Fig. 329.—Top-knot Quail, or California Partridge. (West Texas to California.)

The kingbird, or martin, is largely insectivorous. In an examination of 62 stomachs of this bird, great care was taken to identify every insect or fragment that had any resemblance to a honeybee; as a result, 30 honeybees were identified, of which 29 were males or drones and 1 was a worker.

Blue Jay.—In an investigation of the food of the blue jay 300 stomachs were examined, which showed that animal matter comprised 24 per cent and vegetable matter 76 per cent of the bird’s diet. The jay’s favourite food is mast (i.e. acorns, chestnuts, chinquapins, etc.), which was found in 200 of the 300 stomachs, and amounted to more than 42 per cent of the whole food.

FIG. 330.—Penguin of Patagonia. Wings used as flippers for swimming.

Crow.—That he does pull up sprouting corn, destroy chickens, and rob the nests of small birds has been repeatedly proved. Nor are these all of his sins. He is known to eat frogs, toads, salamanders, and some small snakes, all harmless creatures that do some good by eating insects. Experience has shown that they may be prevented from pulling up young corn by tarring the seed, which not only saves the corn but forces them to turn their attention to insects. May beetles, “dorbugs,” or June bugs, and others of the same family constitute the principal food during spring and early summer, and are fed to the young in immense quantities.

Ricebird.—The annual loss to rice growers on account of bobolinks has been estimated at $2,000,000.

Fig. 331.—Umbrella holding the nests of social weaver bird of Africa; polygamous.

Meadow Lark.—Next to grasshoppers, beetles make up the most important item of the meadow lark’s food, amounting to nearly 21 per cent. May is the month when the dreaded cut-worm begins its deadly career, and then the lark does some of its best work. Most of these caterpillars are ground feeders, and are overlooked by birds which habitually frequent trees, but the meadow lark finds and devours them by thousands.

Sparrows.—Examination of many stomachs shows that in winter the tree sparrow feeds entirely upon seeds of weeds. Probably each bird consumes about one fourth of an ounce a day. Farther south the tree sparrow is replaced in winter by the white-throated sparrow, the white-crowned sparrow, the fox sparrow, the song sparrow, the field sparrow, and several others; so that all over the land a vast number of these seed eaters are at work during the colder months reducing next year’s crop of worse than useless plants.

Fig. 332.—African Ostrich, × ¹⁄₂₀. (order?)

Robin.—An examination of 500 stomachs shows that over 42 per cent of its food is animal matter, principally insects, while the remainder is made up largely of small fruits or berries. Vegetable food forms nearly 58 per cent of the stomach contents, over 47 per cent being wild fruits, and only a little more than 4 per cent being possibly cultivated varieties. Cultivated fruit amounting to about 25 per cent was found in the stomachs in June and July, but only a trifle in August. Wild fruit, on the contrary, is eaten in every month, and constitutes during half the year a staple food.

Questions.—Which of these birds are common in your neighbourhood? Which of them according to the foregoing report are plainly injurious? Clearly beneficial? Doubtful? Which are great destroyers of weed seeds? Wood-borers? Ants? Grain? Why is the destruction of an ant by a night hawk of greater benefit than the destruction of an ant by a woodpecker? Name the only woodpecker that injures trees. If a bird eats two ounces of grain and one ounce of insects, has it probably done more good or more evil?

CHAPTER XIV
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?

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?

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?

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?

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.)

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]).

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.

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.

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.

Fig. 341.—Weasel, in summer; in Canada in winter it is all white but tip of tail.

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?

Fig. 343.—Polar Bear (Ursus maritimus).

KEY, OR TABLE, FOR CLASSIFYING MAMMALS (class Mammalia) INTO ORDERS

			Orders
A₁ Imperfect Mammals, young hatched or prematurely born
	B₁ Jaws a birdlike beak, egg-laying		Mon’otremes
	B₂ Jaws not beaklike, young carried in pouch		Marsu’pials
A₂ Perfect Mammals, young not hatched, nor prematurely born

B₁ Digits with claws	C₁	Front part of both jaws lack teeth	Eden’tates
	C₂	Teeth with sharp points for piercing shells of insects	Insect’ivors
	C₃	Canines very long, molars suited for tearing	Car’nivors
	C₄	Canines lacking, incisors very large	Rodents

B₂ Digits not distinct	C₁	Head large; carnivorous	Ceta’ceans
B₂ Digits not distinct	C₂	Head small; herbivorous	Sire’neans

B₃ Digits with nails or hoofs	C₁	Five toes, nose prolonged into a snout	Proboscid’eans
	C₂	Toes odd number, less than five	E’quines	Ungulates
	C₃	Toes even number, upper front teeth lacking, chew the cud	Ru’minants
	C₄	Toes even number, upper front teeth present, not cud-chewers	Swine
	C₅	All limbs having hands	Quad’rumans
	C₆	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

Fig. 344.—Skull and front of lower jaw of Cow.

Fig. 345.—Rabbit. A, B, incisors; C, molars

Fig. 346.—Walrus (see Fig. [341]).

Fig. 347.—Bat.

Fig. 348.—Cat.

Fig. 349.—Armadillo.

Fig. 350.—Horse (front of jaw).

Fig. 351.—Greenland Whale.

Fig. 352.—American Monkey.

Fig. 353.—Sloth (Fig. [363]).

Fig. 354.—Ant-eater (Fig. [364]).

Fig. 355.—Horse.

Fig. 356.—Dog. Upper (A) and lower (B) jaw.

Fig. 357.—Hog.

Fig. 358.—Sheep.

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.

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?

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.

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?

Fig. 363.—Sloth of South America.

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]).

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? ______.

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?

Fig. 367.—The Mole.

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.

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?

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].)

Fig. 371.—Pouched Gopher (Geomys bursarius) × ¼, a large, burrowing field rat, with cheek pouches for carrying grain.

Fig. 372.—Hind foot a, fore foot b, tail c, of Beaver.

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.

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?

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.

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?

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]).

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?____.

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?

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.

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.

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.

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.

Fig. 384.—Tapir of South America (Tapirus americanus). × ¹⁄₂₅.
Questions: How does it resemble an elephant? (Fig. [376].) A horse? (p. [210].)

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.

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.

Fig. 387.—Food traced through stomachs of cow. (Follow arrows.)

Fig. 388.—Section of cow’s stomachs. Identify each. (See text.)

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.

Fig. 390.—African Camel (Camelus dromedarius).

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.

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.

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?

Fig. 394.—Bird.

Fig. 395.—Horse.

Fig. 396.—Ox.

Fig. 397.—Dolphin.

Fig. 398.—Fish.

Fig. 399.—Man.

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].)

Fig. 401.—Sacred Monkey of India (Semnopithecus entellus). × ¹⁄₁₂.

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.

Fig. 403.—Broad-nosed Monkey. × ⅒. America.

Fig. 404.—Narrow-nosed Monkey. × ¹⁄₁₂. Old World.

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.

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].)

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

St. Bernard	German mastiff	Pointer	Newfoundland
Eskimo	English bloodhound	Bulldog	Shepherd
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.