Methods of expressing feeling.—Animals express their feelings in various ways—by the voice, by the face, by the tail, and by the general attitude of the body. Perhaps no animal’s feelings are more readily recognised by man than the dog’s. “It is a remarkable fact,” says Darwin,[13] “that the dog, since being domesticated, has learnt to bark in at least four or five distinct tones. Although barking is a new art, no doubt the wild parent-species of the dog expressed their feelings by cries of various kinds. With the domesticated dog we have the bark of eagerness, as in the chase; that of anger, as well as growling; the yelp or howl of despair, as when shut up; the baying at night; the bark of joy, as when starting on a walk with his master; and the very distinct one of demand or supplication, as when wishing for a door or window to be opened.” The movements of the tail are also full of meaning, and capable of expressing several different moods. It seems likely that in a dog the movements of the tail were originally of use chiefly to signal to the rest of the pack. The use of the movements of a cat’s tail is not very clear, although these also differ according to the animal’s feelings.
Carnivores.—Dogs and cats, with several other mammals, which are mostly flesh-eaters, are called Carnivores. They have never fewer than four distinct toes on each foot, and the claws (nails) are often capable of being withdrawn into sheaths. The teeth ([Fig. 171]) are characterised by the large, interlocking canines, which are conical, curved, and pointed; and by one of the cheek teeth on each side having a sharp, cutting edge which bites against the similar tooth of the other jaw, almost in the manner of the blades of scissors. The seals and walruses, however, which are carnivores adapted to living in water, have no such clipping teeth.
Fig. 171.—Skull of Wolf, seen from left side.
49. THE BAT.
1. Habits.—At what time of the year have you seen bats flying about? Do they fly in broad daylight, or only in the evening? How can you distinguish a bat’s flight from that of a bird? Have you ever heard a bat squeak? Upon what does it feed? Are flying insects plentiful in winter? Have you ever seen a bat drink? How does it drink? What does the bat do in winter? Try to find a sleeping bat in winter in a barn, a hollow tree, or a belfry. What is its position?
2. Appearance.—Examine a sleeping bat or a stuffed specimen. What is its body covered with, hair or feathers? Is it a bird or a mammal? Is the hair soft and furry? How large are the ears? Are the whiskers large or small? What are the wings like? Can you see any fingers? How many fingers are there? Do any of the fingers bear claws? Do the fingers support the wings? Which are longer, the fore limbs or the hind limbs? Do the toes of the hind limbs bear claws? What is their use? If possible, put a live bat on the ground; does it walk easily? Apart from the wings, what animal does the bat seem most to resemble? Do you know of any other flying mammal?
The Bat (Figs. [172] and [184 a]).—On summer evenings in most country districts of Britain bats may be seen flitting about catching insects. The flight is peculiar, and somewhat suggestive of that of a butterfly, so that even in the dusk the animal may be distinguished easily from a small bird. “Bats drink on the wing like swallows, by sipping the surface as they play over pools and streams. They love to frequent waters, not only for the sake of drinking, but on account of insects, which are found over them in the greatest plenty.”[14]