英文科學(xué)讀本 第四冊·Lesson 29 Mammals

Lesson 29 Mammals

Animals which suckle their young form a very large and important class. They comprise individuals which differ from each other in nature, habits, food, and therefore in structure.

Mammals are divided into orders.

Considered as an animal, man stands at the head of these orders. He is the only two-handed animal, and forms the sub-order Bi-mana. There is another sub-order which makes a very near approach to man, although the members of it differ widely from each other. They form a separate group, and are distinguished by their hand-like feet, each having a thumb for grasping, exactly like the thumb of the real hand. It is this distinction that gives the name Quadrumana, which means four-handed animals.

It is not merely the possession of two hands instead of four, however, that places man so much higher than this leading group of the brute creation. We have only to compare the head of one of the great four-handed animals with the head and brain of a man. It is intellect that makes man something more than a mere animal.

Man is the only animal that stands and walks erect. The four-handed animals all move about with an awkward stooping gait, resting their forehands on the ground at each step. If you notice the enormous length of their arms you will see that they are specially fitted for that kind of locomotion.

This four-handed structure is no mere accident; it was designed to meet the wants of these animals, all of whom live mostly in the trees, and require hands for grasping.

The Quadrumana arrange themselves naturally in different groups. First we may take the monkeys, which are the smallest and least savage of the whole sub-order. They are distinguished by their long tails, and also by cheek-pouches inside the mouth for storing away food till it is wanted. Most of them, too, have bare patches of hardened skin where they sit (callosities, they are called).

The monkeys of the New World mostly use their long tails as a fifth hand in climbing trees and swinging from bough to bough. They may be distinguished from those of the Old World by the position of the nostrils, which, in their case, open in long slits on the sides of the nose. The monkeys of Asia and Africa have the nostrils at the end of the nose.

The baboons form another group, and are extremely fierce and formidable. They too have cheek-pouches and callosities. They are distinguished by their very short tails.

The largest of the Quadrumana are the apes, or man monkeys. These have no tails, no cheek-pouches, no callosities. This group includes the gorilla, the chimpanzee, and the orangoutang. The gorilla is an extremely savage and powerful beast, and often reaches the height of seven feet.

The wing-handed animals usually follow the Quadrumana as the next order. They include the various members of the bat family. These animals live on insects which people the air, and they must therefore have the power of flight. To provide for this the two hands are modified to form wings. The fingers are lengthened to an enormous extent, and a thin membrane stretched between them forms a wing.

We will next look at another class of insect-eaters, of which the mole is a type. The insects which form the food of these animals (mostly beetles and their grubs) are found in the ground, and so are the slugs, snails, and earthworms, with which they vary their diet. If you think over our earlier lesson on the mole, you will doubtless remember that he is provided with teeth specially fitted for crushing his prey, and with fore-paws for digging in the ground.

The hedgehog and the shrew belong to the same order. They too are insect-eaters.