The science of life : fully illustrated in tone and line and including many diagrams

THE FIRST GREAT PHYLUM:

porcupines, beavers, jerboas), the Insectivora or imnsect-eating mammals (hedgehogs, shrew-mice, moles), the Chiroptera or bats, the Carnivora or beasts of prey (cats, dogs, bears, civets, weasels, badgers, hyznas, otters, seals, walruses), and the toothless

1g. 72. A Primate.

Edentata (sloths, true ant-eaters, armadillos). They are on the whole smaller than the ungulates, and they are an altogether more varied cohort. Their feet are not so exclusively used for carrying their weight as are those of the hoofed mammals and they may be turned to a variety of other purposes. Many of the clawed mammals can grasp and hold things with their paws (which no ungulate can do) and many of them can climb. In some the claws are strong and the hand is specialized for digging ; the mole and the ant-eater illustrate this. In seals and walruses, which spend a large part of their lives in water, the hands and feet are paddles. And many of the unguiculates can fly. The flying-squirrels and the so-called flying-lemur have parachute-like folds of skin between their arms and legs by means of which they can skim down from the rees on which they live; and the Dats, having flying membranes between the enormously elongated fingers of their hands, can flutter and twist and turn as nimbly as any bird. The clawed mammals are also more catholic in their diet than the hoofed mammals; as a general rule (and except for the rodents, which will eat anything), they do not consume leaves and stems as the flat-toothed ungulates do, but feed on

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VERTEBRATES

other animals or on fruits and the juicier parts of plants.

The third cohort is the Primates, and includes the lemurs, the monkeys and apes, and ourselves. It is difficult to separate this cohort clearly from the unguiculates, for the lemurs are in many respects like some of the insectivores and extinct carnivores. The primates may be called the inquisitive mammals ; they are characterized first and foremost by their intelligence, and include the animals with the largest brains, the most useful, mobile hands, and the clearest-seeing eyes. The latter point may be associated in some way with another primate character —the presence of a more or less complete bony partition separating the eyeball from the muscles moving the lower jaw.

Moreover (except for one or two lemurs and the marmosets, which are clawed) they are distinguished from all other mammals by having flat nails on their fingers and toes, instead of claws or hoofs. Their hands contrast very strikingly with the feet of ungulates. In the latter group the foot is purely and solely a prop, a single shaft, and there is consequently a tendency to have few toes and to have them all bound together into one column. It is very strong and firm, but its possible uses are severely limited. In the primates the hand is used for grasping and examining things, and here, therefore, there is a full complement of five fingers which can move more or less independently of each other. It is a hand designed for variety and adaptability of movement rather than strength. For the most part the primates live among trees and climb.

A Cetacean.

Fig. 73.

The fourth and last cohort of placentals is the Cetaceans, the whales, dolphins, and porpoises. ‘They are wholly aquatic mammals. Many other kinds of mammal have taken more or less to water, but, except for those strange ungulate-like creatures, the dugong and manatee, none of them have

Tee.