It is very curious to see the different ways in which the three chief lines of vegetable-feeders secured these advantages to themselves. First, there were the hogs and hippopotamuses. The hogs did not grow to any enormous size, but their thick skins were a great protection to them, and their eye-teeth became their defence, growing out from the lower, and sometimes from both jaws into huge tusks; while their broad, round, flexible snouts served them to turn up the ground, and so get at roots and underground

Footnote 161. Paleotherium.

Footnote 162. Eohippus.

Footnote 163. Xiphodon.

fruits such as other grass-feeding animals could not find; though at the same time they did not despise snakes or toads, and have become omnivorous animals. And so they have spread nearly all over the world; in Europe and Asia as wild hogs, and their wives the sows; one peculiar form, the Babirusa, being found only in Celebes; in Africa as

large Wart-hogs, some as big as donkeys, with two pair of strong tusks curling out of the mouth; while in South America the family is represented by the small Peccaries, which travel about in herds, and have no tusks to show; but which, nevertheless, are bold and fearless, for they have within their lips short lancet-shaped tusks, which inflict fearful wounds. Only in North America, north of Texas, no wild creature of the hog family now lives, though in ancient times there were plenty of them.

Fig. 67.

The Babirusa; the double-tusked hog of Celebes.

Meanwhile the warmth-loving hippopotamuses, the hog’s nearest relations, with huge grinding teeth behind, sharp front teeth, and tusks within their lips, took to a water-life in the Old World.[164] When we look at their immensely powerful bodies, and their short stout legs with four strong hoof-covered toes, and learn how rapidly they can gallop on land, and how furiously they charge an enemy in the water, snapping their great jaws which will kill a large animal at one crunch, we do not wonder that they can hold their own, especially as they always live in herds. Yet large and powerful as they are, they have not spread far over the earth, for though in past ages the hippopotamus swam in the river Thames, and grazed and left his bones in the ground upon which London streets now stand, yet after a time they crept down to warm Africa, where they may now be seen lazily basking on the surface of the Nile or of the river Zambesi by day, and making tracks by night into the swamps and jungle to feed on the coarse rank grass. They are well fitted for their life, for their thick naked skin, with pores which

Footnote 164. See picture heading.

give out a fatty oil, keeps them from chill in the water; their eyes are set well back on their heads, so that as they float deep they can still look around, and the slits of their nose, and the openings of their ears, can both be closed and made water-tight when they dive, while their slow breathing enables them to remain a long while under water.

The second line was that of the rhinoceroses, tapirs, and horses, or the uneven-toed animals which have one or three toes on the hind feet. They took to very different means of defence. The Tapirs,[165] large, heavy, and with enormously tough hides, seem to depend chiefly upon their great strength for defence. Starting in warm times in the Old World, they have wandered in their day nearly all over the globe, dying out in later times, till now one kind is left solitary in Sumatra and Malacca, and the remainder have found their way down to South America, where they tear the branches from the trees with their short movable snouts, and feed peaceably at night unless attacked, when they make a furious rush at their enemy and conquer by sheer force.

The rhinoceros, the tapir’s nearest relation, is even better defended; his skin is so thick and hard that in the Indian rhinoceros it actually forms a kind of jointed armour; his skull is wonderfully strong, and his nose is supported by thick bones, on the top of which are one or two solid horns, which are formed by a modification of the hairs of the skin growing matted together.[165]

And now notice, just as we saw that the horned

Footnote 165. See picture heading.

cow has no front upper teeth, so too the rhinoceros, though his horn is of quite a different kind, has in some cases lost his front teeth, which he does not need, since he rushes with his horn at his enemy instead of biting. Like the hippopotamus, the rhinoceros once wandered all over Europe and Asia, and when the great cold came on, the woolly species which roamed far north was often caught in the frost and snow of Northern Asia, where his fleshy body has been found preserved in the ice. Now he too has taken refuge in the warm parts of Asia and Africa, where he either grazes on the plains or plucks the leaves from the trees in the jungle with the fleshy flap of his upper lip.

Fig. 68.

Skeleton of a Wild Ass.

i, incisor teeth; g, grinding-teeth, with the gap between the two sets as in all large grass-feeders; k, knee; h, heel; f, foot; t, middle toe of three joints carrying the hoof; s, splint, or remains of one of the two lost toes; e, elbow; w, wrist; h, hand-bone; 1, 2, 3, joints of the middle toe.

But of all the animals of this three-toed group the Horse has the most interesting history, because we can read it most perfectly. The only certainly original wild animals of the horse tribe now living are the Zebras, Quaggas, and Asses of Asia and Africa; yet strange to say, it was in America that this tribe began, for there we find that tiny pony[166] not bigger than a fox, with four horn-covered toes to his front feet (and traces of a fifth) and three toes on his hind ones. Then, as ages went on, we meet with forms, still in America, first with four toes on the front foot, and then with only three toes on all the feet, and a splint in place of the fourth on the front ones. In the next period they have travelled into Europe, and there, as well as in America, we find larger animals with only three toes of about equal size. One more step, and we find the middle toe large and long, and covered with a strong hoof,

Footnote 166. See p. 213, and picture heading, p. 209.

while the two small ones are lifted off the ground. Lastly, in the next forms the two side toes became mere splints; and soon after, in America and in Europe, well-built animals with true horse’s hoofs abounded, the one large hoof covering the strong and broad middle toe. For what we call a horse’s knee is really his wrist, and just below it we can still find under the skin, those two small splints (sw) running down the bone of the hand, while the long middle finger or toe, with its three joints (1, 2, 3), forms what we call the foot. It is by these small splints

the horse still reveals to us that he belongs to the three-toed animals.[167]

Now while these changes in the toes were going on, the space between the front teeth and eye-teeth gradually increased, till we arrive at the large gap now seen in the horse and ass (see Fig. 67). The chief bone of the fore arm (radius) increased in size, and the other bone (ulna) became joined to it, and the same in the hind leg. The brain increased in size mainly in the front part, and the body grew much larger, improving in form and build, till the long, slender, flexible legs became the perfection of running and galloping limbs such as we find in the zebra of to-day, poised upon a strong jointed toe, with its last joint broadened into a firm pad, and covered with a thick nail—the hoof. We have only to compare the well-proportioned leg of a horse with the thick, strong, clumsy leg of an elephant, to see, on the one hand, what a shapely and beautiful limb it has become; while, on the other hand, if we put it by the side of a giraffe’s leg, we must acknowledge at once that it is a far

Footnote 167. The genealogy of the horse is so important, that it may be well to give a table of the seven principal stages, though transitions are known even between these.

| | | | | | | | | --- | --- | --- | --- | --- | --- | --- | | | Period. | In America. | Front Toes. | Hind Toes. | No. of Teeth. | In Europe. | | 7. | Recent and Upper Pliocene | -- Equus | 1 --------- 2 splints | 1 --------- 2 splints | 40 | Equus. Equus. | | 6. | Upper Pliocene | Pliohippus | 1 --------- 2 splints | 1 --------- 2 splints | 42 | -- | | 5. | Lower Pliocene | Protohippus | 1 large -------- 2 small | 1 large --------- 2 small | 44 | Hipparion. | | 4. | Upper Miocene | Miohippus | 3 | 3 | 44 | Anchitherium. | | 3. | Lower Miocene | Mesohippus | 3 -------- 1 splint | 3 | 44 | -- | | 2. | Upper Eocene | Orohippus | 4 | 3 | 44 | -- | | 1. | Lower Eocene | Eohippus | 4 -------- 1 splint | 3 | 44 | -- | stronger and more serviceable limb than if it had gone to the other extreme. There can be no doubt that when the horse arrived at this point of the strong single hoof and well-shaped body, he had a wide range over the world, both Old and New; but curiously enough, while in Asia and Africa the tribe branched out into many forms, such as asses, quaggas and zebras, in America it died out, so that till we found the fossil-forms,[168] it was thought that no horses had ever been there till they were brought by the Spaniards.

Meanwhile, in the Old World, they must have led as free and joyous a life as those horses do now which have run wild in Tartary and America, galloping, frolicking, feeding, and neighing to each other with delight, as they roamed over the wide plains in troops of thousands, for solitary wanderers they would soon have fallen a prey to wolves or jaguars; and if the mothers wished to protect their foals they had to learn to follow one leader and act together in time of danger.

“A thousand horse, the wild, the free,

Like waves that follow o’er the sea,

Headed by one black mighty steed

Who seemed the patriarch of his breed,”

they grew accustomed, as generations passed on, to unite against their common foes, placing the mares and their foals in the centre when attacked, while the fathers met the enemy with hoofs and teeth. And so they became intelligent and tractable even in their wild state, to those of their own kind, and laid the foundation of those noble qualities of which man now reaps the benefit.

Footnote 168. See table, above.

But the horses were not the only group which combined in this way for protection. The third great line of hoofed animals, those which have “cloven” feet of two toes, and which “chew the cud,” have learnt many a lesson of vigilance, fidelity, and affection, by their social habits. Everyone has read of the herds of antelopes or deer, where the sentinels stand faithfully watching while their companions feed, and stamp or whistle when danger is near; while in the herds of wild cattle, not only will the mothers keep a watchful look-out for danger, but the bulls will join to protect the young ones at the risk of their own lives. Mr. Allen relates how, in America, a young bison, which had strayed from the troop and was followed by wolves, was surrounded by a number of old bulls, who, facing about, warily conducted him across the plain till he was safely among the dense mass of buffaloes, which the wolves dared not attack.

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