ones see the light, the mother has nourishment ready for them: part of the food which she herself eats is turned into milk, and secreted by special glands, so that the newly-born calf or kitten is suckled at its mother's breast till it has strength to feed itself.

Among the earliest milk-givers must have been the ancestors of the curious pouched creatures of Australia, the "marsupials," which have a large pouch of skin, into which the mothers put their little ones when they are less than two inches long, and so imperfect that their legs are mere knobs, and they can do nothing more than hang on to the nipple with their round, sucking mouths, as if they had grown to it.

There the little ones hang, day and night, and their mother, from time to time, pumps milk into their mouths, while they breathe by a peculiar arrangement of the windpipe, which reaches up to the back

of their nose. Then, as they grow, the pouch stretches, and by-andby they begin to jump out and in, and feed on grass as well as their mother's milk.

Other singularly old-fashioned animals may be found in a Brazilian forest. The furry little opossum, the dreamy sloth, the strange ant

bear, and the armadillo, whose back is covered with long shields like the crocodile.

Having now taken leave of the curious pouch-bearers and the strange primitive sloths and armadillos, we find ourselves left to deal with an immense multitude of modern mammalia, which have spread in endless variety over the earth, and which may be divided into five great groups the Insectivora, or insect-eaters; the Rodents, or gnawers; the climbing and fruit-eating lemurs and monkeys; the Herbivora, or large vegetable-feeding animals; and the Carnivora, or flesh

eaters.

It is clear that the Rodents and Insectivores do not hold their place in the world by strength or audacity. Both lowly groups, of simple structure and with comparatively feeble brains, they have chiefly escaped destruction from higher forms by means of their nocturnal and burrowing habits or arboreal lives, and the marvelous rapidity with which they breed, combined with their power of sleeping without food during the winter in all cold countries. But the insect-eaters have no water-animal to match the beaver among rodents in sagacity or engi neering. With his chisel-like front teeth he gnaws a deep notch in the trunk of a larch or pine or willow, and then, going round to the other side, begins work there till the trunk is severed and falls heavily on the side of the deep notch, and therefore away from himself. He always makes the deep notch in the trunk on the side near the water, so that the tree in falling comes as near as possible to the stream. Then, after stripping off the bark and gnawing the trunk into pieces about six feet long, he uses his fore-paws and his teeth to drag them into position to build his dam. He does not always clear away all the branches, but he and his companions place the logs with these lying down the stream, so that they act as supports to resist the current and prevent the dam being washed away. Thus they make a broad foundation, sometimes as much as six feet wide, and upon this they pile logs and stones and mud till they have made a barrier often ten feet high and more than a hundred feet long. The lighter branches he uses to make his oven-shaped lodge, laying them down in basket-work shape, plastering them with mud, grass, and moss, and lining the chambers with wood-fiber and dry grass.

There remain to be noticed two groups of much larger animals : first, the Herbivora, or grass-feeders; and, secondly, their great enemies, the Carnivora, or flesh-feeders. We shall see that the vegetable-feeders have filled every spot where they could possibly find a footing, and if we could only trace out their pedigree we should be surprised to find how wonderfully each one has become fitted for the special work it has to do. But three things they all require and have. The first of these is a long face and freely-moving under jaw, with large grinding teeth to work up and chew the vegetable food; the second, a capacious stomach to hold and digest green meat enough to

nourish such bulky bodies; and, the third, good defensive weapons to protect themselves against each other and against their enemies.

In the three-toed group of the vegetable-eaters, the horse has the most interesting history. It was in America that the tribe began, for there we find that tiny pony not bigger than a fox, with four horncovered 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 with only three toes on all the feet, and a splint in the place of the fourth on the front ones. In the next period they have traveled into Europe, and 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, 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, well-built animals with true horse's hoofs abounded, the one large hoof covering the strong and broad middle 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 running down the bone of the hand, while the long middle finger, or toe, with its three joints, forms what we call the foot. It is by these small

toe.

splints that the horse still reveals to us that he belongs to the threetoed animals.

A far different race from the Herbivora is the large army of fleshfeeders, which we find throughout all past ages harassing and destroying the vegetable-feeders on all sides. And yet it would not be fair to speak of these larger flesh-feeding animals as if they had worked nothing but evil to their more peaceful neighbors, for how would Life educate her children if she put no difficulties in their way to be conquered, no sufferings to be endured? It was in the long struggle for life that the animals with the largest and strongest horns got the upper hand, that the swiftest horses or antelopes survived and left young ones; while we must remember that it is more often the sickly, wornout, and diseased animals that fall a prey to the devourers, and their life is ended far less painfully than if they dragged themselves into some hole to die.

"On revient toujours à ses premiers amours," says the French song. But who would have thought that, after rising step by step above the fish, and tracing the history of the backboned animals through their development in the air and over the land till we brought them to a state of intelligence second only to man, we should have to follow them back again to the water and find the highly-gifted milk-givers taking on the form and appearance of fishes? Nevertheless it is so, for seals and whales are as truly flesh-eating milk-givers as bears and wolves. "Do you really mean, then," exclaim nearly all people who are not naturalists, "that a whale is not a huge fish?" Certainly I do! A whale is no more a fish than crocodiles, penguins, or seals, are fishes, although they too live chiefly in the water.

A whale is a warm-blooded, air-breathing, milk-giving animal. Its fins are hands with finger-bones, having a large number of joints; its tail is a piece of cartilage, and not a fish's fin with bones and rays; it has teeth in its gums, even if it never cuts them; and it gives suck to its little one just as much as a cow does to her calf. Nay, the whalebone whales have even the traces of hind legs entirely buried under the skin, and in the Greenland whale the hip-joint and knee-joint can be distinguished with some of their muscles, though the bones are quite hidden and useless.

There was once a time when the great army of milk-givers had its difficulties and failures as well as all the other groups, only these came upon them not from other animals, but from the influence of snow and ice.

For we know that, from the time of tropical Europe, a change was creeping, during long ages, over the whole northern hemisphere. The climate grew colder and colder, the tropical plants and animals were driven back or died away, glaciers grew larger, and snow deeper and more lasting, till large sheets of ice covered Northern Europe, and in America the whole of the country as far south as New York.

True, there were probably warmer intervals in this intense cold, when the more southern animals came and went, for we find bones of the hippopotamus, hyena, and others buried between the glacial beds

in the south of England. But there is no doubt that at this time numbers of land-animals must have perished, for in England alone, out of fifty-three known species which lived in warmer times, only twelve survived the great cold, while others were driven southward, never to return.

Moreover, when the cold passed away, and the country began again to be covered with oak and pine forests where animals might feed and flourish, we find that a new enemy had made his appearance. Manactive, thinking, tool-making man-had begun to take possession of the caves, making weapons out of large flints bound into handles of wood, and lighting fires by rubbing wood together, so as to protect himself from wild beasts and inclement weather.

Many and fierce must have been his conflicts, for the wild beasts were still strong and numerous, and man had not yet the skill and weapons which he has since acquired. But, rough and savage though he may have been, he had powers which made him superior to all