Among the vertebrate vegetable-eating animals we note the elephant, the great woolly elephant now extinct, and the mighty mammoth, known only by its remains, yet very well known, because the frozen mud of Siberia has preserved for us the entire animal, even to its eye-balls. We have in another lesson indicated the life history of the horse-like animals which belonged to these successive periods. There were also many families related to the tapirs, deer, bears, and musk-oxen of the present day. In fact the majority of the mammalian forms of the earlier ages have their modified representatives in the present age; while others, as the mastodon and many more, have made way for more modern families and are known only by fossil remains. The Ice period no doubt made a great change in the fauna of the globe. During its desolation and cold many families of animals perished. Other creatures changed their homes, migrating from the formerly temperate polar regions to the tropics, retreating to warmer latitudes as the ice-sheet advanced. Some of the carnivora especially were capable of resisting the cold by increasing the thickness of their coats; but animals dependent upon a vegetable diet must either perish with the flora of the regions they inhabited, or follow the changed lines of vegetable growth, as the northerly plants perished and vegetation flourished only in the warm southerly lands. The last of the mammals to appear in the brute creation were the quadrumana or monkey tribe, which hold the highest place in the brute creation. FOOTNOTES: [47] A later lesson will describe a mammal that comes from an egg! [48] The Mohammedan soldiers were forbidden to destroy fruit trees. LESSON XXI. A VERY OLD FAMILY. “’Twas when the world was in its prime, When the fresh stars had just begun Their race of glory, and young Time Told his first birth-days by the sun.” --MOORE. [Illustration: ANCIENT ARISTOCRACY.] One June morning I was sitting by the ocean. The tide was out and was unusually low, laying bare beds of sand that were seldom uncovered. The stone on which I sat had been dried by breeze and sun, but living barnacles fretted its sides, and wet bladder-weed draped its edges, indicating that usually the waters flowed above it. A little farther out, a multitude of small black sea-snails lay, each with tightly closed operculum to retain moisture sufficient until the sea returned; but now and then some few crawled to a more favorable position; and here and there a pale pink foot shod with a little black shoe reached forth, and taking hold upon the sand the creature pulled itself over by a muscular contraction.