While the foraminifera, crabs, corals, mollusks, fish, and other creatures came successively into the world of life, there is nothing to prove that any one class descended from the class preceding. There is no evidence that any mollusk, crinoid, or fish, though in existence a few thousand years before the reptiles, could claim to be the reptiles’ grandfather, and there is no likelihood that the inside skeleton of the backboned animal was developed out of the outside skeleton of the mollusk. We must take these successive classes as we find them: we see each class in itself, developing into higher and better types; then, some maintain this improved development, some dwindle away and disappear. There will always be many things in nature which we cannot understand, but this need not discourage us in efforts to know; for the old saying is a good one--“He who grasps after a gold coat, is likely to get at least a sleeve.” In those old ages before man arrived, there were new things in the world. Since man came, there is nothing new under the sun: the facts which we learn and call new, are all old, very old. The reptiles were of the improving classes of animals. To be in full harmony with their habitations, and not miss any of the possibilities of their kingdom, we find the reptiles accommodating themselves to the earth, the air, and the sea. There was, for instance, the hadrosaurus, a two-legged reptile, which had long, strong hind legs, and a strong, pointed tail. These legs and the tail formed a tripod, like the three legs of a milking-stool, or the two legs and cane whereon an aged man supports himself. The enormous body of the hadrosaurus was upheld by the strong hind legs, and it paced slowly about: then when it wished to rest, or seat itself at ease, while with its small, hand-like fore-paws, it picked fruits and leaves from the tree-tops, it brought its strong tail into play, and rested on this and its legs. Thus we see the lucky hadrosaurus always carried about its own camp-stool. This creature was a land-living, herb-eating reptile. One very great reptile of the sea was the ichthyosaur, or fish reptile. This creature had paddles and a very strong tail-fin for swimming. The ichthyosaur could roll in the heavy billows like a porpoise, and liked to be far out on the sea busy at fishing. As it chased fish at sea, it held its head high above the water and breathed air with true lungs. Probably no fish could hold its own against a monster twenty-five feet long and protected by broad, solid plates of armor. The empire of the fish had finally departed.