Two or three years passed by. Bodo was now about ten years old. He still lived on the wooded hills. One afternoon he went to the river. The wild horses were drinking there. Bodo watched them wade through the shallow water. He watched them toss their shaggy manes. He listened to their whinnying calls. He tried to whinny, too. The horses drank until they were satisfied, then they started toward their evening pasture. [Illustration: "_Bodo watched them wade through the shallow water_"] The largest horse led the herd up the trail. Others followed one by one. What a long line they made! The leader was far away over the hill before all the horses had left the stream. [Illustration: "_Farther out was a herd of mammoths_"] The smallest and the weakest ones lagged behind. Spotted hyenas were lying in wait for them. Bodo wondered if he could catch a wild horse. He wondered where the horses went at night. He followed the herd a long, long way. He went swinging along from branch to branch. At last he came to a grassy plain. He did not dare to go out on the plain. [Illustration: _A bison_] So he sat on a branch and peeped through the leaves. Wild horses were feeding on the edge of the plain. Farther out there was a herd of mammoths. Beyond these still other herds were feeding. They may have been bisons or wild cattle. All these animals were eating the fresh green grass. Bodo watched them till nearly sunset. But while the sky was still red in the west, Bodo tied himself to a branch and fell asleep. THINGS TO DO _Cut from paper some of the wild animals that Bodo saw eating grass._ _Make a picture of what Bodo saw when he was in the tree._ XVI. THINGS TO THINK ABOUT Can you think why our horses are larger than the wild horses? How many toes does a horse have on each foot? On what part of the foot does he walk? Where is the horse's heel? Do you think the horse's foot has always been the same shape that it is to-day? On what part of the foot does the cow walk? How many toes does she have? On what part of the foot does the cat walk? How many toes does she have? _Ancestors of Our Mammals_ The wild horses that Bodo saw were about the size of ponies. Long before the Tree-dwellers lived there were horse-like creatures the size of a fox. Long before that there was a time when there were no horses at all. Great reptiles moved about on the land, they swam in the seas, or they flew through the air. All other creatures feared them. The tiny mammals that lived then were about the size of rats and mice, but these mammals were not like rats and mice. The little mammals ran, but they did not run fast, for their feet were not well fitted for running. They climbed rocks and trunks of trees, and hid in holes in the ground. They ate the eggs of the large reptiles, and became their enemies. [Illustration: _A reptile_]