Many years had passed since the Tree-dwellers lived. It was no longer warm on the wooded hills. There was snow on the ground the greater part of the year. After many years it became very cold. Then all the animals came down from the north. The coming of the musk sheep was the sign of the coming cold. THINGS TO DO _Bend your arms to show how the musk sheep's horns curve._ _How do you think the musk sheep used its horns?_ _Model a musk sheep in clay._ XXXII. THINGS TO THINK ABOUT What animals stay here in the winter? How do they keep warm? How do they find food? _The Woolly Rhinoceros_ About the same time that the musk sheep came from the north, another strange animal appeared. It was a huge creature. Not one like it has lived for ages. It was a woolly rhinoceros. The big-nosed rhinoceros liked to live where it was warm. It lived on the wooded hills before the Tree-dwellers did. The small-nosed rhinoceros liked the warm country, too. It came from the south when the Tree-dwellers appeared. But the woolly rhinoceros came down from the north. It was able to live in the cold. It had an inner coat of fine curly wool. This coat kept it warm. It had a coarse, hairy outer coat. This coat kept it from feeling heavy blows. It had two horns on its ugly snout. They kept it safe from harm. When it was not disturbed it was a peaceable animal. But when it was attacked there was no animal that was more fierce. The other animals learned to let it alone. Sometimes the wolves and hyenas frightened it over a precipice. But it was a long time before men tried to hunt it. THINGS TO DO _Tell a story of how the wild animals were taught to let the woolly rhinoceros alone._ _See if you can find an animal that has both an inner and an outer coat._ XXXIII. _How We Have Learned About the Tree-dwellers_ The Tree-dwellers lived such a long time ago that we do not know all that they did. But they have left some things to tell their story. A few of their bones and stone weapons have been found in the gravel. We have learned something about the Tree-dwellers from studying these. Bones of animals that lived then have been found in the caves. They tell something more about the life of the Tree-dwellers. Marks of plants have been found upon the rocks. They, too, help to tell the story. Wise men have studied all these things. They have tried to learn all that they could about these people. We have written their story in this book for you, so that you may know how our forefathers lived before they learned how to use fire. [Illustration] SUGGESTIONS TO TEACHERS [Illustration]