Although we know an immense number of the flint instruments, bone harpoons, and carvings and drawings of the ancient cave-dwellers, yet skulls and bones of the men themselves are extremely rare. Bones, skulls, and teeth of the animals they killed and ate are abundant in the caves—such as those of great bulls, deer, and horses. The bones also of animals which lived in these caves and contended with the ancient men for the possession of the shelter afforded by them, are abundant: bones of hyæna, of bear, of lion, and wolf. But human bones are exceedingly rare. This arises partly from the fact that human bones are not so thick and strong as those of large animals, and more easily soften, break up, and are lost. It is also due partly to the fact that the men were not nearly so numerous as the wild animals; but it is chiefly due to the fact that these people usually, but not always, buried their dead in the open; and whilst the bones of animals which had been eaten were left about in heaps on the floor of the caves, and became cemented together by the petrifying deposit caused by water dripping from the walls of these limestone caverns or by streams actually flooding the caverns, the bodies of the men themselves were removed when they died by their friends and families, and buried in the open ground, where they have gradually dissolved and broken up. Only a few here and there of the more ancient races were buried in a cave, and are in consequence preserved until the present day. Obviously, it would only be an exceptional honour or superstition which would cause the giving up of a cave to the interment of a dead body, or only rarely that a corpse could be tolerated in the floor of the cave still inhabited by living men.