The yak lives among the mountains, sometimes climbing to a height of fully twenty thousand feet, and scrambles about among the boulders with wonderful activity. Large herds of these animals, however, have been domesticated, and are used as beasts of burden, while their flesh is said to be almost as tender and well-flavored as beef. The big, tufted tail, too, is highly valued, for it is dyed in various colors, and is then employed in making the fly-flappers which are used so much in Eastern countries for driving away flies. THE BISON The famous bison, commonly called buffalo, of North America, sad to say is now almost extinct, for there are only a few small herds living under special protection. Yet, not so very many years ago, these magnificent animals wandered over the prairies in millions. Even a single herd, sometimes, would extend farther than the eye could reach, and we read of one herd which covered a tract of country fifty miles long and twenty-five miles broad! But these herds were recklessly destroyed for the sake of their hides and tongues, and now there are only a few wild buffaloes left alive altogether. Generally, however, buffaloes are to be seen in zoos, and if you go to look at them you will most likely think that the male looks rather like a very big lion. For it has an enormous mane of long, shaggy hair, which covers the head and shoulders. There is also a sort of long beard under the chin, and the hair of the sides and hind quarters is very thick. The consequence is that the animal looks a great deal bigger than it really is, although it stands well over five feet high at the shoulders. In spite of its great mass of hair, this is a very active animal, and it can both trot and gallop with considerable speed. When galloping it always holds its head close to the ground, and its tail high up in the air. It is not by any means a courageous animal, notwithstanding its size and strength. But the bulls fight most savagely with one another, roaring so loudly that in the days of the great herds the noise was compared to thunder, and could be heard for miles. Another kind of bison, called the aurochs, lives in the great forests of Northern Europe. Its mane is not so long and thick as that of the American animal, but its horns are longer and not so strongly curved. THE CAPE BUFFALO Smaller than the bison, but very much more formidable, is the cape buffalo, which is spread over almost the whole of Africa south of the equator. It is about as big as an ordinary bullock, and has a pair of massive and sharply pointed curved horns, which are sometimes as much as three feet in length.