The fact that these animals can develop such an extraordinary speed was a great surprise to me, as undoubtedly it will be to most naturalists. Had we not been able to determine it accurately by means of the speedometers on our cars, I should never have dared state that they could reach fifty-five or sixty miles an hour. It must be remembered that the animals can continue at such a high speed only for a short distanceperhaps half a mileand will never exert themselves to the utmost unless they are thoroughly frightened. They would run just fast enough to keep well away from the cars or our horses, and it was only when we began to shoot that they showed what they were capable of doing. When the bullets began to scatter about them they would seem to flatten several inches and run at such a terrific speed that their legs appeared only as a blur.

Of course, they have developed their fleetness as a protection from enemies. Their greatest menace is the wolves, but since we demonstrated that these animals cannot travel faster than about thirty miles an hour, the antelope are perfectly safe unless they happen to be caught off their guard. To prevent just this, the gazelles usually keep well out on the open plains and avoid rocks or abrupt hills which would furnish cover for a wolf. Of course, they often go into the rolling ground, but it is usually where the slopes are gradual and where they have sufficient space in which to protect themselves.

The gazelles have a perfectly smooth, even run when going at full speed. I have often seen them bound along when not particularly frightened, but never when they are really trying to get away in the shortest possible time. The front limbs, as in the case of a deer, act largely as supports and the real motive power comes from the hind legs. If an antelope has only a front leg broken no living horse can catch it, but with a shattered hind limb my pony could run it down. I have already related (see [the end of chapter IV]) how, in a car, we pursued an antelope with both front legs broken below the knee; even then, it reached a speed of fifteen miles an hour. The Mongolian plains are firm and hard with no bushes or other obstructions and, consequently, are especially favorable for rapid travel.

The cheetah, or hunting leopard of Africa, has the reputation of being able to reach a greater speed, for a short dash, than any other animal in that country, and I have often wondered how it would fare in a race with a Mongolian gazelle. Unfortunately, conditions in Africa are not favorable for the use of automobiles in hunting, and no actual facts as to the speed of the cheetah are available. At this camp, and during the journey back to Urga, we had many glorious hunts. Each one held its own individual fascination, for no two were just alike; and every day we learned something new about the life history of the Mongolian antelope. We needed specimens for a group in the new Hall of Asiatic Life in the American Museum of Natural History, as well as a series representing all ages of both males and females for scientific study. When we returned to Urga we had them all.