Of sheep there is only one wild species in North America, the Rocky-Mountain sheep, or big-horn (Ovis montana, Fig. 7). This animal is of a much larger size than the ordinary domestic sheep, and its horns are of enormous size. A large animal of this species weighs about three hundred pounds. In Siberia there is a wild-sheep, called the argali, which Cuvier believed to be the same as our big-horn. It is certainly very remarkable that there should be only one species
of wild-sheep on this continent, and that that one should be confined to our highest system of mountains. The inquiring mind naturally asks, "Whence has this sheep come?" But this question is not easily answered. It may, however, be stated here that Cuvier was inclined to believe that it came from Siberia, and crossed Behring's Straits on the ice.
The Rocky-Mountain sheep lives in flocks, and is exceedingly wild, especially in regions that have been frequented by the hunters; and he who would get a shot at one of these animals has often to make wide détours, and always to proceed with the greatest caution. The flesh of this animal is very highly prized, being regarded by some as even better than venison, or ordinary mutton. The hunters tell remarkable stories of the big-horn. They assert that this animal will leap sometimes from high precipices, head foremost, and, striking upon the tips of its enormous horns, bound away on its course as if nothing had happened!
Characteristics belonging to different kinds of animals are some-