Page:Natural History (1848).djvu/173

Rh there are, on each side, two small rudimentary bones, which represent two lateral toes. The teeth are thus arranged: inc. $6⁄6$; can. $1—1⁄1—1$; mol. $7—7⁄6—6$;=42. The incisors, during youth, have their crowns furrowed with a groove; the molars have square crowns, marked with four crescents of enamel, the ends of the laminæ which penetrate them. The canines are developed only in the male sex: between them and the first molar, there is a broad open space, admitting the operation of the bit, with which man governs these powerful and useful animals in a state of discipline. The stomach is simple, and incapable of rumination, but as the natural food consists exclusively of herbage, the intestines are greatly lengthened, to permit a more perfect extraction of the nutrition contained in it. One young one, called a foal, is ordinarily produced at a birth, which is suckled during six or seven months: the mammæ of the female are situated between the posterior limbs. Africa and Asia are the native regions of the animals of this family; which, associating in numerous herds, range over the vast plains and tablelands, which are unincumbered with forests. Two species, however, the Horse and the Ass of domestication, have been widely dispersed over the earth by man.

The few species, (not exceeding ten,) which are known to belong to the family under consideration, have so many characters in common, that many zoologists of high reputation consider them as constituting but one genus. Mr. Gray, how-