But of all the animals of this three-toed group the Horse has the most interesting history, because we can read it most perfectly. The only certainly original wild animals of the horse tribe now living are the Zebras, Quaggas, and Asses of Asia and Africa; yet strange to say, it was in America that this tribe began, for there we find that tiny pony[166] not bigger than a fox, with four horn-covered toes to his front feet (and traces of a fifth) and three toes on his hind ones. Then, as ages went on, we meet with forms, still in America, first with four toes on the front foot, and then with only three toes on all the feet, and a splint in place of the fourth on the front ones. In the next period they have travelled into Europe, and there, as well as in America, we find larger animals with only three toes of about equal size. One more step, and we find the middle toe large and long, and covered with a strong hoof, while the two small ones are lifted off the ground. Lastly, in the next forms the two side toes became mere splints; and soon after, in America and in Europe, well-built animals with true horse’s hoofs abounded, the one large hoof covering the strong and broad middle toe. For what we call a horse’s knee is really his wrist, and just below it we can still find under the skin, those two small splints (_sw_) running down the bone of the hand, while the long middle finger or toe, with its three joints (1, 2, 3), forms what we call the foot. It is by these small splints the horse still reveals to us that he belongs to the three-toed animals.[167]