An interesting question in regard to the movements of the horse is that as to how far any known "pace" is natural to that animal, and how far it has been acquired by training and is, in a sense, artificial. We know so little of the wild horse, and of the more abundant wild asses and zebras, that it is difficult to say anything precise on this question. There is only one region in which the true original wild horse of the northern part of Asia and Europe still exists. That is the Gobi Desert, in Central Asia. This horse is known as Prevalsky's wild horse, in honour of the Russian traveller who discovered it. Live specimens are now to be seen in the Zoological Gardens and elsewhere. It closely resembles the drawings of horses made by the palaeolithic Cromagnard cave-men. A century ago a wild horse, probably of the same race as this, inhabited the Kirghiz Steppes, and was known as the Tarpan: it is now extinct. The more southern Arabian horse is not known in the wild state, whilst the wild horses of America are descendants of domesticated European horses which have "run wild." I do not know of any studies of the movements of the true wild horse, nor of those of wild asses and zebras, carried out by the aid of instantaneous photography. It would be interesting to know whether untaught wild "equines" would fall naturally into the gaits known as "the amble" and "the rack," or whether the walk, the trot, and the gallop are their only natural gaits. The amble, in which the fore and hind leg on the same side are advanced simultaneously, is a natural gait of the elephant, the fastest Muybridge could get from that great beast. He made a menagerie elephant amble at the rate of a mile in seven minutes. The only other animal known to habitually exhibit "the amble" is the giraffe. It is often exhibited by the giraffes in the Zoological Gardens in London, but has not, I believe, been recorded by a series of instantaneous photographs. When going at full speed over the grass wilds of Central Africa the giraffe exhibits a gait more like the galloping of deer and antelopes, and carries the long neck horizontally. No complete study of the "gaits" of large animals other than the horse has been made, since menagerie specimens and menagerie conditions are not satisfactory for the purpose, and, unfortunately, it has not been possible as yet to take series of photographs of them in their wild conditions.