The hoofed animals were represented by a great variety of forms, both immigrant and indigenous, of which the latter belonged to orders now entirely extinct. Horses were common in all parts of the continent, where fossils of this epoch have been obtained, and are referable to two very distinct groups: (1) to the typical genus _Equus_, of which three species have been described, all somewhat more primitive than the True Horse (_E. caballus_) and, like most of the Pleistocene species of North America, with a certain resemblance to the zebras and asses; (2) to an extinct group of four genera, the best known of which is _†Hippidion_. The species of this genus (which has also been reported from North America, though upon hardly sufficient evidence) had most exceptional characters in the skull, and the head was relatively large and clumsy, with narrow and very high facial region. The neck was comparatively short, the limbs heavy and the feet short. These animals can hardly have been very swift runners. A very interesting member of this group is _†Hyperhippidium_, a small horse found in the Andes, with remarkably short feet, well adapted for a mountain life. The only other perissodactyls were tapirs, which ranged down to the Argentine pampas, much farther south than now. [Illustration: FIG. 119.—A Pampas Horse (_†Hippidion neogæum_). Restored from a skeleton in the National Museum, Buenos Aires.] The Artiodactyla were much more varied; there were peccaries, many species of llamas, which then extended into Brazil, and were not confined, as at present, to the colder portions of the continent. There were also numerous deer, all of the South American type, and two different antelopes have been reported, though that family has no representatives in the southern continent now. Several species of †mastodons have been found in Brazil, Argentina, Bolivia and elsewhere, but none of the true elephants. Why the †mastodons were able to make their way into South America, while the elephants were not, is one of the puzzling questions of mammalian distribution to which no answer can be given.