In all _ARTIODACTYLA_ the third and fourth digits are large, but a gradual reduction in the second and fifth can be well traced. Thus in the Suina the second and fifth digits, though smaller than the third and fourth, are well developed and all four metacarpals are distinct. In the Tragulina too all four metacarpals are developed, and in _Dorcatherium_ the third and fourth commonly remain distinct as in the Suina. In the other Artiodactyla however the third and fourth metacarpals are almost always united, though indications of their separate origin remain. In some Ruminantia, such as many Deer, the second and fifth digits are reduced to minute splint bones attached to the proximal end of the fused third and fourth metacarpals, and to small hoof-bearing phalanges, sometimes attached to splint-like distal vestiges of the metacarpals, sometimes altogether unconnected with any other skeletal structures. In some other Ruminants, such as the Sheep and Oxen, the only remnants of the second and fifth digits are nodules of bone supporting the hoofs, and in others, such as the Giraffe, _Anoplotherium commune_, some Antelopes and the Tylopoda, all traces of these digits have disappeared. The Camels differ from all living Ungulata vera in not having the distal phalanges completely encased in hoofs, and from all except the Hippopotami in placing a considerable amount of the manus on the ground in walking. [Illustration FIG. 106. MANUS OF PERISSODACTYLES. _A._ LEFT MANUS OF _Tapirus_. (After VON ZITTEL.) _B._ RIGHT MANUS OF _Titanotherium_. (After MARSH.) _C._ LEFT MANUS OF _Chalicotherium gigantium_. (After GERVAIS.) 1. scaphoid. 2. lunar. 3. cuneiform. 4. trapezoid. 5. magnum. 6. unciform. 7. trapezium. II, III, IV, V. second, third, fourth and fifth digits.]