In the upper molars the two outer columns or tubercles of the primitive tubercular molar coalesce to form an outer wall, from which proceed two crescentic transverse crests, the connexion between the crests and the wall being slight or imperfect, and the crests themselves sometimes tubercular.
They are heavily built ruminants, with horns of nearly equal size in both sexes, short tapering tails, large hoofs, narrow goat-like upper molars, and usually small face-glands.
These three are therefore reckoned as milk-molars, and their successors as premolars, while the last three correspond to the true molars of other mammals.
It also shows that the anterior molars of elephants do not correspond to the premolars of other ungulates, but to the milk-molars, the early loss of which in consequence of the peculiar process of horizontal forward-moving (From Owen.) FIG.