digits touched the ground and were not entirely functionless and, in addition, there was a small splint, the rudiment of the fifth digit. The hind foot was three-toed, without splint. The little Uinta horse (_†Epihippus_) is still very incompletely known, but gives us one point at least of greater primitiveness than the White River genus in that only the last two premolars had taken on the molar-pattern, the forward two being smaller and simpler. The known species of the Uinta genus was very much smaller than any of the White River forms and even smaller than some of those of the preceding Bridger formation; but it should be remembered that the Uinta has been but partially explored and much remains to be learned regarding its fauna. The Bridger horses are fortunately much better known. There are several species of the genus _†Orohippus_, which form a connected and progressive series; and, though much smaller than the smallest and oldest of the White River forms, they were somewhat larger than the known representative of the Uinta, _†Epihippus_, but distinctly more primitive in all other respects. The incisors were simple cutting teeth, with no trace of even an incipient “mark,” and only one premolar in each jaw, the hindmost one, had taken on the molar-pattern. The orbit was farther forward in the skull and less enclosed behind than in _†Mesohippus_, the cranium narrower and less capacious; the neck was even shorter and the odontoid process of the axis still retained the primitive peg-like form. The limbs and feet were conspicuously shorter in proportion than those of the White River genus; the ulna and fibula were stouter and less reduced and entirely separate from the radius and tibia respectively. The front foot had four functional toes; the fifth digit, which in _†Mesohippus_ had been reduced to a splint, was completely developed in the Bridger horses, but the hind foot was three-toed. [Illustration: FIG. 153.—The “Dawn Horse” (_†Eohippus_) of the lower Eocene. Restored from a skeleton in the American Museum.]