The remainder of the known John Day fauna was composed of artiodactyls and perissodactyls. The latter had suffered serious losses as compared with the preceding or White River stage. Up to and through White River times the perissodactyls had held their own in actual diversity, though the rise of the artiodactyls had put an end to the dominant position which they had maintained in the Eocene. With the John Day the actual decline may be said to have begun. The rhinoceroses were represented chiefly by the †diceratheres, with a transverse pair of horns, some species of which were much larger than those of the lower Miocene. Hornless rhinoceroses have not yet been certainly found, though there is every reason to believe that they then existed, as they unquestionably did both before and after. Tapirs occurred but rarely and the horses were individually abundant, though in no great diversity; they were smaller and lighter than the horses of the lower Miocene. Enough has been found to demonstrate the presence of the clawed †chalicotheres, but not to show how they differed from their immediate successors. In the number of individuals, species, genera and families, the artiodactyls of the John Day much exceeded the perissodactyls. The peccaries were numerous, but smaller and more primitive than those of the succeeding age, as were also the †giant pigs, or †entelodonts, but the latter were very large. The peculiarly North American family of the †oreodonts was very numerously represented, and one genus (_†Promerycochœrus_), comprising animals not unlike the Wild Boar in size and shape, was the probable beginning of the series of proboscis-bearing †oreodonts, which led to such grotesque forms in the middle and upper Miocene. A family closely allied to the †oreodonts, and by many writers included in the latter, is the very remarkable group of the †Agriochœridæ, which was distinguished by the long, stout and cat-like tail and by the possession of claws instead of hoofs. The family is not known to have existed later than the John Day and no trace of it has been found in the succeeding formations. The camels seem to be all comprised in a single genus (_†Protomeryx_) which was the same as that found in the lower Miocene. A very small and dainty little creature (_†Hypertragulus_) belonged to another family, the relationships of which are not clear.