The rhinoceroses of the upper Miocene did not differ sufficiently from those of the lower Pliocene to call for particular attention. Needless to say, there were differences between the species of the two epochs, but in such a sketch as this only the broader and more obvious changes can be taken into account. Even in the middle Miocene the only feature which calls for notice was the first appearance in North America of the Old World genus _†Teleoceras_, which became so abundant in the upper Miocene and lower Pliocene. The middle Miocene species (_†T. medicornutus_) would seem to have been descended from _†T. aurelianensis_ of the lower Miocene of France; the two species agreed not only in having a small horn on the tip of the nose, but also in the presence of a still smaller one on the forehead. In the lower Miocene but two phyla of rhinoceroses have been found, both of which were the comparatively little changed descendants of Oligocene ancestors; and there was thus a notable difference from the rhinoceroses of the middle Miocene and subsequent stages, which were decidedly more modern in character. One of these phyla was constituted by those rhinoceroses (_†Diceratherium_, Fig. 129, p. 239) which had a transversely placed pair of horns on the nose, not one behind the other, as in all of the subsequent two-horned species, of which North America had but the one middle Miocene form (_†T. medicornutus_) mentioned above. The lower Miocene species of _†Diceratherium_ was a very small animal, and smaller than any member of the family from later formations. The †diceratheres originated in North America, and the stages of their development may be clearly made out; they also migrated to the eastern hemisphere and have been found in France, though it is possible that the genus was not truly monophyletic and arose independently in both hemispheres. The second phylum is that of the hornless forms (_†Cænopus_) which were so abundantly represented in the Oligocene and persisted with little change into the Pliocene. In the upper Oligocene, or John Day, the †diceratheres are the only rhinoceroses certainly yet obtained, and of these there were several species, large and small. The hornless forms may have been present in Oregon, but this has not been clearly demonstrated. That they continued to exist somewhere during that stage is hardly open to question, for they reappeared in the lower Miocene.