2z6 THE INTERNATIONAL MONTHLY. 
steady modifications, which are, for the most part, in a direction 
opposite to that taken by the equine series. The tendency to 
a reduction of digits ceases, for the increasing stature and mas- 
siveness of body require a broad and strong support in the feet. 
The limbs do not become elongated, as in the horses, but grow 
relatively shorter and heavier. The anterior teeth are reduced in 
number, but enlarged in size, and the premolars become more 
like the molars. 
In the White River beds may also be found the beginnings of 
a short side branch from the main series, a branch which culmi- 
nated in the John Day beds, and then died out ; namely, a succes- 
sion of species with a pair of small horns placed transversely upon 
the end of the nose. The nasal bones are thickened and 
strengthened, to carry the horns, but otherwise these species are 
like those of Canopus. These curious animals extended their 
range to the eastern hemisphere, but their career was short, and 
they appear not to have given rise to any subsequent type. 
The rhinoceroses of the Loup Fork beds are very different 
from those of the White River and are believed by Osborn, who 
has made a special study of the group, not to be descended from 
the latter, but to be immigrants from the Old World. They 
were very short limbed and massive creatures, with heavy bones 
and enormous bodies, with proportions, in brief, quite resembling 
those of the hippopotamus. The females were hornless, but 
the males were provided with a single, small horn, placed upon 
the tip of the snout ; the teeth had attained to practically the 
modern stage of development. In North America the rhinoc- 
eroses continued into the Pliocene, but gradually became more 
rare, until, in the Pleistocene, they had entirely disappeared, 
except, perhaps, in a few favored localities of the continent, such 
as Florida and California. So far as is at present known, they 
never entered South America at all. 
In the Old World this main line was much longer lived and 
more diversified than in America, and the species were very 
varied and abundant throughout the Miocene and Pliocene. 
Already in the Miocene, the forerunners of the modern African 
