838 SS AOLDILES TA OL STROUD EAN ES: 
cene beds of Europe. The two subfamilies differed chiefly in 
the larger size and the more complex dentition and foot structure 
of the 7itanotherine. 
Paleosyops is the most characteristic member of the first sub- 
family. It is found in the Lower and Middle Eocene of North 
America (Wind River and Bridger). The dentition was com- 
plete, that is, the incisors and premolars were all present; the 
premolars were simpler than the molars; the skull was without 
horns and without the concave outline of the upper surface that 
is so apparent among the Titanotheres. One species was about 
six feet long and three feet high. 
Diplacodon from the Upper Eocene of the United States, 
Uinta, is of great interest in that it is in many characters related 
to the Rhinoceroses, and at the same time stands as an almost 
perfect connecting link between Paleosyops of the Lower Eocene 
and the Titanothers of the Miocene. 
Litanotherium was a large form confined to the Lower Miocene 
and reaching its greatest development in the United States; a 
few specimens have been found in Europe. Despite the rather 
short time in which the animal lived upon the earth it developed 
an astonishing degree of variability, with the result that it has 
probably received as many different names as any form known. 
Thirteen genera and thirty-one species have been described from 
what Osborne, after a careful study of the cranial characters, 
regards as ‘“‘one or possibly two genera, and about fourteen 
definable species.” The Titanotheres are characterized by the 
development of a pair of horns on the anterior portion of the 
snout; the gradual loss or the tendency to the loss of the incisor 
teeth; the complex dentition, in which the premolars are as 
complex as the molars and the increased size. The largest 
species reached a length of between twelve and fifteen feet and 
a height of about seven feet. Remains are known from a large 
number of regions in the United States and Canada, showing 
that the animal roved over a wide territory. 
EG Gases 
