xii LIFE OF TERTIARY PERIOD 221 



kind of horns. This seems the more probable, as many of 

 the species had no tusks, and in that case mere rounded bony 

 protuberances would have been of little protective use. 

 Figure 75 (on p. 222) represents the skeleton of one of 

 the largest species without tusks. From the scale given, it 

 must have been 1 1 or 12 feet long and nearly 8 feet high. 

 Professor Marsh informs us that these strange-horned 



FlG. 74. UlNTATHERWM CORNUTUM. 

 From the Middle Eocene of Wyoming, U.S.A. (Nicholson's Palaeontology.) 



animals have been found only in one Eocene lake-basin, in 

 Wyoming, U.S.A. He says : 



" These gigantic beasts, which nearly equalled the elephant in 

 size, roamed in great numbers about the borders of the ancient 

 tropical lake in which many of them were entombed. This lake- 

 basin, now drained by the Green River, the main tributary of the 

 Colorado, slowly filled up with sediment, but remained a lake so 

 long that the deposits formed in it during Eocene time reached a 

 vertical thickness of more than a mile. ... At the present time 

 this ancient lake-basin, now 6000 to 8000 feet above the sea, shows 



