26 



Dinocerata. 



Coryphodon. 



Dinocerata. 

 Pier-case, 

 No. 20. 



the Eocene of North. America have been described : plaster 

 casts of the fore and hind feet of one of these are exhibited. 



Coryphodon was the largest of the early Eocene 

 Ungulates ; it had six npper incisors and moderate- sized upper- 

 canines ; the cranium has no protuberances or horn-cores; the 

 astragalus has no head ; there is a third trochanter to the 

 femur. The five-toed feet, which resemble in structure those 

 of the Dinocerata, indicate some affinity to that group, which 

 it also preceded in time. 



Sub-order 4. — Dinocerata. 



This division contains a most remarkable group of huge 

 extinct herbivorous mammals, the remains of which have been 

 found in great abundance in the Eocene Tertiary strata of 

 Wyoming, North America. 



Fig. 35.— Restoration of Tinoceras ingens (Marsh). One-thirtieth natural size. Eocene Tertiary 

 lake-basin, Wyoming, North America. 



The fore and hind limb had feet with five well-developed 

 toes, each terminating in a hoof : the femur and tibia were 

 placed vertically in a line, as in the hind leg of the elephant. 

 The nasal bones were elongated, having two small pre-nasal 

 bones in front of them ; the animal does not appear to have 

 been furnished with a proboscis. 



The most striking feature is the skull, which is surmounted 

 by three pairs of rounded protuberances or horn-cores, which 



