3 i4 HISTORICAL PALEONTOLOGY. 



Whilst true Ruminants appear to be unknown, the Eocene 

 strata of North America have yielded to the researches of 

 Professor Marsh examples of an extraordinary group (Dino- 

 cerata}, which .may be considered as in some respects inter- 

 mediate between the Ungulates and the Proboscideans. In 

 Dinoceras itself (fig. 232) we have a large animal, equal in 

 dimensons to the living Elephants, which it further resembles 

 in the structure of the massive limbs, except that there are 

 only four toes to each foot. The upper jaw was devoid of 

 front teeth, but there were two very large canine teeth, in the 

 form of tusks directed perpendicularly downwards; and there 

 was also a series of six small molars on each. Each upper 

 jaw-bone carried a bony projection, which was probably of the 

 nature of a "horn-core," and was originally sheathed in horn. 



Kg. 232. Skull of Dinoceras mirabtlia, greatly reduced. Eocene, North America. 

 (After Marsh.) 



Two similar, but smaller, horn-cores are carried on the nasal 

 bones; and two much larger projections, also probably of the 

 nature of horn-cores, were carried upon the forehead. We 

 may thus infer that Dinoceras possessed three pairs of horns, 



