370 



CHAPTER XLIV. 



(JIWEES OF MAMMALIA (Continued). 

 DiNOCERATA, TiLLODONTIA, AND TOXODONTIA. 



Order VII. Dixocerata. — This order comprises certain extra- 

 ordinary extinct Mammals from the Eocene of North America 

 which are regarded by Professor Cope as an aberrant group 

 of Ungulates, whilst Professor Marsh considers them as a dis- 

 tinct order intermediate between the Perissodactyle Ungulates 

 and the Probosciclea. 



The members of this order are all of gigantic dimensions, 

 and of massive construction. Both the fore and hind feet 

 possessed five loell-developed toes, each of which terminated in 

 a hoof. The nasal hones were elongated, and do not seem to have 

 supported a proboscis. The cranium carries three pairs of horn- 

 cores, which were prohaUy enveloped in horny sheaths. There 

 are no upper incisors, and the up-pcr canines liave the form of 

 long tushs directed doiomvards. (These characters are taken 

 from Dinoccras, the best known genus of the group.) The 

 order is distinguished from the Proboscidecc by the absence of 

 upper incisors, the presence of canines, the possession of three 

 pairs of horn-cores, and the absence of a proboscis. 



In Dinoceras itself, which may be taken as the type of the 

 group, we have a large animal equal in dimensions to the 

 living Elephants, which it resembles also in the osteology of 

 its limbs, in most essential respects. It is in the skull (fig. 

 656) and dentition, however, that the most striking peculi- 

 arities of Dinoceras are to be found. As regards the denti- 



