XITI 



PHYLUM CHORDATA 



607 



Eocene of Egypt, is probably also a primitive member of the same 

 group. 



The Hyracoidea were represented in the Pliocene by an extinct 

 genus (Pliohyrax) ; and Archceohyrax from the Patagonian 

 Tertiary is perhaps also an allied form. 



A separate sub-order, the Condylarthra, has been established 

 for a number of Eocene Ungulates, which differ somewhat widely 

 from all the other members of that group, and approach the 

 Carnivora in some respects, though having certain resemblances to 



Fi<;. 1-23.J. Dinotherium giganteum. Side view of skull. y 6 th natural size. 

 (From Zittei's Paleontology, after Kaup.) 



the Hyracoidea. The pre-molars and molars are short and usually 

 bunodont,the pre-molars being simpler than the molars, the latter 

 sometimes tritubercular, like those of many of the Carnivora; the 

 incisors and canines also sometimes resemble those of the Carni- 

 vora. The humerus differs from that of the other Ungulata, 

 and resembles that of the Carnivora, in the presence of a foramen 

 over the inner condyle. The arrangement of the carpals corres- 

 ponds with what is observable in the Hyracoidea and also, as in 

 the latter group, the femur has a third trochanter. The limbs are 

 usually pentadactyle, with pointed ungual phalanges. The astragalus 

 has, as in the Carnivora, a uniformly rounded distal articular 



p P 2 



