XIII 



PHYLUM CHORDATA 



607 



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

 group. 



The Hymcoidea were represented in the Pliocene by an extinct 

 genus {Pliohyrax) ; and Archwohyrax 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 ia some respects, though having certain resemblances to 



FjG. 1235.— Dinotherium giganteum. Side view ot skull. 

 (From Zittel'a PiiUwntoloyy , after Kaup.) 



^stli natural size. 



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 arp 

 usually pentadactyle, with pointed ungual phalanges. The astragalus 

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



p P 2 



