ORDER UNGULATA. 



1385 



Section A. Taligrada. — The astragalus has a head ; there is a 

 third trochanter to the femur ; and superior incisors are present. 



Family Pantolambdid^e. — The one family of this section is re- 

 presented by the genus Pa?itolambda, from the Puerco, or Lowest, 

 Eocene of New Mexico, which presents the feature, quite unique 



Fig. 1258. — Left upper cheek-dentition ot Coryphodon hamatus ; from the Wasatch Eocene 

 of North America. One-half natural size. (After Marsh.) 



among lophodont Ungulates, of having the upper true molars with 

 narrow subtriangular crowns like those of the premolars of Coryph- 

 odon (fig. 1258). This is a very important feature, as showing 

 the relationship of the dentition of the Ungulata to that of the 

 Carnivora ; and also as indicating that those Ungulates which have 

 the upper premolars as complex as the true molars, are more special- 

 ised than those in which the reverse condition obtains. 



Section B. Coryphodontia. — In this group, which Professor 

 Cope terms Pantodonta, the astragalus has no head ; there is a 



Fig. 1259. — Palatal aspect of the cranium ot Coryphodon hamatus ; from the Wasatch Eocene 

 of New Mexico. Two-ninths natural size. (After Cope.) 



third trochanter to the femur ; and upper incisors are present. 

 The cranium has no protuberances, and the development of the 

 upper canines is not excessive. 



