ORDER UNGULATA. 



1409 



resemble those of Palceotherium, but the upper true molars are of 

 the triangular tritubercular type. The first pair of incisors is 

 small, but the second is large and scalpriform, with persistent 

 pulps like the incisors of the Rodents. In many respects the 

 skeleton approximates to that of the Creodonta ; the femur has a 

 third trochanter ; the feet were five-toed, with the whole sole applied 

 to the ground, and having ungual phalanges similar to those of the 

 Bears. The brain-cavity is of small size, and the cerebral hemi- 

 spheres did not extend over the cerebellum or the olfactory lobes. 

 The orbits are not complete, but open into the temporal fossae. 

 Clavicles were probably present. 



Family Platychceropid^:. — The type genus of this family is 

 Platychosrops (Miolophus), from the London Clay, to which the 



Fig. 1290. — Esthonyx Burmeisteri. — The palate and mandible ; from the Wasatch Eocene of 

 Wyoming, U.S.A. Two-thirds natural size, a, Lateral view of part of cranium and mandible ; 

 b, Oral view of right half of palate ; c, Oral view of mandible. (After Cope.) 



North American Esthonyx (fig. 1290) appears to be allied. In the 

 latter the first upper and the second lower incisors are scalpriform, 

 but do not grow from persistent pulps ; the dental formula is 



I. -, C. -, Pm. ?-, M. ^ 



3i 3 3 



rops, the former must constitute the type of a family, which should 

 be known as the Esthonychidce. The genus Psittacotherium, of 

 which the family position is uncertain, has the mandible of great 



If Esthonyx be not allied to Platychaz- 



