374 



ORDERS OF MAMMALIA. 



The type-genus of tlie order is TillotJierium, which presents 

 a remarkable combination of the characters of tlie Ungulata, 

 Rodnitia, and Cariiivora. The general form of the skeleton 

 most closely resembles that of the Carnivores, the sknll being 

 like that of the Bears in many respects, whilst the feet are 

 five-toed, with the whole sole applied to the ground, and 

 having ungual phalanges similar to those of the Ursidw. The 

 brain-cavity is of small size, and tlie cerebral hemispheres 

 did not extend over the cerebellum or the olfactory lobes. 

 The orbits are not complete, but open into the temporal 

 fossae. The prsemolars and molars liave grinding crowns, the 

 canines are of small size, and the pnemaxilke carried a pair 

 of large scalpriform incisors (fig. 658), which resemble those 



Fig. 6i>S.—Tillodontia. Side view of the slvull of Tillotheriumfodiens, with tlie lower jaw 

 disjilaced downwards, one-fourth of the natural size. (After Marsh.) 



of the Eodents in having chisel-shaped crowns, and in grow- 

 ing throughout the life of the animal. As in Eodents, there 

 is a corresponding pair of scalpriform incisors in the lower 

 jaw. The dental formula is — 



jjni 



m 



34. 



1—1 ' 2—2 3- 



Allied to TiUothcrivm is the Anchippodus ( = Trorjosvs) of 

 Leidy, from the Eocene deposits of Wyoming. 



