184 THE WASATCIJ AND liKID(iEK FAUX^. 



zygomata. The muzzle is broad and but little elevated, so that the nasal 

 meatus is between the alveolae of the superior incisors. The enamel of 

 the superior incisors is not grooved, but has a delicate striate sculpture. 

 The inferior incisor does not project as far as the alveolar border of the 

 jaw, its surface worn by the upper incisor is horizontal and anterior. The 

 inferior diastema is a thin edge, and the ramus is deep there. The temporal 

 surface of the parietal bones is rugose. The cranium is depressed, and 

 has a trace of sagittal crest. The anterior margin of the temporal fossa is 

 marked by a curved angle on each side of the frontal bone. The supra- 

 orbital arch is very short. The mandibular incisors ai'e narrowly separa- 

 ted by a naiTOW prolongation of the symphysis. The exposure of the 

 tooth is lateral, its direction nearly anterior. It projects anteriorly very 

 little beyond the symphysis, and has a horizontal triturating surface below 

 the level of the latter. There are alveolae for but three molar teeth, each 

 with three roots. The teeth themselves are not contained in them, but were 

 apparently lost before the cranium was entombed in tlie Eocene mud. 

 The position of the first molar is occupied by spongy bone in both maxil- 

 laries, and appears as though such teeth might have existed eai-lier in life, 



and been shed. 



Measurements. 



M. 



Longth of cranium (3.75 in.) 095 



Width of cranium (without zygomas) 040 



Width of cranium (with zygomas) 072 



Width of occiput 032 



Width of occiput near end of nasals . 027 



Width of ui)pcr cutting tooth 007 



Depth of upper cutting tooth 0085 



Length exposed i)art lower tooth 009 



Width exposeil i)art lower tooth 006 



The species differs from the P. delicatus Leid}', in its superior size, being, 

 in fact, the largest species of the genus. 



The typical specimen was found by myself on Cottonwood Creek, Wy- 

 oming, in the IJridger beds. 



