36 Annals of the Carnegie Museum. 



Promerycochoerus vantasselensis, 10 sp. nov. 



(Type. No. 1230 Carnegie Museum Catalogue of Vertebrate Fossils. ) 



This species is based upon a number of skulls and parts of skeletons 

 in the collection of the Carnegie Museum. The material was collected 

 in the middle of the Lower Harrison beds on Vantassel Creek, Con- 

 verse County, Wyoming. The type consists of the skull, the ramus of 

 the right side of the mandible with the dentition, and other parts of 

 the skeleton. 



This species is very closely allied to Promerycochcerns carrikeri, but 

 in P. vantasselensis the zygomatic arch is less robust, the sagittal crest 

 is not so high, the anterior nares are more obliquely inclined poster- 

 iorly, and the nasals consequently are shorter than in Promerycoclwrus 

 carrikeri. These differences apparently suggest a change leading 

 up to forms belonging to the genus Merycochoirus which are found in 

 later horizons. The small incisors and the more anterior position of 

 the infraorbital foramen of the present species are, however, characters 

 of too much importance to allow us seriously to regard this species as 

 ancestral to Merycochoerus. A comparison with the type of the imper- 

 fectly known species Merychyus major Leidy u shows that the infraor- 

 bital foramina of the two species nearly agree. 



Measurements. 



mm. 



Greatest length of the skull 320 



Distance from the occipital condyle to and including the incisors 305 



Distance from the tip of the nasals to the anterior border of the orbit... 115 



Distance from the anterior border of the orbit to the condyles 172 



Distance from the anterior border of the orbit to the incisors lla 200 



Length of the alveolar border of the maxillary 170 



Distance from the posterior end of the alveolar border of maxillary to 



the occipital condyle 127 



Greatest transverse diameter of the skull 225 



Transverse diameter of the occipital condyles 53 



Vertical diameter of the tympanic bulla 30 



Transverse diameter of the tympanic bulla 24 



Greatest transverse diameter of the brain cavity 93 



10 The specific name indicates the locality where the type specimen was found. 



;1 An emargination which undoubtedly represents the infraorbital foramen is found 

 on the broken border of the maxillary bone above P^ in the type of Merychyus major. 



lla A slight depression by crushing in the region of the inion causes this measure- 

 ment to be somewhat greater than it otherwise would be. 





