312 DAVIDSON BLACK 



siiprasylvian sulcus in every hemisphere but one examined; 

 relations and extent of lobus anterior and lobulus simplex cere- 

 belli; presence of parieto-temporal canal. B, suilline characters: 

 internal carotid artery transmitted through the posterior lacer- 

 ated foramen; caudal ectosylvian operculum extensive; ramus 

 descendens suprasylvii and ramus suprasylvii posterior as in Sus; 

 course of presylvian sulcus; possible continuity of coronal and 

 splenial sulci in one specimen. Thus the appropriateness of 

 Leidy's original designation of Oreodon as a 'ruminating hog' 

 becomes increasingly evident as the endocranial characters are 

 summarized. 



It will be noted that in point of numbers the suilline exceed 

 the ruminant endocranial resemblances in the above list but it 

 remains questionable which should be given the greater weight. 

 On other grounds Osborn and Matthew (v. Osborn, 1. c, p. 549) 

 have placed the Oreodontidae under a separate Sectional heading 

 of the Order Artiodactyla, while Gregory (1. c, p. 466) places the 

 family Oreodontidae within his Suborder Ruminantia. A con- 

 sideration of the possible bearing that the data here collected 

 may have upon the question of the systematic position of Oreo- 

 don will be deferred until a study can be made of endocranial 

 casts from contemporaneous Entelodonts and if possible of their 

 Achaenodont precursors. 



The endocranial configuration of Oreodon presents no char- 

 acters that can be considered as specific per se. Their speci- 

 ficity depends upon their presence in combination with the gen- 

 eralized and determinate artiodactyl features, and in this sense 

 the following apparently specific characters have been noted: 

 extreme rostral position of the trigonum Sylvii of HoU ; presence 

 of a lobulus petrosus cerebelli (as defined above). 



To recapitulate, it is evident from a study of its endocranial 

 morphology that Oreodon was a primitive, macrosmatic, artio- 

 dactyl ungulate presenting a curious blending of suilline and 

 ruminant characters; and further that any edentate (e. g., Oryc- 

 teropus) resemblances are of a superficial nature and wholly 

 confined to the rhinencephalon. 



