E. L. Troxell — Entelodonts in Marsh Collection. 377 



cipital and the temporal ; the opening is very large extern- 

 ally, but narrows rapidly inward, curving forward to the 

 end of the portion of the bone preserved, which includes a 

 half of the foramen ovale on the lower front side but does 

 not form a part of the cranium wall. 



Within the opening of the external auditory meatus, 

 two foramina lie on the posterior wall of the temporal 

 near the outer extremity of the tympanic ; likewise on the 

 opposite side of the temporal are two foramina, one of 

 which is quite large. 



Archceotherium crassum (Marsh), paratype, Gat. No. 

 10036. — In Marsh's publication of the description of 

 Archceotherium crassum he referred to two skeletons, and 

 of the second he said : 



"A rather smaller specimen, apparently of the same species, 

 afforded the following 



"Measurements. 



mm. 



Length of symphysis 122 



Depth of jaw below first premolar 57 



Depth below last lower molar 69 



Space occupied by lower molar series 216 



Space occupied by three lower true molars 76 ' f 



To those of Marsh, these dimensions have now been 

 added : 



Lower jaws 



mm. 



Narrowest part, ventral, behind the anterior mental tubercles 49 



Narrowest part, anterior to mental tubercles 63 



Anterior mental tubercles, lateral extent 116 



Posterior mental tubercles, lateral extent 143 



Marsh here gave the measurements of a specimen which 

 is found to be that now bearing the catalogue number 

 10036, consisting of the lower jaws only, with most of the 

 teeth broken away. The incisor teeth extend out at a wide 

 angle and the whole alveolar border seems more open and 

 spread than in other specimens. P x is double-rooted and 

 is not set near the canine. P 2 appears to be relatively 

 large ; while P 4 has a large flat heel which is not as wide as 

 the base of the cone in front of it. The talonid on M 3N is 

 not large, but a well developed cingulum encircles the 

 hypoconid of M 2 ; this is not seen elsewhere. M 2 is rela- 

 tively wide anteriorly. 



A feature which excites one 's curiosity is the thick bony 



