9!) 



The cranium of Uiiilaihcruiiu, represented in Fig. 1, Plulc XXVI, is of 

 rcnuirkablc form and unlike tliat of any other known animal. The specimen, 

 though much mutilated, is yet sufficiently well preserved to give us sonic 

 notion of the peculiarities of the skull. 



The top of the cranium presents a deep basin-like concavity separated on 

 each side from the temporal fossfe l)y a wide projecting crest. The entire 

 extent ot" tliis cannot be determined from the broken condition of its edirc in 

 the specimen, l)ut on one side it projects obliquely outward and upward for 

 three inches beyond the inner surface of the temporal fossa. Posteriorly, the 

 crest is continuous with a thick broken border extending across the top of 

 the occiput so as to make it api)ear as if the lateral projections of the 

 cranium were continuous behind. The depth of the supra-cranial hollow in 

 the specimen is upward of several inches, and was, no doubt, greater in the 

 complete skull. 



The temporal fossa is a long deep concavity overarched by the wide lateral 

 crest separating it from the supra-cranial hollow. Its lower part spreads out- 

 wardly on a l:)road ledge extending from the lateral occipital border forward 

 upon the upper surface of the zygomatic root. This ledge resembles the 

 long extension backward of the zygomatic root in the bear, and in like man- 

 ner it projects over the auditory archway and the contiguous processes. 



From the fractured condition of the specimen, I am unable to ascertain the 

 ])osition of the squamous suture, and this may be said also of other sutures. 

 The temporal surface as formed Ijy the squamosal plate and the iieighb(jring 

 portion of the parietal is pierced with a number of large vascular foramina. 

 The occipital surface is broad, and it slopes inwardly from above to the occi- 

 pital foramen. 



The large condyles project strongly backward and downward, and are not 

 in the least degree sessile, but well defined from the occipital surfiace by a 

 deep groove. Their articular surface is broad, being within a fourth as great 

 as the depth, and the flexure near its middle appears less pVonounced than 

 usvial. The articular surfaces are not prolonged below on the basi-occipital, 

 and the condyles in this position are separated by a deep notch twenty lines 

 from each other. 



The basilar process is broad and thick, and moderately tapering. Its undcM- 

 surface is transversely convex, especially antericn-ly. On each side ol tlie 

 middle it presents a broad rough eminence for muscular attachment. 



