130 



Annals of the Carnegie Museum. 



The Cranium and Mandible. 

 The cranium is somewhat smaller than the type of Dolichorhinus 

 longiceps, the sagittal area of the parietals is more compressed laterally, 

 the zygomatic portion of the squamosal is slenderer and less expanded 

 laterally, and the basicranial axis has a greater bend.^ These char- 

 acters together with the slightly larger teeth constitute the most 

 marked differences in the two crania compared, but that they should 

 be regarded as of specific value is rather questionable. 



The sudden downward bend of the occiput of Dolichorhinus 

 heterodon, the flatter frontal region, the smaller pre-orbital ledge, and 

 the smaller and more delicate nasals seem to separate that species 



Fig. 2. Dolichorhinus longiceps (?) Douglass, No. 2865. Top view of cranium. 

 y^ nat. size. 



more widely from the present specimen. Furthermore, the difference 

 in the geological horizons in which D. heterodon and the present 

 specimen were found is to be considered. The former came from 

 horizon "Lower C" while the latter was found in the lower part of 

 horizon "Upper A" of the Uinta sediments. 



The high coronoid process and its sudden backward turn at the top, 

 so characteristic of the mandible of Dolichorhinus, is well shown in this 

 specimen. The angle is much compressed laterally, the temporal 

 fossa is located high up, but is quite deep, and the horizontal ramus 

 has but small vertical diameter. 



The Hyoid Arch. 

 The hyoid arch may best be compared with that of the tapir, 

 because in that genus there is apparently no extended anterior appen- 

 dix or process such as is seen on the basihyal of the horse or the 



^ The base of the skull has received some crushing fore-and-aft, a fact to which 

 the greater curvature of the basicranial axis may partly be due. 



