382 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



Width of zygoma above last superior molar 0.023 



Depth of maxillary bone at second premolar 0.053 



Depth of common premaxillary at middle '. 0.014 



Depth of ramus mandibuli at condyle 0.084 



Depth of ramus mandibuli at last molar 0.044 



Depth of ramus mandibuli at second premolar 0.032 



Length of superior molar series 0.095 



Length of superior premolars 0.044 



Length of superior last molar 0.021 



There is some resemblance between this species and some of the Mery- 

 eochceri, including under this head the MerycJiyi according to Leidy's 

 latest view. It may be readily distinguished from the M. elegans and M. 

 rusticus by the deep nareal fissure of the premaxillary, and the salient 

 ridges of the molar teeth, together with very prominent malar bone and 

 zygomatic arch. The same characters distinguish it also from the M. 

 proprius and 31. majoTj which are besides much larger species. 



From the Upper Miocene of Montana 5 found by my assistant, J. C. 

 Isaac. 



A brief notice of this species appeared in the American Naturalist 

 for February, 1878. 



Blastomeryx borealis, Cope, Palsentological Bulletin, 28, p. 222. 



Additional specimens of this species enable me to add some points 

 of importance to the generic and specific characters which I have already 

 given. 



The posterior lake of the superior premolars is represented by a loop 

 or circle of enamel. The borders of the lakes of the true molars are 

 plicated, as in some of the species of horses. There is a strong sagittal 

 crest and a high inion. The bases of the horns are expanded outward 

 in a vertical laminar border. 



Aphelops fossiger, sp. nov. 



This rhinoceros is known from a considerable number of specimens. 

 Among these are three more or less complete crania, in some of which a 

 large part of the dentition remains. These are all from the Loup Fork 

 beds of Kansas. They afford an excellent basis of comparison with 

 the Aphelops already described from Nebraska, Colorado, and New 

 Mexico. 



This species reached larger dimensions than any of those already 

 described from this continent, excepting only the Aphelops jemezanus 

 Cope, from New Mexico. I compare it with the A. megalodus, of which 

 I procured a perfect and some imperfect skulls in Colorado in 1873. 



The occipital outline is expanded latterly, aud is nearly horizontal 

 above. It is vertical in profile, and the fossa for the ligamentum nuchw 

 is divided by a vertical massive keel. The condyles are rounded, and 

 not flattened at their extremities. The paramastoid and postglenoid 

 processes are of nearly equal lengths, and the meatus auditorius is 



