150 



PROCEEDINGS OF THE ACADEMY OF 



Cosoryx teres, sp. nov. 



Established on the connected frontal bones supporting the 

 horns of one specimen, and represented by portions of horns of 

 two others. The former individual is larger than any one belong- 

 ing to the other species, and the species is doubtless the largest 

 of the genus. The horns stand above the posterior part of the 

 orbit, which excavates its base, and presenting a considerable face 

 descending into the temporal or z3'gomatic fossa. There is no 

 free superciliarj- rim outside of the base as in C. ramosus^ Cope. 

 The section of the beam near the base is a regular oval, the long 

 axis directed longitudinally and a little outward in fi'ont. The 

 beam is erect with a slio^ht curvature outwards at the inner base 

 onl}'. So far as preserved it does not branch, but may do so in 

 its distal portion which is lost. The tissue is more spongy in- 

 teriorly than in the other species; supra-orbital foramen far within 

 the superciliary border. 



Measurements. m. 



Outer width between bases of horn cores 112 



Inner width between bases of horn cores 

 Width of temporal fossa behind horns . 

 Long diameter horn core 

 Short diameter horn core 

 Length of part preserved 



.055 

 .053 

 .028 

 .021 

 .033 



This species was as large as the Antilocapra americana of the 

 plains. 



Hesperomys loxodon, sp. nov. 



An entire mandibular ramus w^tli all the teeth preserved, was 

 found in the same deposits as the preceding species. Molars sub- 

 equal, short-crowned, triturating surface sigmoid. The apices of 

 the sigma on the inner side, tubercular, and anterior to the outer 

 apices. First molar with an additional transverse crest in front. 

 Incisor compressed, outer angle of enamel face rounded, smooth. 

 Molar series oblique, rising anteriorly. 



