Rhinoceros and Palceotherium.* The present genus is established on 

 mandibular rami only, which cannot be certainly associated with crania. 



Char. gen. Dentition : I. ? ; C. 1 ; Pm. 3 ; M. 3 ; the canines slightly 

 separated from each other, but not from the first premolar. Crowns of 

 the premolars with L-shaped crescents as in Rhinoceros ; of the molars 

 with completed c'rescents ; the last molar with third posterior crescent. 

 Symphysis manclibuli coossified ; crowns of canines not projecting, conic. 



Char, specif. Symphysis oblique, ramus rather shallow. Last molar 

 with three columnar ribs on the outer side, four on the inner, produced 

 by the continuance inwards of the ridges from the anterior and posterior 

 outer cusps. Enamel nearly smooth ; a cingulum round inner basis of 

 crown of canine. 



Measurements. 



M. 



Length mandibular ramus 520 



' ' symphysis 144 



" series of molars 320 



" " true molars 215 



" last molar 088 



" penultimate do 072 



The genus differs from Titanotherium and Brontotherium in the ab- 

 sence of incisors, and from the former in the presence of but three pre- 

 molars. If there had been a deciduous incisor on each side I was unable 

 to detect any trace of it. 



Miobasiletjs ophryas. Gen. et sp. no v. 



Established on a cranium with nearly complete dentition, but without 

 mandibular ramus. Head elongate, concave in profile from the inter- 

 orbital region to the supraoccipital crest. This is transverse and con- 

 cave, the posterior borders of the temporal fossae extending behind it. 

 These fossse leave a narrow flat vertex between them. Zygomatic arch 

 stout and rather deep ; a strong postglenoid process. Nasal bones very 

 massive, their free portion elongate, hornless. A massive horn-core 

 rising from above each orbit, no superciliary angle or ridge. Orbit not 

 enclosed behind. Of molar teeth only Pm. 2, M. 3, preserved, the M. 

 with two, the Pm. with one inner cone, and two outer continuous cres- 

 cents. The latter send inwards to one side of the cones a transverse 

 ridge. Incisors and canines unknown. 



Char, specif. Front concave transverse just behind between the horns. 

 Latter massive and little compressed. Nasal bones convex longitudinally 

 and transversely, slightly rugose. Transverse ridges of teeth with trans- 

 verse expansions at their inner extremity being thus T-shaped. 



* Leidy and Marsh have described two genera of this group, viz. , Titanotherium and 

 Brontolherium, hut without certain indication of their possession of horns. 



