42 



tures. Distinction founded on the possession of two conic 

 tubercles, of tlie inner series, on the last superior molar in- 

 stead of one. 



LiMNOHYUS LATICEPS, Marsh. 



Pahrosyops Laticeps. Am. Journ. of Sc. v. iv. p. 122. 



Specific cliaracters. — " Cranium is broad. The zygomatic 

 arches much expanded. The nasals are narrow and elon- 

 gated, and more like the corresponding bones in Hyrax than 

 those in the larger pachyderms." 



Fragments of the upper molar and premolar series. The 

 species is determined by measurements given by Dr. Leidy 

 of the second upper molar. 



LEUROCEPHALUS, Gen. Nov. 



Established on a specimen having a nearly complete den- 

 tition, and portions of the cranium. 



Dental Formula : (I. |, C. |, Pm. |, M. |,) X 2 = 44. 



Upper incisors acute, with strong posterior ridges, lower 

 incisors compressed and laniariform , canines compressed, with 

 serrated cutting edges ; first upper premolar with rudimentary 

 anterior lobe, last upper molar with rudimentary postero- 

 internal cusp. Molars constructed as in Palceosyops , but 

 higher, with sharper cones and more erect external lobes. 

 Internal median valley very much deeper. Little or no 

 depression at the forehead ; zygomatic arch round, compara- 

 tively straight and does not project outwards, and with ob- 

 scure postorbital process. Premaxillaries short and straight. 

 Mandible with nearly straight lower margin, and shallow 

 masseteric fossa ; mental foramen single. 



LEUROCEPHALUS CULTRIDENS, Sp. Nov. 



This species was considerably larger than PalcBosyops major, 

 with which it shows affinities, as also with Titanotherium 

 Proutii. See Plate IV. 



The Frontal is narrow and flat, or slightly arched. It 

 sends out a strong curved postorbital process, which projects 

 outwards, but not so much outwards as in Palceosyops. The 

 sagittal crest runs back from the postorbital in a low rounded 

 ridge, rising but little as it recedes. The superciliary ridge 



