LOXOLOPHODON AND UINTATHERIUM. 



17 



ment of the nasal bones, and the relations of the bones forming the hard palate 

 that the following genera have been determined. 



Synopsis of the Genera of the Dinocerata. 



A. Lower jaw with powerful downward flange, wide diastema between 

 lower canine and incisor series. Three premolars on lower jaw. Premaxil- 

 laries send in narrow plate to form forward portion of hard palate. Nasal 

 tuberosities do not overhang nasal tips. Median protuberances anterior to 

 orbit--- - - Uintatherium. 



B. Lower jaw has a slight, narrow, downward convexity opposite upper 

 canine, wide diastema between lower canine and incisor series. Three premo- 

 lars in lower jaw. Premaxillaries send in a broad plate to form the forward 

 portion of the hard palate. Nasal tuberosities overhang nasal tips. Median 

 protuberances above or anterior to orbit - -Loxolophodon. 



C. Ramus of lower jaw is arched downwards from the symphysis to the 

 angle. The incisors, canine, and anterior premolar form a continuous series. 

 Between the anterior premolar and the remainder of premolar series is a dias- 

 tema. There are four premolars in the lower jaw — Bathyopsis^ 



The first of the above genera was Umtatherium, discovered and described 

 by Dr. Leidy in the Bridger Beds, in the exposures referred to above as lying 

 wholly in the Bridger basin or west of the Green River of Wyoming. Prof. 

 Marsh, who reached this field soon afterwards, rapidly obtained a large collec- 

 tion of the remains of these huge mammals, the greater part of which he 

 referred to a distinct genus, Dinoceras. This is considered in this report as 

 synonymous with Uintatherium, as we find the generic characters nowhere 

 distinctly stated. The second genus, Loxolophodcn, was discovered by Prof. 

 Cope, in 1872, in the Washakie exposures of the Bridger beds. He gave the 

 generic characters soon after the discovery.' The individuality of the genus 

 was strengthened in 1878 by the fortunate discovery of the lower jaw by the 

 Princeton party. The third genus, Bathyopsis, has been quite recently obtained 

 in the country surrounding the head-waters of the Wind River. Cope is 

 doubtful whether to place these beds among the Wahsatch or the Bridger 

 Eocene groups. Some of the genera they contain are found in both the lower 

 and the higher groups. At all events, the discovery of this genus gives the 

 sub-order a still wider geographical distribution. A fourth genus, Eobasileus, 

 has been based by Cope on some very short cervical vertebras. This seems 

 of rather uncertain position. 



'Cope. Bull. U. S. Geol. Survey, Vol. VI. pp. 194, 195. 

 'Proceedings American Philosophical Society, 1872, p. 5S0. 



