634 THE WASATCH FAUNA. 



A detailed comparison of this species with the H. ventorum^ shows, 

 besides the superior size, the following characters: (1) The postgleuoid 

 process is every way more robust, and is more obtuse. (2) The basioc- 

 cipital bone is flatter, and the median keel does not reach the condyles as 

 it does in H. ventonmi. (3) The paroccipital process is longer. (4) The 

 postorbital process is rounded and not acute. 



The dentition of this species is in its dimensions and proportions inter- 

 mediate between the two species of Systemodon. Its three premolars equal 

 four of those of the S. semikians, while the molars of the two species are 

 about equal. 



The two individuals of this species were found by Mr. Wortman, from 

 the Bad Lands of the Wind River, Wyoming. 



A specimen having the ])roportiqns of the H. craspedotuni was found by 

 Mr. Wortman on the Big Horn, but unfortunately it does not exhibit the 

 characteristic cingula of the two dental series. The second superior pre- 

 molar, like that of Systemodon semiJdans, has no internal tubercle. It is not 

 certain whether there is any diastema posterior to the first superior pre- 

 molar. I therefore cannot yet ascertain whether this specimen represents 

 an undescribed species of Systemodon or Hyracotherium, or a strong variety 

 of the H. craspedotum. The accompanying inferior true molars are inter- 

 mediate in size between those of the latter species and the H. vasacciense. 



HyracothexIium vassacciense Cope. 



Expl. Surv. W. of 100th Meridian. G. M. Wlieeler, Vol. IV, Part II, p. 264. Plate LXVI, figs. T-11. 



Orohippus vasacciensis Cope, System. Cat. Vert. Eoceue New Mexico, U. S. Geog. Survs. W. of 100th 

 M., 1875, p. 21. 



Lophiotherium vasacciense, Proo. Amer. Philos. Soc, 1872, p. 474. 



The locality from which the typical specimen of this species was pro- 

 cured is near Evanston, Wyoming, in the beds of the Wasatch Epoch. 

 They consist of two inferior molar teeth, one of which is attached to a part 

 of the mandible. The latter tooth had suffered some erosion of one of its 

 cusjjs, which led to the introduction of some abnormalities into the descrip- 

 tion. Better specimens from New Mexico furnished the fuller descriptions 

 and the figures given in the report of the Wheeler Survey above cited. As 



