DINOGEEATA. 565 



The bones above described were discovered b}- the writer in an amphi- 

 iheater of the bad lands of the Washakie Basin, known as tlie Mammoth 

 Buttes, in Southwestern Wyoming. They were in greater or less part 

 exposed, lying on a table-like mass of soft Eocene sandstone. A descrip- 

 tion of this remarkable locality is given in the Penn Monthly Magazine for 

 August, 1872. 



EOBASILEUS FURCATUS Cope. 



Xoxolophodoti bifurcatus Cope, in extra copies on Proboscidians of the Eocene of Wyoming, August 19, 

 1872.* Loxolophodon furcatus iu the s.ame, Proceed. Amer. Philos. Soc, 1872, p. 580, August 20. 

 L. c. 488, August 22. Eobasileus furcatus Cope, Annual Report U. S. Geol. Surv. Terrs., 1872 

 (1873), p. 580. 



Plates xxxii, xxxiii. 



This species was originally described from a posterior horn, which was 

 obtained near the locality which furnished the typical specimen of ^. pressi- 

 cornis. It was found in an old camp separate from the other specimens. 

 The trail from this camp passed the front of the bad-land bluffs, and where 

 it reached the foot of the latter I found projecting from the rock parts of a 

 .skull and skeleton, M^iich I suspect to be the animal to which the horn 

 belonged. It is very probable that the horn was picked up at this point, 

 although, of course, there is no direct evidence to that effect. It is repre- 

 sented in Fig. 5, Plate XXXIII, and presents the following characters: 



The basis is very naiTOw and lenticular; a short distance above it the 

 outer side is convex. The anterior and posterior extensions of the base 

 differ; the one is thinner, the other more massive and with a shallow 

 groove above its commencement. The latter is posterior. The compressed 

 apex of the horn-core sends down a rib outwardly to the anterior base 

 and one inwardly, which disappears on the convex base. The general 

 form is spatulate, with the apex expanded obliquely across the lateral 

 crest of the skull, and regularly rounded in superior outline. Its anterior 

 face is flat, the posterior convex; its surface is grooved by very small blood 

 vessels. 



As compared with the posterior horn-core of Loxolophodon cornutus, 

 there is every difference. That is continuous with one margin of the crest, 

 ihis erect above it; that has a round base, this a lenticular one. It is more 



*See Proceed. Amer. Pbilos Soc, 1872, p. 515, where this name is recorded. 



