Cope.] 1 < 6 [Dec. 16, 



those seen in the genus named in that the internal portion is much smaller 

 than the external, having a small conic apex, distinct from that of the 

 exterior portion. Its postero-external face is nearly vertical, and it 

 diverges a little posterior to parallel with the anterior crest. The latter 

 (the first cingulum) is elevated, and is widely separated externally from 

 the posterior crest, to whose base it descends on the external extremity of 

 the crown. The basal cingulum is present all round the crown except 

 at the base of the posterior crest, and externally. It is narrow on the 

 inner extremity of the crown. It sends upwards a strong branch to the 

 apex of the internal cusp. The enamel of all the molars is strongly 

 wrinkled, but is worn smooth wherever rubbed. 



Measurements. M. 



Length of superior molar series 179 



" premolar series 085 



^. .^ „ f anteroposterior 019 



Diameters P-m. II < ^ no- 



t transverse 03a 



_. __ _ f anteroposterior 029 



Diameters M. I -{ . „oo 



\ transverse 033 



.^. „ „ r anteroposterior 036 



Diameters M. 11^ , „.„ 



(. transverse 043 



r anteroposterior 0285 



Diameters M. Ill < transverse 041 



' vertical 015 



The Metalophodon testis differs from the M. armatus, in the more 

 triangular form of its penultimate superior molar. Its form is quite 

 different from that of the last molar, while in M. armatus, the two teeth 

 resemble each other closely. The species are of about the same size. 



The individual from which the above description is taken is rather aged. 



DiKOCERATA. 



Bathyopsis fissidens Cope. 



Bulletin U. S. Geolog. Survey, Terrs., Feb. 1881, 194. 



A considerable part of the dentition of the mandible of this species was 

 found in the Big-Horn bad lands. This includes an incisor tooth, which 

 is quite characteristic, and renders it probable that the anterior parts of the 

 jaws differ considerably from those of other Uintatheriida. The root is 

 sub-round. The crown resembles a good deal that of the species of Cory- 

 phodontidce. It is higher than wide and has a subacute apex. One edge 

 of the crown is convex, and the other concave. The external face is con- 

 cave in both directions, and has no ridges nor cingulum. The inner face 

 is concave longitudinally and convex transversel3\ The convexity is 

 median and has a longitudinal concavity on each side of it. No internal 

 cingulum except a trace at the base of the concave edge. Tlie edges are 

 obtuse even when unworn, and the enamel is obsoletely rugulose. 



