CORYPHODOK 531 



I refer seven individuals from the Big-Horn Wasatch Basin provision- 

 ally to this species. Three of these are represented only by superior teeth, 

 &c., and in four the last inferior molar is preserved. Of the latter, three 

 have an angle, sometimes almost a crest, descending from the posterior 

 inner tubercle, as in C. obliquus, but the specimens are all of superior size to 

 that species, some of them very much exceeding it. It is also possible 

 that this i-idge is not a constant character. This species has the dentition 

 which I have referred to the Bathmodon radians, but no astragalus of that 

 species occurs in the Big-Horn collection. I refer it to the C. latipes, 

 although the teeth of the typical specimen have not yet been identified. I 

 hope soon to be able to decide this question. 



CORTPHODON ELEPHANTOPUS Cope. 



Report of Vert. Fobs. New Mexico, U. S. Geogr. Surveys W. of 100th Mer., 1874, p. 10. Id. Annual 

 Rep. U. S. Geol. Snrv. W. of 100th Mer., 1875, p. 95, plates v, vi. Report do. iv, pt. ii, 1877, p. 

 217. Plates L-LIV. 



Plate XXIX e. 



Portions of the dentition of both jaws, including the last molar teeth 

 of two individuals, prove that this species inhabited Wyoming in the early 

 Eocene period. One of the individuals, represented only by the last 

 molars of both jaws, is a little smaller than the typical specimen of which 

 an entire cranium is figured in Captain Wheeler's report (4to, 1877, PI. LI- 

 III), while a second specimen, which includes the entire superior molar 

 series, is a little larger than the same. 



This species is characterized by the obliquity of the edge of the poste- 

 rior crest of the posterior superior molar backwards away from a transverse 

 line ; and by the slope of the external side of this crest. In other words, 

 the inner half of the posterior crest nearly forms a V, like that of the penul- 

 timate molar. The posterior edge of the V is present, running outwards 

 from the inner end of the posterior crest, which thus becomes the apex of 

 the V. The C. elephantopus thus most nearly approaches the genus Man- 

 teodon of all the species. To accommodate the obliquity of the crest the 

 posterior outline of the last upper molar is strongly angulate, giving a sub- 

 triangular outline. The heel of the last inferior molar is insignificant 



