Cope.J 1 ' [Dec. 16, 



An internal conic cusp ; posterior crest oblique ; heel very small ; size 



medium C. cuspidatus. 



An internal crest ; posterior crest oblique ; heel small ; size medium 



C. obliquns. 

 An internal tubercle ; posterior crest little oblique ; heel large ; size large. 



C. lobutus. 



II. Posterior inferior molars with two posterior cusps ; without internal 

 accessory tubercle : 



a. Posterior inferior molars with small or no heel : 

 Large ; posterior superior molar oval, with distinct straight posterior 



crest ; inferior molars elongate ; symphysis mandibuli produced and 



narrowed ; premaxillary elongate C. latipes. 



Medium ; inferior molars nearly as wide as long ; premaxillary short 



(7. latidens. 



aa. Posterior inferior molars with prominent or wide heel : 

 Medium ; posterior superior molar with posterior angle, and angulate 



posterior crest ; inferior molars elongate ; symphysis mandibuli broad 



and short ; premaxillary elongate ; tusk trihedral C. elephantopiu. 



Smaller ; premaxillary bone short ; tusk trihedral C. simus. 



Medium ; premaxillary elongate ; tusk compressed and grooved 



O. molestus. 

 Large ; last superior molar oval, with angulate posterior crest ; its anterior 



lobe connected with anterior cingular crest C. repandus. 



III. Last inferior molar with but one posterior cusp from which a curved 

 crest extends round the posterior border of the crown. 



Superior true molars narrow ; external incisors sharply angulate on ex- 

 ternal face C. curcicristis. 



IV. Posterior inferior molar unknown. 



Posterior superior molar oval ; posterior crest straight ; internal crest 

 . fissured (? normally) ; a complete internal cingulum. . . C. marginatus. 



CORYPHODON CUSPIDATUS Cope. 



This species was found in a single individual obtained in New Mexico ; 

 a second one was discovered by Mr. Wortman in the Wind River basin, 

 and a third has now been brought from the Big-Horn. 



CORTPHODON LATIPES CopC. 



I refer seven individuals provisionally to this species. Three of these 

 are represented only by superior teeth, etc., 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. ohliquus, but 

 the specimens are all of superior size to that species, some of them very 

 much exceeding it. It is also possible that this ridge is not a constant 

 character. This species has the dentition which I have referred to the 

 Bathmodon radians, but no astragalus of the species occurs in the collec- 

 tion. It may be the C. latipes, of which the teeth have not yet been iden- 

 tified. I hope soon to be able to decide this question. 



