Cope.} L14: [Dec. 16, 



The numerous characteristic marks, show that this species is one of the 

 most distinct of the genus. It is also one of the largest, heing second only 

 to the O. anax. 



CORTPHODON MARGINATUS, Sp. nOV. 



This is one of the smaller species, having nearly the dimensions of the 

 C. molestus. It is only represented by the superior canine, first inferior 

 premolar, and last superior molar of one individual found together by Mr. 

 Wortman. Their size, mineral condition and degree of wear, render it 

 probable that all belong to one individual. 



The superior molar is of the oval type, without posterior shoulder. The 

 posterior crest is therefore straight, and parallel with the anterior crest. 

 Its inner extremity does not display the least tendency to form a V, as is 

 seen in O. elephantopus. Its exterior extremity is widely separated from 

 the external' prominence of the anterior crest (cingulum). The latter dis- 

 plays, at its inner extremity, the peculiarity of a deep fissure of the anterior 

 side, which nearly divides the crest, and partially isolates the internal 

 tubercle. Adjacent to the fissure its crest is tubei-culate. The posterior 

 upper cingulum descends from the inner cusp to the basal cingulum. The 

 basal cingulum is well developed on the anterior and interior sides of the 

 crown, and on the posterior as far as the base of the inner cusp of the 

 posterior crest, where it gradually fades out. Enamel wrinkled. 



The superior canine is remarkable for its small size. The posterior face 

 is a little the widest, and its bounding edges are sharp, but not expanded. 

 There are no prominent ridges of the enamel. The anterior face is mode- 

 rately wide. The first inferior premolar presents no peculiarities. 



Measurements. M. 



r anteroposterior 028 



Diameters of M. Ill superior } transverse .038 



' vertical 019 



Diameters of P-m. I inferior \ anteroposterior 015 



c transverse . . 009 



Diameters of C. superior { anteroposterior 014 



(. transverse posterior 018 



The superior molar is but little worn, and shows that the animal was 

 just adult. The canine is more worn than the molar. 



There are several characters which mark this species as distinct from 

 those previously known. It is the only member of the genus which has 

 a complete internal cingulum. The fissure of the anterior crest, if normal, 

 is peculiar to this species. The superior canine is disproportionately 

 small. 



Besides the Corypjiodons already mentioned, a number of more or less 

 complete skeletons were obtained, some of which can be identified by 

 comparison with those which are accompanied by teeth, and which are 

 enumerated in the preceding pages. 



