Cope.] Dl.% roec. 7, 



Academy of Philadelphia, 1883, p. 80, and two species were mentioned, 

 C. pelvidens (type) and 0. angulatus. The former of these is from the 

 Puerco, the latter from the Wasatch formation ; the former is the larger 

 species ; the latter quite small. I now add two species to the genus which 

 are intermediate in dimensions between those already known. 



I. Posterior cingulum of superior molars with large tubercle. 



Large species ; G. pelvidens ; small species, G. truncatus. 



IT. Posterior cingulum with small tubercle ; small species ; C. angulatus. 



III. Posterior ciugulum without tubercle ; small species ; G. simplex. 



In the G. truncatus the posterior singular (inner) tubercle reaches the 

 largest development, but is not present on the cingulum of the last supe- 

 rior molar. The anterior cingulum is weak on that tooth and on the first 

 true molar, but on the second it is thickened into a small anterior or 

 inner tubercle. This with the posterior inner gives the crown a truncate 

 internal outline, as is also the case in the G. pelvidens. The intermediate 

 tubercles are distinct, and the external cusps are separate at the base. An 

 external cingulum. The fourth premolar has a triangular base ; a single 

 compressed external cusp, and a small acutely conical internal one. The 

 internal tubercle is small and acute on the third premolar. The second pre- 

 molar is small and probably one-rooted, and it is possible that there is no 

 first premolar. The canine is directed vertically downwards, and the base 

 of the crown is oval. 



Besides the considerably smaller size, the posterior internal cusps are 

 relatively larger than in G. pelvidens. 



Measurements. M. 



Length of superior dental series including canine 039 



Length of true molar series 014 



Diameters P-m. iU { anteroposterior. . . 004 



<- transverse 003 



Diameters P-m. iv { anteroposterior 004 



*. transverse 005 



Diameters M. ii j anteroposterior 005 



t transverse 0064 



Diameters m. iii j anteroposterior 0033 



*- transverse 005 



Two individuals from New Mexico. D. Baldwin. 

 Chriacus simplex, sp. nov. 



This species is represented by a part of the left maxillary bone, which 

 supports the true molars except a part of the last one ; and by parts of the 

 mandible, with the first and second true molars, and perhaps one of the 

 premolars. The true molars are about the size of those of the G. truncatus, 

 but of very different detailed structure, as already pointed out. The pos- 

 terior cingulum is stronger than the anterior, but does not support a trace 

 of a cusp, and they do not unite on the inner face of the crown. External 



