560 GEOLOGICAL SURVEY OF THE TERRITORIES. . 



Measurements. 



M. 



Depth ramus at last molar 0.011 



Length last molar 007'2 



Width last molar, posteriorly 0040 



Height iDner tubercle 0062 



Height external tubercle, (anterior) 0040 



This species was about the size of the gray fox. 

 From the bluffs of Cottonwood Creek, Wyoming. 



Stypolophus beevicalcaratus, Cope. 



Loc. cit., p. 469; published August 7, 1872. 



Established on a portion of the left mandibular ramus, containing the 

 penultimate and ante-penultimate molars, of an animal of larger size 

 than the type of the genus, f^. ptmgens. The molars have the general 

 characters of the corresponding ones of that species, but differ in their 

 greater elevation in comparison with their length, and the greater con- 

 vexity of the outer side. The shortness is occasioned by the abbrevia- 

 tion of the heel, which, in the last molar present, is very small and flat, 

 without keel or tubercle on its surface. That of the molar preceding it 

 is larger, and presents in its elevated outer margin a trace of the keel 

 seen in the smallest species. Enamel smooth. 



Measurements. 



M. 



Length of two molars 0. 016 



Lengthj. of penultimate crown . OOS 



Width of penultimate crown . 0047 



Length of penultimate heel 002 



There is some similarity between Stypolophus and Triacodon, Marsh.' 

 If the heel of the molars of the former were wanting, they would 

 be those of the latter. The premolars might be sup]:)f)sed to have this 

 structure, but the form seen in S. insectivorus disproves this view. 

 In fact, I have seen both molars and premolars of Triacodon aculeatus, 

 Cope, and the former lack the heel of the tStypolopM entirely. 



YIYERRAVUS, Marsh. 



Amer. Journ. Sci. Arts, 1872, p. 127. 



Yiverravus paeviyorus. Cope. 



Miacis parvivorus, Cope. Proceed. Amer. Philos. Soc. 1872, p. 470, August 7. 



Established on a portion of the right ramus mandibuli, containing 

 portions of three molars, the j)enultimate being perfect. As in Canidai, 

 the molars diminish in size posteriorly, the last being single-rooted, the 

 penultimate being two-rooted. The structure of that tooth is approxi- 

 mately that of Stypolophus^ i. e., with three trihedral cusps in front and 

 a heel behind ; but the cusps are of equal height, and their point of 

 union not raised above the surface of the heel. This is a valley bounded 

 by a sharp margin which is incurved to the outer cusp, leaving a ver- 

 tical groove on the outer side, as in Stypolophus sp. This genus further 

 differs from that one in the single-rooted, small, tubercular posterior 

 molar, which is wanting in that one. The ante-penultimate molar is 

 much larger than the penultimate. The crown of the latter is laterally 

 expanded, and bears a cingulum at the base antero-exterually. Enamel 

 smooth. 



