CREODONTA. 309 



No. 2. 



M. 



Anteroposterior length of sectorial 0150 



Length of heel OOG 



Elevation of external side of crown anteriorly 01& 



Width at same point 009 



Length of crown of tubercular 009 



Elevation anteriorly 005 



Width of same 006 



Wind River beds, Wyoming. J. L. Wortman. 



DiDYMICTIS LEPTOMYLUS CoPE. 



American Naturalist, 1880, Dec, p. 908; Bulletin U. S. Geol. Surv. Terrs., 1881, vi, p. 191. 



Plate XXV a; fig. 12. 



The specimens which I refer at present to this species belong to two 

 varieties, which may perhaps be specifically distinct ; but this cannot be 

 demonstrated at present They differ in dimensions only. Thus the true 

 molars of the type, which comes from the Wind River beds, measure M. 

 .016 in length. Five specimens from the Big Horn basin agree in having 

 this dimension .018. The entire inferior molar series is only a little shorter 

 than that of the smaller variety of the D. protenus from New Mexico. (See 

 my report to Captain Wheeler, Plate XXXIX.) The species is characterized 

 by the narrow and relatively elongate form of the tubercular molar. Its heel 

 is considerably produced behind the posterior oblique ridge, which is not 

 the case in the D. altidens. Its anterior part has the three low cusps well 

 defined and close together, and behind them is the oblique longitudinal 

 cutting edge. The middle of the posterior margin rises into a tubercle. 

 The external cusp of the tubercular-sectorial is much elevated. The heel 

 has a strong external cutting edge and internal ledge, which reaches the 

 posterior border, and is not quite so long as the internal tubercle is high- 

 The cusps are rather obtuse, especially the internal pair, which are of equal 

 height. The representative of the blade is not very sharp. There are no 



basal cingula on these teeth. 



ii. 



Length of tubercular-sectorial 009 



Width of same 005 



Length of tubercular 007 



Width of same in front 004 



Big Horn basin, Wyoming. J. L. Wortman. 



