CREODOKTA. 



303 



second root of the fourth premolar is much larger than the anterior. 

 The sectorial, though the largest tooth, is of but moderate dimensions ; its 

 heel supports two posterior tubercles. The first tubercular is a little shorter. 

 It presents the three anterior tubercles of the sectorial, but they are obtuse 

 and placed close together. The heel is well developed, and its external 

 border is elevated into a ridge, which extends obliquely inwards and for- 

 wards. 



The second tubercular is a very small tooth, but has two roots, the pos- 

 terior of which is posterior to the anterior border of the ascending ramus. 



According to Leidy's measurements, this species is about the size of his 

 M. vorax of the Bridger formation. That species has, Hke the two others of 

 that horizon, a second tubercular tooth with only one root. 



Measurements. 



u. 



Length of dental line posterior to caniues 0440 



Length of premolar series ^'^^ 



Length of base of fourth premolar 0065 



Length of base of sectorial ■ OOoo 



Length of base of first tubercular 0060 



Length of base of second tubercular 0040 



Depth of ramus at second premolar : 0150 



Depth of ramus at secoud true molar 0100 



From the Wind River beds of Wyoming, J. L. Wortman. 



MlACIS BREVIROSTRIS Cope. 

 BuUetin U. S. Geol. Surv. Terrs., v,p. 190, February 26, 1881. 



This species differs from those of the Bridger epoch in the same way 

 that M. canavus does, *. e., in the biadicate last inferior molar. Its dimen- 

 sions are intermediate between those of M. edax and M. vorax, hence a Uttle 

 smaller than those of the M. canavus. This difference is partially seen in 

 the shortening of the premolar series of teeth They are closer together 

 than in the M. canavus, and the roots are larger. The sectorial tooth is 

 shorter. The fourth premolar has a low anterior basal cingulum; the pos- 

 terior part of the crown is robust. The first tubercular molar is wide, and 

 consists of a basin-shaped heel and a short anterior portion which is more 

 elevated. The latter consists of two cusps, which are connected by an 

 anteriorly convex ledge, but there is no third anterior tubercle as in M.parvi- 

 vorus. The nmiiis is quite robu.st, and the basis of the canine tooth is 



