1892.] NATURAL SCIENCES OF PHILADELPHIA. 307 



tend thau in M. obtusidens, the trochlea lower and wider with more 

 rounded and hemispherical intertrochlear ridge ; the entepicondyle is 

 more prominent, but has no foramen, and the supinator ridge less so. 

 The ulna and radius do not differ in any important "respect, except 

 size, from those of the Bridger species, the greater transverse breadth 

 of the shaft of the ulna and the shorter and broader olecranon. The 

 manus is also constituted very much as in 31. ohtuside7is, but the 

 ulnar side of the carpus, and especially the cuneiform, is broader. 

 The metacarpals are even shorter in proportion and nic. V more 

 slender and displaced more to the ulnar side of the unciform. The 

 following measurements exhibit the proportions of the various parts 

 of the fore limb in the two species. 



lU 



Humerus, width of trochlea, 

 Ulna, length. 

 Ulna, length olecranon. 

 Ulna, width, distal end, 

 Radius, length, 

 Radius, width proximal end, 

 Radiu?, width distal end, 

 Metacarpal II, width prox. end, 

 Metacarpal III, width prox. end. 

 Metacarpal IV, length, 

 Metacarpal IV, width prox. end. 

 Metacarpal V, length. 

 Metacarpal V, width prox. end. 



This species, so far as it is at present known, is of no particular 

 morphological importance, but geologically it is of much interest, as 

 adding another to the increasing list of White River genera of 

 ancient type which justify Cope's comparison of that horizon with 

 the Oligocene of Europe. 



PROVIVERRID.a: Schlosser. 

 Syn. Leplictid(£ Cope, in part. 



Superior molars tritubercular and somewhat trenchant ; para- 

 and metacones closely approximated and with a cutting crest pos- 

 terior to the latter ; inferior molars with elevated trigonid, forming 

 a trenchant blade. 



