290 Wortman — Studies of Eocene Mammalia in the 



ful deltoid crest, which extends well down the shaft. As in 

 all the later Mesonychids, the distal extremity has the appear- 

 ance of being compressed from side to side, resulting from the 

 decrease in size of the supinator ridge and internal condyle, in 

 marked contrast with the broad extremity of this bone in the 

 earlier forms. The internal condyle, while reduced, exhibits 

 an entepicondylar foramen for the passage of the principal 

 vessels and nerves to the forearm, although the bony bridge 

 covering it is small. The condyle is considerably enlarged 

 posteriorly and is separated from the inner edge of the trochlea 

 below, by a deep notch. The anconeal and anticubital fossae 

 are deep, but there is no supertrochlear foramen. Of the 

 articular surface the capitellum is distinct, wedge-shaped, and 

 separated from the trochlear groove by a tolerably distinct 

 ridge. The trochlear groove is wide and moderately deep ; 

 the inner edge is unusually prominent and extends consider- 

 ably below the general level of the articulation. 



With the exception of a distal end of a femur, which does 

 not offer any characters of especial interest, no other limb 

 bones are certainly known. 



The principal measurements are as follows : 



mm. 



Length of superior dental series from incisive border 197*5 



Width between outer border of incisors 54* 



Anteroposterior diameter of canine at base of crown 31* 



Transverse diameter of canine at base of crown 23* 



Length of canine including root 135*5 



Length of molar and premolar series from posterior border 



of canine - 138'5 



Length of diastema between first and third premolars 29* 



Length of true molars (antero-posterior) _ _ _ _ 44*5 



Transverse diameter of first molar (posterior border) 26* 



Transverse diameter of second molar _ _ 21*5 



Length of palate from incisive border to posterior narial 



opening . 222*5 



Width of palate between the canines 39*5 



Width of palate between last molars 65* 



Length of humerus _ _ 275* 



Transverse diameter of head . __ 54* 



Width (transverse) of distal end 67*5 



Length of lower molar series _ 83* 



Depth of lower jaw at last molar . 85*5 



The specimen is from the lower part of the Eridger Beds, 

 near the mouth of Smith's Fork, and was found by R. E. 



Son. 



