1913] 



Stock: Nothrotherium and Megalonyx 



357 



In the co-ossified first and second phalanges of the third 

 right digit, no. 20004 (figs. 17 and 18), the offsets on each side of 

 the median concavity of the proximal end are transversely con- 

 cave. This is especially noticeable on the inner offset, which is 

 wider than the outer one. In M. jeffersonii there is "an oblique 

 offset on each side inferiorly." 10 The inner condyle of the distal 

 trochlea is well worn. The groove between the two condyles 

 widens inferiorly. 



Figs. 17 and 18. Megalonyx calif omicus, n. sp. Third right metatarsal 

 and digit, nos. 20001 and 20004, X %. Eancho La Brea Beds. Fig. 17, 

 lateral view; fig. 18, superior view. 



The claw-core is broken away anterior to the ventral tuber- 

 osity in the ungual phalanx. The median ridge of the proximal 

 articular face is sharp and widens inferiorly. Just above the 

 median ridge on the overhanging process of the proximal end 

 is a small emargination. In M. jeffersonii the overhanging 



io Leidy, J., A Memoir on the Extinct Sloth Tribe of North America, 

 Smithson. Contrib. Knowl., vol. 7, p. 44, pi. 13, figs. 17 and 18, 1855. 



