59 



viduals to which they belonged. The distal epiphysis has been detached 

 from the present specimen. 



358. The radius of the Megalonyx Jeffersonii, from the cavern in Green-briar 



County, Virginia. 



The original specimen from which the present cast was made, is de- 

 scribed and figured by Cuvier, Annates du Museum, torn. v. (] 804) p. 372, 

 pi. xxiii. 



359. The metacarpal bone of the index or second digit of the left fore-foot of 



the Megalonyx Jeffersonii. It is relatively longer and narrower than in 

 the Mylodon : the triangular base is more inequilateral, and its anterior 

 emargination is deeper, but the flat surface on the radial side of the base 

 of the bone, for the metacarpal of the pollex, resembles that of the My- 

 lodon rather than that of the Megatherium ; whence it may be inferred 

 that the entire pollex of the Megalonyx resembled that of the Mylodon, 

 instead of being reduced to a rudimental metacarpal bone as in the Me- 

 gatherium. The original of this cast is described and figured by Cuvier, 

 loc. cit,, p. 367, pi. xxiii. fig. 8. 



360. The second phalanx of the second digit of the left fore-foot of the Mega- 



lonyx Jeffersonii. 



361. The third or ungual phalanx of the second digit of the left fore-foot of 



the Megalonyx Jeffersonii. 



362. The metacarpal bone of the third or middle digit of the left fore-foot of 



the Megalonyx Jeffersonii. The general proportions of this bone are 

 very similar to those of its analogue in the Mylodon, but in the more 

 vertical position and greater projection of the distal articular ridge, and 

 in the flatter under-surface of the bone, it more closely resembles that 

 of the Megatherium. The articular surface on the radial side of the base 

 of the present metacarpal is flat instead of being convex as in the Mylo- 

 don, and adapted to a corresponding flat surface in the second metacarpal 

 bone. The original of the present cast is described and figured by Cuvier, 

 loc. cit., p. 367, pl- xxiii. fig. 4. 



I 2 



