IV.] 



SKELETON OF UPPER LIMB. 



173 



fourth), as in Chceropus ; or the same two with a rudiment 

 of the first metacarpal also, as in Cholcepns. 



We may have the second and third metacarpals well de- 



FIG. 146. RIGHT PECTORAL LIMB OF HORSE. 



t, cuneiforme ; k, humerus ; In, lunare ; ; 3 , metacarpal of the third digit the 

 only one fully developed ; w 4 , rudimentary fourth metacarpal ; ing, magnum ; 

 pi, pisiforme ; p l , proximal phalanx; / 2 , middle phalanx; / 3 , third or 

 ungual phalanx ; i, sesamoid ; nu, unciforme. 



veloped, with a rudiment also of the first, all three being 

 fused together into a single bone as is the case in Birds. 



There may be but three sub-equally 

 developed, and these may be the second, LVi 



third, and fourth, as in Proteus and 4j?i 



Rhinoceros ; or they may be the first, u JU 



second, and third, as in Seps tridactylits. 

 The three may be anchylosed together 

 at their proximal ends, as in the Three- FJ G . 147 . __ PALMAR 



loed Sloth. VIEW OF LEFT HAND 



The metacarpals may decrease in size OF SEPS TR1DACTYLUS - 

 from the first to the fifth, as in Seals ; or (After Furbringer.} 

 increase from the first to the fifth, as in There is h , e . re but a T' 



- ,, mite rudiment of the 



the Manatee. 4 th digit. Thepollex, 



They may be singularly unequal, the index, and third digit 

 third being by far the thickest and ex- are wel1 

 tremely short, as in the Great Armadillo ; or the third being 

 far the slenderest and extremely long, as in the Aye-aye. 



