28 THE STRUCTURE OF THE FOWL 



the proximal row of 

 mammalian carpal bones. 

 In the embryo the distal 

 row is also represented 

 by cartilaginous nodules; 

 but, as development pro- 

 ceeds, these fuse with the 

 metacarpus.^ 



In the adult the meta« 

 carpus is in the form of 

 a single bone, which has 

 been produced by the 

 union of three elements 

 corresponding to the first, 

 second, and third meta- 

 carpal bones of the mam- 

 malian limb.^ The second 



^ According to embryological in- 

 vestigations, it appears that the 

 embryonic carpus contains seven 

 elements. Each of the two carti- 

 laginous nodules of the proximal 

 row contains two elements : a radiale 

 and an intermedium have combined 

 to form the radial nodule, and an 

 ulnare and a centrale have in like 

 manner coalesced to form the ulnar 

 nodule. The distal row consists of 

 three elements corresponding to the 

 three persistent metacarpal bones. 

 2 Some authorities are of opinion 

 that the metacarpal bones of the adult fowl correspond to the second, 

 third, and fourth bones of the mammalian limb. According to this 



Mc? 



Fig. 6.— Skeleton of the Fore- 

 arm and Manus. 



U,,ulna; R., radius; C, carpus; Mc.i 

 Mc.2, Mc.3, metacarpal bones. 



