io6 



Elementary Zoology. 



formed by a growing together of the lower ends of the ribs, 

 and cannot, therefore, have any relation to the omosternum of 

 the frog, which, as has been said, is an outgrowth of the 

 epicoracoid. It may, however, correspond to the xiphisternum 

 of the amphibian, which is produced by the concrescence of 

 two plates of cartilage. As ribs are wanting in the frog, it 



DG.I 



MCI 



D.C.2 



DG.2 . DG.3 



Fig. 47. —Hand of Fowl. (After Parker.) 

 D.C.2, D.C.3, carpals ; MC.1-3, metacarpals : D.G.1-3, digits 



may be that these lower bars of cartilage are the remains of 

 formerly more extensive ribs. 



With the glenoid cavity, formed by both scapula and cora- 

 coid, articulates the httmerus. This is followed by the radius 

 and ulna, which are here distinct bones, the ulna being the 



Ist.DIGt 



^RD DIGt 



Fig. 48. — Hand of young Chick. (After Parker.) 

 H, humerus ; R, radius ; u, ulna ; M.c, metacarpals ; c, carpals. 



longer of the two, and bowed on its outer side, where the 

 impress of the strong remiges can often be detected. 



The carpus of the adult bird has only two elements ; but 

 more are present in the embryo. 



The hand of the fowl, as of all birds, is provided with only 

 three fingers. Of these the three metacarpals are firmly welded 



