440 



Vertebrata. 



nearly in a line, and fuse with age ; in these formSj tlie coracoid is 

 short and broad. The clavicles are two long thin bones, fused 

 ventrally (in most Birds) to form the merrythought {furcula), 

 which is attached to the anterior end of the sternal keel, by a 

 ligament, passing from the ■ point of fusion. Each of the other 

 extremities of the fork is attached to the dorsal end of one of the 

 coracoids, from which it is otherwise separated by a large fenestra. 

 In the Ratitae and some others, the clavicles are rudimentary or 



Fig. 366. 



Pig. 367. 



Fig. 366. Sternum and 

 shoulder girdle of the 

 E a V e n , viewed from the 

 left side, cl claviole, co cora- 

 coid, so scapula, st sternum. — 

 Orig. 



Fig. 367. Manus of a 

 young Ostrich (Struthio) . 

 a, i carpals which remain 

 separate, c carpals of distal 

 row (already united, later to 

 be fused with the metacarpals), 

 nr* first — third meta- 

 carpals (still distinct), r radius, u ubia, la and lb phalanges 

 of the poUex, 2a — 2c second digits, 3 third digit. — Orig. 



Fig. 368. Foot of a young Chick, mt '^ first- 

 third metatarsals (the metatarsals 2 — 4 are already fused, but there are traces of their 

 original distinctness), t tibia, ta and fa' proximinal distal portion of the tarsus. — Orig. 



absent. The fore limb is usually very long. The ulna is much 

 more powerful than the radius; the carpus of the adult consists 

 of two separate bones only.* The manus is very slim, and never 

 exhibits more than three fingers with their metacarpals ; the fourth and 

 fifth fingers of Reptiles are absent. Of the three metacarpals, 

 the first is short, the two others much longer ; all three are fused in 

 the adult, the second and third, however, only at the two ends, not 



* One of these is the radiale, the other corresponds to the ulnare and intermedium. 

 The carpals of the distal row are represented by two bones which fuse with the 

 metacarpus. 



