26 THE STRUCTURE OF THE FOWL 



reception of the head of the humerus, and a 

 projection which assists in forming an opening 

 for the passage of the tendon of the supra- 

 coracoid muscle. 



The rod-hke coracoid is the strongest bone 

 of the shoulder -girdle. One extremity is 

 flattened and expanded with a saddle-shaped 

 articular surface to fit into a concavity on the 

 sternum. At this end there is also an opening, 

 or foramen, leading into the interior and 

 permitting a communication between the clav- 

 icular air-sac and the cavity within the bone. 

 The other extremity is prolonged into a hook- 

 like process which completes the opening 

 {foramen triosseum) for the supracoracoid 

 tendon and articulates with the clavicle. Be- 

 low the hook is a depression which forms the 

 greater part of the glenoid cavity for the 

 reception of the head of the humerus. 



The clavicle is thin, rod-hke, and slightly 

 bent. Its upper (dorsal) end is expanded and 

 connected with the coracoid. Ventrally the 

 two clavicles are united at an acute angle into 

 a single, flattened expansion connected by 

 ligament with the cranial medial process or 

 rostrum of the sternum. The combined 

 clavicles, therefore, form a continuous bone, 



