92 ORGANS OF SUPPORT, 



tapering terminal cartilage of the sternum, continued from 

 the posterior end of the ento-sternal portion (o,) is com- 

 posed of the two xiphi-sternal elements (q,) analagous to 

 the xiphoid cartilage of the human sternum. The scapular 

 arch is very strong in birds, to form a solid resisting fulcrum 

 for the powerful movements of the humerus ; and the -mag- 

 nitude and strength of these bones corresponds in the dif- 

 ferent species with the power of flight, or the resistance 

 they have to oppose to the pectoral muscles on the one side, 

 and the branchial on the other. The scapulae (Fig. 49. a, a,) 

 are long, curved, compressed bones, extending along the 

 back, on each side of the dorsal vertebrae ; they become 

 more narrow and rounded as they approach the glenoid 

 cavity, where they suddenly expand to enlarge that cavity 

 (b^ and they are partially 



anchylosed at that place to ' IG * 49 * 



the large and strong cora- 

 coid bones (c, k.) The two 

 coracoid bones (k, k y ) extend 

 from the articular cavity (c,) 

 for the head of the humerus 

 downwards and inwards, to 

 rest their broad expanded 

 base (i,) in a deep groove on 



each side of the anterior margin of the ento-sternal bone. 

 These coracoid bones almost alone resist the approximation 

 of the humeri on the median plane, and their descent in the 

 direction of the pectoralis major on each side, and they have 

 generally more than double the thickness and strength of 

 the scapulae. The two clavicles (d, d,) descend converging 

 from the upper or humeral ends of the coracoid bones (c,) 

 and they are anchylosed together at their lower ends (e,) 

 where they commonly present a flat compressed prominence 

 (/,) connected by cartilage, by tendinous expansions, or 

 sometimes by anchylosis, with the anterior projecting point 

 of the crest of the sternum (g.) The clavicles are very 

 thick and strong, and meet at an obtuse rounded angle in 

 the most powerful of the rapacious birds, and are long, thin, 

 and slender, and meet at an acute angle in the gallinaceous 

 and other birds of feeble flight. In the ostrich the clavicles 

 are very small and short, and disunited on the median 



