AVES BIRDS. 



595 



life, still closely to adhere to die general type in accordance with 

 which this part of the skeleton is invariably constructed. The 

 framework of the shoulder exhibits the scapula (fig. 269, 6), the 

 clavicle (of), and the coracoid element (c) ; notwithstanding that 

 these bones, form- Fig. 269. 



ing, as they do, 

 the basis of a limb 

 so vigorous, and 

 wielded by such 

 powerful muscles, 

 are necessarily mo- 

 dified in their form 

 and general ar- 

 ran gement, so as to 

 constitute strong 

 buttresses adapted 

 to keep the shoul- 

 der-joint firm and steady during flight. The scapula (b) is a long 

 and slender bone placed upon the ribs, and lying parallel to the 

 spine along the dorsal region of the thorax, imbedded in the mus- 

 cles to which it gives attachment, while at its fixed extremity it 

 assists in forming the cavity of the shoulder-joint. The coracoid 

 bone (c) is the great support of the shoulder ; for, while at one ex- 

 tremity it sustains the wing, at the opposite it is firmly and securely 

 united to the sternum by a broad articulation. But the most pecu- 

 liar element of this apparatus is the/wrcM/wra, or forked bone (d), 

 composed of the conjoined clavicles; which, being anchylosed to- 

 gether in the mesial line, and also strongly connected with the 

 shoulder-joint, materially add to the stability of the whole. 



In the wing itself the humerus (f) is at once recognised, as 

 also the ulna (g) and the radius (h) ; but in some birds, as in the 

 Penguin, the student might be at a loss to identify one or two 

 small bones (/?), forming a kind of patella to the elbow-joint ; 

 these appear to be the representatives of the olecranon process de- 

 tached from the ulna. The carpus (i) consists of only two 

 small bones. The metacarpus is formed of two pieces (, /), 

 anchylosed together at their two extremities ; and these, with two, 

 or in some cases three, rudimental fingers complete the wing. The 

 largest finger consists of two, or sometimes three, phalanges (m, o) : 

 a second (n) offers but a single joint ; and the third, which is a 



a 2 



