406 



STKRSUM OF THE POCHARD. 



usually lower than the width of half the sternum. 

 The lower edge of the keel is sometimes convex, 

 sometimes straight, and the anterior one generally 

 concave, and in some of the species there is a cavity 

 at the base of the crest, in which a duplicature of the 

 trachea is lodged. The coracoids are never very 

 long ; they are large at their bases, and rather firmly 

 attached to the sternum. 



There are seven or eight ribs (in some cases nine) 

 on each side of the sternum, and the posterior part of 

 that bone is generally divided by notches, though the 

 heads of the processes are so much produced as nearly 

 to meet each other. The clavicle is of moderate 

 length, and well arched, and the shoulder bones rather 

 slender, and arched through the whole extent. The 

 general character is that of having the bones of the 



Whitc-cyed Pochard. 



shoulder much more exclusively supported from the 

 sternum than is the case in the wading birds. The 

 above figures of the sternal apparatus of the 



