BIRDS 



155 



the length of neck in birds correlate with the length of 

 legs? Examples? (See Figs. 314, 315, 332.) Exceptions? 

 (Fig. 324.) Why does a swan or a goose have a long 

 neck, though its legs are short ? 



To make a firm support for the wings the vertebrae of 

 the back are immovably joined, also there are three bones 

 in each shoulder, the collar bone, 

 the shoulder blade, and the 

 coracoid bone (Fig. 286). The 

 collar bones are united (why ?) 

 and form the " wishbone ' or 



' pulling bone." To furnish sur- 

 face for the attachment of the 

 large flying muscles there is a 

 prominent ridge or keel on the 

 breastbone (Fig. 286). It is 

 lacking in most birds which do 

 not fly (Fig. 289). 



The feathers are perhaps the 

 most characteristic feature of 

 birds. The large feathers of the 

 wings and tail are called quill 

 feathers. A quill feather (Fig. 

 291) is seen to consist of two 

 parts, the shaft , or supporting 

 axis, and the broad vane or web. 

 What part of the shaft is round ? Hollow ? Solid ? Is 

 the shaft straight ? Are the sides of the vane usually 

 equal in width ? Can you tell by looking at a quill whether 

 it belongs to the wing or tail, and which wing or which 

 side of the tail it comes from ? Do the quills overlap 

 with the wide side of the vane above or beneath the next 

 feather ? Can you cause two parts of the vane to unite again 



FIG. 291. QUILL FEATHER. 



D, downy portion. 



