T86 Bird Comrades 



bases of the long quill feathers are called the coverts, 

 which are found on both the upper and under surfaces of 

 the wing. Thev are divided into several sets, according 

 to the position they occupy, and are called the "primary 

 coverts" (because they overlie the bases of the primaries), 

 the "greater coverts/' the "middle coverts," and the 

 " lesser coverts." Forming a vast expansion of the bony 

 and fleshy framework are the quills, or flight-feathers, 

 called collectively the "remiges." These plumes mainly 

 determine the contour of the wing, and constitute a thin, 

 elastic surface for striking the air one that is suffi- 

 ciently resilient to give the proper rebound and yet firm 

 enough to support the bird's weight. The longest quills 

 are those that grow on the hand or outer extremity of the 

 wing and are known as the primaries. What are called 

 the secondaries are attached to the ulna of the forearm, 

 while the tertiaries occupy the humerus and are next to 

 the body. All these feathers are so placed relatively 

 that the stiff outer vane of each quill overlaps the more 

 flexible inner vane of its successor, like the leaves of certain 

 kinds of fans, thus presenting an unbroken surface to the 

 air. As to the structure of these plumes, they combine 

 firmness, lightness, and mobility, the barbs and barbules 

 knitting the more flexible parts together, so that they do 

 not separate, but only expand, when the wing is unfolded. 

 While the primary purpose of wings is flight, there is 

 quite a number of notable exceptions. A concrete exam- 

 ple is the ostrich, whose wings are too feeble to lift it from 

 the ground, but evidently aid the great fowl in running, 



