INTRODUCTION. 



The power of flight possessed by any bird depends upon the 

 arrangement, the proportionate size, and the shape of the wings : 

 hence it will be necessary to explain the principal modifications 

 observable in these admirable structures. 



"^m? 



(h) The humerus ; (r) the radius ; (c) the cu- 

 bital bone, the outer side of which is entirely 

 occupied by the insertion of the secondary quills 

 (S), which are separated by a small space from 

 the primaries (P), all of which take their origla 

 from the metacarpal bone representing the hand. 

 The joint (x) representing the wrist-joint, indi- 

 cates the point of separation between the pri- 

 mary and the secondary quills. The bastard 

 quills, or those attached to the thumb, are in- 

 dicated by the letter b. 



Fig. 2.— Figure of Wimg, showing the Origins of the Quill-Feathers. 



The formation of the wing in reference to its office depends 

 almost entirely upon the arrangement, the proportions, and the 

 shape of the quills; and these again determine the powers of 

 flight. 



The principal modifications in the structure of these important 

 organs are, therefore, briefly expressed by simple epithets, the 

 precise meaning of which it \\\\\ be necessary to remember 



In regard to their comparative length, a wing, however other- 

 wise constructed, is termed lung when it extends beyond the 

 middle of the tail ; moderate when it reaches nearly or quite to 

 that member ; and short when it does not extend to the base of 

 the tail. 



As relates to their shape — 



