WINGS 



23 



of the wing. These form the flight feathers proper. Their 

 number is smallest in the hummingbird (16) and very large in 

 the albatross (50 or more). jVIost of the other feathers are 

 small and very weak ; they are used for covering up the bases 

 of the quills, both above and below, and for this reason are 

 called iving coverts. Besides the remiges and coverts of the 

 wing there is a third group of small quills, fastened to the thumb. 

 These quills form the alula or little wing ; they are generally of 

 little use to the bird. 



Quills. — The remiges or quills are readily divided into 

 three groups, according to the joint of wing to which they 

 are attached. Those fastened to the pinion are called jjr«- 

 maries; those to the forearm, secondaries ; and those to the 

 upper arm, tertiaries or tertials. This third term is generally 

 applied rather indifferently to the inner secondaries, those 

 attached to the elbow, which are frequently different in form, 

 size, and color from the other secondaries. 



Primaries. — In number, the primaries are wonderfully uni- 

 form, being in almost all birds either nine or ten. Not only is 



