INTR on UCTION. 



little more than half the length of those which are longest, which 

 are generally the fourth or fifth. 



Emarginated wings are characterized by having a sudden 

 notch or sinuosity, more or less abrupt, on the margin of the 

 inner shaft of the longest quills ; this notch, in some cases (True 

 Falcons), is situated near the end of the shaft ; in others (the 

 ignoble Hawks) it is placed near the base (Fig. 5). 



' iG. 5. — Emarginated Wings. 

 a. Falcon. b, Sparrow-Hawk. 



Rounded wings are always short, and there is so little differ- 

 ence between the last six or seven primaries and the secondaries, 

 that the distinction between the two series is scarcely perceptible. 

 The tertiaries also are nearly of the same dimensions, so that 

 when the wing is fully expanded, the contour forms a semicircle. 



Rasorial wings are characterized by their peculiar shape, 

 and by the great development of the secondary quills ; these 

 latter being so long as nearly to equal the primaries. The 

 primary quills in their substance have an unusual strength and 

 rigidity; their shape is almost falcate, and they are very narrow; 

 their curved shape gives to the wing a great degree of convexity, 

 and also indicates much strength. 



Ample wings have the primaries short, and the secondaries 

 and tertiaries remarkably broad. The flight of birds possessing 

 wings of this description is slow and heavy, but regular, lofty, 

 and can be long sustained. By this broad expanse of wing the 

 Heron mounts high in the air, flying steadily, but slowly, to its 

 distant retreat. 



Abortive wings are such as are incapable of being used as 

 instruments of flight. These are of two kinds : the first belongs 

 to land birds of the Ostrich race, the second to the Pen'^uins, 

 Auks, and other swimming birds. 



The tail of a bird is a very important auxiliary in flight, during 

 which it is expanded, and used as a rudder. There are very few 

 species without this ornamental appendage, though in some it is 



