THE CLASS BIEDS. 



287 



the air, the bird is obliged to fly against the wind. The 

 relative length of the remiges influences the facility with 

 which the bird rises in calm air. Birds which have the ante- 

 rior remiges the longest and most resistant, have a more 



Fig. 226. The Bird called Frigate. 



oblique flight than those which have the wings truncated at 

 the extremities. 



Fig. 227. Wing of the Sparrow Hawk.* 



Thus the falcons (Fig. 225), which have the wings pointed, 

 rise only in zig-zag, like a vessel tacking; whilst the hawk, 



* a a, primary quills ; b, secondaries. 



