100 



STRUCTURE AND COMPARISON. 



and the whole head seems to have disappeared down its own 

 throat. Though the bill itself is so small, the fissure, or gape, 

 of the mouth extends nearly the whole length of the jaws, so 

 that the mouth begins to open as far back as the eye. 



The night-hawks and whip-poor-wills, which fly with their 

 mouths open, have the sides of the gape fenced in with rows 

 of bristles which prevent insects trapped in the wide mouth 

 from escaping at the sides. 



The swallows and swifts, which fly with closed mouths and 

 catch each insect separately with a snap, have few bristles, 

 or, in most cases, none. These birds that hawk after insects 

 have very small tongues. The swifts have a pouch just be- 

 neath the tongue, in which they keep the flies that they carry 

 home to their little ones. 



FIG. 29. HEAD OF LONG-BILLED CURLEW. 



Of the long-billed birds in this country none compares with 

 the long-billed curlew, which uses his sensitive slender probe 

 in searching out food that lies deeply buried in the mud. 

 Near relatives of his, as the snipe and the woodcock, have 



