606 



CYPSELINVE. 



SWIFTS AND ALLIED SPECIES. 



Almost all authors have included the Swifts in the same 

 family, and many in the same genus, as the Swallows. The 

 similarity of their mode of flying, their kind of food, and 

 the manner in which they obtain it, together with an obvious 

 resemblance in the form of the bill and wings, have caused 

 this association, which however appears to me to be too 

 intimate, for these birds differ in several respects fully as much 

 as many families w^hich are widely separated from each other. 

 Their distinctive characters will readily be perceived on com- 

 paring the following generic description with that of the Hi- 

 rundinfe. 



The body is moderately full, somewhat elongated, and rather 

 depressed ; the neck very short ; the head roundish and flat- 

 tened. The bill extremely short, weak, depressed, opening to 

 beneath the hind part of the eyes, compressed at the end, the 

 upper mandible with the dorsal outline convex, the ridge 

 rather narrow, the edges inflected toward the end, the tip de- 

 clinate, lower mandible much smaller, with the angle very 

 large, the dorsal line extremely short and slightly convex, the 

 edges a little inflected toward the end, the tip slender. 



Palate nearly flat, covered wih minute papillae, and having 

 two faint elevated lines ; both mandibles slightly concave, with 

 a median prominent line. Tongue short, triangular, fleshy, 

 sagittate and finely papillate at the base, horny beneath, and 

 obtuse or somewhat bifid at the tip. In the space between the 

 crura of the lower jaw are two large masses of salivary crypts 

 arranged in series. (Esophagus wide above, of moderate length 

 in the rest of its extent, without crop ; stomach elliptical, its 

 muscular coat of moderate thickness ; the epithelium dense, and 



