74 HIRUNDIN^E. HIRUNDO. 



coeca very small ; cloaca oblong. Trachea with four pairs 

 of inferior laryngeal muscles. Nostrils small, linear- 

 oblong. Eyes of moderate size. Aperture of ear rather 

 large, elliptical. Feet extremely short, slender ; tarsus 

 bare or feathered, always with some scutella below ; toes 

 small, three before, one behind, bare and scutellate, or 

 feathered, with the usual number of joints ; claws rather 

 long, moderately arched, compressed and laterally grooved, 

 tapering to a very acute point. Plumage soft, blended ; 

 bristles about the mouth very small ; wings extremely 

 long, pointed, the outer two quills longest, and slightly 

 incurved toward the end ; tail of twelve feathers, even or 

 forked. Trachea with four pairs of inferior muscles. 



The Hirundinse feed entirely on insects, which they 

 capture on wing. They are therefore obliged to retire 

 southward, in autumn, from the colder and temperate 

 regions. Their flight is extremely rapid and buoyant ; 

 their ordinary cry a chirp, or twitter ; but most of them 

 have a modulated song. They nestle in holes, or against 

 the face of rocks, buildings, or trees, forming their nest 

 of mud, or of twigs held together by a glutinous substance, 

 and laying four or five white eggs, which are either plain 

 or spotted. 



GENUS XIX. HIRUNDO. SWALLOW. 



Bill very short, much depressed, of a triangular form ; 

 upper mandible with the dorsal line convexo-declinate, the 

 edges slightly inflected, with a distinct notch, the tip slen- 

 der, but blunt ; lower mandible with the angle very large 

 and wide. The characters of the digestive apparatus, organs 

 of sense, and limbs, as above. Plumage soft, glossy on the 

 upper parts ; the feathers oblong ; bristle-feathers at the 

 base of the upper mandible scarcely apparent ; wings ex- 

 tremely long, pointed, with the outer two quills longest ; 

 tail emarginate or forked. 



As in the genus Buteo, one species has the tarsi bare, 

 while they are feathered in another ; so may it be with 



