326 NORTH AMERICAN BIRDS. 



Family HIRUNDINID^. — The Swallows. 



Char. Rill short. tri;iii<riiliir, very broad at ba>5e (nearly as wide as longr) and much de- 

 pressed, narrowiiii; rapidly to a coinprc^sed, notched tip; mouth opening nearly to the 

 eyes. l*riinaries nine, <rraduatin2: rai>idly less Worn the exterior one ; tail-feathers twelve. 

 Feet W( rik : tan-i s<ut«'llate. shorter than mitldle toe and claw. Number of joints in toes 

 normal : basal joint of middle toe partially or entirely adherent to lateral toes. Wings 

 long, liilcate. Tail forked. Eyes small. Phunage compact, usually lustrou.s!. All the 

 American species with u white patch on the sides under the wing, and with *he irids 

 hazel or brown. 



Tln' HinnuUnidw form a verv well marked ijroiip of l)irtls easily distin- 

 jjuished from all otliers. They exhibit a close reseiiddance, in external a]>- 

 l)earance and liabits, to the Cf/psvlitlfn ; horn which, a]);irt from the internal 

 structure, they are readily distinj^uished 1)V the possession of nine, instead of 

 ten primaries ; twelve, instead of ten tail-feathers ; scutellate tarsi, toes with 

 normal number of joints (1, 2, 3, and 4, respectively, exclusive of ungual 

 phalanges), instead of a different ]>r(>])ortion ; ditt'erently shaped nostrils, etc. 

 In both families the wings are developed to an extraordinary degree ; the 

 outer jmniary nearly twice or more tlian twice the length of the inner, and 

 enabling its possessor to sustain flight ahnust indetinitely. The relations of 

 the family among the Oscincfi ap]>ear c losest to the Old World Muscicapi(1a\ 



In comp ling the wings of the ?Hrunduii(ta' witli those of the Cf/psc/ida\ 

 we readily notice one of the essential characters of the Osclne'^, namely, that 

 the greater wing-coverts hide only half or less than half of the secondary 

 quills, instead of reaching much beyond their middle, or nearly to the end. 

 (See Sundevall, Ornith. Syst.) 



The precise diameter of scutellation of tarsus is somewhat (^'fficult to 

 make out, owing to a tendency to fusion of tlie ] dates, although not essen- 

 tially different from UKtst Oscinri^. There is a series of scutella^ along tlie 

 anterior face of the tarsus, and a longitudinal jilate on each side, meeting, but 

 not coalescing, beliind. The anterior scutelhe sometimes appear to fuse into 

 the outer lateral jdate ; or sometimes the latter is more or less subdivided ; 

 the inner plate is genemlly more distinct from tlie anterior scutelhe, and 

 usually entire, excejit })erliaps at the lower extremity. 



Genera of North American Hirundlnidse. 



A* Nostrils broadly oval, or circular ; opening upwards and forward, and exposed ; 

 without overhanging membrane. 



a. Edge of wing smooth. Tarsus short, stout; equal to middle toe witiiout 

 claw; feathered on the inner side above. Nostrils almost or entirely without 

 membrane. 



Bill stout; culmen and commissure nmch curved. Frontal feathers 

 A, itliout bristles. Tail deeply forked. Color lustrous-black; belly and 

 crissum sometimes white ......... Prot/nc. 



