326 ^UJlTIl AMERICAN BIRDS. 



Family HIRUNDINID^ffil. — Tiik Swallows. 



CnAi?. T?ill short, irimifruliU', vciy hroail at base (nearly ns wido as long) and much de- 

 prosst'd, narrowinu: rapidly to a (■oiii])r(.'.<sc'd, not(;licd tip ; mouth opcniiijr nearly to the 

 eyes. Primaries nine, irraduatinr^ rapidly less Irom thu exterior one ; tail-feathers twelve. 

 Feet weak ; tarsi .scutellate, .shorter than middle toe and (daw. Numlx.T of joints in toes 

 normal ; basal joint of middle too partially or entirely adherent to lateral toes. Wings 

 long, lideate. Tail forked. Eyes small. Plumage eompaet, usually Instron.s. All the 

 Ameriean .speeies with u white patch on the sides under the wing, and with the irids 

 hazel or brown. 



The Kirnnilinida'. form a very well marked group of birds easily di.stin- 

 gui.slied from all others. They exhibit a close reseuddaucc, in external ap- 

 pearance and ]ial)its, to tlie Cypwlid^r. ; from which, apiirt from the internal 

 structure, they are readily distino'-.i.Miod l)y the possession of nine, instead of 

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

 normal nund)er of joints (1, 2, 3, and 4, respectively, exclusive of ungual 

 phalanges), instead of a ditlereut ]iro])ortion ; diH'erently shaped nostrils, etc. 

 In both families the wings are develo])ed to an extraordinary degree ; the 

 outer primary nearly twice or more than twice the length of the inner, and 

 enabling its possessor to sustain tlight almost indefinitely. Tlie relations of 

 the family among the ttsv/wcs apjiear cdosest to the Old World Mimricnpida'. 



In comparing the wings of the HiraiuUiiidw with those of the C//psc/ida', 

 we readily notice one of the essential chtiracters of the Oscinr% 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 character of scutcllation of tarsus is somewhat difflcidt to 

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

 tially ditferent from most Oschws. There is a series of scntelhv. along the 

 anterior iace of the tarsus, tind a longitudinal plate on each side, meeting, but 

 not ct)alescing, behind. The anterior scutelhe sometimes ajipear to fuse into 

 the outer lateral i)late ; or sometimes the latter is more or less subdivided ; 

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

 usuidly entire, exce])t ))erhaps at the lower extremity. 



Genera of North American Hirundinidse. 



A. Nostrils broadly oval, or circular ; opening upwards and forward, and expcscd ; 

 without ovinhanging mcudu'ane. 



a. Edge of wing smooth. Tarsus short, stout; equal to middle toe without 

 claw; leathered on the inner side aliovc. Nostrils almost or entirely without 

 membrane. 



Bill stout; cnlmen and commissure nmeh curved. Frontal feathers 

 without bristles. Tail deeply forked. Color lustrous-black ; belly and 

 crissum sometimes white Pmi/iic. 



