BIRDS OF NORTH AND MIDDLE AMERICA. 29 



Very large Hirundinidro (wing 115 mm. or more, usually more than 

 130) with stout bill, tarsus shorter than middle toe (without claw), only 

 the upper part of tarsus feathered on the iiuier side, tail long(!r than 

 distance from hend of wing to tip of longest secondaries, the lateral 

 rcctrices taix'riiig terminally and obtusely pointed at tips, the adult 

 nudes unifoi'in glossy l)lu(^-black oi- violaceous steel blue above (some- 

 times underneath also). 



Culmen strongly curved almost from the base, the tip distinctly 

 though not abruptly uncinate: maxillary tomium distinctly notched 

 subterminally, distinctly concave for anterior half and convex poste- 

 riorly, the edge of the maxilla, from nostril to rictus, conspi(!Uously 

 expanded laterally; gonys slightly convex or nearly straight. Nostrils 

 roundish, opening superiorly, in anterior end of nasal fosste, without 

 ol)vious superior operculum, posteriorly in contact with feathering of 

 frontal antia-. Rictal bristles short and inconspicuous, scarcely pro- 

 jecting beyond expanded edge of maxilla. Tail about half as long as 

 wing (longer than distance from bend of wing to tip of longest second- 

 aries), forked for not more than one-third its length (usually les^;), the 

 lateral rectrices tapering terminally and obtusely pointed at tip. Tar- 

 sus shorter than middle toe without claw but decidedly longer than 

 exposed culmen, its extreme upper portion feathered except the pos- 

 terior edge; claws of lateral toes not reaching to base of middle claw. 



Coloration. — Adult males uniform glossv blue-black above, some 

 species entirely of this <'olor, but others with under parts partly white, 

 the throat, chest, and sides being either glossy blue-black, like upper 

 l^arts, or ))rownish gray. 



Xld[iicatloit. — Nest in holes of trees or buildings, composed of tine 

 grasses, feathers, etc. ; eggs immaculate white. 



RdiKji . — The whole of temperate and tropical America, including 

 West Indies and (hdapagos Archipelago. (Six species.) 



KKV TO THE SPECIES AND SUBSPECIES OK PKOGXE. 



a. Under parts entirely dark steel blue like upper parts. 



b. Wing 138 mm. or more; a concealed white patch ou sides of lower back. 

 <•. A conceaU'd w hitc patch on outer margin of sides, immediately below the one 

 on sides of lowcrback; tail forked for less than 25 mm. (usually for much less.) 

 (/. Feathers of lower abdomen without concealed broad white bars (if with 

 any coiu-ealed white, this in form of small spots or narrow bars); tail 

 relatively shorter and less deeply forked, with lateral rectrices relatively 

 broader and less pointed. {Progne xubix.) 

 e. Averaging larger, with less deeply forked tail." (Temperate North 

 America, except Pacific coast district, including northern, central, and 

 western Mexico; parts of South America in winter. ) 



Progne subis subis, adult male (p. 31 ) 

 ee. Averaging smaller, with more deeply forked tail. (Pacitic coast district, 

 from Cape St. Lucas to British Columbia. ) 



Prog-ne subis hesperia, adult male (p. 35) 



" .Vdiilt males of the geograi)hic races of P. suhL^^ are often undistinguishable, only 

 the adult females and young differing constantly. 



