BIRDS OF NORTH AND MIDDLE AMERICA. 29 



Very large Hirundinidse (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 inner side, tail longer than 

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

 rectrices tapering terminally and obtusely pointed at tips, the adult 

 males uniform glossy blue-black or 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, conspicuously 

 expanded laterally ; gonys slightly convex or nearly straight. Nostrils 

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

 obvious superior operculum, posteriorly in contact with feathering of 

 frontal antise. 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 less;), 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 glossy blue-black above, some 

 species entirely of this color, but others with under parts partly white, 

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

 parts, or brownish gray. 



Nidification. — Nest in holes of trees or buildings, composed of fine 

 grasses, feathers, etc. ; eggs immaculate white. 



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

 West Indies and Galapagos Archipelago. (Six species.) 



KEY TO THE SPECIES AND SUBSPECIES OP PEOGNE. 



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

 h. Wing 138 mm. or more; a concealed white patch on sides of lower back, 

 c. A concealed white patch on outer margin of sides, immediately below the one 

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

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

 any concealed 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 subis. ) 

 e. Averaging flrger, 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. (Pacific coast district, 

 from Cape St. Lucas to British Columbia. ) 



Progne subis hesperia, adult male (p. 35) 



« Adult males of the geographic races of P. mbis are often undistinguishable, only 

 the adult females and young differing constantly. 



