458 NORTH AMERICAN BIRDS. 



c 2 . Upper parts plain grayish brown ; lower parts similar, but lighter, be- 

 coming white on belly; edge of outer quill roughened with stiff, 

 recurved hooked tips to the barbs... Stelgidopteryx. (Page 463.) 

 a 2 . Nostrils opening laterally, and bordered above by a broad membrane, or over- 

 hanging scale. 

 b l . Tail forked for much more than length of tarsus. 



e\ Tail forked for about half its total length, the outer pair of feathers 

 abruptly narrowed for terminal portion, and inner webs of all (ex- 

 cept middle pair) marked with a large whitish spot ; lower parts 

 cinnamon or buffy, the throat darker, more rusty. 



Chelidon. (Page 460.) 

 c 2 . Tail forked for much less than half its total length, the outer pair of 

 feathers not abruptly narrowed terminally ; inner webs of tail- 

 feathers without white spots ; lower parts entirely pure white. 



Callichelidon. (Page 462.) 

 V. Tail forked for less than length of tarsus. 



c 1 . No feathers on hind part of tarsus ; entirely white beneath, the adults 



brightly colored above Tachycineta. (Page 461.) 



c 2 . A small tuft of feathers on lower portion of tarsus, behind; lower 

 parts white, interrupted by a broad band of grayish brown across 

 chest; upper parts grayish brown Clivicola. (Page 462.) 



Genus PROGNE Boie. (Page 457, pi. CXIV., fig. 1.) 



Species. 



Common Characters. — Adult males with upper parts uniform glossy blue-black 

 or dark steel-blue (sometimes inclining to violet) ; lower parts similar to upper 

 surface, or with belly white and elsewhere glossy blue-black, or with anterior por- 

 tions grayish, the posterior white. Adult females with upper parts plain glossy 

 blue-black (sometimes interrupted by a grayish collar), the lower parts dull gray- 

 ish anteriorly and white posteriorly. Young: Similar to adult female (the male 

 two years, or more, in attaining the full plumage). 



a 1 . Adult males with lower parts wholly glossy blue-black, like the upper ; adult 

 females with steel-blue of upper parts duller and less continuous, usually 

 broken by more or less distinct grayish borders to feathers, the forehead and 

 hind-neck dull grayish ; anterior lower parts dull light grayish, or grayish 

 white (centres of feathers darker) ; sides and flanks similar, but darker ; 

 belly and under tail-coverts white. 

 ft 1 . Larger, with broader tail-feathers. Adult male with feathers of ventral re- 

 gion entirely sooty grayish beneath surface. Adult females and immature 

 males with anterior and lateral lower parts pale gray, the feathers, espe- 

 cially on chest, with distinctly darker (sooty grayish) centres. Length 

 7.25-8.50, wing 5.65-6.20, tail 3.00-3.40 (forked for .70-.90). Nest in holes 

 of trees or about houses, in boxes, etc. Eggs 3-5, .97 X -72, plain pure 



