458 NORTH AMERICAN BIRDS. 



c*. 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*. 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. 



c 1 . 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.) 

 b*. 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.) 



&. 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 grajnsh 

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

 belly and under tail-coverts white. 



b l . 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 



