Plumage with no marked contrast of shades.
C. pelagica. Nearly uniformly dusky grayish-brown, the throat, however, very much lighter, and the rump just appreciably so.
Above glossy dusky-brown, hardly appreciably paler on the rump; abdomen scarcely paler than the back. Wing, 5.20. Hab. Eastern Province North America … var. pelagica.
Above glossy blackish-dusky, very decidedly paler on the rump; abdomen very much paler than the back. Wing, 4.50. Hab. Pacific Province of North America, south to Guatemala (from whence specimens are much darker, almost black above, and slightly smaller) … var. vauxi.
Above glossy black, fading into sooty dusky on the rump; abdomen like the rump. Wing, 4.80. Hab. Northern South America (Cayenne, Tobago) … var. poliura.[110]
Plumage with marked contrast of shades.
C. cinereiventris.[111] Upper parts, except the rump, glossy, intense blue-black; rump and lower parts bluish-cinereous, conspicuously different.
C. spinicauda.[112] Upper parts glossy black, with a white band across the rump. Below sooty-whitish, with indistinct black marks on the breast, wing, 3.90. Hab. Cayenne and Brazil.
Chætura pelagica, Baird.
CHIMNEY SWALLOW.