344 



NORTH AMERICAN BIRDS. 



Subgenus TACHYCINETA, Cah. 

 Tachycineki, Cab. Mus. Hein. 1850, 1851, 48. (Type, H. thalassina, S\v.) 



Hirunrlo thalassina. 



Gen. Char. Nosliils lateral, overhung or bordered internally by incumbent membrane. 



Tarsi with the tibial joint covered by overhang- 

 ing feathers, adherent a short distance along 

 inner face, about equal to middle toe without 

 claw. Latei'al toes equal. Adhesion of basal 

 joint of middle toe variable. Tail emarginatc 

 only, or slightly forked ; fork not exceeding half 

 an inch in depth. Color blue or green above, 

 with or without metallic gloss ; with or with- 

 out white rump. Entirely white beneath. 

 Net usually in holes of trees or rocks ; eggs pure white, unspotted. 



Of this section there are two North American species, differing as follows, 

 both being green above and white beneath : — 



Species. 



Plumage above soft and velvety Avithout metallic gloss. Sides of head, space 

 around eyes, and whole under parts, white ; with the feathers all plumbeous at 

 base. Female duller in plumage. Young with bases of throat-feathers gray to 

 roots. 



T. thalassina. Above velvety-green, with various shades and tinges of 



violet and purple. 

 Plumage above compact, and with rich green metallic gloss. Sides of head to 

 line Avith eyes like its upper part. Beneath white ; the feathers of chin and 

 throat, and generally of crissum, white to base. A concealed spot in jugulum. 

 Female duller. Young with bases of throat-feathers pure white to roots. 



T. bicolor. Above metallic-green. Inside of wings and axillars ash-color. 



Hirundo bicolor, Vieill. 



WHITE-BELLIED SWALLOW. 



Hirundo bicolor, Vieill. Ois. Am. Sept. I, 1807, 61, pi. xxxi. — Aud. Orn. Biog. I, pi. 

 xcviii. — Ib. Birds Am. I, pi. xlvi. — Oassin. — Brewer, N. Am. Obi. I, 1857, 100, 

 pi. iv, fig. 47 (eggs). — Lembeye, Aves de Cuba, 1850, 46, lam. vii, fig. 2. — Baird, 

 Birds N. Am. 1858, 310. —Lord, Pr. R. A. Inst. Woolwich, IV, 1864, 15 (Br. Colum- 

 bia ; nesting). — Jones, Bermudas, 34 (Sept. 22, 1849). —Cooper & Suckley, P. R. P. 

 Rep. XII, II, 184. — DALL& Bannister, 279 (Alaska). — Samuels, 257. —Cooper, 

 Orn. Cal. I, 1870, 106. Petrochelidon bicolor, Sclater, P. Z. S. 1857, 201. — Ib. 1859, 

 364 (Xalapa). — Scl.4TER & Salvin, Ibis, 1859, 13 (Guatemala). Tachycineta bicolor, 

 Cab. Mus. Hein. 1850, 48 ; Jour. Orn. 1856, 4 (Cuba). — Gundlach, Jour. Orn. 1861, 

 330 (common in Cuba). Hirundo {Tachycineta) bicolor, Baird, Rev. Am. B. 1864, 

 296. Hirundo viridis, WiLS. Hirundo leucogaster, Stephens. 



Sp. Char. Glossy metallic bluish-green above ; entirely white beneath. Female duller 

 in color. Length, 6.25 inches ; wing, 5.00 ; tail, 2.65. 



Young hird dull sooty-gray above, much like that of H. thalassina; but may readily be 



