Bill much attenuated; outer three quills nearly equal, first or second longest; tail almost even, with the feathers pointed. Male with the upper parts light blue, the fore part of the back yellowish-green; two broad bands of white on the wing, formed by the tips of the secondary coverts, and first row of small coverts; quills and tail-feathers dusky, margined with blue; a white spot on the outer three of the latter; loral space black; both eyelids with a white spot; throat yellow, with whitish patches, a lunular band of blackish on the fore neck; breast yellow, spotted with dull orange, the rest of the lower parts yellowish, fading into white, the sides pale greyish-blue. Female similar but paler; the loral band wanting; throat, fore neck, and breast yellow, without the black lunule. Although the bill of this species is much attenuated, it is not essentially different in form from that of S. Blackburniæ, and others of this genus; the wings are similar to those of the rest, and there seems no reason for setting it apart to form a genus, as has been done by Bonaparte. _Male_, 4-1/6, 6-1/2. From Texas, generally distributed. Exceedingly abundant. Migratory. Blue Yellow-back Warbler, Sylvia pusilla, Wils. Amer. Orn. v. iv. p. 17. Sylvia Americana, Bonap. Syn. p. 33. Blue Yellow-backed Warbler, Sylvia Americana, Aud. Orn. Biog. v. i. p. 78. 92. 17. Sylvicola Townsendi, Nutt. Townsend's Wood-Warbler. Plate CCCXCIII. Fig. 1. Male. Wings of moderate length, rather pointed, with the second and third quills longest, the first and second nearly equal and very little shorter; tail scarcely emarginate. Upper parts light greenish-olive, more yellow behind, all the feathers dusky in the centre; cheeks, ear-coverts, and throat black; a band over the eye, a broader band on the side of the neck, and the fore part of the breast bright yellow; the rest of the lower parts white, but the sides marked with oblong dusky spots; wings blackish-brown; the secondary coverts and first row of small coverts largely tipped with white, the quills margined with light grey; tail-feathers blackish-brown, edged with grey; outer two on each side almost entirely white, the next with a small white spot. _Male_, 4-10/12, wing 2-8/12. Columbia River, northward. Migratory. Sylvia Townsendi, Townsend's Warbler, Towns. Journ. Acad. Nat. Sc. Philadelphia, v. vii. p. 191. Townsend's Warbler, Sylvia Townsendi, Aud. Orn. Biog. v. v. p. 36. 93. 18. Sylvicola occidentalis, Towns. Hermit Wood-Warbler. Plate CCCXCV. Fig. 3. Male. Fig. 4. Female.