COMMON CHARACTERS. Upper parts more or less olivaceous-green, with the feathers streaked centrally with black (sometimes concealed). Sides of head yellow. Chin and throat black; rest of the under parts, including inside of wings, white, with or without yellow on breast. Wings with two white bands. Inner web of lateral tail-feather almost entirely white from the base. Above bright olive-green with concealed black streaks; tail-coverts ashy. Sides conspicuously streaked with black; crissum unspotted. Jugulum sometimes faintly tinged with yellowish. An obscure dusky-olive stripe through the eye, and a crescentic patch of the same some distance beneath it … _virens_. Above olivaceous-ashy (rump pure ash), with more distinct black spots. Top and sides of head clear yellow, the feathers of the crown tipped with black, or clouded with dusky plumbeous. No dark markings or stripes on side of head. No distinct black streaks beneath; black of throat restricted to front of neck … _occidentalis_. Prevailing color of upper parts black, with olivaceous edgings on the back; rump and upper tail-covert pure black. Sides and crissum streaked with black. A simple black stripe through the eye; no patch beneath it … _chrysopareia_. Above olive-green. Upper tail-coverts ashy, with central black streaks. Feathers of head above black, with olive-green edges. A broad olivaceous black stripe through eye from lores, involving the ears, in which is a yellowish crescentic patch below the eye. Black feathers of throat and chin edged with yellow. Jugulum and sides of breast also yellow. Sides streaked with black. No distinct black streaks on crissum … _townsendii_. HABITS.—The Black-throated Green Warbler, like nearly all the members of this highly interesting genus, has, to a very great degree, escaped the closer observations of our older ornithologists. Wilson only noticed it as it passed through Pennsylvania in its early spring migrations. He mentions its frequenting the higher branches of forest trees in search of the larvæ of the smaller insects that feed upon the opening buds, and describes it as a lively, active bird, having only a few chirping notes. All had passed on by the 12th of May. Their return he was never able to notice, and he became afterwards satisfied that a few remained all the summer in the higher grounds of that State, having obtained several in June, 1809.