A. Sides streaked; black of throat with its posterior outline concave.
a. Side of head white and black.
19. D. nigrescens. A small yellow spot over the lore; above ash; beneath white. ♂. Whole crown, uniform glossy black; back streaked with black. ♀. Crown ash streaked with black; throat mixed with white anteriorly. Juv. Crown and cheeks ashy; throat mostly white; back without streaks. Hab. Western and Middle Province of United States, south, in winter, into Western Mexico (Oaxaca).
b. Side of head yellow and black, or yellow and olive.
Black of throat covering jugulum; a hidden yellow spot in middle of forehead.
20. D. chrysopareia. Black above, pure white below; no tinge of yellow behind the black jugular patch. Hab. Eastern Middle America, from Guatemala to Texas (San Antonio).
21. D. virens. Olive-green above, the crown and back without streaks; beneath white, the breast and anal region tinged with black. Hab. Eastern Province of North America, from Greenland to Panama; Cuba; Oaxaca; Heligoland, Europe!
Black of throat confined anteriorly to the jugulum; no yellow spot on forehead.
22. D. townsendi. Above olive-green, the crown and back with conspicuous black streaks; beneath yellow anteriorly, and white posteriorly. ♀, black of throat mixed with yellow; juv., no black on throat, and streaks on back obsolete. Hab. North and Middle Province of United States, south, in winter, into Guatemala.
B. Sides not streaked; black of throat with its posterior outline convex.