The characters of Vireo are essentially those of Vireosylvia; the bill, however, is shorter; the first quill always present, better developed, sometimes more than half the second. The wings are shorter, and more rounded; the tarsi usually longer. The, sections are as follows:—
Vireo. Wings pointed; first quill less than half the second, which is about equal to seventh or eighth, and decidedly longer than the tenth primary and the secondaries. Type, V. noveboracensis.
Vireonella. Wings rounded, scarcely longer than the tail; the first quill half as long as the second (or more than half), which is not longer than the tenth primary and secondaries, or even less. Bill and feet generally much stouter than the preceding. Type, V. gundlachi.
None of the species of Vireonella are found in the United States.
Species.
Common Characters. All the species olivaceous or ashy above, beneath whitish, or olivaceous-yellow. Wings with light bands. A light stripe from bill over the eye, but not beyond it, except in carmioli. Iris brown, as far as known, except in V. noveboracensis, where it is white.
A. Two conspicuous light bands on wing.
a. Sexes different. Whole lore white.
1. V. atricapillus. Above olive-green, outer edges of tail-feathers bright yellowish-green; wing-bands greenish-white. Sides olivaceous-yellow. Male. Head and neck (except lore, orbital ring, chin, and throat) deep black; lower parts pure white medially. Female with the black replaced by dull slate; lower parts ochraceous-white medially. Wing, 2.30; tail, 1.80; tarsus, .68; bill, from nostril, .24. Hab. Southern Texas; Mazatlan, Mexico.
b. Sexes alike. Lore dusky, with light mark above it.