ATA NORTH AMERICAN BIRDS. 
(3.16), tail 2.30-2.55 (2.41), bill from nostril .30-.35 
(.31), tarsus .72—.79 (.75). Hggs .79 x 59. Hab. 
Rocky Mountain district of United States; south, in 
winter, through central Mexico.... 629). V. solitarius 
plumbeus (Covzs). Plumbeous Vireo. 
a. Spurious primary always present and well developed, equal to or longer than 
tarsus, and broad, like other quills; wing more rounded. (Subgenus 
Vireo.) 
b', Wing much longer than tail (the difference equal to or greater than length 
of bill from nostril). 
c. Sides olivaceous or yellowish. 
d'. Median lower parts pure white or buffy white, in marked contrast 
with olive-greenish or yellowish of sides and flanks. 
é. Wings blackish or dusky, the middle and greater coverts 
broadly and sharply tipped with white or pale sulphur- 
yellow. 
f?. Lores and orbital ring white; cheeks and ear-coverts 
black or deep brownish gray, in marked contrast with 
pure white or buffy white of throat. 
Adult male: Top and sides of head deep black, the 
lores and orbital ring pure white; lower parts 
pure white, the sides and fianks olive-greenish, 
tinged with yellow; upper parts olive-green, the 
wings and tail black, with pale olive-yellow 
edgings. Adult female similar to male, but black 
of head usually duller, more slate-colored. Young 
in first autumn and winter: Top and sides of head 
dull grayish brown; lores, orbital ring, and lower 
parts dull buffy white, or pale dull buffy, the 
sides brown-olive; upper parts more brownish 
than in adult. Length 4.40-4.75, wing 2.15-2.30, 
tail 1.80-2.00. Nest 3-5 feet from ground, in 
bushes or small trees. Eggs usually 4, .72 x 51, 
plain white. Hab. Southern portion of Great 
Plains, north to Kansas; in winter, south into 
Mexico (Mazatlan, etc.)...... 630. V. atricapillus 
Woopu. Black-capped Vireo. 
f’. Lores and orbital ring yellow; cheeks and ear-coverts 
grayish, fading gradually into grayish white of 
throat. (Above olive-green, usually tinged, more or 
less, with ashy on hind-neck; wings and tail dusky, 
with light olive-green edgings; chin, throat, and chest 
grayish white; belly and under tail-coverts pure white, 
the latter usually faintly tinged with sulphur-yellow; 
sides and flanks sulphur-yellow, tinged with olive. 
