472 NORTH AMERICAN BIRDS. 
Western United States, east to Rocky Mountains; south 
through central and western Mexico in winter. 
—. V. gilvus swainsoni (Barrp). 
Western Warbling Vireo. 
b. Wing with two distinct white bands across tips of middle and greater 
coverts. (Subgenus Lanivireo Barn.) 
¢. No spurious primary ; loral streak, orbital ring, chin, throat, and breast 
yellow; top of head olive-green. 
Posterior under parts white; rump, upper tail-coverts, and scapu- 
lars ash-gray ; hind-neck and back olive-green ; tertials broadly 
edged with white; length 5.00-5.85, wing 3.00-3.20, tail 2.00- 
2.30. West in woods, usually at a considerable height from 
ground. Zggs .79 x .58, usually more heavily spotted than in 
other species. Hab. Eastern United States, west to edge of 
Great Plains; south, in winter, to Costa Rica. 
628. V. flavifrons ViziLL. Yellow-throated Vireo. 
c’. A more or less distinct spurious primary; loral streak, orbital ring, 
chin, throat, etc., white; top of head ash-gray or plumbeous (more 
brownish in winter). 
@. Spurious quill minute (much shorter than exposed culmen); hind- 
part and sides of neck olive-green, like back and scapulars; 
chest and breast (especially sides of the latter) strongly washed 
with sulphur-yellow. (Otherwise much like V. solitarius.) 
Wing 3.05, tail 2.20, bill from nostril .30, tarsus .72. Hab. 
Highlands of Guatemala (Coban, Vera Paz). 
V. propinquus (BairD). Vera Paz Vireo,” 
@, Spurious quill well developed (much longer than exposed culmen) ; 
hind-part and sides of neck grayish, like top of head and ear- 
coverts; chest and breast without yellow tinge. 
e'. Sides and flanks conspicuously olive or olive-green, distinctly 
tinged with yellow; back, rump, and upper tail-coverts olive- 
green. (Young in first winter with anterior upper parts 
dull grayish brown, the lower parts dull buffy white, the 
general aspect quite different from full adult plumage.) 
f'. Smaller (wing not more than 3.00, tail rarely more than 
2.20). 
g. Back, etc., brighter olive-green, more abruptly con- 
trasted with plumbeous-gray of head and neck, 
the latter deeper and clearer; gray of cheeks more 
abruptly contrasted with white of throat; sides 
and flanks usually more strongly tinged with 
1 Vireo swainsoni Batrp, B. N. Am. 1858, 336 (in text). Vireo gilvus, var. swainsoni oe Key, 1872, 121. 
2 Vireosylvia propinqua BarrD, Review Am. B, i. May, 1866, 348. 
This is either a very distinct species or else, as suggested by Messrs. SALVIN & GODMAN (Biol. Centr.-Am., 
Aves, i. p. 197) a hybrid between V. solitarius and V. flavifrone. 
