472 NORTH AMERICAN BIRDS. 



Western United States, east to Eocky Mountains; south 

 through central and western Mexico in winter. 



— . V. gilvus swainsoni (Baird). 



Western Warbling Vireo. 1 



b 1 . Wing with two distinct white bands across tips of middle and greater 



coverts. (Subgenus Lanivireo Baird.) 



c 1 . 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. Nest in woQds, usually at a considerable height from 

 ground. JEggs .79 X -58, usually more heavily spotted than in 

 other species. Sab. Eastern United States, west to edge of 

 Great Plains ; south, in winter, to Costa Rica. 



628. V. flavifrons Vieill. Yellow-throated Vireo. 

 <?. 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). 

 d 1 . 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. Hob. 

 Highlands of Guatemala (Coban, Yera Paz). 



V. propinquus (Baird). Vera Paz Vireo. 2 

 d 1 . 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 1 . 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 1 . 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 BAIRD, B. N. Am. 1858, 336 (in text). Vireo gilvus, var. swainsoni Coues, Key, 1872, 121. 



2 Vireosylma propinqua Baird, Review Am. B. i. May, 1866, 348. 



This is either a very distinct Bpeoies or else, as suggested by Messrs. Salvin & Godman {Biol. Centr.-Am., 

 Aves, i. p. 197) a hybrid between V. solitarius and V. flavifrons. 



