Mniotiltide 439 
parts of the United States. Colorado has 29 species 
out of about 155 distributed in summer from Alaska 
to the Argentine. 
The following is a plumage key to the Colorado species, 
as the genera are not easily discriminated. The key 
will not invariably hold good for the females and 
juveniles, for which the main text should be always 
consulted. 
Promace Key or THE CoLoRADO WARBLERS. 
A. Tail particoloured, dusky or slaty marked with white. 
With a bright yellow patch on the wing. V. chrysoptera, p. 443. 
b. Without a conspicuous yellow patch on the wing. 
ai Below white, with or without black markings or streaks, 
but no yellow. 
a? Head and back streaked with black and white. 
M. varia, p. 441. 
b? Head black, not streaked. 
a® Back slaty ; a yellow spot in front of the eye. 
D. nigrescens, p. 457. 
b? Back olive-grey ; no yellow spot. OD. striata, p. 455. 
ce? Crown and back greyish-blue. 
a? =Throat black. D. czrulescens, p, 451. 
b? Throat white. D. cerulea, p. 455. 
d? Crown and back yellowish-green ; sides of the face yellow. 
D. virens, p, 459. 
b! Below with some yellow. 
a? Crown and back slaty-blue, and an olive patch in the 
middle of the back. C. a. usnez, p, 447. 
b? Crown and head all round bright orange-yellow. 
P. citrea, p. 442. 
ce? Crown with a yellow patch surrounded by black or dusky. 
a? Throat yellow. D. auduboni, p. 453. 
b? Throat white. D. coronata, p. 451. 
dad? Crown grey, rump yellow. D. magnolia, p. 454. 
e? Crown grey, streaked with black, rump like the back, 
not yellow. D. gracia, p. 456. 
f2 Crown black, with a yellow superciliary line on either 
side ; rump like the back. D. townsendi, p. 459. 
gz? Crown chestnut. D. palmarum, p. 460. 
h? Crown and back olive-green. D. cerulescens 2, p, 451. 
