6C)8 BULLETIN 50, UNITED STATES NATIONAL MUSEUM. 



dull white or very pale yellowish of chin and throat; chest and sides 

 pale olive or pale yellowish bnfly gray, fadin^^ toward flanks; rest of 

 under parts varying from yellowish white to pale (primrose) yellow;'* 

 axillars and under wing-coverts yellowish white to primrose yellow; 

 inner webs of remiges edged with very pale grayish buff; maxilla 

 dusky brown, deepening into brownish black terminally; mandible 

 usually more or less extensively pale basally (sometimes wholly so), 

 dusky terminally — rarely entirely brown ;^ iris brown; legs and feet 

 brownish black or blackish brown. 



Young. — Essentially like adults, but wing-bands more pronouncedly 

 buffy, pileum and hindneck grayer, and imder ])arts more whitish. 



Adult male.—hength (skins), 123-136 (129); wing, 65.5-72.5 (69.5); 

 tail, 59-66.5 (62.6); exposed culmen, 11.5-13 (12); tarsus, 17.5-19 

 (18.2); middle toe 9-10 (9.3).^^ 



Adult female. —Length (skins), 124-137 (130); wing, 63-73 (67.4); 

 tail, 57.5-66.5 (60.6); exposed culmen, 11.5-12.5 (11.9); tarsus, 17-19 

 (18.2); middle toe, 8.5-10 (9.4). ^' 



Western United States, breeding, in Transition and Canadian life- 

 zones, south to southern Arizona (Huachuca Mountains) and New 

 Mexico (San Miguel County; Apache, Grant County), north to Oregon 

 (Fort Klamath; Des Chutes River; Narrows), Idaho, and Montana (Co- 

 lumbia Falls), east to main range of Rocky Mountains; in winter, 

 southern California (Panamint Valley; Death Valley; San Buena- 

 ventura, etc.), and southward through ^lexican States of Sonora 

 (Micoba), Chihuahua (Casas Grandes), Nuevo Leon (Monterey), Du- 

 rango (Chacala; Durango City), Jalisco (Atenguillo; San Sebastian; 

 Bolanos; Ocotlan; Barranca Ibarra), Zacatecas (Hacienda San Juan 

 Capistrano), Guanajuato, San Luis Potosi (San Luis Potosi; Sole- 

 dad), Puebla (C^lialchicomula; Tlalcotalpan), Vera Cruz (Orizaba), 

 Mexico (Chimalpa; Coapa; Hacienda Eslava ; ]\Iexicalcingo ; Tetelco; 

 Alixco; Amacameca), Morelos (Yecapixtla), Tlaxcala (A])ixaco), and 

 Michoacan (Morelia; near Almacan; Zamora; Los Reyes) to Guerrero 

 (Amula; Omilteme) and Oaxaca (La Parada; Cuicatlan; Reyes). 



Empidonax obscvrus (not Tyrannida obscura Swainsonrf) Baird, Rep. Pacific K. R. 

 Surv., ix, 1858, 200 (El Paso, Texas); Cat. N. Am. Birds, 1859, no. 14G; Rep. 



« While strongly yellowish examples of this species are apparently more common 

 in autumn and winter, they are almost equally so in spring and summer, ai^ I am 

 convinced that, as in E. hammondii, the two phases are really a sort of dichromatism. 



t> The variation in the color of the mandible in this species is very great, more so, 

 apparently, than in any other form. 



cTen specimens. 



f'Philos. Mag., n. s., i, 1827, 367 (Mexico). Doubtless an Empidonax, but the 

 species unidentifial)l('. (See Baird, Rep. Pacific R. R. Surv., ix, 1858, 200; Brew- 

 ster, Auk, vi, 1889, 89.) 



