576 



IJUT.LETTN 50, UNITED STATES NATIONAL MUSEUM. 



ish l)liick, maiidiblc wholly pale yellowish; ii'ls brown; legs and feet 

 brownish black or blackish brown. 



Adults in winter. — Similar to the spring plumage, but coloration 

 slightly deeper, the upper parts slightly more In-ownish olive, the chest 

 and sides less grayish olive. 



Adult ma/e.— Length (skins), 132-140 (136); wing, 72-79 (73.8); 

 tail, 61-69.5 (64.5); exposed culnien, 11.5-12 (11.8); tarsus, 17-17.5 

 (17.2); middle toe, 9.« 



Adult >/rtaZe.— Length (skins), 126-134 (128); wing, 64.5-72.5 

 (69.4); tail, 56-61 (59.1); exposed culmen, 11-12 (11.7); tarsus, 16- 

 17.5 (16.7); middle toe, 8.5-10 (9).^^ 



Breeding in ])ine forests of northeastern Mexico, in State of Coa- 

 huila (Sierra Guadalupe), and possibly across to Jalisco (San Sebas- 

 tian, March 21); migrating southward to Chiapas (San Cristobal, 

 September), and Guatemala (Hacienda Chancol, January). 



Empidonax trepidus Nelson, Auk, xviii, Jan., 1901, 47 (Hacienda Chancol, Guate- 

 mala, January 5; coll. U. S. Nat. Mus.), 48 (range). 

 [Empidonax] txe pidus Sharfe, Hand-list, iii, 1901, 140. 



EMPIDONAX DIFFICILIS DIFFICILIS Baird. 



WESTERN FLYCATCHER. 



Somewhat like E. JJaviventris, but outermost (tenth) primary 

 shorter than fifth, instead of longer; olive of upper parts much less 

 greenish (more brownish or grayish), wing-bands pale buffy grayish or 

 grayish buff instead of clear light yellow, yellow of under parts less 

 pure, and chest and sides more buffy olive or brownish; tail longer. 

 Young much more buffy, both above and below, than that of E. JJavi- 

 ventris, and with wing-bands cinnamon-buff or ochraceous. 



Adults {sexes alike) .'^ — Above plain brownish olive (varying to gray- 



« Three specimens. 

 b Six sjDecimens. 



Locality. 



Wiiig. 



Ex- 

 posed 

 culmen. 



Tarsus. 



Middle 

 toe. 



MALES. 



One adult male from Coahuila (Sierra Guadalupe, May) 



Two adult males from Guatemala (Hacienda Chancol, Jan- 

 uary) 



FEMALES. 



One adult female from Coahuila (May) 



One adult female from .Talisco (San Sebastian, March 21) . . . 



One adult female from Chiapas (September) and three from 



Guatemala (Januarj') 



68. 5 

 71.5 



(J9. 1 58.4 



9 



8.5 



9.1 



cAs in E. flaviventris there seems to be no difference in coloration between adult 

 birds taken in autumn or winter and those taken in spring and early summer. In mid- 

 summer, however, when the plumage has become more or less worn or faded, the color- 

 ation is duller, the upper parts more grayish, and the yellow of the under parts paler. 



