544 OKNIXnOLOGY. 



OOS, 9 ad.; East nuuiboltlfc Mountaius (Camp 23), September S, 1868. S'j— SJ — 

 'Jfg. Lower inaudible, rich brown. 



9(19, (? ad.; East Humboldt Mountaius (Camp 23), September 8, 1868. 5i— 8/;;— 

 (?) — 2^\. Lower maudible, with rictus, wood-brown. 



910, <? ad.; East Hunibohlt Mountains (Camp 23), September 8, 1868. 5^—85— 

 (?) — 2^'^. Same remark.s. 



EmPIDONAX DIFFICILIS.' 

 Western Vcllow-bellied Flycatcher. 



Empidonax difficiUs, Baird, B. N. Am., 1858, 198 (in text); ed. 1860, pL 76, tij;-. 2; 



Cat. N. Am. B., 1859, No. 144a. 

 Empidonax flaviventris var. difficiUs, Allen, Bull. Mus. Comp. Zool., Ill, 1872, 179. 



— CouES, Key, 1872, 176 (in text).— B. B. & R., Hist. N. Am. B., II, 1874,380. 



— Henshaw, 1875, 362. 

 Empidonax flaviventris. b. difficiUs, CoUES, B. N.W., 1874, 256. 

 Empidonax flaviventris, Cooper, Oru. Cal., I, 1870, 328. 



This species was the rarest of the Empidonaccs met with by us, a few 

 only being seen in the pine forests high up on the Wahsatch Mountains, 

 and a still smaller number on the eastern slope of the Sierra Nevada. At 

 the fomier place a few pairs were found in July and August, and when 

 observed were usually perched upon a dead twig, sitting in a nearly ver- 

 tical position, the tail constantly jerked to one side. The only note heard 

 was a distinct chip, much like that of the Yellow-rump Warbler (Dendrosca 

 roroiiafa). 



List (>/ specimens. 



1 190, i ad ; Parley's Park, Wahsatch Mountains, Utah, August 5, 1809. (!— 9^. 

 Upper mandible, black, lower lilaceouswhite; iris, deep reddish hazel; tarsi and toes, 

 jiurplish black. 



1491, 9 ad.; Parley's Park, Wahsatch Mountaius, Utah, August 5, 1809. HJ— 8§. 

 Same remarks. 



' It is with little hesitation that we consider this bird as distinct specifically from 

 E. flaviventris. Xot only are there very conspicuous and constant ditJ'erences in pro- 

 portions and colors (especially the former), but numerous observers have noticed 

 remarkable and important peculiarities in the nesting habits, the present species 

 almost invariably building its nest in cavities, either of stumps, trees, or rocks, or on 

 beams inside of buildings, a habit not yet noticed in E. flaviventris, nor, indeed, in any 

 other species of the genus. [See Cooper, Proc. Cal. Acad. Sciences, December 0, 1875, 

 who, however, is mistaken in supposing that " the dififereuces in the two races seem 

 to bo wholly in shades of color and size, and not in proportions, as formerly supposed."] 



