544 or.NiTnor,or,v. 



008, 9 ad.; East Humboldt Mountaius (Camp 23), September S, 1808. 5.^—81— 

 L'l^^. Lower mandible, ri(;li brown. 



909, <f ad; East Humboldt Mountains (Camp 23), September 8, 18G8. 54— 8-^^— 

 (T) — 2^^^. Lower mandible, with rictus, wood brown. 



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

 (?) — 2,'g. Same remarks. 



EmPIDONAX DIFFICILIS.' 

 Wcsiorn Yellow-bellied FIj'catclicr. 



Kmpldonas diffic-lis, Baird, B. N. Am., 1858, 198 (in text); ed. 1800, pi. 70, (i;;. 2; 



Cat. N. Am. B., 18.59, No. 144a. 

 Empidonax flariventris var. difficilis, Allen, Bull. Mus. Comp. Zool., Ill, 1872, 179. 



— CouKS, Key, 1872, 170 (in text;.— B. B. & R., Hist. N. Am. B., II, 1874,380. 



— FIENSIIAW, 1875, .302. 

 Empidonax flaviventrix. b. difficilis, CouES, B. N.W., 1874, 266. 

 Empidonax flaviventrin, Cooper, Orn. Cal., I, 1870, 328. 



Tills species was the rarest of the Empidonaces met with by us, a few 

 only being seen in the pine forests high up on the Wahsatch ]\rountaiiis, 

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

 the former 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 (Detulrceca 

 coronata). 



Lint of gpecimens. 



1490, <J ad.; Parley's Park, Wahsatch Mountains, Utah, August 5, 1869. 0— Of 

 Up])('r mandible, black, lower lilaceouswhite; iris, deep reddish hazel; tarsi and toes, 

 puiplish black. 



1491, 9 ad.; Parley's Park, Wahsatch Mountains, Utah, August 5, 1869. o^— 8§. 

 Same remarks. 



'It is with little hesitation that we consider this bird as distinct specilic^ally from 

 E. flaviventris. Not only are there very conspicuous and constant dift'ereuces in pro- 

 portions and colors (esi)ecially 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, cither 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 6, 1875, 

 who, however, is mistaken in supposing that " the difl'erences in the two races seem 

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



