62 PROCEEDINGS OF THE ACADEMY OF 



Iris blackish brown. Legs and feet and upper mandible black ; lower man- 

 dible dusky flesh. No. 36945, measures 5-9 X 8-7 ; No. 36944, 6-1 X 9-2. 



A young bird in my Fort Yuma collection, (Sept. 17, 1865, > differs greatly 

 from the adult in colors, though the proportions are accurately preserved. It 

 is everywhere very strongly suffused with olive, becoming olivaceous yellow 

 beneath, almost like flaviventris or difficilis. The middle of the abdomen, how- 

 ever, is rhore decidedly whitish, and the sides of the breast somewhat rufous. 

 The bands on the wings and the edges of the primaries are very strongly 

 tinged with ferrugineous, especially the former. The tail is margined with a 

 duller shade of the same color, as is also the under coverts of the wing near 

 its edge The upper mandible is black ; the lower with the whole mouth 

 bright yellow. The feet are brownish. But with this similarity of colors the 

 shape of the bill, and the proportions of some other parts will always readily 

 distinguish it from flaviventris or diffieilis. 



The Platyrltynchus pusillus of Swainson (Syn. Mex. Birds in Phil. Mag. 

 May, 1827, 366,) is one of several Tyrannince which Dr. Sclater finds it difficult 

 to determine satisfactorily, (P. Z. S. , 1859, p. 44.) The species is, I thiuk, 

 most undoubtedly the same as that subsequently described and figured by 

 Swainson and Richardson, (F. B. A. ii. 1831, p. 144,) which Prof. Baird has 

 shown quite conclusively to be the species now under consideration. I have 

 elsewhere (vide infra) shown where I think belongs Tyrannula affinis of 

 Swainson's Mexican synopsis. 



66. Empidonax difficilis Baird. 



E. difficilis Baird. B. N. A., 1858, p. 198; name proposed in text of 

 flaviventris for western specimens. 

 Rather rare ; summer resident ; arrives middle of April ; remains until lat- 

 ter part of September. 



Iris brown ; feet black ; upper mandible black, lower light yellow. 

 It is somewhat diffiunlt to distinguish this supposed species from the eastern 

 flaviventris. 



67. Empidonax Hammondii (Xantus) Baird. 



Rather rare summer resident. Arrives 1 >te in April ; remains until third 

 week in October. 



A species readily discernible among the little North American Empidonaces 

 by its diminutive bill, the deep forking of the tail, and the proportions of the 

 primaries, independently of its peculiar shades of color. The grayish white 

 tips of the lesser and median wing coverts are very conspicuous. The white 

 margin of the inner primaries and secondaries are well defined ; but stop ab- 

 ruptly before reaching the greater coverts, so that a well marked area is thus 

 left entirely dark colored ; except on a single feather, (the innermost secon- 

 dary), which is margined for its whole length. Specimens hardly vary in 

 size ; not more than a fourth of an inch in length, and a little more in extent 

 The bill is almost wholly dark colored ; the under mandible being only slightly 

 lighter in color. The legs and feet are black. The mouth at all seasons is 

 bright yellow. 



In the fall, as usual, the whole colors of young birds are tinged more or less 

 strongly with yellowish olive ; and sometimes on certain parts with pale fer- 

 rugineons. The back especially towards the rump is quite decidedly olivace- 

 ous brown ; the head not so purely biown as iu spring. The bands on the 

 wing, and the margins of the primaries are tinged with rufous olive. The under 

 parts, especially on the abdomen and flanks, are strongly olive yellow, giving 

 somewhat the aspect of flaviventris ; but the throat and breast remains much 

 as in spring. 



iW. Empidonax ob^curus (Swains.) Baird. 



Tyrannula obscura, Swains. Syn. Mex. Phil. Mag. i. 1827, p. 3(37. 

 Empidonax Wrightii, Baird, Birds N. A., 185>s, p. 200. (Provisional 

 name, in text under E. obscuru.i.) 



[March 



