PASSERES— TYRANNIDAE— E. FLAVIVENTRIS VAR. DIFFICILIS. 359 



the summer in the region generally north of the fortieth parallel. It has, 

 however, recently been ascertained to be a component of the Middle Fauna, 

 being given by Mr. Snow as a bird of Kansas, and as probably breeding 

 there. Its occurrence west of the Great Plains rests, so far as I am aware, 

 upon the observations of Mr. Aiken, and my own detection of the species in 

 May about Denver, Colo., where it made its appearance on the 12th, and 

 subsequently was noticed in a few instances only ; all the individuals appar- 

 ently being migrants. Mr. Aiken has taken this flycatcher in spring in El 

 Paso County, Colorado, and thinks that a few pass the summer in that 

 locality, though the evidence of its breeding does not appear quite as positive 

 as could be desired. 



No. 



Sex. 



Locality. 



Date. 



Collector. 



Wing. 



Tail. 



Bill. 



Tarsus. 



97 



S ad. 



Denver, Colo 



May 17, 1S73 



H. W. Henshaw 



2.58 



2-43 



0.40 



0.41 



EMPIDONAX FLAVIVENTRIS, Bd., var. DIFFJC1LIS, Bd. 

 Western Yellow-bellied Flycatcher. 



Empidonax diffitilis, Bd., Birds N. A., 1858, 19S (in text).— Xantus, Proe. Acad. Nat. 

 Sei. Phila,, 1850, 190 (Fort Tejon, Cal.).— Cotjes, Proa Acad. Nat. Sci. 

 Phila., 1866, 61' (Fort Whipple, Ariz.). 



Empidonax flaviventHs var. difficilis, Allen, Bui. Mus. Comp. Zool., 1872, 170 (Ogden, 

 Utah).— Coues, Key N. A. Birds, 1872, 176 (iu text).— Bd., Brew., & 

 Ridg., N. A. Birds, ii, 1S74, 380.— Henshaw, An. Lye. Nat. Hist. N. Y., 

 xi, 187-1, S.— Id., An. List Birds Utah, 1872, Wheeler's Exped., 1874, 47.— 

 Id., Rep. Oru. Specs., 1873, Wheeler's Exped., 1874, 87, 127.— COUES, Birds 

 Northwest, 1874,256. 



Distributed in all favorable localities throughout Utah, Colorado, 

 and in Eastern Arizona. During the breeding season, they are most often 

 found in the narrow canons and the deep shady glens of the pine woods, 

 almost invariably near a stream of water, or among the trees that border 

 the open, meadowy tracts. It is a rather energetic insect hunter, continu- 

 ally swooping down after passing insects, and when waiting for its prey 

 moving its tail with nervous and excited jerks. The note is a long drawn 

 plaintive pea, agreeing perfectly with that described by Messrs. Maynard 

 and Brewster as belonging to the Yellow-bellied Flycatcher of the East 



