88 The Ohio Journal of Science [Vol. XVIII, No. 3, 



decidedly greenish with no yellowish tinge; (2) yellowish green, 

 which is very much less commonl}^ observed, a condition in 

 which the greenish of the upper surface is decidedly tinged with 

 yellowish, particularly on the interscapulum ; and (3) a grayish 

 phase, in which the olive upper surface is decidedly grayish 

 with no yellowish and but little greenish tinge. So different 

 are some specimens of these six phases that they look like 

 different species. One specimen, an adult from Fort Simpson, 

 Mackenzie, taken in July, 1861, is so brown that in color it 

 actually is not with certainty distinguishable from California 

 birds of this species; in fact, were it from a breeding locality 

 anywhere within the range of the Great Basin bird, one would 

 unhesitatingly refer it to that form. It is an example of the 

 difficulty which attends identification of some of the individuals 

 of this flycatcher, and shows that single individuals occur 

 which are practically impossible to assign subspecifically without 

 assistance from some other source than the color of the plumage. 



Seasonal variation further complicates the case. By the 

 w^ear of the plumage some adults become, by July, very much 

 paler and more brownish above, as well as somew^hat so on the 

 lower parts; in which condition examples of the eastern and 

 northern race (Empidonax traillii traillii) are easily mistaken 

 for the form of the western United States, hereinafter described 

 as Empidonax traillii breusteri* A bird taken on June 25, 

 1894, at Canton, Illinois, is in this condition, and is practically 

 indistinguishable from worn specimens of the western race. 

 This specimen was doubtless partly responsible for Mr. 

 Brewster's reference of the Illinois birds to the western sub- 

 species. Since, however, breeding birds from all the surrounding 

 region now prove to belong to the eastern race, Empidonax 

 traillii traillii, this example is certainly but a w^orn, abnormally 

 brown individual of the same form. 



Birds in juvenal plumage are also sometimes difficult to 

 decide subspecifically, because those of the eastern race are, 

 on the upper parts, much more brownish than the adults, and 

 thus often readily, at least superficially, to be mistaken for 

 western representatives. 



Mr. Brewster's transferrence of the name Empidonax 

 traillii traillii to the western subspecies was made on the 



"Postea, p. 12. 



