Nelson North American Mainland Myiarchus. 23 



some specimens the winter condition of the colors remains until 

 late in spring or early summer, but ordinarily they are much 

 faded at this season. The sexes are alike in color, but the fe 

 males are usually smaller than the males, as shown by the meas 

 urements. 



In most of the published descriptions of the rufous-tailed 

 species described in the present paper, little or no range of va 

 riation in distribution of the dusky pattern on the tail feathers 

 has been mentioned. This has given the erroneous impression 

 that these markings are rather constant and has led to the iden 

 tification of female individuals of cinerascens from Arizona as 

 nuttingi. By the examination of several hundred specimens of 

 the various species it has been demonstrated that the dusky pat 

 tern on the inner webs of the outer. tail feathers (and to a simi 

 lar degree on the inner tail feathers) of cinerascens^ mexicanus, 

 crinitus, and nuttingi with their subspecies have a wide range 

 of variation in extent, though usually preserving a character 

 istic outline, although at times this also disappears. Thus we 

 have the dusky area practically gone on the inner web of the 

 outer tail feather of some of the females of cinerascens, pro 

 ducing a pattern exactly as in nuttingi. One specimen of 

 otherwise typical cinerascens from Guanajuato has the dusky 

 line along the shaft as in typical inquietus, and a specimen of 

 nuttingi from Honduras has the dusky shaft line of inquietus. 

 M. crinitus may or may not have a dusky shaft line on inner web, 

 while in mexicanus this line varies greatly in width. The 

 rufous border to inner webs of tail feathers in yucatanensis also 

 varies much in width and may or may not be present on the 

 outer feather. The considerable amount of individual varia 

 tion thus shown renders it difficult to make a key that is ser 

 viceable in identifying more than average specimens of some 

 species. 



In the cases of cinerascens and nuttingi the differences in 

 dimensions are decisive and almost equally diagonostic between 

 these two and inquietus. 



The first plumage of the young in all of the species is char 

 acterized by a much greater amount of rufous on the wings and 

 tail than in the adult. This is especially marked on the tail, in 

 which the characteristic dusky pattern of the adult is not ap 

 parent. The extension of the rufous on the tail usually includes 



