N'elson — North American Ifainland 3fyiarchus. 23 



some specimens the winter condition of the colors remains until 

 late in spring or early suTiiiner, 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 shewn by the meas- 

 urenients. 



In most of the ]Miblished 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, 

 crinittis, and nuttingi with their subsijecies 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, pi^- 

 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 

 nutti)igi 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 mexicanMS this line varies greatly in width. The 

 rufous border to inner webs of tail feathers in yiicatanensis 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 



