1920] Swurth: Revision of Avian Genus Pmserella 117 



brown; upper parts almost uniform, a faint suggestion of gray underlying the 

 broAVTi of the head and neck, the back slightly mottled, and the wing bars barely 

 apparent. The character of the bill, however, is closely similar to that in iliaca. 



From the appearance of the specimens described above several 

 deductions may be drawn. These birds are all to be referred to the 

 subspecies iliaca, but, with two exceptions (no. 4932, coll. A. B. 

 Howell, and no. 867, coll. J. R. Pemberton), they vary from typical 

 iliaca sufficiently to be noticeable if inserted among a series of eastern 

 collected skins. The specimens all resemble iliaca most nearly in the 

 ventral marking's ; the greatest variation is evident on the upper parts. 

 These birds all show a tendency toward elimination of dorsal streak- 



Fig. K. Wings of the two subspecies of fox sparrow of the Iliaca group, 

 natural size. 



a. Passerella iliaca iliaca, adult male ; no. 6088, Mus. Vert. Zool. ; Eastf ord, 

 Connecticut; April 12, 1876. 



b. Passerella iliaca altivagans, adult male; no. 26039, Mus. Vert. Zool.; Aspen 

 Valley, Yosemite National Park, California; October 14, 1915. 



ings, with consequent greater uniformity of color on the upper parts. 

 This color in some is reddish, of a darker shade than is seen in typical 

 iliaca, while in others it is decidedly gray. Such variation as appears 

 in the breast streakings tends toward the darker shades of red. 



In the subspecies iliaca there is, according to Ridgway (1901, 

 p. 387), great variation in color, the extremes being designated by 

 him as the "gray phase" and "red phase," respectively,, and these 

 differences are sufficiently correlated with different regions to suggest 

 the possibility of the eventual recognition of two subspecies. "The 

 extreme rufous phase seems to be represented only in the Atlantic 

 Coast district, and is altogether wanting in Alaska and other north- 

 western portions of the continent, where only birds representing the 

 gray extreme occur" (Ridgway, loc. cit.). However, it is extremely 

 unlikely that the reddish-colored birds occurring in California in win- 

 ter are migrants from the Atlantic Coast, where the red phase of iliaca 

 has its habitat. The probabilities are that the Californian migrants 



