PLATE 4 



Fig. 1. Reading from top to bottom, the birds figured are the Shumagin fox 

 sparrow {PasscreUa iliaca unaJaschcensis) , Mus. Vert. Zool., no. 23282; sooty fox 

 sparrow (PassereUa iliaca fuliginosa), Mus. Vert. Zool., no. 16253; Stephens fox 

 sparrow (PassereUa iliaca stepherisi), J. Grinnell collection, no. 7311; and YoUa 

 Bolly fox sparrow (PassereUa iliaoa hrevicauda) , H. S. Swarth collection, no. 199. 

 About one-half natural size. 



The Shumagin fox sparrow and the sooty fox sparrow illustrate the extremes 

 of coloration reached in the subspecies of PassereUa iliaca occurring on the north- 

 west coast of North America (the " Unalaschceusis group"). The Shumagin fox 

 sparrow, the northernmost race, is the palest in color of this group, the sooty fox 

 sparrow, the southernmost race, is the darkest. These extremes are linked together 

 by four other subspecies occurring at intermediate points and variously inter- 

 mediate in coloration. Color is the principal character differentiating the members 

 of this group. 



The Stephens fox sparrow and the YoUa Bolly fox sparrow represent extremes 

 attained along two different lines of development followed by the subspecies 

 of PassereUa iliaca in the western United States (the "Schistacea group"). 

 Each has an extremely large bill, but of different shapes. These subspecies also 

 differ in proportionate length of vnng and tail, and slightly in color. In the 

 Stephens fox sparrow the bill is more narrow and sharp-pointed, the tail is rela- 

 tively long, and the general coloration is quite grayish. In the Yolla Bolly fox 

 sparrow the bill is broad and stubby, the tail is relatively short, and there is a 

 distinctly brownish tinge to the coloration. There are no intergrading subspecies 

 directly connecting the two forms stephensi and hrevicxiuda, but there are such 

 intergrades connecting each one Avith still another subspecies, scliistacea. 



[218] 



