G78 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



sonius proper. Two specimens, however, from Cliicf Mountain Lake, forty- 

 ninth parallel, nearly typically represent this variety. On the other hand, speci- 

 mens from the Cascade Range and thence westward merge gradually into 

 van douglassi, differing mainly from the latter in being white below instead 



of fulvous. 



Var. douglassi. 



Western Cluckaree. 



Varietal Chars. — Length to base of tail 7.50; tail-vertebrae 4.75; tail to 

 end of hairs 6.75. Above fuscous, minutely varied with pale rufous and black, 

 Ihe middle of the back more or less dark rufescent. Beneath varying from 

 white through pale fulvous to bright tawny and buffy-orange ; at the north- 

 ward, much annulated with black, as in var. hudsonius. In winter specimens, 

 the ears are conspicuously tufted with black. A prominent black lateral line, 

 especially in summer specimens. Tail gray, fulvous or rufous centrally, with 

 a broad subterminal bar of black, and a broad edging of pure white, gray, or 

 fulvous. 



The specimens in the collection vary considerably in respect to the color 

 of the dorsal surface, and still more so in respect to that of the ventral sur- 

 face. The general color of the upper surface is fuscous yellowish-brown, 

 minutely varied with black, with the middle of the back generally more or 

 less strongly dark reddish-brown, forming sometimes a well defined dorsal 

 band, as in var richardsoni. Often the middle of the back is not perceptibly 

 more rufous than the sides, and, when it is so, the color of the middle of the 

 back generally fades gradually into the general color. Specimens from the 

 same locality vary greatly in tint, both above and below. Thus, the Fort 

 Crook specimens vary in the tint of the middle of the back from dark chest- 

 nut-brown to reddish-yellow, and in the general color above from fuscous red- 

 dish-brown to clear gray, faintly tinged with fulvous. The lower surface in 

 the same specimens varies from pure white to gamboge-yellow. The tail 

 varies in color to a similar degree, in some being cent rally gray above, with a 

 subterminal broad bar of black and a white border; while in others the gray 

 is replaced by fulvous-gray, or even by dark rufous. 



The Fort Steilacoom specimens are equally variable, and also differ 

 quite appreciably in the average from the Fort Crook specimens. No. 1958 

 has the dorsal surface, including the tail, exactly as in a common dark phase 



