840 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Tail below dark brownish-red, with a subterminal bar of black, which extends 

 back I'm- a short distance along the sides; above mixed gray, brown, and 

 black, with a broad border of black edged with yellowish-white. A melan- 

 istic race, wholly intense black, is frequent at some localities. 



The general form of the body is rather stout and thick; the tail short 

 and busliy, incompletely distichous, in form somewhat resembling that of Arc- 

 tomys; cars low and broad, about one-fifth to one-sixth of an inch high. 



Specimens from the same localities vary considerably in color, especially 

 in respect to the distinctness of the white spots and the amount of rufous 

 suffusion. In Fort Anderson specimens, the white spots are generally large 

 and well defined ; the lower parts are strongly rufous, often bright tawny, 

 particularly on the sides, throat, and breast ; sometimes bright tawny through- 

 out below, with the top of the head bright brownish-orange. Specimens 

 pure glossy black, with a faint wash of gray or yellowish-gray on the shoul- 

 ders and thighs, are of frequent occurrence in the vicinity of Fort Yukon. 



Var. KODIACENSIS. 



Varietal chars. — Size of var. empetra. Grayer; the white blotches 

 finer and more crowded; the top of the head and the back of a darker 

 brown ; sides and beneath gray, sometimes washed with fulvous over the 

 abdomen ; tail shorter and more bushy. 



A considerable number of specimens from Kodiak Island agree in being 

 of a much paler or grayer phase of coloration than specimens from the Yukon 

 and Anderson's Rivers. While the top of the head is of a much darker shade 

 of brown, with the brown of the middle of the back also darker, the nape, 

 sides of the head and neck, the outer side of the limbs, and the sides of the 

 body, as well as the lower surface generally, but especially the throat and 

 breast, are much lighter, being nearly pure gray instead of tawny, as in var. 

 empetra. While the general size is nearly the same, the tail is about one-fourth 

 to one-third shorter and more bushy. The Kodiak form is characterized by 

 generally an almost entire absence of fulvous, which in var. empetra is gener- 

 ally intensified into brownish-golden; in some specimens of kodiaeensis, the 

 middle of the belly is more or less fulvous, as are sometimes the shoulders. 

 In genera] color, var. kodiaeensis much more closely resembles S. eversmanni, 

 but, in its much shorter tail, differs more from it than does var. empetra. 



