682 



MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



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ever, io much bruwner. Specimens without ihe dorsal band, and with more 

 black in the tail, also so approach \ar. fremonti as to be an well referable to 

 this as to var. hudsonius. Some of the Uintah Mountain specimens also pre- 

 sent a decided approach toward var. richardsoni. 



OENEBAL REMARKS R£ori::CTIHa S01UBU8 HUDSONIUS AND ITS TABIETIE8. 



Differential ciiaractebs and affinities.— The four subspecies of Set* 

 vrus hudionius, namely, hudsonius,richardsoni.doui!lam, aad /remonti, are gener- 

 ally readily distinguishable by their coloratii>n, especially by the markings of tha 

 tail. In respect to size, var. hudsonius, as represented in the United States, 

 is rather smaller than either of the others, but examples from Alaska and 

 British North America equal the largest specimens of the other varieties. 

 Vars. richardsoni, douglassi, and fremonti do not differ materially in size. All 

 the varieties except fremonti have usually a more or less distinct reddish 

 band along the middle of the back, wliich extends from the top of the head 

 nearly to the end of the tail. This, in var. hudsonius, is yellowish-red; in vars. 

 richardsoni and fremonti, it is of a much darker tint, generally dark brownish- 

 red. All are white or grayish-white below, except var. douglassi, rvbich has 

 the ventral surface fulvous or huffy. The northern representatives of the 

 three northern varieties (hudsonius, richardsoni, and douglassi) are generally 

 finely annulated on the ventral surface with black; in their southern repre- 

 sentatives and in var. fremonti, these annulations are generally absent The 

 dorsal surface in all is finely annulated with black, the general color varying 

 from fulvous to rufous-gray. A conspicuous black lateral line is more or less 

 prevalent in all, especially in summer, and particubrly among young specimens 

 of var. hudtionius. In winter, it is frequently, if not generally, absent in all, 

 and in var. hudsonius almost invariably so; late in autumn, it is generally 

 obscure. 



Var. hudsonius is distinguished by its lighter and more fulvous tints, 

 being above generally pale yellowish-gray or grayi«>h- fulvous, finely annulated 

 with black, with generally a rather broad dorsal stripe of yellowish- red. The 

 middle of the tail dorsally is of the same color '.is the middle of the back ; 

 the central reddish portion is bounded with blauk, the latter being fringed 

 with jwle yellow. 



Var. richardsoni differs mainly from var. hudsonius in the general color 

 of the upper surface being darker pr more rufous, with the dorsal stripe 



