262 The American Naturalist [March, 



belly, but shading insensibly into that of the back ; dorsally yellowfch 

 wood-brown, becoming grayish between the ears and over the head and 

 muzzle, everywhere much intermixed with black-tipped hairs which 

 produce a decided blackish shade throughout the region from shoul- 

 ders to base of tail and well down over the sides ; a narrow dusky ring 

 around eye; tail brownish, slightly paler ventrally, without distinct 

 line of demarkation ; whiskers reaching about to shoulders, mixed 

 dark-brown and silvery gray ; dorsum of manus and pes white ; color 

 of sides extending about to wrists and ankles, which latter are dusky 



Measurements taken from the fresh specimens by the collector: 



Date. 

 Jan. 15, '92 

 Nov. 23, '91 

 Nov. 28, '91 



VsV $ Jan. 7, '92 180 103 20 18 



VW S Jan. 8, '92 182 102 20 15 



W 9 Nov. 21, '91 188 105 20 16 



%V 9 Dec. 8, '91 200 113 22 16 



Wi 9 Jan. 7, '92 192 110 20 15 1 



\rW. 9 Jan. 12, '92 185 105 20 — 



It will be seen that Vesperimus fratercuhis agrees very closely in 

 size with V. eremicus? The very much darker color of the former 

 will, however, serve to distinguish the two species at a glance. 



The series show but little individual variation in color. The color- 

 ing of the dorsal surface is remarkably constant, the variation among 

 the adults being practically confined to the amount of shading pro- 

 duced by the black-tipped hairs. They are tolerably evenly distri- 

 buted and do not tend to form a dark dorsal streak. Three specimens 

 younger than the rest are grayer, but have the fulvous lateral stripe 

 nearly as well developed as the adults. The dirty yellowish white 

 'Type. 



