The American Voles of the Genus Evotomys. 129 



Specimens examined. Total number, 71, from 14 localities. 

 British Columbia: Nelson, 24; Sicamous, 1; Glacier, 1. 

 Washington: Colville, 1. 



Idaho: Mission, 1; Kingston, 1 ; Mnllan, 6; Craig Mountains, 4. 

 Montana : Thompson Pass, 5 ; Prospect Creek, 3. 

 Oregon: Blue Mountains (10 miles north of Harney), 8 ; Strawberry 

 Butte, 3 ; Elgin, 8 ; Kamela, 5. 



Evotomys brevicaudus Merriam. 



Evotomi/s gapperi brevicaudus Merriam, North American Fauna, No. 5, 

 p. 119, pi. iii, figs. 7 and 8, July 30, 1891. 



Type locality. Custer, Black Hills, South Dakota. Exact locality, 3 

 miles north of the town ; altitude about 6000 feet [1830 meters]. 



Geographic distribution. Boreal cap of Black Hills in South Dakota. 



General characters. As large as E. gapperi, with rather larger hind foot 

 and much shorter tail ; coloration in summer pelage paler. Larger than 

 E. loringi, with relatively shorter tail. 



Color. Summer pelage: Similar to loringi, but paler, with black hairs 

 more conspicuous; sides ash gray, strongly suffused with buffy ; belly 

 creamy white ; side spots dusky gray. In the type and topotype the tail, 

 feet, and ears are discolored by corrosive sublimate. 



Cranial characters. Skull similar to that of gapperi in large size and 

 broad brain case ; zygomatic arches low and flaring out, so that the inner 

 instead of the outer side shows in a top view ; audital bullae as large as in 

 gapperi, but less rounded ; pterygoids wide, flat, and close together ; 

 molars large ; incisors slender and pale yellow, palate approximately 

 straight-edged. 



Measurements. Type specimen measured in flesh by Vernon Bailey : 

 total length, 125 ; tail vertebrae, 31 ; hind foot, 19. A topotype (No. 4506) 

 measures 130; 32; 19. Skull of type: basal length, 21.2; nasals, 6.6; 

 zygomatic breadth, 12.5 ; mastoid breadth, 11.3 ; alveolar length of upper 

 molar series, 5.4. Skull of more fully adult topotype : basal length, 21.8 ; 

 nasals, 7 ; zygomatic breadth, 12.8 ; mastoid width, 11 ; alveolar length 

 of molar series, 5.3. 



General remarks. The two original specimens, collected July 18 and 21, 

 1888, show only the perfect summer pelage. The skulls show that the 

 animals were not fully adult, though probably full grown. Though based 

 on so scanty material, the characters distinguishing the species are fairly 

 pronounced. Its range is isolated, and widely separated from that of any 

 other members of the genus by open prairie country and a wide belt of 

 the Transition zone. There seems to be no valid reason for considering 

 it a subspecies. It is even difficult to decide to which form it is most 

 nearly related. 



Specimens examined. Total number, 3, from two localities in the Black 

 Hills. 



South Dakota: Custer, 2; Dead wood, 1. 



29 HIOL. Soc. WASH., VOL. XI, 1897 



