130 Bailey — The American Voles etf fjie Gemis Evotomys. 



Icdis. It is evident, tlierefore, that E. j>i/gin:eus Rhoads is the young of 

 E. occidt'iilulis. 

 Specliiieit.'i exiimhwd. — Total uuinl)ei", 10, from 5 loeaHties. 



Wanhingloii: Aberdeen, 6; Teniuo, 10; Steihicoom, 2; head of Cas- 

 cade River, 1 ini. 

 British Columbia: Port Moody, 1. 



Evotomys nivaiius * sp. nov. 



Tijpe from Olympic Mountains, Washington, at altitude of 4000 feet 

 [1220 meters], on N W. slope of Mt. EUinor. No. t)6203, 9 ad., U. S. Nat. 

 Mus., Biological Survey Coll. Collected July 9, 189-t, by C. P. Streator. 

 Collector's number, 4025. 



Geographic distribution. — Mt. EUinor and probably other high peaks in 

 the Olympic Mountains. 



General characters. — Size and [iroportions about as in E. occidentaUs, but 

 color lighter and brighter, with skull more angular. Fur long and lax ; 

 ears small and scantily liaired ; tail and feet slender, well covered with 

 short hair. 



Color. — Dorsal stripe well defined, extending from anterior base of ears 

 to base of tail, dull light chestnut; sides dark gray with little buffy suf- 

 fusion ; belly thinly washed with soiled whitish, darkened by plumbeous 

 under fur ; postauricular spots whitish ; ears dusky ; tail distinctly bicolor, 

 soiled whitish below, dusky above ; feet dirty white. 



Cranial cJiaracters. — Skull short, wide, angular, and flat; zygomatic 

 process of maxilla projecting at right angles to axis of skull ; zygomatic 

 process of squamosal spreading ; frontals deeply concave postorbitally ; 

 lateral ridges of frontals and parietals prominent ; audital bullre as large 

 as in ^. occidentaUs; pterygoids slender; palatines short, anterior edge 

 truncate or rounded, posterior edge straight; tooth pattern different in 

 each of the three specimens; incisors yellow like those of E. occidentaUs. 



Measurements. — Average of I! adult females froiu type locality, measured 

 in the flesh by C. P. Streator: total length, 150; tail vertebrae, 50; hind 

 foot, 18. Skull oi type: basal length, 21 ; zygomatic breadth, 13; nasals, 

 0.5 ; mastoid breadth, 11.5 ; alveolar length of upper molar series, 5. 



Remarks. — The specimens from the type locality were caught on July 9, 

 at the edge of an alpine lake, at aljout 4000 feet altitude. At that date 

 Mr. Streator roports about one-third of the lake covered with ice and 

 snow from the previous winter, while deep snow drifts lay on most of the 

 neighboring slope. Ice formed over the water almost every night during 

 his stay, from Juh^ 8 to 11. The snow banks do not entirely leave Mt. 

 EUinor during the summer. At this altitude the timber is smaller and 

 more scattered and the undergrowth less dense than lower down. 



The species shows no close relationship with any other, except occi- 

 dentaUs. The types of these two are widely different, but specimens from 



*The name nivarius seems appropriate to this alpine species, found in 

 close proximity to snow banks that never melt. 



