122 Bailnj — The American. Voles of tJte Genus Evoiomys. 



Theconibiniition of laro;e size and short tail, notched palate and small 

 andital Imllje, while distinctly separating the sj)ecies from all others south 

 of its range in America, brings it in closer relationship with E. rutlhis. 

 From rulilu», however, it differs in longer, slenderer, less hairy tail, 

 slenderer feet, duller color, with less rufous on ears, and the following 

 important cranial characters: skull less massive; rostrum longer and 

 slenderer; audihU buli;e smaller; pterj'goids more prominent; nasals 

 sharp tipped or I'ounded posteriorly instead of truncate ; molar series 

 much narrower and slenderer. In external characters it slightly resem- 

 bles E. rufccanus* of northern Europe, but differs widely from that 

 species in cranial characters. 



Specimens examined. — Total number 38, from 5 localities. 

 NortJnvesi Territory: Finlayson Kiver, 1, the type. 

 British Colnmbia: Fort Liard, 2. 

 Alaska: Yakutat, 29; Juneau, 3; Prince William Sound, 3. 



Evotomys gapperi (Vigors). 



Arricola gapperi Vigors, Zool. Jour., vol. V, p. 204, pi. ix, 1S30. 

 Erolami/s fuscodorsalis Allen, Bull. Am. Mus. Nat. Hist., vol. VI, p. 103, 

 1894. 



Type locality. — Vicinity of Lake Simcoe, Ontario, Canada. 



Geographic distribution. — From Massachusetts, New Jerse}^ and Penn- 

 sylvania northward and from the Atlantic coast westward to the Rocky 

 Mountains in Canada. 



General clairacters. — SnniW, slender, and bright colored, with slender feet 

 and a medium length tail. Of the American species it most nearly resem- 

 bles E. glareolus of Europe.f 



Color. — Winter pelage : dorsal stripe from just back of eyes to base of 

 tail, bright chestnut, with numerous black hairs and a slight frosted tinge 

 from subterminal white portion of j)art of the rufous-ti})ped hairs ; sides 

 bright buify-ochraceous ; belly washed with i)ale l)utf; feet silvery gray; 

 tail bicolor, grayish butt to the tij) below, brownish above, with upper 

 part of pencil black. In high pelage a rufous stripe extends through e}'e 



*Erotomys riifocanus (Sundevall) of northern Europe is remarkable for 

 its large molars and almost microtine form of skull. It is the most 

 divergent form of the genus known, with dorsal stripe yellowish rufous; 

 sides, face, and rump clear gray ; tail short ; hind feet large. 



Measurenieni of a dry skin from Lapland (No. f|ff, (J^, Merriam collec- 

 tion) : total length, 138; tail vertebne, 33; hind foot, '20. Skull: basal 

 length, 25; nasals, 7.6; zygomatic breadth, b5 ; mastoid breadth, 12.2; 

 alveolar length of ui^per molar series, ().7. 



f Erotom>/s ga]>j>eri differs from E. glarerdus of Oxfordshire, England, in 

 better defined dorsal stripe and less extensive rufous on ears and face, 

 slightly lighter coloration, and relatively shorter tail. I fail to discover 

 tangible cranial differences. 



