122 Bailey T lie American Voles of the Genus EvotomyB. 



The combination of large size and short tail, notched palate and small 

 andital bulhe, while distinctly separating the species from all others south 

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

 From rutilus, 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; audital bullie smaller; pterygoids more prominent; nasals 

 sharp tipped or rounded posteriorly instead of truncate; molar series 

 much narrower and slenderer. In external characters it slightly resem 

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

 species in cranial characters. 

 Specimens examined. Total number 38, from 5 localities. 



Northwest Territory : Finlayson River, 1, the type. 



British Columbia : Fort Liard, 2. 



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



Evotomys gapperi (Vigors). 



Arvicola gapperi Vigors, Zool. Jour., vol. V, p. 204, pi. ix, 1830. 

 Evotomys 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 Jersey, and Penn 

 sylvania northward and from the Atlantic coast westward to the Rocky 

 Mountains in Canada. 



General characters. Small, 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 part of the rufous-tipped hairs ; sides 

 bright buffy-ochraceous ; belly washed with pale buff; feet silvery gray; 

 tail bicolor, grayish buff to the tip below, brownish above, with upper 

 part of pencil black. In high pelage a rufous stripe extends through eye 



*Evotomys rufocanus (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. 



Measurement of a dry skin from Lapland (No. fff-f, <3\ Merriam collec 

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

 length, 25; nasals, 7.6; zygomatic breadth, 15; mastoid breadth, 12.2; 

 alveolar length of upper molar series, 6.7. 



| Evotomys gapperi differs from E. glareolus of Oxfordshire, England, in 

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

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

 tangible cranial differences. 



