208 Firetp Museum oF NaturaL History — Zoéroey, Vor. XI. 
Subfamily MICROTIN~. 
A subfamily confined to the northern portions of the old and new 
worlds. The crowns of molars show irregular enamel loops or triangles. 
Genus EVOTOMYS Coues. 
Evotomys Coues, Proc. Acad. Nat. Sci. Phila., 1874, p. 186. Type 
Mus rutilus Pallas. 
Skull narrow and slender; front teeth (incisors) without grooves; 
molars with pronged roots; crowns of molars with irregular triangles; 
tail comparatively short; middle of back (normally) reddish brown, in 
decided contrast to the color of the sides of body; mamme 8. 
2—*, M. 3-3=16 
o-0 o-o 3-3 
Dental formula: 
Evotomys gapperi (Vicors). 
RED-BACKED MovusE. RED-BACKED VOLE. 
Arvicola gappert Vicors, Zool. Jour., V, 1830, p. 204. Kennicott, Agr. Rept. 
for 1857, U.S. Patent Office Rept., 1858, p. 88 (Wisconsin, Minnesota). STRONG, 
Geol. Wis., Surv. 1873-79, I, 1883, p. 439 (Wisconsin). 
Hypudeus rutilus var. gapperi HERRIcK, Geol. & Nat. Hist. Surv. Minn., Bull. 
No. 7, 1892, p. 194 (Minnesota). 
Evotomys gapperit BaiLey, Proc. Biol. Soc. Wash., XI, 1897, p. 122 (Minnesota, 
Ontario, etc.). SNYDER, Bull. Wis. Nat. Hist. Soc., II, 1902, p. 116 (Dodge Co., 
Wisconsin). Jackson, Bull. Wis. Nat. Hist. Soc., VI, 1908, p. 22 (Wisconsin) , 
Type locality — Vicinity of Lake Simcoe, Ontario. 
Distribution — The Atlantic states from Pennsylvania northward and 
west along the northern border of the United States to Minnesota 
and in Canada to the Rocky Mountains. 
Special characters — A broad rufous chestnut stripe on middle of back 
extending from the crown to the rump; sides of body grayish buff, 
sometimes with a slight olive tinge but always strikingly different 
from the color of the back; tail comparatively short. 
Description — Normal phase: A broad stripe of rufous chestnut frei 
the back of the head extends down middle of the back to the rump; 
sides of body and fore part of head and face grayish buff, sometimes 
faintly tinged with olive; a dusky mark at base of the whiskers; 
under parts ashy or whitish, often faintly tinged with buff; the bases 
