78 MAMMALS OF UTAH 



BIG-FOOTED VOLE 



MICROTUS RICHARDSONI MACROPUS (Merriam) 



Arvicola macropus Merriam, N. A. F. No. 5, 59-60, 1891. 



Description — Summer pelage : Upper parts dark sepia, 

 lined with long, black hairs; slightly paler on sides; belly 

 washed with silvery white; feet dusky gray, tail distinctly 

 bicolor throughout its length, sooty above, whitish below. 

 Winter pelage (imperfect in October and May specimens.) 

 Lighter, clearer gray above, black hairs less conspicuous, 

 more heavily washed with white below. Young : Like adult 

 or slightly darker, with long, woolly fur and dusky feet and 

 tail; during one stage of pelage with entirely dusky belly. 

 (Bailey.) 



Distribution — Boreal zone of the Rocky mountains from 

 the Wasatch north to Canada, and most of the intermediate 

 ranges. Specimens have been taken from Park City. 



PIGMY VOLE 



MICROTUS PAUPERRIMUS (Cooper) 



Arvicola pauperrima Cooper, Am. Nat. II, 535-536, Dec. 1868. 



Description — Summer pelage: Upper parts uniform 

 buf f y gray, slightly darkened with dusky-tipped hairs ; ears 

 and nose strongly tinged with buff; belly pale buffy; tail 

 darkened above by a dusky line, buffy below ; feet like belly. 

 Young: Less buffy and slightly more dusky than adult. 

 (Bailey.) 



Distribution — Eastern Washington and Oregon, central 

 Idaho, and the north slope of the Uinta mountains, Utah, in 

 Transition zone. All of the specimens thus far taken in Utah 

 are from the Uinta mountains. 



ROCKY MOUNTAIN MUSKRAT 



FIBER ZIBETHICUS OSOYOOSENSIS (Lord) 



Fiber osoyoosensis Lord, Proc. Zool. Soc. London, 1863 I, 97, 



1863. 

 Fiber zibethicus osoyoosensis Hollister, Proc. Biol. Soc. Wash. 



XXIII, I, 1910. 



Description — Fresh pelage: Upper parts varying from 

 uniform glossy mummy brown to black ; slightly darker than 



