22 
Bulletin Wisconsin Natural History Society. [Vol. 6, Nos. 1—3. 
dark slate color dorsally, much different from adult specimens, 
and were formerly mistaken for a distant species, Pennoinoyscns 
hairdii (Hoy & Kennicott). 
Evotomys gapperi (Vigors). 
Eed-backed ]Mouse. 
This is the mouse frequently found in pine regions along the 
steep banks of streams and lakes and in sphagnum bogs and marshes ; 
on a few occasions in Oneida County I have seen this species 
in hayfields, and one I saw in a deserted lumber camp. Evotomys 
gapperi is taken occasionally in southern Wisconsin along Lake 
Michigan, but in the interior of the state it is rarely seen south of 
Columbia County. The species is dichromatic, there being the 
ordinary red phase, and the brown phase. I have never seen spe- 
cimens from Wisconsin in the brown pelage ; Mr. Gerrit S. Miller 
reports such specimens from the north shore of Lake Superior (2). 
Microtus pennsylvanicus (Ord). 
Meadow Mouse ; Meadow Vole. 
This species occurs over the whole state in suitable locations. 
It is found principally in wet meadows, in hayfields and in corn- 
fields, but it sometimes inhabits open woods and marshes. In 
the autumn Microtus pennsylvanicus leaves the lower lands for the 
sides of grassy hills ; after the first snow falls it builds nests and 
makes runways on the surface of the ground beneath the snow, 
seeming to prefer the deeper snow and drifts for this purpose. 
When the snow melts in the spring, the majority of the animals 
again migrate to the lower lands, where they dwell during the 
summer months. 
Meadow voles are quite diurnal in habits and may be seen 
frequently scampering through their runways at mid-day ; more 
especially is this noticeable in the early spring. 
I have known the species to become a pest in a house, but 
such cases are rare. 
