72 
JOUKNAL OF MAMMALOGY 
west of the Missouri River, about 10 miles south of Williston, I caught 
a specimen which I could not identify. Other specimens in the Biolog- 
ical Survey collection taken at Sentinel Butte, Glen Ullin, Oakdale, 
Fort Clark, Mandan, Bismarck, and Cannon Ball, in North Dakota; 
and at Glendive, Wibaux, Ekalaka, Capitol, Elgin, Johnson Lake, near 
Highwood Mountains, Billings, and Fort Custer in Montana, prove 
to be of this form. The large series and broad range represented 
enables me to select a type from a central locality where the charac- 
ters are comparatively uniform. The subspecies may be known by 
the following description: 
Microtus pennsylvanicus wahema^ subsp. nov. 
BEAN MOUSE 
Hetunka of the Dakota Indians (Drs. Beede and Gilmore). 
Ty'pe, from Glendive, Montana. No. 212370, U. S. National Museum, Bio- 
logical Survey collection, adult male. Collected by Remington Kellogg, May 
8, 1916. Collector’s No. 425. 
General characters. — In size slightly smaller than Microtus 'pennsylvanicus or 
M. p. modestus and with relatively narrower skull. Conspicuously larger than 
M. p. drummondi and with relatively heavy skull compared with the very delicate, 
slender skull of that species. Paler than any other member of the group except 
M. hreweri of Muskeget Island, which it closely resembles in the general ashy 
gray tone. 
Color. — In short, fresh, summer pelage, back buffy gray; sides clear gray or 
slightly tinged with buff; under parts, feet, and lower surface of tail light gray 
or buffy white; upper surface of tail dusky gray. Winter pelage long and soft 
with buffy gray tips to the hairs of upperparts; underparts white or slightly 
creamy; tail sharply bicolor. In faded winter pelage, color ashy gray with little 
trace of buffy tinge. Young buffy gray, but little darker than adults, except the 
tails and feet which are more plumbeous. 
Cranial characters. — Skull noticeably narrower and slenderer than in pennsyl- 
vanicus and modestus, but almost as long and quite as heavy in structure. Both 
the braincase and the zygomatic arches are noticeably compressed to give the 
skull its narrow appearance. 
Measurements of type specimen. — Total length, 178 mm., tail vertebrae, 43; 
hind foot, 20. Skull: basal length, 27; nasals, 7.6; zygomatic breadth, 15.4; 
mastoid breadth, 13 ; alveolar length of upper molar series, 6.8. 
* Omaha name meaning “to bury,” given on the authority of Dr. Melvin R. 
Gilmore. Intshunga wahema “the burying mouse,” from this habit of storing 
food. 
