County_:
Dawson, 1 (USBS); 6 mi. W Steele, 6 (MZ). _McHenry County_: 1/2 mi.
E Upham, 1 (USBS). _Morton County_: 12 mi. W Mandan, 2 (MZ).
_Oliver County_: Ft. Clark, 8 (USBS). _Sargent County_: 7-2/10 mi.
E, 1-2/10 mi. S Oakes, 1200 ft., 1 (KU). _Sioux County_: Cannon
Ball, 6 (USBS). _Stark County_: 1 mi. S Dickinson, 1 (MZ); 9 mi. W
Dickinson, 3 (MZ); 2 mi. W Taylor, 4 (MZ). _Stutsman County_: 7 mi.
N Jamestown, 1 (MZ); 14 mi. W Jamestown, 1 (MZ). _Wells County_:
Bowdon, 1 (USBS). _Williams County_: Buford, 9 (USBS). SOUTH
DAKOTA: _Todd County_: Minichaduza River, 2 (USBS); Rosebud Agency,
1 (USBS). _Tripp County_: Colome, 3 (MZ). _Walworth County_: Swan
Creek, 13 mi. S Shelby, 1600 ft., 1 (KU).

=Perognathus fasciatus olivaceogriseus= Swenk

_Perognathus flavescens olivaceogriseus_ Swenk, Missouri Valley
Fauna, 3:6, June 5, 1940, type from [Little Bordeaux Creek,
sec. 14, T. 33 N, R. 48 W, 3 mi. E] Chadron, Dawes County,
Nebraska.

_Geographic distribution._--Southeastern Alberta, southeast to
eastern Wyoming and adjacent parts of South Dakota and Nebraska.

_Diagnosis._--External measurements of the holotype and average and
extreme external measurements of six adults (five males and one
female) from several localities in eastern Wyoming are,
respectively, as follows: Total length, 124, 132 (125-140); length
of tail-vertebrae, 53, 63 (59-68); length of hind foot, 16.5, 17
(17-18); length of ear, 6.5, 6.6 (6.0-7.0). Color: Upper parts
Cream Buff, lined with black and giving a pale olivaceous
appearance; lateral line near (16'd) Light Ochraceous-Buff;
postauricular patches Cream Buff; subauricular patches and
underparts white; tail indistinctly bicolor, dusky above, whitish
below. Skull: Size medium for species (see Table 1); braincase and
auditory bullae moderately inflated; interorbital region narrow;
mastoidal region broad.

_Remarks._--From topotypes of _Perognathus fasciatus fasciatus_,
geographically adjacent to the northeast, _P. f. olivaceogriseus_
differs in: Upper parts paler, especially face which is heavily washed
with buff; hind foot smaller; skull averaging slightly smaller in all
measurements taken (especially least interorbital breadth and cranial
depth), except mastoidal breadth which is slightly more and
interparietal breadth, length o