_Specimens examined._--Total number, 59, as follows: ALBERTA: Foremost, 2 (UADZ). Manyberries, 1 (Alberta Dept. Pub. Health). Medicine Hat, 1 (Alberta Dept. Pub. Health). MONTANA: _Carter County_: Little Missouri River, 8 mi. NE Albion, 1 (USBS). _Custer County_: Calf Creek, 2 (AMNH); 13 mi. E Miles City, 1 (MZ). _Garfield County_: Piney Buttes, 1 (USBS). _Powder River County_: Powderville, 2 (USBS). _Yellowstone County_: Lake Basin, 1 (USBS). _County undesignated_: Wolf's Creek, 1 (AMNH). NEBRASKA: _Cherry County_: 10 mi. E Gordon, 1 (CNHM); 12 mi. ESE Gordon, 2 (CNHM). _Dawes County_: Chadron State Park, 1 (NGFPC); 1 mi. SW Chadron, 1 (NSM); Little Bordeaux Creek, 3 mi. E Chadron, 1 (MVZ); 10 mi. S Chadron, 3 (MZ); 3 mi. SW Crawford, 1 (KU). _Sheridan County_: Mirage Township, 1 (MZ). _Sioux County_: Glen, 1 (NSM); Monroe Canyon, 1 (NGFPC). SOUTH DAKOTA: _Custer County_: Cheyenne River, 1 (AMNH); Elk Mountain, 4800 ft., 4 (USBS). _Meade County_: Smithville, 1 (USBS). _Shannon County_: Corral Draw, 3 (AMNH); Pine Ridge, 3 (CNHM 1, USBS 2). _Washabaugh County_: White River flood plain, 7 mi. S Kadoka, 1 (MZ). WYOMING: _Campbell County_: 1-1/4 mi. N, 1/2 mi. E Rockypoint, 3850 ft., 1 (KU). _Carbon County_: Ft. Steele, 1 (USBS). _Fremont County_: 40 mi. E Dubois, 1 (MZ). _Hot Springs County_: Kirby Creek, 5000 ft., 1 (USBS). _Johnson County_: 6-1/2 mi. W, 2 mi. S Buffalo, 5620 ft., 4 (KU); 1 mi. WSW Kaycee, 4700 ft., 1 (KU). _Natrona County_: Casper, 1 (USBS); 1 mi. NE Casper, 5150 ft., 1 (KU). _Platte County_: 2-1/2 mi. S Chugwater, 1 (KU). _Sheridan County_: Arvada, 2 (USBS); 5 mi. NE Clearmont, 3900 ft., 1 (KU). _Weston County_: Newcastle, 1 (USBS); 23 mi. SW Newcastle, 4500 ft., 4 (KU). =Perognathus fasciatus infraluteus= Thomas _Perognathus infraluteus_ Thomas, Ann. Mag. Nat. Hist., ser. 6, 11:406, May, 1893, type from Loveland, Larimer County, Colorado. _Perognathus fasciatus infraluteus_, Osgood, N. Amer. Fauna, 18:19, September 20, 1900. _Geographic distribution._--Known only from the type locality and from 7 mi. N Ramah, Colorado. Probably in other parts of northeastern Colorado (see Figure 1). _Remarks._--For comparisons with _Perognathus fasciatus olivaceogriseus_ Swenk, geographically adjacent to the north, see the preceding account of that subspecies on page 520.