Type.—Adult female, skin and skull, number 50204, University of Kansas, Museum of Natural History, obtained by J. K. Jones, Jr., original number 906, 5 miles north and 2 miles west of Parks in Dundy County, Nebraska, on August 16, 1952.

Range.—The valley of the north fork of the Republican River in eastern Colorado and southwestern Nebraska.

Diagnosis.—Entire animal and skull large; color dark for the species; zygomatic breadth large; upper molars large and upper molar tooth-row relatively long; braincase elongate; auditory meatus relatively small; bullae large; incisors relatively procumbent.

Comparisons.—From M. p. uligocola, the subspecies to the west, M. p. finitus differs in darker color. These subspecies resemble each other in large size and large molar teeth. A comparison of nine pairs of skulls by the "method of pairs" shows three features in which finitus (from at, or near, the type locality) differs from uligocola (from at, or near, the type locality); in 7 of 9 pairs finitus had a relatively more elongate braincase (Confidence Limit .60); in 9 of 9 pairs uligocola had larger auditory meatuses (C. L. .99); in 7 of 9 pairs uligocola had relatively larger bullae (C. L. .80). From M. p. pennsylvanicus (Ord) from eastern Nebraska and eastern South Dakota finitus differs in larger size; darker color; larger molar teeth and longer upper molar tooth-row. Five pairs of skulls were compared; in all 5 pairs, finitus had more procumbent incisor teeth (C. L. .97) and wider first upper molars (C. L. .97); and in 4 of 5 pairs finitus had a relatively more elongate braincase (C. L. .60). From M. p. insperatus, the subspecies to the north, finitus differs as follows: color darker, size larger, molar teeth relatively larger and alveolar length of the upper molar tooth-row greater. Five pairs of skulls were compared and in all 5 pairs finitus had more procumbent upper incisors (C. L. .97) than insperatus; in 4 of 5 pairs insperatus had a relatively more elongate braincase (C. L. .60), narrower first upper molariform tooth (C. L. .75), and shorter distance between the alveoli of the first upper molars (C. L. .88).

Specimens examined.—Total 26. Colorado: Yuma Co.: Wray, 3 (USBS); 1 mi. W Laird, 2. Nebraska: Dundy Co.: 5 mi. N, 2 mi. W Parks (Rock Creek State Fish Hatchery), 19; Haigler, 2 (USBS).

Type.—Adult male, skin and skull, number 37873, University of Kansas, Museum of Natural History, obtained by Rollin H. Baker, original number 1343, 12 miles north and 2 miles east of Sage, 6100 ft., in Lincoln County, Wyoming, on July 19, 1950.

Range.—North-central Utah, eastern Idaho, western Wyoming, and southwestern Montana. See Figures 1 and 2.

Diagnosis.—Size average; color dark, especially in southern part of range; tail relatively long; molar teeth small; nasals relatively broad; maxillary septum relatively small.

Comparisons.—From M. p. uligocola, the subspecies to the southeast, M. p. pullatus differs as follows: relatively darker in southern part of its range (see Figure 1); smaller, tail relatively longer. In 6 of 7 pairs of skulls compared of pullatus (from Lincoln Co., Wyoming) and uligocola (from Larimer Co., Colorado), pullatus had relatively broader nasals (Confidence Limit .85); uligocola had larger maxillary septa (C. L. .97) and larger molar teeth (C. L. .90). From insperatus, the subspecies to the east, pullatus differs as follows: both summer and winter pelage darker; tail longer both actually and relatively; upper molar tooth-row shorter. Ten pairs of skulls of specimens from near Afton, Wyoming, representing pullatus, and from northeastern Wyoming, representing insperatus, revealed no significant differences in the features observed by the "method of pairs". Although not compared in detail with the subspecies to the north, M. p. drummondi (Audubon and Bachman), examination of specimens from western Montana and the accounts of other authors indicate that topotypes of pullatus are darker, longer-tailed, slightly larger-skulled and perhaps longer over all.