Microtus pennsylvanicus insperatus, Anderson, Canadian Field-Nat., 57:92, October 17, 1943.

Microtus pennsylvanicus wahema Bailey, Jour. Mamm., 1:72, March 2, 1920.

Type.—Adult male, skin and skull, number 8105/6731 American Museum of Natural History, obtained by W. W. Granger, at Custer, Black Hills, South Dakota, August 9, 1894.

Range.—Western South Dakota, southwestern North Dakota, eastern Montana, southern Alberta and Saskatchewan, eastern Montana, and northeastern Wyoming.

Comparisons.—Microtus pennsylvanicus insperatus is paler than any adjacent subspecies. It has been compared with pullatus in the preceding account. Bailey's studies of M. p. wahema [=insperatus] and his comparisons with M. p. pennsylvanicus and M. p. drummondi to the east and north, in North Dakota (1920, 1927), are the basis for the northern and eastern boundaries of the range of insperatus in Figure 1. Comparison of insperatus with finitus to the south is made in the account of the latter.

Table 1. Average Measurements (in Millimeters) of Adult
Microtus pennsylvanicus

Locality
(or area)		No. of
adults
averaged		Total
length		Length
of
tail		Length
of
hind feet		Condylobasilar
length,
kull		Zygomatic
breadth
M. p. insperatus, Wyoming
Crook and Campbell Cos.12166.541.420.725.8514.80
Sheridan County20169.546.721.226.2015.25
Johnson County20167.847.920.725.6715.29
Weston County, mean15161.039.820.725.5514.91
" Co., stand. dev. ...11.33.00.6.82.43
" Co., minimum...150.35.20.24.214.2
" Co., maximum...168.45.22.26.815.6
M. p. pullatus, Wyoming
Park County10164.844.520.325.9615.92
Teton County20161.943.619.825.5914.68
Sage, Lincoln Co.6165.047.221.225.8714.93
Afton, " " , mean14163.348.820.825.5914.70
" , stand. dev....7.410.41.41.00.61
" , minimum...142.39.19.24.513.8
" , maximum...181.57.23.27.515.9
M. p. uligocola, Colorado
Park Co. (Denv)7.........26.0015.40
Boulder Co. (Chi)30171.243.022.226.5315.28
Denver8156.940.021.326.7715.31
Colorado Springs16158.441.421.126.4015.43
Loveland, mean16166.046.621.526.5415.60
" , stand. dev....15.95.90.81.421.23
" , minimum...142.38.20.24.613.9
" , maximum...192.56.23.29.417.8
M. p. finitus
Wray, Colorado3169.039.322.327.3016.20
Dundy Co., Nebr., mean12165.842.621.827.6516.10
" , stand. dev....16.55.20.72.57.92
" , minimum...147.36.21.25.014.7
" , maximum...202.55.23.29.717.6
M. p. modestus, Colorado
Alamosa, Colorado3160.746.322.025.5715.00
Cochetopa Pass, Colo.25[1]172.744.721.226.4215.43
" , stand. dev....8.83.10.8.69.52
" , minimum...160.38.20.25.214.6
" , maximum...191.51.23.28.516.8

[ ]

[ 1 ] 29 specimens were used in taking measurements of the skull.

Locality
(or area)		No. of
adults
averaged		Lambdoidal
breadth		Prelambdoidal
breadth		Molar
length
(alveolar)		Interorbital
breadth		Depth
of the
braincase
M. p. insperatus, Wyoming
Crook and Campbell Cos.1211.709.056.903.527.92
Sheridan County2012.209.336.903.557.95
Johnson County2012.049.027.143.527.84
Weston Co., mean1512.039.256.843.608.02
" " stand. dev.....40.37.16.13.23
" " minimum...11.48.76.63.47.7
" " maximum...12.79.97.23.88.5
M. p. pullatus, Wyoming
Park County1012.349.526.723.508.30
Teton County2011.588.986.773.547.66
Sage, Lincoln Co.611.879.086.773.587.88
Afton, " " mean1411.749.066.533.557.90
" , stand. dev.....50.15.23.12.43
" , minimum...11.08.96.13.27.1
" , maximum...12.59.47.03.68.2
M. p. uligocola, Colorado
Park Co. (Denv)712.209.407.073.607.91
Boulder Co. (Chi)3012.149.247.073.367.85
Denver812.239.357.273.557.99
Colorado Springs1612.189.227.203.437.89
Loveland, mean1612.319.467.143.598.14
" , stand. dev.....65.41.32.16.42
" , minimum...11.49.06.83.37.5
" , maximum...13.810.67.63.89.4
M. p. finitus
Wray, Colorado312.309.437.403.538.23
Dundy Co., Nebr., mean1212.649.397.523.668.22
" " , stand. dev.....61.40.31.26.43
" " , minimum...11.68.57.03.27.6
" " , maximum...13.59.87.93.98.7
M. p. modestus, Colorado
Alamosa, Colorado311.979.276.833.608.01
Cochetopa Pass, Colo.25[1]12.169.046.813.548.18
" , stand. dev.....37.31.21.14.23
" , minimum...11.48.66.53.37.7
" , maximum...13.110.07.53.98.8