E
Sage_, 4; 6 mi. N, 2 mi. E Sage, 2.

Microtus pennsylvanicus insperatus (Allen)

_Arvicola insperatus_ Allen, Bull. Amer. Mus. Nat. Hist.,
6:347, December 7, 1894.

_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

========================+======+========+=======+=======+=========+=======
| | | | | |
|No. of| | Length| Length| Condylo-| Zygo-
Locality |adults| Total | of | of | basilar | matic
(or area) | ave- | length | tail | hind | length, |breadth
|raged | | | feet | skull |
| | | | | |
------------------------+------+--------+-------+-------+---------+-------
|
| _M. p. insperatus_, Wyoming
|
Crook and Campbell Cos. | 12 | 166.5 | 41.4 | 20.7 | 25.85 | 14.80
Sheridan County | 20 | 169.5 | 46.7 | 21.2 | 26.20 | 15.25
Johnson County | 20 | 167.8 | 47.9 | 20.7 | 25.67 | 15.29
Weston County, mean | 15 | 161.0 | 39.8 | 20.7 | 25.55 | 14.91
" Co., stand. dev. | ... | 11.3 | 3.0 | 0.6 | .82 | .43
" Co., minim