E. Raymond Hall

“ Remarks.—Northwardly in the Bitterroot Valley, specimens of M. m. pratincolus morphologically approach M. m. nanus, especially in the reduced degree of inflation of the tympanic portion of the bullae. On geographic grounds we think that the geographic range of M. m. pratincolus extends southward to the southern end of the Bitterroot Valley; we have not seen specimens from that area. Although we have not examined the specimen reported upon by Davis (Murrelet, 18:26, September 4, 1937) from Canyon Creek, "a few miles west of Hamilton", Montana, we think that it will be found to belong to M. m. ”

“ The four specimens from Wapinitia seem to be those that Bailey (N. Amer. Fauna, 17:29, June 6, 1900) listed as Microtus montanus. [Pg 78] The diagnostic characters mentioned by Miller in the original description (Proc. Biol. Soc. Washington, 11:67, April 21, 1897) included the following: size approximately the same as in Microtus [montanus] nanus; upper parts yellowish; tail usually nearly uniform grayish above and below; auditory bullae much inflated; lateral pits at posterior edge of bony palate unusually shallow. ”

“ Our examination of specimens from localities in Montana east of the range here ascribed to M. m. pratincolus indicates that, among named kinds of Microtus, those specimens are best referred to M. m. nanus. These specimens are listed below under comparative materials. It should be mentioned here that although Bailey (loc. cit.) applied the name Microtus nanus canescens to Montanan specimens from Flathead Lake and Hot Springs Creek, the subspecies M. montanus canescens now is thought to be restricted to Washington and the adjoining part of British Columbia; M. m. ”