1891. _Arvicola_ (_Mynomes_) _mordax_ Merriam, N. Amer. Fauna,
5:61, July 30, type from Sawtooth (= Alturas) Lake, 7200 ft., east
base of Sawtooth Mountains, Blaine County, Idaho.
1938. _Microtus longicaudus mordax_, Goldman, Jour. Mamm., 19:491,
November 14.
Dalquest (Univ. Kansas Publ., Mus. Nat. Hist., 2:353, April 9, 1948)
assigned all the meadow mice of the species _Microtus longicaudus_ from
approximately the eastern half of Washington State to _Microtus
longicaudus halli_ Hayman and Holt and, in doing so, excluded the
subspecies _Microtus longicaudus mordax_ from that state. This
assignment of specimens in Washington had the effect of separating the
geographic range of _M. l. mordax_ into two parts. One part was in
south-central British Columbia and the other part was mainly in the
Rocky Mountain region of the United States. Hall and Kelson examined
specimens in the Biological Surveys collection in the U. S. National
Museum in an attempt to determine more precisely the ranges of the
subspecies in southern Canada, Washington, and Idaho.
_Microtus longicaudus angustus_ [= _M. l. halli_] was described by one
of us (Hall, Univ. California Publ. Zool., 37:13, April 10, 1931) as
differing from _mordax_ in narrower braincase, higher skull near the
anterior end of the frontals, darker coloration, and seemingly smaller
size. After examining the material in the U. S. National Museum no
reason is seen at the present time to amend this characterization,
except to add that some specimens of _M. l. mordax_ are as dark as
seasonably comparable specimens of _M. l. halli_.
Examination of specimens of _Microtus longicaudus_ from Washington east
of the Cascade Range (those from the Blue Mountain area excepted)
discloses that the skulls do not differ essentially from those of
topotypes of _M. l. mordax_, but do differ, as outlined above, from
near-topotypes of _M. l. halli_. There is considerable variation in
color among the Washington-taken specimens of _Microtus longicaudus_.
Animals from the eastern flanks of the Cascades average darker than
those taken, north of the Snake River, still farther east in
Washington. Possibly Dalquest (_op. cit._) relied mainly upon this
darker color in assigning the specimens from eastern Washington to _M.
l. halli_. Relying principally upon cranial characters, we conclude
that most of the specimens are better referred to _M. l. mordax_ and
that _M. l. halli_ is restricted, in Washington, to the Blue Mountains.
_Specimens examined of Microtus longicaudus mordax._--Total, 74,
all in the Biological Surveys Collection, distributed as follows:
Washington: _Okanogan_ _County_: mouth of Holmar Creek, W Fork
Paysaten River, 4700 ft., 1; Conconully, 3; Twisp, 1; Omak Lake,
1200 ft., 3. _Stevens County_: 5 mi. N Colville, 1. _Pend Oreille
County_: 9 mi. N Metalina, 2600 ft., 1; Sullivan Lake, 3000 ft., 3.
_Chelan County_: Sethekin, 1079 ft., 3; head of Lake Chelan, 900
ft., 12; Hart Lake, Railroad Creek, 3900 ft., 1; Entiat, 20 mi from
mouth of Entiat River, 1680 ft., 13; Wenatchee, 4. _Douglas
County_: Waterville, 1. _Jefferson County_: Cleveland, 2. _Kittitas
County_: 2 mi. S Blewett Pass, 3000 ft., 6: Ellensburg, 1500 ft.,
4. _Whitman County_: Colfax, 2. _Yakima County_: McAllister
Meadows, Tieton River, 3000 ft., 3; Gotchen Cr., 5500 ft., near
Sava Spring, Mt. Adams, 2. _Klickitat County_: 8 mi. S Glenwood,
base Mt. Adams, 2. _Asotin County_: Anatone, 3300 ft., 4; Bly, 1000
ft., 2.