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Title: Geographic Variation in Red-backed Mice (Genus Clethrionomys) of the Southern Rocky Mountain Region
Author: Cockrum, E. Lendell, 1920-2009, Fitch, Kenneth L.
Language: English
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Copyright Status: Not copyrighted in the United States. If you live elsewhere check the laws of your country before downloading this ebook. See comments about copyright issues at end of book.

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                      Geographic Variation
              in Red-backed Mice (Genus Clethrionomys)
               of the Southern Rocky Mountain Region

                                 BY

              E. LENDELL COCKRUM and KENNETH L. FITCH


                University of Kansas Publications
                      Museum of Natural History

          Volume 5, No. 22, pp. 281-292, 1 figure in text
                         November 15, 1952

                        UNIVERSITY OF KANSAS
                              LAWRENCE
                                1952



  ~University of Kansas Publications, Museum of Natural History~

      Editors: E. Raymond Hall, Chairman, A. Byron Leonard,
               Edward H. Taylor, Robert W. Wilson

          Volume 5, No. 22, pp. 281-292, 1 figure in text
                         November 15, 1952

                      ~University of Kansas~
                        Lawrence, Kansas

                             PRINTED BY
                   FERD VOILAND, JR., STATE PRINTER
                           TOPEKA, KANSAS
                                1952
                     [Illustration: Union Label]
                              24-4369



                        Geographic Variation
              in Red-backed Mice (Genus Clethrionomys)
               of the Southern Rocky Mountain Region

                                 BY

               E. LENDELL COCKRUM and KENNETH L. FITCH


In the course of the preparation of a synopsis of the North American
terrestrial microtines by one of us (Cockrum), and the completion of a
Master's thesis on the geographical variation of the red-backed mice
of Wyoming by the other (Fitch) we had occasion to study the
red-backed mice of the southern Rocky Mountain region (see figure 1).
Results of these studies are the recognition of two heretofore unnamed
subspecies of the red-backed mouse in the southern Rocky Mountain
region, and a clarification of the taxonomic status of two additional
kinds.


+Clethrionomys gapperi galei+ (Merriam)

1890. _Evotomys galei_ Merriam, N. Amer. Fauna, 4:23, October 8.

1931. _Clethrionomys gapperi galei_, Hall, Univ. California Publ.
   Zool., 37:6, April 10.

1897. _Evotomys gapperi galei_, Bailey, Proc. Biol. Soc. Washington,
   11:126, May 13.

_Type locality._--Ward, 9500 feet, Boulder County, Colorado.

_Range._--The Rocky Mountains of extreme southern Alberta, Montana,
northwestern and southern Wyoming, and north and central Colorado.


_Remarks._--_C. g. galei_, with the largest geographic range of any
of the Rocky Mountain subspecies, is also the most variable. Three
principal areas of geographic variation were found. These areas are:
The mountains of north-central Colorado and southern Wyoming (this
area includes the type locality); the Big Horn area probably northwest
into Montana (no adult specimens from Montana or Alberta examined);
and the Teton area which includes the mountains east and southeast of
Yellowstone National Park. Specimens from these areas have noticeable
differences in pelage, but no constant cranial differentiation could
be detected. Specimens from the Medicine Bow Mountains of southern
Wyoming have a more reddish dorsal stripe, and more buff and less gray
on the sides than either of the northern geographic variants. The
dorsal stripe continues farther anteriorly and is better defined
through its entire length. There are fewer differences between the two
northern geographic variants than between either one of them and the
southern variant. Specimens from the Teton Mountains, however, have
grayer sides, and the outer margin of the ear is tipped with chestnut
(little or no chestnut shows on the ears of the specimens from the Big
Horn Mountains); the dorsal stripe is less distinct (with slightly
more gray throughout) than in either of the other geographic variants
of the one subspecies.

Three specimens (two adults) are available from the Little Medicine
Range in Converse County (22 miles south and 24.5 miles west of
Douglas, 7600 feet), Wyoming. Although red-backed mice probably are
found in the mountains of Natrona and Albany counties, the population,
in the Little Medicine Range is somewhat isolated. In coloration these
mice are lighter than any of the three geographic variants described
above; the dorsal stripe is narrower; the sides are more buffy; the
dorsal stripe does not project anteriorly beyond the ears as it does
in the specimens from the Medicine Bow Mountains; and the face is
grayer. These specimens resemble the population in the Big Horn
Mountains to the north more than the population in the Medicine Bow
Mountains.

The specimens from the Little Medicine Range, the Big Horn Range, and
the Tetons are possibly subspecifically distinct from the southern
specimens. Examination of specimens now allocated to _galei_ from
Montana and Alberta should aid in revealing whether the northern
animals are an unnamed subspecies.

_Specimens examined._--Total, 167, distributed as follows and unless
otherwise stated, in the collection of the University of Kansas Museum
of Natural History:

+Wyoming+: _Park County_: 28 mi. N and 3 mi. W Cody, 7200 ft., 1. _Big
Horn County_: Medicine Wheel Ranch, 28 mi. E Lovell, 9000 ft., 22;
17-1/2 mi. E and 4-1/2 mi. S Shell, 1. _Teton County_: Moran, 6244
ft., 4; Moran, 3 (James Findley Collection); 2-3/4 mi. E Moran, 6300
ft., 1; 3-3/4 mi. E and 1 mi. S Moran, 6200 ft., 10. _Washakie
County_: 9 mi. E and 9 mi. N Tensleep, 8200 ft., 3; 9 mi. E and 4 mi.
N Tensleep, 7000 ft., 1. _Johnson County_: 4 mi. W and 1 mi. S
Klondike, 6500 ft., 1; 6-1/2 mi. W and 2 mi. S Buffalo, 5620 ft., 1.
_Lincoln County_: 3 mi. N and 11 mi. E Alpine, 5650 ft., 1. _Sublette
County_: 31 mi. N Pinedale, 8025 ft., 1. _Fremont County_: Togwotee
Pass, 5 (James Findley Collection); 20-1/2 mi. W and 2 mi. S Lander,
1; Mocassin [=Moccasin] Lake, 19 mi. W and 4 mi. N Lander, 10,100 ft.,
3; 18 mi. W and 3 mi. N Lander, 1; Mosquito Park Ranger Station,
17-1/2 mi. W and 2-1/2 mi. N Lander, 9500 ft., 10; 6-1/2 mi. W and 17
mi. S Lander, 8450 ft., 4; 5-1/2 mi. W and 22 mi. S Lander, 8800 ft.,
3. _Converse County_: 22 mi. S and 24-1/2 mi. W Douglas, 7600 ft., 3.
_Carbon County_: 18 mi. SW Rawlins, 7500 ft., 2; 19 mi. E and 8 mi. N
Encampment, 9150 ft., 4; 19-1/2 mi. E and 6 mi. N Savery, 8800 ft., 1;
11 mi. E and 6 mi. N Savery, 8400 ft., 1; 14 mi. E and 6 mi. N Savery,
1. _Albany County_: 3 mi. ESE Browns Peak, 10,000 ft., 59.

+Colorado+: _Rio Blanco County_: 9-1/2 mi. SW Pagoda Peak, 7700 ft.,
2. _Boulder County_: 2-1/2 mi. S Estes Park, 8400 ft., 2; 3 mi. S
Ward, 8. _Clear Creek County_: 2 mi. S Idaho Springs, 8000 ft., 1.
_Gunnison County_: Gothic, 8 mi. N Crested Butte, 6 (James Findley
Collection).

_Additional records._--+Colorado+: _Rio Blanco Co._: 25 mi. NE Meeker
(Cary, N. Amer. Fauna, 33:120, 1911). _El Paso Co._: Lake Moraine,
10,250 ft. (Warren, Mammals of Colorado, p. 224, 1942).


[Illustration: Map Geographic Range Clethrionomys gapperi]

~Fig. 1.~--Geographic ranges of the subspecies of
     _Clethrionomys gapperi_ in the southern Rocky Mountains.

[Map Numbers For shaded areas.]
1. _C. g. galei_        3. _C. g. uintaensis_  5. _C. g. limitis_
2. _C. g. brevicaudus_  4. _C. g. gauti_       6. _C. g. arizonensis_


+Clethrionomys gapperi brevicaudus+ (Merriam)

1891. _Evotomys gapperi brevicaudus_ Merriam, N. Amer. Fauna, 5:119,
   July 30.

1897. _Evotomys brevicaudus_, Bailey, Proc. Biol. Soc. Washington,
   11:129, May 13.

1942. _Clethrionomys gapperi brevicaudus_, Bole and Moulthrop, Sci.
   Publ. Cleveland Mus. Nat. Hist., 5:153, September 11.

_Type locality._--Three miles N Custer, 6000 ft., South Dakota.

_Range._--The Black Hills of South Dakota and Wyoming.


_Remarks._--Merriam (N. Amer. Fauna, 5:119, July 30, 1891) named this
subspecies on the basis of two specimens collected in the Black Hills
of South Dakota in July, 1888, and assigned it to the species
_Evotomys_ [= _Clethrionomys_] _gapperi_. He reported the diagnostic
characteristics as: "Similar to _E. gapperi_, but with larger ears and
shorter tail. The hazel of the dorsal area is not so bright as in
_gapperi_; the sides are the same golden brown." Of the cranial and
dental characteristics he wrote: "Much as in _E. gapperi_."

Bailey (Proc. Biol. Soc. Washington, 11:129, May 13, 1897), in his
"Revision of the American voles of the genus _Evotomys_," with one
additional specimen available, raised the Black Hills population to
specific status, re-emphasizing the shortness of the tail, and
pointing out a few slight cranial differences ("zygomatic arches low
and flaring out, so that the inner instead of the outer side shows in
top view; auditory bullae as large as in _gapperi_, but less
rounded").

Bailey (_loc. cit._) remarked that: "though based on so scanty
material, the characters distinguishing the species are fairly
pronounced. Its range is isolated and widely separated from that of
any other members of the genus by open prairie country and a wide belt
of the Transition zone. There seems to be no valid reason for
considering it a subspecies."

Additional specimens have been taken in recent years from the Black
Hills of South Dakota and northeastern Wyoming. This material has shed
light on the relationships and morphological characteristics of the
red-backed mice of this region. Bole and Moulthrop (Sci. Publ.
Cleveland Mus. Nat. Hist., 5:153, September 11, 1942) listed, as
comparative material, eight specimens from Bull Springs, Custer
County, South Dakota, under the name _Clethrionomys gapperi
brevicaudus_ (Merriam). They gave no reason for arranging
_brevicaudus_ as a subspecies of _C. gapperi_.

Twenty adults (11 skins and skulls, 9 skulls only) from Pennington
County, South Dakota (specimens in the University of Michigan
Museum of Zoology), have the following measurements (averages of
external measurements based on 11 specimens only): Total length, 142
(123-155); tail, 35 (30-39); hind foot, 19.5 (18.6-21.0); basal
length, 23.3 (21.7-24.5); condylobasilar length, 23.3 (21.9-24.5);
zygomatic breadth, 13.7 (12.9-14.7); lambdoidal breadth, 11.7
(11.3-12.9); alveolar length upper cheek-teeth, 5.5 (5.2-5.8);
interorbital breadth, 3.9 (3.6-4.1); length of nasals, 7.7 (7.1-8.5);
breadth of rostrum, 3.2 (2.9-3.6); and length of incisive foramina,
5.0 (4.6-5.3).

Measurements of the type and one "more fully adult topotype" (as given
by Bailey, _op. cit._) are: Total length, 125, 130; tail length, 31,
32; hind foot, 19, 19; basal length, 21.2, 21.8; length of nasals,
6.6, 7.0; zygomatic breadth, 12.5, 12.8; mastoid breadth, 11.3, 11.0;
alveolar length of upper molar series, 5.4, 5.3. In every measurement
the figures for Bailey's specimens are smaller than the average of the
same measurement in the 20 adults from Pennington County, and, in most
measurements, are even lower than the minimum of the latter series.
Therefore, we conclude that the material available to Merriam (_op.
cit._) and Bailey (_op. cit._) consisted of only subadults.

In comparison with a series of 23 adult _Clethrionomys gapperi galei_
from 28 mi. E Lovell, Big Horn County, Wyoming, _C. g. brevicaudus_
has a slightly shorter tail, longer hind foot, greater basal and
condylobasilar lengths, greater zygomatic and lambdoidal breadths and
conspicuously longer nasals.

In comparison with three adult _C. g. loringi_ from Elk River,
Sherburne County, Minnesota, _C. g. brevicaudus_ has a greater total
length, longer hind foot, greater basal length, conspicuously greater
zygomatic and lambdoidal breadths, much longer nasals, and a narrower
rostrum.

_Clethrionomys gapperi brevicaudus_, although isolated geographically
and although morphologically more distinct than many of the currently
recognized subspecies of _C. gapperi_, is probably best arranged as a
subspecies of _C. gapperi_ rather than as a full species. In certain
characters, such as interorbital breadth and breadth of rostrum, it is
intermediate between _C. g. galei_ and _C. g. loringi_, but it
resembles _C. g. galei_ more than it does any other named kind.

_Specimens examined._--Total, 66. Unless otherwise indicated,
specimens from Wyoming are in the University of Kansas Museum of
Natural History and specimens from South Dakota are in the University
of Michigan Museum of Zoology. Specimens are distributed as follows:

+Wyoming+: _Crook County_: 3 mi. NW Sundance, 5900 ft., 3. _Weston
County_: 1-1/2 mi. E Buckhorn, 6150 ft., 21; 12 mi. SE Newcastle, 1
(Univ. Michigan).

+South Dakota+: _Pennington County_: 1/2 mi. E Rochford, 1; 17 mi. NW
Custer, 1; 16 mi. NW Custer, 20; 16 mi. SW Rapid City, 1; 3 mi. SE
Hill City, 2; 4 mi. SE Hill City, 13; 5 mi. SE Hill City, Harney Peak,
7240 ft., 1. _Custer County_: 1-1/2 mi. E Sylvan Lake, 1.



+Clethrionomys gapperi uintaensis+ Doutt

1897. _Evotomys gapperi galei_, Bailey, Proc. Biol. Soc. Washington,
   11:127 (part from Uinta Mts. of Wyoming), May 13.

1941. _Clethrionomys gapperi uintaensis_ Doutt, Proc. Biol. Soc.
   Washington, 54:161, Dec. 8.

_Type locality._--Paradise Park, 10,050 feet, 45 miles by road
northwest Vernal, Uintah County, Utah.

_Range._--The Uinta Mountains of northern Utah and southwestern
Wyoming.


_Remarks._--From the description given by Doutt (Proc. Biol. Soc.
Washington, 54:161, 1941) in his original description of this
subspecies, it appears that he had available for comparisons, only
subadult specimens of _C. g. galei_. As judged from the material of
_C. g. uintaensis_ available to us (1 topotype, KU 38081, and 7
specimens from Uinta County, Wyoming, listed below) and from Doutt's
(_op. cit._) description and measurements, the subspecies _C. g.
uintaensis_ is but weakly differentiated from _C. g. galei_. No marked
cranial differences are evident between the two subspecies; the
differences in pelage noted by Doutt (_op. cit._:161), however
("Similar to _Clethrionomys gapperi galei_ from Ward, Colorado, but
head and cheeks grayer; sides and back paler; belly whiter."), do seem
to be valid.

On the basis of these differences in pelage and the geographic
isolation of the range, we judge that _uintaensis_ should be retained
as a subspecies of _C. gapperi_. It is clear, however, that _C. g.
uintaensis_ is less distinct from _C. g. galei_ than are the other
adjacent subspecies.

_Specimens examined._--Total, 8, all in the University of Kansas
Museum of Natural History, distributed as follows:

+Wyoming+: _Uinta County_: 9 mi. S Robertson, 8000-8400 ft., 3; 9 mi.
S and 2 mi. E Robertson, 8000 ft., 2; 11-1/2 mi. S and 2 mi. E
Robertson, 9200 ft., 1; 14 mi. S and 2 mi. E Robertson, 9000 ft., 1.

+Utah+: _Uintah County_: Paradise Park, 21 mi. W, 15 mi. N Vernal,
10,050 ft., 1.

_Additional, marginal records_ (Durrant, Univ. Kansas Publ., Mus. Nat.
Hist., 6:356, August 19, 1952).--+Utah+: _Rich Co._: Monte Cristo, 18
mi. W Woodruff, 8000 ft. _Salt Lake Co._: Emigration Canyon, 8 mi.
above forks, 6,000 ft.; Silver Lake Post Office (Brighton), 9,500 ft.
_Wasatch Co._: Wolf Creek Summit, 9,800 ft. _Daggett Co._: Beaver
Dams, 10,500 ft.



+Clethrionomys gapperi gauti+, new subspecies

_Type._--Male, adult, skin and skull; No. 133515, Biological Surveys
Collections, United States National Museum, from Twining, 10,700 ft.,
Taos County, New Mexico; obtained on August 7, 1904, by James H. Gaut,
original number 3086.

_Range._--The Rocky Mountains of north-central New Mexico and
south-central Colorado.

_Diagnosis._--A brightly colored _Clethrionomys gapperi_; dorsal
stripe near Chestnut (capitalized color terms after Ridgway, Color
Standards and Color Nomenclature, Washington, D. C., 1912) with an
underwash of near Light Ochraceous-Buff and a mixture of black-tipped
guard hairs giving an over-all effect of between Tawny and Russet;
braincase relatively large; zygomatic width and lambdoidal width
large; nasals long.

_Comparisons._--As compared with topotypes of _C. g. galei_, the color
is lighter, the dorsal reddish stripe slightly narrower, sides
brighter, with a wash of Light Ochraceous-Buff, grading ventrally into
a slight wash of Pale Ochraceous-Buff, instead of a silvery-white
venter characteristic of _C. g. galei_; zygomatic and lambdoidal
breadths are greater, nasals slightly shorter, auditory bullae
slightly more inflated, teeth larger, and braincase larger.

As compared with topotypes of _C. g. limitis_, _C. g. gauti_ is
darker, has a greater zygomatic breadth, longer upper tooth-row,
longer nasals, and narrower rostrum.

_Measurements._--External and cranial measurements of the type, and
the average and extreme measurements of four adult males and one adult
female from the type locality (including the type) and five miles
south of the type locality are: Total length, 144, 147 (140-152);
tail, 40, 42 (39-45); hind foot, 20, 19.3 (19-20); condylobasilar
length, 22.3, 22.9 (22.2-24.0); zygomatic breadth, 13.6, 13.7
(13.5-14.0); lambdoidal breadth, 11.9, 11.7 (11.4-12.0); alveolar
length of upper cheek-teeth, 5.1, 5.2 (5.1-5.4); interorbital breadth,
4.0, 3.9 (3.8-4.0); length of nasals, 7.0, 7.2 (7.0-7.6); breadth of
rostrum, 2.9, 3.1 (2.9-3.4); length of incisive foramina, 4.8, 5.1
(4.8-5.3).

_Remarks._--Two specimens from a locality 21 mi. W and 3 mi. N
Saguache, Saguache County, Colorado, although referred to this
subspecies on the basis of paler pelage, inflation of auditory bullae,
and heavier teeth, show characters of _C. g. galei_ in the narrowness
across the zygomata and lambdoidal crest. Four specimens from
Silverton (1 adult and 3 young adults) are referable to this
subspecies on the basis of color of pelage and cranial proportions but
are smaller than either _C. g. gauti_ or _C. g. galei_.

The specimen from Pecos Baldy, Pecos Mountain, San Miguel County, New
Mexico, referred by Bailey (N. Amer. Fauna, 52:192) to _Clethrionomys
gapperi galei_, is here referred to _C. g. gauti_ on geographical
grounds.

The name _gauti_ is proposed in honor of the collector of the type
specimen, James H. Gaut.

_Specimens examined._--Total, 14, distributed as follows and, unless
otherwise stated, in the Biological Surveys Collection:

+Colorado+: _Saguache County_: 21 mi. W and 3 mi. N Saguache, N 38°,
106° 31´, 9100 ft., 2 (Univ. Kansas Mus. Nat. Hist.). _San Juan Co._:
Silverton, 4.

+New Mexico+: _Taos County_: Twining, 10,700 ft., 3; 5 mi. S Twining,
11,400 ft., 3. _Sandoval County_: Goat Peak, Jemez Mountains, 1.
_Colfax County_: 15 mi. SW Cimarron, 9000 ft., 1 (Amer. Mus. Nat.
Hist.).

_Additional records._--+New Mexico+: _San Miguel Co._: Pecos Baldy,
Pecos Mountain, 1 (Bailey, N. Amer. Fauna, 52:192, 1932).



+Clethrionomys gapperi limitis+ (Bailey)

1913. _Evotomys limitis_ Bailey, Proc. Biol. Soc. Washington, 26:133,
   May 21.

_Type locality._--Willow Creek, a branch of the Gilita, 8500 ft.,
Mogollon Mountains, Catron County, New Mexico.

_Range._--Known from the Mogollon, San Mateo, and Magdalena mountains
of western New Mexico.


_Remarks._--Bailey (Proc. Biol. Soc. Washington, 26:133, May 21,
1913) described this animal as a species and gave as general
characteristics: "Size slightly larger than _E._ [= _Clethrionomys
gapperi_] _galei_; colors duller, grayer and less buffy; skull and
dentition heavier." He further characterized the skull as: "Larger,
heavier and conspicuously more ridged than in _galei_; bullae large
and especially deep; dentition heavy throughout." The type of _C.
limitis_, as judged from the measurements given by Bailey (_loc.
cit._), is an exceptionally old male.

Our comparison of six adult topotypes with a series of _C. g. galei_
from Wyoming (18 adults from 3 mi. SSE Browns Peak, 10,000 ft., Albany
County, in Univ. Kansas Mus. Nat. Hist.) and with three near-topotypes
of _C. g. galei_ (3 mi. S Ward, 9000 ft., Boulder County, Colorado, in
Univ. Kansas Mus. Nat. Hist.) revealed that most of the differences
noted by Bailey (_loc. cit._) are not evident when individuals of
comparable ages are examined. Some specimens of _C. g. galei_ exceed
_C. limitis_ in ridging of the skull and size of the teeth although
conspicuous ridges and large teeth are supposedly distinctive of _C.
limitis_. The bullae, although averaging larger in _C. limitis_, can
be matched in size by those of specimens of _C. g. galei_ from
Wyoming.

The differences evident between _C. limitis_ and _C. g. galei_ are of
the kind and degree that serve to separate subspecies in the species
_Clethrionomys gapperi_ and, although actual evidence of
intergradation is lacking, we think that the relationships of
_limitis_ are better expressed by arranging it as a subspecies of _C.
gapperi_ than by retaining it as a full species.

_Specimens examined._--Total, 7, all in the Biological Surveys
Collection, distributed as follows:

+New Mexico+: _Catron County_: Willow Creek, 8500 ft., Mogollon
Mountains, 4. _Socorro County_: San Mateo Peak, 10,000 ft., San Mateo
Mountains, 2; Copper Canyon, 9000 ft., Magdalena Mountains, 1.



+Clethrionomys gapperi arizonensis+, new subspecies

_Type._--Female, adult, skin and skull; No. 158401, Biological Surveys
Collection, United States National Museum; from Little Colorado River,
8300 ft., White Mountains, Apache County, Arizona; obtained September
12, 1908, by C. Birdseye, original number 152.

_Range._--Known only from the White Mountains of eastern Arizona.

_Diagnosis._--Dorsal stripe near Chestnut, with an underwash of
between Tawny and Russet, and a mixture of black-tipped hairs,
resulting in an overall effect of near Chestnut. Skull wide across
zygomatic arches and narrow across mastoids; rostrum narrow and
posterior border of palate straight.

_Comparisons._--This subspecies needs close comparison only with the
adjacent subspecies _C. g. limitis_. As compared with topotypes of
_limitis_, _C. g. arizonensis_ has darker pelage, narrower rostrum,
greater width across zygomatic arches, lesser lambdoidal breadth,
longer nasals, wider palate, and more inflated auditory bullae. The
posterior border of the hard palate is straight in five skulls of the
series that are complete (two skulls have the palatal regions broken);
all _C. g. limitis_ examined have a median posterior projection on
the posterior border of the hard palate.

_Measurements._--External and cranial measurements of the type, and
the average and extreme measurements of three adult males and two
adult females from the type locality (including the type) are: Total
length, 160, 145.6 (137-160); tail, 44, 40.8 (37-46); hind foot, 18.5,
19.3 (18-20); condylobasilar length, 23.3, 22.8 (22.1-23.5); zygomatic
breadth, 13.8, 13.4 (12.6-13.8); lambdoidal breadth, 11.5, 11.4
(11.0-11.6); alveolar length upper cheek-teeth, 5.5, 5.4 (5.2-5.5);
interorbital breadth, 3.8, 3.9 (3.8-4.0); length of nasals, 7.6, 7.1
(6.9-7.6); breadth of rostrum, 3.1, 3.1 (3.0-3.2); length of incisive
foramina, 5.5, 5.2 (5.0-5.5).

_Remarks._--Hall and Davis (Proc. Biol. Soc. Washington, 47:55,
February 9, 1934) reported 12 specimens of red-backed mice from
Hannagan Meadow, 9500 to 9600 ft., and ten from Hannagan Creek, 8600
ft., all in Greenlee County, Arizona. Although they pointed out most
of the cranial differences here described as diagnostic of _C. g.
arizonensis_, they did not name the animals as new since they had no
seasonally comparable materials; thus they were unable to evaluate the
differences noted in pelage. We have not examined the material
referred to by Hall and Davis (_loc. cit._), but, on the basis of
their description, here refer it to _C. g. arizonensis_.

_Specimens examined._--Total, 7, all from the type locality and all in
the Biological Surveys Collection in the United States National
Museum.



Grateful acknowledgment is made of the opportunity to study the
specimens from New Mexico and Arizona in the Biological Surveys
Collection of the United States National Museum and the material from
South Dakota in the University of Michigan Museum of Zoology, as well
as for the financial support afforded one of us (Cockrum) by the
University of Kansas from its Research appropriation. Cockrum's work
was part of a larger investigation of the geographic distribution of
all North American native mammals, aided by a contract between the
Office of Naval Research, Department of the Navy, and the University
of Kansas (NR. 161-791). Also, assistance with some of field work was
given by the Kansas University Endowment Association.

_Transmitted June 21, 1952._

[Illustration: printers mark]
        24-4369


Transcriber's Notes.

This file was derived from scanned images.
The original text is presented.


Emphasis Notation:
     _text_ - italicized
     +text+ - bold
     ~text~ - small caps





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