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+The Project Gutenberg EBook of Geographic Variation in the Harvest Mouse,
+Reithrodontomys megalotis, On the Central Great Plains And in Adjacent Regions, by J. Knox Jones and B. Mursaloglu
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Geographic Variation in the Harvest Mouse, Reithrodontomys megalotis, On the Central Great Plains And in Adjacent Regions
+
+Author: J. Knox Jones
+        B. Mursaloglu
+
+Release Date: August 1, 2009 [EBook #29563]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE HARVEST MOUSE ***
+
+
+
+
+Produced by Chris Curnow, Joseph Cooper and the Online
+Distributed Proofreading Team at http://www.pgdp.net
+
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+
+[Transcriber's Note: The last name of one of the author's is spelled
+with a breve over the letter g. This accent is shown as [)G].
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS
+MUSEUM OF NATURAL HISTORY
+
+Volume 14, No. 2, pp. 9-27, 1 fig. in text
+July 24, 1961
+
+
+
+Geographic Variation in the Harvest Mouse,
+Reithrodontomys megalotis,
+On the Central Great Plains
+And in Adjacent Regions
+
+By
+
+J. KNOX JONES, JR. AND B. MURSALO[)G]LU
+
+UNIVERSITY OF KANSAS
+LAWRENCE
+1961
+
+
+
+UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY
+
+Editors: E. Raymond Hall, Chairman, Henry S. Fitch,
+Robert W. Wilson
+
+Volume 14, No. 2, pp. 9-27, 1 fig. in text
+Published July 24, 1961
+
+UNIVERSITY OF KANSAS
+Lawrence, Kansas
+
+PRINTED IN
+THE STATE PRINTING PLANT
+TOPEKA, KANSAS
+1961
+
+
+
+
+Geographic Variation in the Harvest Mouse,
+Reithrodontomys megalotis,
+On the Central Great Plains
+And in Adjacent Regions
+
+By
+
+J. KNOX JONES, JR. AND B. MURSALO[)G]LU
+
+
+The western harvest mouse, _Reithrodontomys megalotis_, inhabits most
+parts of the central Great Plains and adjacent regions of tall grass
+prairie to the eastward, shows a marked predilection for grassy
+habitats, is common in many areas, and is notably less variable
+geographically than most other cricetids found in the same region. _R.
+megalotis_ occurs (see Hall and Kelson, 1959:586, map 342) from
+Minnesota, southwestern Wisconsin, northwestern Illinois, Iowa and
+Missouri westward to, but apparently not across, the Rocky Mountains
+from southeastern Alberta to Colorado; it is known in Oklahoma only from
+the Panhandle, thence southward through the Panhandle and Trans-Pecos
+areas of Texas to southern Mexico, westward across the mountains in New
+Mexico to the Pacific Coast, and northward to the west of the Rockies to
+southern British Columbia.
+
+Hoffmeister and Warnock (1955) studied western harvest mice from
+Illinois, Iowa, northeastern Kansas, Minnesota and Wisconsin, concluded
+that one subspecific name (_Reithrodontomys megalotis dychei_ J. A.
+Allen, 1895, with type locality at Lawrence, Douglas Co., Kansas)
+applied to all, and relegated _Reithrodontomys megalotis pectoralis_
+Hanson, 1944 (type locality at Westpoint, Columbia Co., Wisconsin) to
+synonymy under _dychei_. Our study, based upon an examination of 1350
+specimens, concerns the area west of the Missouri River from Kansas and
+Nebraska westward to Montana, Wyoming, Colorado and northern New Mexico.
+Our objectives were to study variation in _R. megalotis_ in the region
+indicated and to decide what subspecific names properly apply to
+populations of the species that occur there.
+
+Aside from the name _R. m. dychei_, currently applied to western harvest
+mice from a large part of the region here under study, three other
+subspecific names need consideration:
+
+    "_Reithrodontomys aztecus_" J. A. Allen, 1893 (type locality, La
+    Plata, San Juan Co., New Mexico), currently applied to specimens
+    from northern New Mexico and southern Colorado (and adjacent parts
+    of Arizona and Utah) east to southwestern Kansas and the Oklahoma
+    Panhandle;
+
+    "_Reithrodontomys megalotis caryi_" A. H. Howell, 1935 (type
+    locality, Medano Ranch, 15 mi. NE Mosca, Alamosa Co., Colorado),
+    proposed for, and currently applied to, harvest mice from the San
+    Luis Valley, Colorado, but possibly a synonym of _aztecus_ according
+    to Hooper (1952:218); and
+
+    "_Reithrodontomys dychei nebrascensis_" J. A. Allen, 1895 (type
+    locality, Kennedy, Cherry Co., Nebraska), proposed for harvest mice
+    from western Nebraska and adjacent areas, but regarded as a synonym
+    of _dychei_ by A. H. Howell (1914:30-31).
+
+Our comments concerning the taxonomic status of these several names
+appear beyond.
+
+    We are grateful to Dr. W. Frank Blair, University of Texas, for the
+    loan of a specimen from the Texas Panhandle (TU), and to Dr. Richard
+    H. Manville, U.S. Fish and Wildlife Service, for the loan of
+    specimens of _R. m. caryi_ from the Biological Surveys Collection
+    (USNM). We are grateful also to persons in charge of the following
+    collections for allowing one of us (Jones) to examine Nebraskan
+    specimens of _R. megalotis_ in their care: University of Michigan
+    Museum of Zoology (UMMZ); University of Nebraska State Museum (NSM);
+    and U.S. National Museum (USNM). A research grant from the Society
+    of the Sigma Xi facilitated travel to the institutions mentioned.
+    Specimens not identified as to collection are in the Museum of
+    Natural History of The University of Kansas. All measurements are in
+    millimeters, and are of adults (as defined by Hooper, 1952:12)
+    unless otherwise noted.
+
+
+Secondary Sexual Variation
+
+Hooper (1952) did not accord separate treatment to males and females in
+taxonomic accounts of Latin American harvest mice because (p. 11): "In
+no species ... does sexual dimorphism in the measurements, if present at
+all, appear to be sufficient to warrant separating the sexes in the
+analysis." Hooper did not statistically test the validity of treating
+the sexes together in _R. megalotis_. He did test a series of _R.
+sumichrasti_ from El Salvador, in which he found no basis for separate
+treatment of males and females.
+
+Some authors (Verts, 1960:6, for instance) have recorded females of _R.
+megalotis_ as larger than males in external measurements, whereas others
+(Dalquest, 1948:325, for instance) have recorded males as the larger. In
+order to learn something of secondary sexual variation, and to decide
+whether or not to separate the sexes in our study, we compared adult
+males and females from the southern part of the Panhandle of Nebraska
+(Cheyenne, Keith, Kimball, Morrill and Scotts Bluff counties) in four
+external and twelve cranial measurements (see Table 1). The external
+measurements are those customarily taken by collectors and were read
+from the labels of the specimens; cranial measurements were taken to the
+nearest tenth of a millimeter by means of dial calipers, and are those
+described by Hooper (1952:9-11). Females from our sample averaged larger
+than males in all external and several cranial measurements, but
+individual variation greatly exceeded secondary sexual variation in each
+of these measurements and in no case was the greater size of females
+statistically significant. Therefore, and because we found no
+qualitative external or cranial differences between the sexes, males and
+females have been considered together in each population studied.
+
+TABLE 1. ANALYSIS OF SECONDARY SEXUAL VARIATION IN ADULT REITHRODONTOMYS
+MEGALOTIS FROM THE SOUTHERN PART OF THE NEBRASKA PANHANDLE. FOR EACH
+MEASUREMENT, THE NUMBER OF SPECIMENS USED, THE AVERAGE, THE EXTREMES,
+AND ONE STANDARD DEVIATION ARE GIVEN.
+
+  CHARACTER  |           Males            |        Females
+-------------+--+-----+------------+------+--+-----+----------+-----
+Total
+length       |27|135.0|(121-149)   |+-6.14 |32|141.0|(127-149) |+-5.36
+-------------+--+-----+------------+------+--+-----+----------+-----
+Length of
+tail-
+vertebrae    |27| 63.9|( 56-74)    |+-4.63 |32| 65.2|(58-73)    |+-4.06
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Length
+of hind
+foot         |27| 17.0|( 16-18)    |+-0.60 |32| 17.3|(15-19)    |+-0.81
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Length of
+ear from
+notch        |27| 12.9|( 12-14)    |+-0.55 |32| 13.0|(12-14)    |+-0.61
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Greatest
+length of
+skull        |27| 21.0|( 20.2-21.8)|+-0.43 |28| 21.3|(20.4-22.2)|+-0.48
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Zygomatic
+breadth      |25| 10.7|( 10.3-11.0)|+-0.21 |28| 10.9|(10.4-11.3)|+-0.25
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Breadth of
+braincase    |27| 10.0|(  9.6-10.5)|+-0.22 |28| 10.1|(9.8-10.7) |+-0.18
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Depth of
+cranium      |26|  7.9|(  7.4-8.4) |+-0.20 |28|  7.9|( 7.7-8.3) |+-0.15
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Length of
+rostrum      |27|  7.3|(  6.8-7.6) |+-0.21 |28|  7.4|( 6.9-8.0) |+-0.27
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Breadth of
+rostrum      |27|  3.8|(  3.6-4.1) |+-0.11 |28|  3.8|( 3.5-4.0) |+-0.12
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Length of
+incisive
+foramen      |27|  4.4|(  4.1-4.6) |+-0.10 |28|  4.5 ( 4.1-4.9) |+-0.19
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Length of
+palate       |26|  3.5|(  3.1-3.8) |+-0.18 |28|  3.5 ( 3.2-4.0) |+-0.15
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Alveolar
+length of
+maxillary
+tooth-row    |27|  3.4|(  3.2-3.7) |+-0.14 |28|  3.4|( 3.2-3.7) |+-0.13
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Interorbital
+breadth      |27|  3.1|(  2.9-3.3) |+-0.12 |28|  3.1|( 2.8-3.3) |+-0.11
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Breadth of
+zygomatic
+plate        |27|  1.9|(  1.8-2.1) |+-0.10 |28|  2.0|( 1.9-2.3) |+-0.12
+-------------+--+-----+------------+------+--+-----+-----------+-----
+Breadth of
+mesopterygoid
+fossa        |26|  0.9|(  0.6-1.1) |+-0.12 |28|  0.9|( 0.8-1.2) |+-0.12
+-------------+--+-----+------------+------+--+-----+-----------+-----
+
+
+Pelage and Molt
+
+Western harvest mice that attain adulthood acquire at least three
+distinct types of pelage in sequence in the course of their development.
+The first of these, the juvenal pelage, is short, relatively sparse, and
+characteristically grayish brown. The molt (post-juvenal molt) from
+juvenal pelage to subadult pelage seemingly occurs at an early age,
+perhaps frequently before the young leave the nest, as individuals in
+juvenal pelage are few among specimens studied by us. Judging from study
+skins alone, the progress of post-juvenal molt in _R. megalotis_ is
+similar to that described for _R. humulis_ by Layne (1959:69-71). The
+subadult pelage is thicker, longer and brighter than juvenal pelage and
+closely resembles the pelage of adults; it differs from adult pelage
+dorsally in being somewhat duller and in having less contrast between
+back and sides.
+
+The pelage of adults varies depending on season. In summer the
+individual hairs are relatively short (5-6 mm. at the middle of the
+back) and sparse. The over-all color of the dorsum, sides and flanks is
+brownish to dark brownish, and the venter is grayish. In winter the
+pelage is dense, long (8-9 mm. at the middle of the back) and lax. The
+over-all color dorsally in fresh winter pelage in most specimens is
+paler (more buffy) than summer pelage, the sides are markedly buffy, and
+the venter is whitish; even the tail is more pilose and more sharply
+bicolored than in summer. Adults molt, usually completely but
+occasionally only partially, at least twice a year--once in spring (in
+May and June in Nebraskan specimens) from winter to summer pelage, and
+once in autumn (in October and November in Nebraskan specimens) from
+summer to winter pelage. Of the two molts, the one in spring is most
+easily discernible because the contrast in color between worn winter
+pelage and fresh summer pelage is considerably greater than that between
+worn summer pelage and fresh winter pelage, and because the progress of
+spring molt is seemingly more regular than that of autumn molt. In
+spring, molt proceeds posteriorly in a more or less regular line on both
+dorsum and venter; in most specimens it is completed first on the
+venter. In autumn, molt is irregular, or at best is coincident over
+large parts of the body, and frequently is seen only by searching
+through the pelage with a fine probe or dissecting needle. In both
+spring and autumn, molt seemingly is delayed in females that are
+pregnant or lactating.
+
+In both winter pelage and summer pelage, the upper parts have blackish
+or grayish guard hairs and shorter, more numerous cover hairs. All the
+cover hairs are gray basally; some have a buffy band terminally and
+others have a buffy subterminal band with a terminal black tip. The
+generally darker over-all color of upper parts in summer pelage results
+(as seen in Nebraskan specimens) from a narrower band of buff on the
+cover hairs (only approximately one half the width of the band on hairs
+in winter pelage), a darker buffy band (ochraceous buff rather than pale
+ochraceous or straw color), and a relative sparseness of the pelage,
+which allows the gray basal portion of some hairs to show on the
+surface. The more grayish venter of summer-taken specimens results from
+much more of the grayish basal portion of the white-tipped hairs showing
+through than in the longer, denser pelage of winter.
+
+Wear on the pelage seems in general to produce a paler over-all color of
+upper parts, evidently due mostly to abrasion of the terminal black tip
+of the cover hairs, but possibly actual fading of the pelage is involved
+also. Worn winter pelage is especially notable for its paleness; the
+buffy tones are accentuated and the upper parts, especially posteriorly,
+may even appear fulvous. The difference in color of upper parts between
+specimens in worn winter pelage and fresh summer pelage (or for that
+matter specimens in fresh _versus_ worn winter pelage) from the same
+locality is greater in our material than the difference between some
+specimens in comparable pelages from localities more than 500 miles
+apart.
+
+We have seen no specimens taken in winter in which we could discern that
+the autumn molt had been incomplete, but three old adult males in summer
+pelage indicate that spring molt is not always completed. KU 50154,
+obtained on August 14, 1952, 5 mi. N and 2 mi. W Parks, Dundy Co.,
+Nebraska, has the entire posterior back and sides still in old winter
+pelage and does not appear to have been actively molting; the entire
+venter is in summer pelage. KU 50146, obtained on August 22, 1952, 3 mi.
+E Chadron, Dawes Co., Nebraska, has small patches or tufts of winter
+pelage remaining on the rump and likewise does not appear to have been
+actively molting. KU 72085, obtained on October 13, 1956, 4 mi. E
+Barada, Richardson Co., Nebraska, is in the process of molting from
+summer to winter pelage, but has tufts of old winter pelage on the rump.
+
+
+Geographic Variation
+
+Geographic variation, both in color of pelage and in external and
+cranial dimensions, is less in _R. megalotis_ in the region studied than
+in most other cricetine species that occur there. Nevertheless,
+meaningful variation is present. The assumption that variation in _R.
+megalotis_ paralleled in degree that of other species, _Peromyscus
+maniculatus_ for example, led to untenable taxonomic conclusions by some
+previous workers.
+
+
+_Color of Pelage_
+
+Color of pelage is remarkably uniform, considering the geographic extent
+of the area involved, over most of the northern part of the central
+grasslands. Perhaps this uniformity results partly from the predilection
+of the western harvest mouse for grassy habitats, for in most areas on
+the Great Plains the species is restricted to riparian communities,
+principally along river systems, where soils, cover, and other
+conditions approximate those of corresponding habitats farther to the
+east to a much greater degree than do conditions in upland habitats.
+Differential selective pressure, therefore, theoretically would be less
+between eastern and western populations of _R. megalotis_ than in an
+upland-inhabiting species. In any event, specimens from western
+Nebraska, Wyoming, northern Colorado, and adjacent areas average only
+slightly paler dorsally than specimens in corresponding pelages from the
+eastern parts of Nebraska and Kansas, and many individuals from the two
+areas can be matched almost exactly.
+
+To the southwest, on the other hand, a trend toward paler (pale
+brownish, less blackish) upper parts is apparent. Specimens from
+southwestern Kansas and adjacent parts of Colorado and Oklahoma average
+slightly paler in comparable pelages than specimens from northeastern
+Kansas and eastern Nebraska, but most specimens from farther southwest,
+in northern New Mexico and southwestern Colorado, are discernibly,
+although not markedly, paler than mice from northern and eastern
+populations.
+
+A "pectoral spot," fairly common in some populations of _R. megalotis_
+east of the Missouri River (see Hoffmeister and Warnock, 1955:162-163),
+is present in only a small percentage of the specimens we have studied,
+and when present is usually only faintly developed.
+
+
+_External and Cranial Size_
+
+[Illustration: FIG. 1. Geographic variation in five measurements of
+_Reithrodontomys megalotis_ on the central Great Plains. The size of
+each sample is given, along with total length, length of tail expressed
+as a percentage of the head and body, length of ear, greatest length of
+skull, and length of rostrum. The approximate distribution of the
+species in the region shown and the approximate boundary between the
+subspecies _R. m. aztecus_ and _R. m. dychei_ also are indicated.]
+
+As seen in Figure 1, the tail and especially the ear are longer in mice
+from New Mexico and adjacent areas than in specimens from northern
+localities. The ear, only slightly variable in size in the northern part
+of the region, is markedly longer in the southwest, averaging more than
+2 mm. longer in specimens from New Mexico and adjacent southwestern
+Colorado than in specimens from Nebraska and eastern Kansas; specimens
+in a zone from central Colorado through southwestern Kansas and adjacent
+Oklahoma generally have ears of a size between the two extremes. As
+concerns the tail we note a slight trend toward increasing length (best
+expressed as percentage of length of body) from north to south
+throughout the central plains, but in general the trend is more
+pronounced southwestwardly. Variation in length of tail and length of
+ear, therefore, appear to be in accord with Allen's Rule. Length of body
+and length of hind foot seem not to vary significantly in specimens we
+have studied.
+
+The skulls of specimens examined differed only slightly, except that the
+rostrum is significantly longer and relatively, if not actually,
+narrower in specimens from the south and southwest than in mice from the
+rest of the region under study. The rostrum is longest (average 7.7 mm.)
+in specimens from the vicinity of the type locality of _R. m. aztecus_,
+but is relatively long (7.5-7.6 mm.) in populations from as far north as
+northeastern Colorado and southwestern Nebraska. An average greater
+occipitonasal length (greatest length of skull) in specimens from the
+south and southwest results mostly from the longer rostrum.
+
+Recognition of two subspecies of _R. megalotis_ on the central Great
+Plains seems justified on the basis of the geographic variation
+discussed above. One subspecies, for which the name _R. m. aztecus_ is
+applicable, occurs in the southwest and is characterized by the
+culmination of trends in the region studied to paler upper parts, longer
+tail, longer ear, and longer, relatively narrower rostrum--characters
+that appear at least partly independent of each other as concerns
+gradation toward the smaller, darker-colored populations to the
+northward. The latter, while exhibiting some differences in color
+(slightly paler westwardly) and length of tail (shorter northwardly),
+stand more or less as a unit in contrast to the mice from the southwest,
+and represent, in our judgment, a single subspecies, _R. m. dychei_. The
+area of intergradation between the two subspecies is relatively broad,
+considering all the characters mentioned, and assignment of some
+intergrades is admittedly difficult.
+
+
+_Reithrodontomys megalotis aztecus_ J. A. Allen
+
+    _Reithrodontomys aztecus_ J. A. Allen, Bull. Amer. Mus. Nat. Hist.,
+    5:79, April 28, 1893 (type locality, La Plata, San Juan Co., New
+    Mexico).
+
+    _Reithrodontomys megalotis aztecus_, A. H. Howell, N. Amer. Fauna,
+    36:30, June 5, 1914.
+
+    _Reithrodontomys megalotis caryi_ A. H. Howell, Jour. Mamm., 16:143,
+    May 15, 1935 (type locality, Medano Ranch, 15 mi. NE Mosca, Alamosa
+    Co., Colorado).
+
+
+    _Distribution._--Western and southern Colorado, southeastern Utah,
+    northeastern Arizona and northern New Mexico, east to the panhandles
+    of Texas and Oklahoma and to southwestern Kansas.
+
+    _External measurements._--Average and extremes of 10 adults (5
+    males, 5 females) from San Juan County, New Mexico, and adjacent
+    Montezuma County, Colorado, are: total length, 140.1 (126-150);
+    length of tail-vertebrae, 67.4 (56-71); length of hind foot, 17.3
+    (16-18); length of ear from notch, 15.1 (13-17); tail averaging 92.7
+    per cent of length of body. Corresponding measurements of 13 adults
+    (7 males, 6 females) from Bernalillo and Guadalupe counties, New
+    Mexico, are: 142.1 (129-156); 69.4 (60-75); 17.9 (17-19); 16.3
+    (15-18); tail averaging 95.4 per cent of length of body.
+    Corresponding measurements of 22 adults (17 males, 5 females) from
+    Meade County, southwestern Kansas, are: 147.1 (139-162); 71.3
+    (65-77); 17.6 (17-19); 13.8 (13-15); tail averaging 94.1 per cent of
+    length of body. For cranial measurements see Table 2.
+
+
+_Remarks._--For comparisons with _Reithrodontomys megalotis dychei_,
+geographically adjacent to the northeast, see account of that
+subspecies.
+
+When Howell (1935:143) named _Reithrodontomys megalotis caryi_ from the
+San Luis Valley of Colorado he compared it directly only with _R. m.
+megalotis_ from southern New Mexico and northern Chihuahua. Few adults
+were available to Howell from the San Luis Valley, accounting for the
+fact, we think, that the published measurements of _caryi_ average less
+than those given for _R. m. aztecus_ by Howell (_op. cit._:144) and
+herein. We have examined 16 of the 23 specimens from Medano Ranch and
+the single specimen from Del Norte that Howell listed. Unfortunately,
+none is fully adult. The specimens from Medano Ranch, collected in late
+October and early November, are mostly in fresh winter pelage or molting
+from subadult pelage, and closely resemble topotypes of _aztecus_ in
+comparable pelages. Comparison of skulls of the specimens from Medano
+Ranch with skulls of topotypes and other individuals of _aztecus_ of
+approximately equal age indicates that the Coloradan specimens may
+average slightly smaller and have somewhat shorter rostra. Externally,
+topotypes of _caryi_ have the relatively long tail of _aztecus_ and
+approach it in length of ear (measured on dry specimens). To us, they
+appear to be intergrades between _aztecus_ and _dychei_, but to bear
+closer resemblance to the former, and we tentatively regard _caryi_ as a
+synonym of _aztecus_. Benson (1935:140) noted that two adult topotypes
+of _caryi_ were "similar to adult topotypes of _aztecus_." Specimens
+from southern Colorado east of the San Luis Valley, assigned to
+_aztecus_, are intergrades between it and _dychei_, as are two specimens
+from El Paso County, to the north, which resemble _aztecus_ in color but
+resemble _dychei_ in other characters and are tentatively assigned to
+the latter.
+
+Specimens from southwestern Kansas and adjacent Oklahoma, herein
+referred to _aztecus_, also are intergrades with _dychei_. Individuals
+from Meade County, for example, are intermediate on the average between
+typical specimens of the two subspecies in color of upper parts (if
+anything, nearer _dychei_), resemble _dychei_ in length of ear, but
+resemble _aztecus_ in length of tail and rostral proportions
+(consequently also in length of skull). Although a case could be made
+for assignment of the specimens from Meade County (and elsewhere in
+southwestern Kansas) to _dychei_, they are, everything considered,
+nearer _aztecus_, to which subspecies they have been assigned
+consistently since first reported from the area by Hill and Hibbard
+(1943:24).
+
+Of two specimens examined from 10 mi. S and 1 mi. W Gruver, Hansford
+Co., in the Panhandle of Texas, the one adult is clearly assignable to
+_aztecus_ as is the specimen from 9 mi. E Stinnett, Hutchinson Co.,
+Texas, that was referred to _dychei_ by Blair (1954:249).
+
+_Reithrodontomys megalotis aztecus_ has had a rather unstable taxonomic
+history. Allen, who originally named the subspecies (1893:79), regarded
+it two years later (1895:125) as a synonym of _R. m. megalotis_, the
+subspecies with geographic range to the south and west of that occupied
+by _aztecus_. Howell (1914:30) recognized _aztecus_ as valid, but he,
+too, questioned its distinctness from _megalotis_ in a later paper
+(1935:144). Hooper (1952:218), the most recent reviewer, supported the
+validity of _aztecus_ because specimens available to him averaged
+"distinctly larger in skull length and size of brain case" than
+specimens of _megalotis_. Our comparisons of typical specimens of
+_aztecus_ with specimens of _megalotis_ from southern New Mexico and
+southwestern Texas confirm Hooper's observations and indicate also that
+_aztecus_ has a longer rostrum and slightly longer ear.
+
+
+    _Specimens examined._--205, as follows:
+
+    COLORADO. _Alamosa County_: Medano Ranch, 15 mi. NE Mosca, 16
+    (USNM). _La Plata County_: 1 mi. NW Florida, 6700 ft., 1; Florida,
+    6800 ft., 1. _Las Animas County_: 1 mi. S, 7 mi. E Trinidad, 2.
+    _Montezuma County_: 1 mi. W Mancos, 5; north end, Mesa Verde Nat'l
+    Park, 7000 ft., 3; Far View Ruins, Mesa Verde Nat'l Park, 7700 ft.,
+    3; Park Point, Mesa Verde Nat'l Park, 8525 ft., 2; within 3 mi. Rock
+    Springs, Mesa Verde Nat'l Park, 7500-8200 ft., 6. _Prowers County_:
+    Lamar, 2. _Rio Grande County_: Del Norte, 1 (USNM).
+
+    KANSAS. _Finney County_: 1 mi. S, 2 mi. E Garden City, 4. _Ford
+    County_: 1/2 mi. NW Bellefont, 10; 6-1/4 mi. N Fowler, 2. _Grant
+    County_: 2 mi. S, 9 mi. W Santanta, 1. _Kearney County_: 3-1/2 mi.
+    N, 4 mi. E Lakin, 4. _Meade County_: within 2-1/2 mi. Fowler, 10;
+    Meade County State Park, 14 mi. SW Meade, 48; 17 mi. SW Meade, 5.
+    _Morton County_: 7-1/2 mi. S Richfield, 4; 8 mi. N Elkhart, 1; 7-1/2
+    mi. N, 1-1/2 mi. W Elkhart, 2. _Seward County_: 3 mi. NE Liberal, 1.
+    _Stanton County_: 1 mi. N, 6-7-1/2 mi. W Manter, 2; dam of Lake
+    Stanton, 1.
+
+    NEW MEXICO. _Bernalillo County_: 6-1/2 mi. E Alameda, 11; 5 mi. W
+    Albuquerque, 3. _Catron County_: 1 mi. NE Apache Creek, 4; Apache
+    Creek, 2. _Guadalupe County_: 4 mi. SW Santa Rosa, 4700 ft., 10.
+    _McKinley County_: Upper Nutria, 7200 ft., 2. _Rio Arriba County_: 4
+    mi. N El Rito, 1; 1 mi. SE El Rito, 1. _Sandoval County_: 3 mi. N La
+    Cueva Rec. Area, 1. _San Juan County_: 2 mi. N La Plata, 15. _Santa
+    Fe County_: 1 mi. W Santa Fe Municipal Airport, 1; La Bajada Grade,
+    20 mi. W Santa Fe, 1. _Socorro County_: 2 mi. S San Antonio, 4.
+
+    OKLAHOMA. _Beaver County_: 7 mi. S Turpin, 1. _Texas County_: 3-1/2
+    mi. SW Optima, 8.
+
+    TEXAS. _Hansford County_: 10 mi. S, 1 mi. W Gruver, 2. _Hutchinson
+    County_: 9 mi. E Stinnett, 1 (TU).
+
+
+_Reithrodontomys megalotis dychei_ J. A. Allen
+
+    _Reithrodontomys dychei_ J. A. Allen, Bull. Amer. Mus. Nat. Hist.,
+    7:120, May 21, 1895 (type locality, Lawrence, Douglas Co., Kansas).
+
+    _Reithrodontomys megalotis dychei_, A. H. Howell, N. Amer. Fauna,
+    36:30, June 5, 1914.
+
+    _Reithrodontomys dychei nebrascensis_ J. A. Allen, Bull. Amer. Mus.
+    Nat. Hist., 7:122, May 21, 1895 (type locality, Kennedy, Cherry Co.,
+    Nebraska).
+
+    _Distribution._--Southwestern Wisconsin, southern Minnesota,
+    northwestern Illinois, Iowa, Missouri and northwestern Arkansas,
+    west through Kansas (except southwestern part), Nebraska and the
+    Dakotas to the foothills of the Rocky Mountains from central
+    Colorado to southeastern Alberta.
+
+    _External measurements._--Average and extremes of 17 adults (11
+    males, 6 females) from Douglas County, Kansas, are: total length,
+    134.2 (115-151); length of tail-vertebrae, 64.2 (59-72); length of
+    hind foot, 16.7 (15-18); length of ear from notch, 13.4 (12-15);
+    tail averaging 91.7 per cent of length of body. Corresponding
+    measurements of 20 adults (14 males, 6 females) from Cherry County,
+    Nebraska, are: 135.3 (122-155); 62.9 (56-72); 17.5 (17-18); 13.0
+    (12-14); tail averaging 86.9 per cent of length of body. For cranial
+    measurements see Tables 1 and 2.
+
+
+_Remarks._--From _Reithrodontomys megalotis aztecus_, geographically
+adjacent to the southwest, _R. m. dychei_ differs as follows: upper
+parts averaging darker (especially in summer pelage), owing principally
+to more suffusion of blackish middorsally; tail slightly shorter; ears
+markedly shorter, rostrum shorter and relatively broader; occipitonasal
+length shorter owing to shorter rostrum.
+
+"_Reithrodontomys dychei nebrascensis_," named by Allen (1895:122)
+from Kennedy, Nebraska, was distinguished in the original description
+from _dychei_ by "slightly larger size, relatively longer ears, and
+more strongly fulvous coloration." Allen applied the name _nebrascensis_
+to harvest mice from Montana south to central Colorado and western
+Nebraska. Howell (1914:30-31) placed _nebrascensis_ in synonymy under
+_dychei_ because he found specimens from Kennedy to be "indistinguishable
+from specimens of typical _dychei_ in comparable pelage." We concur
+with Howell. Topotypes of _nebrascensis_ that we have examined average
+only slightly paler than topotypes of _dychei_ in the same pelage (some
+specimens from each series can be matched almost exactly), and do not
+differ significantly in any external or cranial measurements. The
+"fulvous" upper parts of the series from Kennedy (all taken in late
+April) that was available to Allen resulted from worn winter pelage. We
+think that Allen was led astray also by his erroneous assumption that
+geographic variation in color of _R. megalotis_ on the Great Plains
+paralleled that found in _Peromyscus maniculatus_. Actually, _R.
+megalotis_ varies in color much less geographically in the region
+concerned than does _P. maniculatus_.
+
+Specimens from the northwestern part of the range of _dychei_ (Wyoming,
+Montana and western South Dakota), like those from western Nebraska,
+average slightly paler dorsally than topotypes and other specimens from
+eastern Kansas and Nebraska (a few approach _aztecus_ in this regard),
+but do not otherwise differ. Most specimens from northern Colorado,
+southwestern Nebraska (Hitchcock and Dundy counties) and western Kansas
+average slightly paler than typical specimens and have longer rostra,
+approaching _aztecus_ in these particulars, but have the shorter ears
+and shorter tail of _dychei_. In general, these intergrades resemble
+_dychei_ to a greater degree than _aztecus_ and are accordingly assigned
+to the former. One exception is a series from Muir Springs, 2 mi. N and
+2-1/2 mi. W Ft. Morgan, Colorado. Specimens in this series approach
+typical _dychei_ in color, but resemble _aztecus_ in having long ears
+and long rostra (average 15.3 and 7.5, respectively, in 13 adults). The
+specimens from Muir Springs resemble _aztecus_ to a greater degree than
+_dychei_, but are assigned to the latter because specimens from farther
+west and farther south in Colorado are assignable to _dychei_. Howell
+(1914:31) earlier noted that specimens from northern and central
+Colorado were intergrades between the two subspecies.
+
+The geographic range occupied by _R. m. dychei_ (from east of the
+Mississippi River in Illinois and Wisconsin to the foothills of the
+Rockies) is large (although not so large as that currently ascribed to
+_R. m. megalotis_, which ranges from southern British Columbia to
+central Mexico). Most other small rodents that occur in the same
+geographic area occupied by _dychei_ are represented there by at least
+two subspecies, a dark one in the east and a pale one in the west.
+Eastern populations of _dychei_ have, it is true, somewhat darker upper
+parts than mice from western localities, but the differences are slight;
+also, judging from the literature, the "pectoral spot" is more common in
+eastern mice.
+
+It should be noted that _R. m. dychei_ probably has extended its range
+both eastward and westward in the last century as a result of
+agricultural practices--clearing of land in the east and irrigation in
+the west.
+
+
+    _Specimens examined._--1145, as follows:
+
+    COLORADO. _Adams County_: South Platte River, 5 mi. N Denver, 1; 3
+    mi. S, 1 mi. W Simpson, 1. _El Paso County_: 5 mi. E Payton, 1; 4
+    mi. S maingate of Camp Carson, 1. _Larimer County_: 3 mi. N
+    Loveland, 1; 9-1/4 mi. W, 1/2 mi. N Loveland, 5600 ft., 1; 16 mi. W
+    Loveland, 6840 ft., 1; 3-1/2-4-1/2 mi. W Loveland, 5030 ft., 7; 6
+    mi. W, 1/2 mi. S Loveland, 5200 ft., 14; 7 mi. W, 2-1/2 mi. S
+    Loveland, 5370 ft., 1. _Morgan County_: Muir Springs, 2 mi. N, 2-1/2
+    mi. W Ft. Morgan, 21. _Washington County_: Cope, 6. _Yuma County_: 1
+    mi. W to 1 mi. E Laird, 6.
+
+    KANSAS. _Atchison County_: 1-1/2 mi. S Muscotah, 10; 4-1/2 mi. S
+    Muscotah, 2. _Barton County_: 3 mi. N, 2 mi. W Hoisington, 3. _Brown
+    County_: 1 mi. E Reserve, 2; 5 mi. S Hiawatha, 4. _Cheyenne County_:
+    23 mi. NW St. Francis, 1; 1 mi. W St. Francis, 12; 8 mi. S, 1-1/2
+    mi. W St. Francis, 1. _Decatur County_: 1 mi. N, 2 mi. E Oberlin, 4;
+    5 mi. S, 8 mi. W Oberlin, 1. _Doniphan County_: Geary, 2. _Douglas
+    County_: 5 mi. N, 1/2 mi. E Lawrence, 1; 1 mi. NW Midland, 1; 4-1/2
+    mi. N Lawrence, 2; 4 mi. N, 1-3/4 mi. E Lawrence (sec. 8, T. 12 S,
+    R. 20 E), 10; 1/2 mi. NW Lecompton, 1; 2-1/2 mi. N, 1 mi. W
+    Lawrence, 2; 2 mi. N Lawrence, 2; U.P. Railroad tracks, N of
+    Lawrence, 1; 9-1/5 mi. W Lawrence, 1; 5 mi. W Lawrence, 1; 2 mi. W
+    Lawrence, 4; 1 mi. W Lawrence, 4; Fort Lake, Lawrence, 1; Lawrence,
+    24; 1 mi. SW Lawrence, 2; 1 mi. S, 1-1/2 mi. W Lawrence, 2; 1-3/4.
+    mi. S, 3-1/2 mi. E Lawrence, 1; 2 mi. SW Lawrence, 2; 7-7-1/2 mi. SW
+    Lawrence, 4; Rock Creek, 850 ft., 10 mi. SW Lawrence, 8; N end Lone
+    Star Lake, 9 mi. S, 7 mi. W Lawrence, 1; no specific locality, 6.
+    _Ellis County_: 1/2 mi. S, 3-1/2-4 mi. W Hays, 2250 ft., 12.
+    _Franklin County_: 4 mi. N Ottawa, 2; 1/2 mi. S, 1-3/4 mi. E Ottawa,
+    4. _Gove County_: Castle Rock, 4; no specific locality, 1. _Jackson
+    County_: 1/2 mi. N, 3 mi. W Holton, 4. _Leavenworth County_: Ft.
+    Leavenworth, 2; no specific locality, 3. _Logan County_: no specific
+    locality, 2. _Marshall County_: 2 mi. N, 4 mi. E Oketo, 1; 1/2 mi.
+    N, 1-1/2 mi. E Waterville, 1; 1 mi. E Waterville, 5; 1/2 mi. SW
+    Waterville, 4. _Mitchell County_: 1/2 mi. S, 3-1/2 mi. W Beloit,
+    1500 ft., 4. _Nemaha County_: Nebraska-Kansas line, 7 mi. N Sabetha,
+    1; 10-1/2 mi. N Seneca, 1; 2-1/2 mi. S Sabetha, 6. _Norton County_:
+    1-1/2 mi. N, 1/4 mi. E Norton, 1; 1/2 mi. N, 4 mi. E Norton, 5; 1
+    mi. SW Norton, 10; 4 mi. W, 1 mi. S Logan, 3. _Osage County_: 3 mi.
+    N Lyndon, 1. _Osborne County_: 1/2 mi. W Downs, 5. _Phillips
+    County_: 2-1/4 mi. SE Long Island, 1. _Pottawatomie County_: 1 mi.
+    NW Fostoria, 1. _Rawlins County_: 2 mi. NE Ludell, 17; 2 mi. S
+    Ludell, 2; Atwood, 3; Atwood Lake, 2. _Republic County_: 1-1/2 mi.
+    S, 1 mi. E Belleville, 1; Rydal, 8. _Scott County_: State Park, 2.
+    _Shawnee County_: 1 mi. S Silver Lake, 857 ft., 2. _Sherman County_:
+    1/2 mi. S, 1-1/2 mi. E Edson, 1. _Smith County_: 2 mi. E Smith
+    Center, 9. _Stafford County_: 16 mi. N, 4 mi. E Stafford, 1. _Thomas
+    County_: 10 mi. N, 6 mi. E Colby, 5. _Trego County_: 16 mi. S, 4-1/2
+    mi. E Wakeeney, 1. _Wichita County_: 15 mi. W Scott City, 5.
+
+    MONTANA. _Big Horn County_: Big Horn River, 14 mi. S Custer, 2750
+    ft., 4. _Dawson County_: 1 mi. W Glendive, 2070 ft., 3. _Phillips
+    County_: 1 mi. N, 1 mi. W Malta, 2248 ft., 1. _Powder River County_:
+    Powderville, 2900 ft., 1.
+
+    NEBRASKA. _Antelope County_: Neligh, 16 (6 NSM, 9 USNM). _Boyd
+    County_: 5 mi. WSW Spencer, 1; 5 mi. S, 2 mi. E Spencer, 2; 6 mi.
+    SSE Spencer, 1. _Box Butte County_: Alliance, 2 (USNM). _Buffalo
+    County_: Kearney, 2 (USNM). _Burt County_: 1 mi. E Tekamah, 3.
+    _Butler County_: 2 mi. N, 2 mi. W Bellwood, 2 (NSM); 4-5 mi. E
+    Rising City, 11; 4 mi. E, 1 mi. S Rising City, 5. _Chase County_: 2
+    mi. SE Enders, 1. _Cherry County_: W of Crookston, 1 (NSM);
+    Valentine, 2 (USNM); Ft. Niobrara Nat'l Wildlife Refuge, 4 mi. E
+    Valentine, 5 (3 NSM); 3 mi. SSE Valentine, 4; 3 mi. S Valentine, 12;
+    8 mi. S Nenzel, 2; Niobrara River, 10 mi. S Cody, 2 (1 USNM); 11 mi.
+    S, 2 mi. W Nenzel, 1; 18 mi. NW Kennedy, 8 (2 NSM, 6 USNM); Two Mile
+    Lake, 6 (4 NSM, 2 USNM); Watt's Lake, Valentine Nat'l Wildlife
+    Refuge, 3; Hackberry Lake, 12 (UMMZ); 2 mi. W to 4 mi. E Kennedy, 25
+    (4 UMMZ, 12 USNM); no specific locality, 1 (USNM). _Cheyenne
+    County_: 15 mi. S Dalton, 4300 ft., 1; 3 mi. N Sidney, 6; 4 mi. E
+    Sidney, 42. _Cuming County_: Beemer, 1 (USNM). _Custer County_: 7
+    mi. NW Anselmo, 1 (UMMZ); within 1 mi. Victoria Spring, 9 (UMMZ); 2
+    mi. E Lillian, 1 (UMMZ); Comstock, 1 (NSM); Callaway, 3 (USNM); 6
+    mi. SE Mason City, 1 (UMMZ). _Dawes County_: Wayside, 1; 3 mi. E
+    Chadron, 2; 6 mi. S Chadron, 1 (NSM); 8 mi. S Chadron, 1 (NSM); 10
+    mi. S Chadron, 1 (UMMZ); 1 mi. W Crawford, 2 (NSM); Crawford, 2
+    (UMMZ). _Dawson County_: 1/2 mi. S Gothenburg, 5; 3 mi. SSE
+    Gothenburg, 4. _Deuel County_: 1 mi. N, 2 mi. W Chappell, 3. _Dixon
+    County_: 3 mi. NE Ponca, 4. _Dundy County_: Rock Creek Fish
+    Hatchery, 5 mi. N, 2 mi. W Parks, 42; 2 mi. N, 2 mi. W Haigler, 1;
+    Arikaree River, Parks, 2; 2 mi. SW Benkleman, 7; Haigler, 3 (1 NSM,
+    2 USNM). _Franklin County_: 1-1/2-2 mi. S Franklin, 10. _Gage
+    County_: 1 mi. SE DeWitt, 3; 1/4 mi. W Homestead Nat'l Mon., 1; 1
+    mi. S, 1 mi. W Barnston, 1; 1-1/2 mi. S, 2 mi. E Barnston, 18.
+    _Garden County_: Crescent Lake Nat'l Wildlife Refuge, 1; 1/2 mi. S
+    Oshkosh, 1. _Hall County_: 6 mi. S Grand Island, 5. _Harlan County_:
+    1 mi. W Alma, 17. _Hitchcock County_: Republican River, Trenton, 3.
+    _Hooker County_: Kelso, 3 (UMMZ). _Holt County_: 6 mi. N Midway, 4;
+    1 mi. S Atkinson, 4 (2 NSM); Ewing, 1 (USNM). _Jefferson County_: 7
+    mi. S, 2 mi. W Fairbury, 6; 3 mi. S, 1 mi. W Endicott, 1. _Johnson
+    County_: 1 mi. S, 1-1/2 mi. E Burr, 1. _Kearney County_: 1-3/4-3-3/4
+    mi. S Kearney, 6. _Keith County_: 4 mi. WNW Keystone, 69. _Keya Paha
+    County_: 12 mi. N Springview, 8; 12 mi. NNW Springview, 5. _Kimball
+    County_: 3 mi. E Kimball, 1; Smeed, 40. _Knox County_: 3 mi. W
+    Niobrara, 2; 1 mi. SE Niobrara, 5; 2 mi. S Niobrara, 2; Verdigre, 2
+    (USNM). _Lancaster County_: within 5 mi. Lincoln, 21 (8 NSM).
+    _Lincoln County_: 2 mi. N North Platte, 1; Conroy Canyon, SW corner
+    sec. 4, T. 11 N, R. 27 W (5 mi. S, 2-1/2 mi. W Brady), 2 (NSM).
+    _Logan County_: 1-2 mi. NE Stapleton, 11. _Madison County_: Norfolk,
+    1 (USNM). _Morrill County_: 1 mi. N Bridgeport, 4. _Nemaha County_:
+    2 mi. SW Peru, 6; 3 mi. S, 1-1/2 mi. E Peru, 2. _Nuckolls County_: 2
+    mi. WSW Superior, 5; 1 mi. SSW Hardy, 9. _Otoe County_: 1 mi. SE
+    Nebraska City, 3; 3 mi. S, 2 mi. E Nebraska City, 3. _Pawnee
+    County_: Turkey Creek, 4 mi. NW Pawnee City, 2 (NSM); 4 mi. S, 8 mi.
+    W Pawnee City, 7; 1 mi. S Du Bois, 4. _Platte County_: Columbus, 3
+    (USNM). _Polk County_: 15 mi. W Osceola, 2. _Red Willow County_: 5
+    mi. S, 2-1/2 mi. E McCook, 2; 8 mi. S, 3 mi. E McCook, 2.
+    _Richardson County_: 5 mi. N, 2 mi. W Humboldt, 2 (1 NSM); 4 mi. E
+    Barada, 16; 3-1/2 mi. S, 1 mi. W Dawson, 6; 2 mi. N Falls City, 2;
+    4-6 mi. W Falls City, 4; 1/2 mi. S, 1-1/2 mi. W Rulo, 1. _Saline
+    County_: 2 mi. NE Crete, 1; 1/2 mi. W DeWitt, 1. _Sarpy County_: 1
+    mi. W Meadow, 1. _Saunders County_: 2 mi. NW Ashland, 3. _Scotts
+    Bluff County_: 8 mi. NNW Scottsbluff, 1; Mitchell, 1 (NSM); 1/2-1
+    mi. S Mitchell, 13; 5 mi. S Gering, 10; 7 mi. S Gering, 1; 11-12 mi.
+    S Scottsbluff, 4600-4800 ft., 8; 12 mi. SSW Scottsbluff, 4700 ft.,
+    5. _Sioux County_: 1 mi. S, 4 mi. W Orella, 1 (NSM); 8 mi. N
+    Harrison, 2 (UMMZ); 6-1/2-7 mi. W Crawford, 3 (1 NSM); 8 mi. N, 1
+    mi. E Glen, 1 (NSM); 3 mi. NE Glen, 1 (NSM); Glen, 3 (NSM); Agate,
+    4600 ft., 1. _Stanton County_: 1-1/2 mi. S Pilger, 3; 6 mi. SE
+    Norfolk, 1. _Thomas County_: 1 mi. W Halsey, 2; Halsey, 1 (NSM).
+    _Thurston County_: 1 mi. S Winnebago, 8. _Valley County_: 2 mi. W
+    Ord, 1; 2 mi. S, 4 mi. E Ord, 6. _Washington County_: 1 mi. E Blair,
+    6; 3 mi. SE Blair, 2; 6 mi. SE Blair, 7; 3 mi. S, 2 mi. E Ft.
+    Calhoun, 1 (NSM). _Wayne County_: 1/2 mi. W-2-1/2 mi. E Wayne, 3.
+    _Webster County_: 3 mi. S Red Cloud, 2.
+
+    SOUTH DAKOTA. _Buffalo County_: 2 mi. S, 3 mi. E Ft. Thompson, 1370
+    ft., 4. _Clay County_: 2-1/2 mi. N, 1/2 mi. W Vermillion, 1.
+    _Pennington County_: 2 mi. S, 3 mi. W Scenic, 1. _Stanley County_:
+    1.2 mi. S, 4 mi. W Ft. Pierre, 1484 ft., 1.
+
+    WYOMING. _Albany County_: 27 mi. N, 8 mi. E Laramie, 6420 ft., 2.
+    _Big Horn County_: 7-1/2 mi. E Graybull, 4050 ft., 1; 7 mi. S, 1/2
+    mi. E Basin, 3900 ft., 1. _Campbell County_: 4 mi. N, 3 mi. E
+    Rockypoint, 3800 ft., 3; 1-3/5 mi. N, 3/4 mi. E Rockypoint, 2;
+    Rockypoint, 5; 5 mi. S, 4 mi. W Rockypoint, 1; Ivy Creek, 5 mi. N, 8
+    mi. W Spotted Horse, 2. _Crook County_: 1-1/2 mi. NW Sundance, 5000
+    ft., 3. _Fremont County_: 2 mi. N, 3 mi. W Shoshoni, 4650 ft., 1;
+    3/10 mi. NW Milford, 5357 ft., 1; Milford, 5400 ft., 1. _Hot Springs
+    County_: 3 mi. N, 10 mi. W Thermopolis, 4900-4950 ft., 7. _Johnson
+    County_: 1 mi. W, 8/10 mi. S Buffalo, 4800 ft., 5; 6-1/2 mi. W, 2
+    mi. S Buffalo, 5620 ft., 4; 1 mi. WSW Kaycee, 4700 ft., 8. _Laramie
+    County_: Horse Creek, 5000 ft., 3 mi. W Meriden, 1; 1 mi. N, 1/2 mi.
+    W Pine Bluffs, 5040 ft., 4; 1 mi. S Pine Bluffs, 5100 ft., 1; 2 mi.
+    S Pine Bluffs, 5200 ft., 2. _Natrona County_: 1 mi. NE Casper, 5150
+    ft., 1; 2-1/4 mi. W Casper, 5250 ft., 1; 7 mi. S, 2 mi. W Casper,
+    6370 ft., 1. _Niobrara County_: 2 mi. S, 1/2 mi. E Lusk, 5000 ft.,
+    1. _Park County_: 4 mi. N Garland, 2; 13 mi. N, 1 mi. E Cody, 5200
+    ft., 2; 6/10 mi. S, 3-2/10 mi. E Cody, 5020 ft., 1. _Platte County_:
+    2-1/2 mi. S Chugwater, 5300 ft., 4. _Sheridan County_: 3 mi. WNW
+    Monarch, 3800 ft., 4; 5 mi. NE Clearmont, 3900 ft., 6. _Washakie
+    County_: 1 mi. N, 3 mi. E Tensleep, 4350 ft., 5.
+
+
+TABLE 2. CRANIAL MEASUREMENTS OF TWO SUBSPECIES OF REITHRODONTOMYS
+MEGALOTIS.
+
+Key to Table Headings:
+
+A =NUMBER AVERAGED AND SEX
+B = Greatest length of skull
+C = Zygomatic breadth
+D = Breadth of braincase
+E = Interorbital breadth
+F = Depth of cranium
+G = Length of rostrum
+H = Breadth of rostrum
+I = Length of incisive foramen
+J = Length of palate
+K = Alveolar length of maxillary tooth-row
+--------------------------+----+----+----+---+---+---+---+---+---+----
+          A               | B  | C  | D  | E | F | G | H | I | J |  K
+--------------------------+----+----+----+---+---+---+---+---+---+----
+_R. m. dychei_, Douglas County, Kansas
+
+Av. 17 (11 male, 6 female)|20.9|10.5|10.1|3.1|7.9|7.2|3.8|4.3|3.5|3.3
+Minimum                   |20.4|10.0| 9.8|3.0|7.7|6.8|3.6|4.0|3.2|3.1
+Maximum                   |21.9|10.9|10.3|3.3|8.2|7.9|4.0|4.5|3.9|3.4
+--------------------------+----+----+----+---+---+---+---+---+---+----
+Cherry County, Nebraska
+
+Av. 20 (14 male, 6 female)|21.0|10.9|10.3|3.1|7.9|7.3|3.8|4.4|3.6|3.5
+Minimum                   |20.4|10.0| 9.8|2.9|7.5|6.8|3.5|4.3|3.4|3.2
+Maximum                   |22.1|11.3|10.7|3.3|8.4|7.8|4.1|4.7|3.9|3.7
+--------------------------+----+----+----+---+---+---+---+---+---+----
+_R. m. aztecus_, San Juan County, New Mexico, and Montezuma County,
+Colorado
+
+Av. 10 (6 male, 4 female) |21.5|10.8|10.2|3.1|8.1|7.7|3.7|4.5|3.4|3.5
+Minimum                   |20.5|10.4| 9.9|2.9|7.9|7.2|3.5|3.9|3.1|3.2
+Maximum                   |22.7|11.1|10.6|3.3|8.4|8.2|3.9|4.8|3.7|3.7
+--------------------------+----+----+----+---+---+---+---+---+---+----
+
+
+
+
+LITERATURE CITED
+
+
+ALLEN, J. A.
+
+    1893. List of mammals collected by Mr. Charles P. Rowley in the San
+          Juan region of Colorado, New Mexico and Utah, with
+          descriptions of new species. Bull. Amer. Mus. Nat. Hist,
+          5:69-84, April 28.
+
+    1895. On the species of the genus Reithrodontomys. Bull. Amer. Mus.
+          Nat. Hist, 7:107-143, May 21.
+
+BENSON, S. B.
+
+    1935. The status of Reithrodontomys montanus (Baird). Jour. Mamm.,
+          16:139-142, 1 fig., May 15.
+
+BLAIR, W. F.
+
+    1954. Mammals of the Mesquite Plains Biotic District in Texas and
+          Oklahoma, and speciation in the central grasslands. Texas
+          Jour. Sci., 6:235-264, 1 fig., September.
+
+DALQUEST, W. W.
+
+    1948. Mammals of Washington. Univ. Kansas Publ., Mus. Nat. Hist.,
+          2:1-444, 140 figs., April 9.
+
+HALL, E. R., and K. R. KELSON
+
+    1959. The mammals of North America. Ronald Press, New York, vols.
+          1:xxx + 1-546 + 79 and 2:viii + 547-1083 + 79, 553 figs., 500
+          maps, 178 unnumbered text figs., March 31.
+
+HILL, J. E., and C. W. HIBBARD
+
+    1943. Ecological differences between two harvest mice
+          (_Reithrodontomys_) in western Kansas. Jour. Mamm., 24:22-25,
+          February 20.
+
+HOFFMEISTER, D. F., and J. E. WARNOCK
+
+    1955. The harvest mouse (Reithrodontomys megalotis) in Illinois and
+          its taxonomic status. Trans. Illinois Acad. Sci., 47:161-164,
+          1 fig.
+
+HOOPER, E. T.
+
+    1952. A systematic review of the harvest mice (genus
+          Reithrodontomys) of Latin America. Misc. Publ. Mus. Zool.,
+          Univ. Michigan, 77: 1-255, 9 pls., 24 figs., 12 maps, January
+          16.
+
+HOWELL, A. H.
+
+    1914. Revision of the American harvest mice (genus Reithrodontomys).
+          N. Amer. Fauna, 36:1-97, 7 pls., 6 figs., June 5.
+
+    1935. The harvest mice of the San Luis Valley, Colorado. Jour.
+          Mamm., 16:143-144, May 15.
+
+LAYNE, J. N.
+
+    1959. Growth and development of the eastern harvest mouse,
+          Reithrodontomys humulis. Bull. Florida State Mus., 4:61-82, 5
+          figs., April 27.
+
+VERTS, B. J.
+
+    1960. Ecological notes on _Reithrodontomys megalotis_ in
+          Illinois. Nat. Hist. Misc., Chicago Acad. Sci., 174:1-7, 1
+          fig., July 25.
+
+
+_Transmitted March 30, 1961._
+
+
+
+
+
+
+End of the Project Gutenberg EBook of Geographic Variation in the Harvest
+Mouse, Reithrodontomys megalotis, On the Central Great Plains And in Adjacent Regions, by J. Knox Jones and B. Mursaloglu
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