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                  Subspeciation in the Kangaroo Rat,
                           Dipodomys ordii

                                 BY
                           HENRY W. SETZER


                  University of Kansas Publications
                      Museum of Natural History

    Volume 1, No. 23, pp. 473-573, 27 figures in text, 7 tables
                          December 27, 1949


                        University of Kansas
                              LAWRENCE
                                1949




   UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY

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

    Volume 1, No. 23, pp. 473-573, 27 figures in text, 7 tables

                         December 27, 1949


                       UNIVERSITY OF KANSAS
                         Lawrence, Kansas


                            PRINTED BY
                 FERD VOILAND, JR., STATE PRINTER
                          TOPEKA, KANSAS
                               1949

                              22-6114




                Subspeciation in the Kangaroo Rat,
                         Dipodomys ordii

                               By

                         HENRY W. SETZER




CONTENTS


                                                 PAGE

  Introduction                                    477

  Methods and Acknowledgments                     478

  Paleontology                                    480

  Phylogeny of the Species of the Genus           484

  Dispersal of the Several Species                498

  Subspeciation                                   499

  Accounts of Subspecies                          511
      _Dipodomys ordii_                           511
          _Dipodomys ordii richardsoni_           511
          _Dipodomys ordii oklahomae_             514
          _Dipodomys ordii compactus_             515
          _Dipodomys ordii sennetti_              517
          _Dipodomys ordii evexus_                518
          _Dipodomys ordii medius_                519
          _Dipodomys ordii obscurus_              521
          _Dipodomys ordii terrosus_              523
          _Dipodomys ordii fremonti_              524
          _Dipodomys ordii uintensis_             525
          _Dipodomys ordii sanrafaeli_            526
          _Dipodomys ordii panguitchensis_        527
          _Dipodomys ordii monoensis_             528
          _Dipodomys ordii ordii_                 530
          _Dipodomys ordii luteolus_              533
          _Dipodomys ordii extractus_             534
          _Dipodomys ordii chapmani_              536
          _Dipodomys ordii montanus_              538
          _Dipodomys ordii cinderensis_           540
          _Dipodomys ordii fetosus_               541
          _Dipodomys ordii utahensis_             543
          _Dipodomys ordii columbianus_           544
          _Dipodomys ordii idoneus_               546
          _Dipodomys ordii priscus_               547
          _Dipodomys ordii celeripes_             549
          _Dipodomys ordii cineraceus_            550
          _Dipodomys ordii marshalli_             551
          _Dipodomys ordii inaquosus_             552
          _Dipodomys ordii attenuatus_            553
          _Dipodomys ordii fuscus_                555
          _Dipodomys ordii longipes_              556
          _Dipodomys ordii pallidus_              558
          _Dipodomys ordii nexilis_               559
          _Dipodomys ordii cupidineus_            561
          _Dipodomys ordii palmeri_               562

  Conclusions                                     563

  Tables of Measurements                          565

  Literature Cited                                571




INTRODUCTION


The geographic range of the kangaroo rats, genus _Dipodomys_, extends
from southern Canada south to the southern limits of the Mexican
Tableland and from the Pacific Coast east to the eastern limits of the
Great Plains in Kansas, Oklahoma and Nebraska. These animals are usually
restricted to sandy soils in semiarid regions. The species _Dipodomys
ordii_, with which this account is primarily concerned, is, to the best
of my knowledge, almost exclusively confined to sandy areas.

Since 1841, when Gray gave the generic name _Dipodomys_ to the kangaroo
rats, basing the name on the four-toed species _Dipodomys phillipsi_,
several other generic names have been applied. Fitzinger, in 1867, used
the name _Perodipus_ for those animals with five toes on the hind foot,
designating _Dipodomys agilis_ as the type of his genus. In 1890,
Merriam proposed the generic name _Dipodops_ with _Dipodomys agilis_ as
the type, apparently being unaware of Fitzinger's name, _Perodipus_.
Trouessart, in 1897, through what was an apparent _lapsus calami_,
applied the generic name _Cricetodipus_ Peale to all of the species of
the then known genera _Perodipus_ and _Dipodomys_, but Trouessart later,
1904 or 1905, in his Supplementum, corrected this _lapsus_ and used the
names _Dipodomys_ and _Perodipus_. Grinnell (1919:203) showed that some
of the four-toed _Dipodomys_ had five toes on one hind foot and four on
the other and that _Perodipus_ must fall as a synonym of the earlier
generic name _Dipodomys_ which was to be applied to all of the kangaroo
rats.

_Dipodomys ordii_ was named by Woodhouse in 1853, from specimens from El
Paso, Texas, but between that time and 1919 the name _ordii_ was used in
combination with all of the generic names mentioned above (see
synonymies under the accounts of the subspecies).

The nearest approach to a revision of the genus was Grinnell's (1922) "A
Geographical Study of the Kangaroo Rats of California." Since that time,
Hall and Dale (1939) revised the _D. microps_ group and Durrant and
Setzer (1945) reported upon the kangaroo rats of Utah. The present paper
is a review of the species _Dipodomys ordii_. Some of the objectives in
this review have been to learn: (1) What kinds of kangaroo rats are
subspecies of the species _Dipodomys ordii_; (2) the limits of
geographic range of this full species; (3) the extremes of color, and of
size and shape of the skull in this one species; (4) the significance
of different sizes, shapes and colors; (5) the reasons for the
existence, or formation, of selected subspecies; and (6) the
relationships of _Dipodomys ordii_ to other species in the genus.




METHODS AND ACKNOWLEDGMENTS


Available specimens were arranged according to geographic origin. These
were segregated as to sex and then under each sex by age. Individual
variation was next measured in each of several samples in which
individuals were of like geographic origin, sex, age and season.
Finally, comparable materials were arranged geographically for detection
of variations of systematic worth. Following preliminary studies of
material thus arranged, additional specimens were collected from
critical areas.

When fully adult animals (see next paragraph) were segregated as to sex,
and then measured, the degree of secondary sexual variation was found to
be less than the degree of individual variation; therefore in the tables
of indices, no distinction as to sex has been made.

The only external measurements of the animals used were those recorded
by the collectors on the labels attached to the skins. These
measurements were total length, length of tail and length of hind foot.
Measurements of the ear have not been used since they were not in all
instances recorded by collectors and since measurements of dry ears
proved to be unsatisfactory. Only measurements of fully adult specimens
have been used. The term fully adult is applied only to those specimens
in which the auditory bulla is shiny and translucent, the permanent P4
is fully erupted and worn, and the tail is fully striped and
penicillate. No one of these characters alone was accepted as proof of
adulthood but only the three in combination.

The following measurements of the skull have been used in the tables:

      _Greatest length._--From the most anterior tip of the nasals to
      the most posterior projection of the auditory bullae.

      _Greatest breadth across bullae._--From the most lateral
      projection of the auditory bulla on one side to the corresponding
      position on the other bulla.

      _Breadth across maxillary arches._--Greatest breadth across arches
      in a plane perpendicular to the long axis of the skull.

      _Width of rostrum._--Width of the premaxillae and the nasals taken
      immediately anterior to the upper incisors (not greatest width of
      nasals which is attained farther anteriorly).

      _Length of nasals._--Maximum length of a nasal bone.

      _Least interorbital breadth._--Least width between the orbits
      immediately posterior to the lacrimal processes.

      _Basilar length._--From the anterior margin of the foramen magnum
      to the posterior border of the alveolus of one of the upper
      incisors.

Capitalized color terms are from Ridgway, "Color Standards and Color
Nomenclature," Washington, D. C., 1912. Color determinations were made
by comparing a masked area of pure color on the side of the animal with
a masked rectangle of named color on Ridgway's plates in natural light
always from the same angle.

Abbreviations used for specimens examined from the various collections
are as follows:

  AMNH--American Museum of Natural History.
  BYU--Brigham Young University.
  CNHM--Chicago Natural History Museum.
  CM--Carnegie Museum.
  CMNH--Colorado Museum of Natural History.
  DJC--Dixie Junior College.
  DRD--Donald R. Dickey Collection.
  KU--Museum of Natural History, University of Kansas.
  LACM--Los Angeles County Museum.
  MHS--Collection of Myron H. Swenk.
  MVZ--Museum of Vertebrate Zoology, University of California.
  OU--Museum of Zoology, University of Oklahoma.
  RH--Collection of Ross Hardy.
  UM--Museum of Zoology, University of Michigan.
  UN--Museum of Natural History, University of Nebraska.
  USAC--Utah State Agricultural College.
  USBS--United States Biological Surveys Collection.
  USNM--United States National Museum.
  UU--Museum of Zoology, University of Utah.
  TCWC--Texas Coöperative Wildlife Collection.

This study is based on 3,732 specimens which were assembled at the
Museum of Natural History, University of Kansas, or studied at other
institutions. For the loan of this material and for the opportunity
afforded for its study, I am extremely grateful to the authorities of
each of these institutions and to the owners of the private collections.

Acknowledgement is made to the Office of Research and Inventions of the
United States Navy for assistance with the field work which permitted
the acquisition of essential specimens from several of the critical
geographic areas while the author was research assistant on a larger
over-all project (N6 ori-164-T02) of which the determination of the
geographic range of this rodent species, a potential host of tularemia,
was one facet. Tularemia was not detected in this genus.

I extend my thanks also to Professor Stephen D. Durrant, of the
University of Utah, for helpful corrections in the preparation of the
manuscript; to Mrs. Virginia Cassell Unruh for the preparation of the
drawings; to Professor E. Raymond Hall, of the University of Kansas, for
guidance in the study and critical assistance with the manuscript; to
Professors H. H. Lane and Worthie H. Horr for valued suggestions; to Mr.
J. R. Alcorn for providing specimens for dissection when he was working
under the University of Kansas endowment fund; and to the other friends
and associates who have given of their time and criticism.




PALEONTOLOGY


The family Heteromyidae was defined by Wood (1935:81) essentially as
follows: Cheek teeth brachydont to hypsodont and even rootless; usually
six cusps per molar, three on each loph; enamel rarely divided into two
plates, never reduced to one; skull light, thin and papery; mastoids
inflated, mastoidal breadth often greatest, never appreciably less than
zygomatic breadth; interorbital space wider than rostrum; palate nearly
horizontal and little if any below level of zygomata; nasals extended
beyond incisors; zygomata slender, with greatly reduced malar, almost,
or quite, abutting against tympanic; frontals and parietals broad, with
latter reaching, or nearly reaching, orbits; frontal trapezoidal;
parietal quadrate, to pentagonal or triangular; interparietal
primitively large, secondarily reduced; squamosal mostly or entirely
confined to orbit; tympanic vesicular and inflated, in some forms highly
inflated; mastoids inflated and bullous, reaching top of skull, and
forming part of occipital surface; occipitals contracted and limited in
area on occiput, but extending onto dorsum of skull; coronoid processes
small, inclined caudad and lying below level of condyle; jaw small and
weak with large, everted angle; tail as long as, or longer than, head
and body; claws of manus elongate, fossorial, but forelimb slender;
pelage usually coarse and frequently spinose; ears and eyes large; body
murine in form; locomotion in many forms saltatorial.

This characterization of the family includes all of the members of the
subfamilies Perognathinae, Heteromyinae and Dipodomyinae as well as the
genus _Microdipodops_ which I am disinclined to place with any of the
three subfamilies. Apparently it is more closely related to the
subfamily Perognathinae.

The subfamily Dipodomyinae, which contains the genera _Dipodomys_,
_Prodipodomys_ and _Cupidinimus_, might be characterized after Coues'
(1875) original description of the subfamily as follows: Cheek teeth
progressively hypsodont, in _Dipodomys_ becoming ever-growing; enamel
progressively interrupted, eventually reduced to anterior and posterior
plates; upper and lower third molars reduced in size; tooth pattern
rapidly destroyed, leaving only an enamel oval; upper incisors smooth
(some fossils) or grooved (living forms); progressive expansion of the
auditory bullae and increase in saltatorial ability; pterygoid fossa
double; calcaneal-navicular or even calcaneal-cuneiform articulation;
tail tufted.

Owing to the fact that so little paleontological material is known and
because even that is fragile and not easily accessible for study,
knowledge of the fossil representatives has been drawn primarily from
the literature, especially from Wood's (1935) account.

Heteromyids are known from the Chadron formation, of early Oligocene
age, in which a single tooth was found. In the Orellan stage of the
mid-Oligocene where the genus _Heliscomys_ occurs, it is notably
generalized, in comparison with other members of the family, but it may
not be ancestral at all. The lower premolar is tricuspidate and the
first and second molars are quadritubercular with a broad cingulum. The
teeth are bunodont and brachydont, with the cusps not uniting to form
lophs. Wood (1935:78) shows _Mookomys formicorum_ (from the Arikeean) as
the next heteromyid in the evolutionary sequence and postulates that
this species arose from _Heliscomys gregoryi_. _Mookomys_ is judged by
Wood to be the common ancestral form of the perognathines and the
dipodomyines.

_Cupidinimus_, the genus next in line, is characterized by smooth upper
incisors; lower molars with incipient H-pattern; cheek teeth
progressively hypsodont and lophate (but always rooted); and
calcaneal-navicular articulation.

The time range of this genus is from the late Miocene (Niobrara River,
Local Fauna) of Nebraska to the medial Pliocene, Thousand Creek
(Hemphillian) of Nevada.

Hibbard (1937:462) described _Dipodomys kansensis_ from the Ogallala
formation (Hemphillian age) of Kansas. He redescribed his species, and
made it the type of the new genus _Prodipodomys_ (Hibbard, 1939:458),
differentiating it from _Dipodomys_ on the basis of the three-rooted p4,
double-rooted m1 and m2 and the single rooted m3. It is shown to be
closely allied to _Dipodomys_ by the form and position of a large
foramen posterior and labial to m3, and by the development of the
masseteric ridge.

The next youngest heteromyid fossils which have been described are of
the genus _Prodipodomys_? from Arizona. Gidley (1922:123) described
_Dipodomys minor_ from the Benson (Blancan) which Gazin (1942:486)
refers to the genus _Prodipodomys_?. Wood (1935:156) described
_Dipodomys gidleyi_ from the Curtis (Pleistocene). Both of these species
are primitive as regards dentition; that is to say, the enamel ring of
the tooth is complete and lacks any sign of a break. The limb bones of
_D. gidleyi_ show lesser saltatorial ability, and therefore appear to be
more primitive, than those of any living _Dipodomys_.

Several heteromyids which have not been assigned to any genus are known.
Wilson (1939:36-37) recognized some from the Avawatz (Clarendonian) and
the Ricardo (Clarendonian). Another, possibly of the genus
_Diprionomys_?, from the Barstow (Barstovian) was described by Wood
(1935:197) as follows: "The general shape of the tooth as figured
strongly suggests either one of the most advanced species of _Dipodomys_
or else a Geomyid.... It is much more advanced than are any known
contemporary heteromyids, and compares fairly well with such late
Tertiary and Pleistocene geomyids as have been described. It certainly
is not referable to any known heteromyid genus other than _Dipodomys_,
and should probably be called a Geomyid." Wilson (_loc. cit._) refers to
these specimens as Dipodomyine (?) n. gen. and sp. If these specimens
referred to by Wood and Wilson are true heteromyids then a change in the
phylogenetic scheme proposed by Wood (1935) would be necessary. Wilson
(_loc. cit._) says, referring to the Avawatz specimen, "The cheek teeth
are very hypsodont but are apparently not persistent in growth,... Wide
enamel breaks are present in M/1 dividing the enamel into anterior and
posterior bands. The enamel of P/4 is complete in the present stage of
wear, but an examination of the tooth indicates that breaks would
develop with additional attrition at the buccal and lingual margins of
the metalophid, and at the buccal border of the protolophid. The incisor
is of the slender heteromyid type."

Wood (1935:118) in referring to the ancestry of _Cupidinimus_ with
regard to the grooving of the incisors says: "The philosophy of
evolution which would prohibit its derivation from _Mookomys_, because
of the grooved incisors in the latter genus, would require a separate
line leading back at least to the Lower Miocene."

In view of the above statements, it is conceivable that additional
material will be found carrying the dipodomyine line back into the
early Miocene. Perhaps the line involving _Mookomys_ and _Cupidinimus_
which was regarded by Wood as the line of descent, is merely an aberrant
side branch that parallels in its structures the main line of evolution
of the dipodomyines (Figure 1).

[Illustration: FIG. 1. Phylogeny of the Dipodomyines (modified after
Wood, 1935).]

As Wilson (1939:37) says: "Indeed it is hard to recognize such a form as
_Cupidinimus nebraskensis_ as directly ancestral to _Dipodomys_ in view
of the occurrence of the much more advanced Avawatz specimen in deposits
that are at most only slightly later than those in which the former is
found. The kangaroo rats were apparently much farther along in their
development by lower Pliocene time than heretofore supposed."

Wood (1935:78) suggested that _Dipodomys gidleyi_ gave rise to
_Dipodomys spectabilis_ and _Dipodomys ordii_, and _Dipodomys minor_
gave rise to _Dipodomys compactus_. However, my own study indicates that
_Dipodomys compactus_ is conspecific with _Dipodomys ordii_ and should
stand as _Dipodomys ordii compactus_. Consequently a different phyletic
arrangement than that proposed by Wood (_loc._ _cit._) is required.
Since _D. compactus_ is more closely allied to _Prodipodomys? minor_
than _D. ordii_ is to _D. gidleyi_, it is possible that _P.? minor_ gave
rise to _D. ordii_ and that _D. spectabilis_ is the end product of the
phyletic trend of _D. gidleyi_ (Figure 1).

The trend of phyletic development in the dipodomyines has been toward
the saltatorial habit. To acquire this habit from a scampering ancestor,
certain morphological modifications were necessary. Among these
modifications were a lengthening of the tail, a lengthening of the hind
legs, the development of a calcaneal-navicular-ectocuneiform contact
instead of a calcaneal-navicular contact for additional strength in
leaping, a shortening of the forelimb, an increase in size and inflation
of the mastoid and tympanic portions of the skull with a consequent
reduction in size of the interparietal region and the fusion of certain
of the cervical vertebrae. Late Miocene (_Cupidinimus_) and Pliocene
(Avawatz specimen and _Prodipodomys_) forms had acquired certain of
these morphological modifications that are present in the modern genus
_Dipodomys_.




PHYLOGENY OF THE SPECIES OF THE GENUS


Representatives of nine species of _Dipodomys_ were dissected in an
attempt to determine the degree of specialization and the relative
systematic position of each species.

The myology was found to agree in detail as to origin, insertion and
innervation with that of _Dipodomys spectabilis_ as reported by Howell
(1932). The only variation noted in the muscular system was the size of
the individual muscles in those animals of widely divergent body size.

_Dipodomys ordii_ is the most generalized and _Dipodomys deserti_ is the
most specialized of the kangaroo rats (see Table 1), as judged by the
osteology. Information gained by the study of the viscera of the various
species supports this judgment. The visceral mass is relatively loose in
_D. ordii_, but is markedly compact in _D. deserti_. This compactness
appears to be brought about by the foreshortening of the mesenteries
which support the entire gut and by the closer apposition of the large
intestine to the caecum; both the intestine and caecum occupy a ventral
position in the abdominal cavity. In _Dipodomys ordii_ the entire
visceral mass is loosely interconnected and the caecum is relatively
small as compared to the tightly compact viscera and the large caecum in
_Dipodomys deserti_. Another striking feature is the size, proportion
and position of the liver. In all animals dissected, even in _D.
deserti_, the right lobe of the liver descends and forms a capsule
around the anterior end of the right kidney. In the Ord kangaroo rat,
the bulk of the liver lies on the right side of the body cavity. That is
to say, there is a greater bulk of the liver on the right side and it is
situated more dorsad than in any of the other species examined. In the
most specialized condition, as in _Dipodomys deserti_, the bulk of the
liver is almost equal on the right and left sides, and instead of having
the greater bulk situated dorsally as in _D. ordii_ it is cup-shaped,
with the dorsal and ventral parts of approximately equal size and
situated on almost the same transverse plane. The entire mass of the
liver is concave posteriorly.


                        TABLE 1

            SKELETAL INDICES OF DIPODOMYS

  ======================================================
                Humeroradial
                 |     Intermembral
                 |      |     Crural
                 |      |      |    Tibioradial
                 |      |      |     |   Femorotarsal-
                 |      |      |     |    | metatarsal
                 |      |      |     |    |      Cranial
                 |      |      |     |    |       |
  ------------------------------------------------------
  ordii        144.5  57.2  127.75 60.55  88.4  63.4

  microps      138.5  56.17 132.3  57.27  90.95 60.8

  panamintinus 146.1  55.3  132.0  57.5   90.5  60.8

  agilis       147.0  55.05 133.65 57.25  94.55 62.65

  heermanni    142.9  54.2  135.9  55.35  92.2  60.93

  ingens       142.9  54.1  130.6  56.2   89.65 66.2

  spectabilis  140.9  53.05 133.9  54.2   95.6  64.6

  phillipsii   163.4  55.05 137.85 58.97 101.5  64.5

  merriami     160.75 53.85 137.5  57.35  99.75 63.9

  nitratoides  155.0  54.1  137.4  57.0   98.25 65.5

  deserti      149.5  53.4  139.4  54.9   96.6  67.6
  ------------------------------------------------------


The right kidney is variable in position in reference to the left. In
all species the right kidney lies anterior to the left but in some, _D.
deserti_ and _D. ingens_, it is markedly anterior.

In _Dipodomys agilis_, _D. merriami_ and _D. deserti_ there are small to
large patches of lymphoid tissue on the caecum. These patches were not
noted in any of the other species examined and I do not know their
function. In the three above mentioned species, however, the large
intestine is shorter in proportion to the small intestine than in any
other species except _D. heermanni_ (see Table 2) and with the exception
of _D. heermanni_, _D. venustus_ and _D. ordii_ the actual measurements
are less.

Inasmuch as little is known of the food habits of the various species of
kangaroo rats, any ascription of adaptive significance to the varying
proportions of the digestive system would be only speculative.

Midgley (1938) describes the visceral anatomy of _D. ordii_ and _D.
microps_. Except for the differences here noted the description of the
viscera as given by Midgley (_loc. cit._) applies to the rest of the
species studied.


                                  TABLE 2

            VISCERAL MEASUREMENTS (in Millimeters) of DIPODOMYS
  =================================================================
  Column Headings:

  H: heermanni
  M: merriami
  A: agilis
  D: deserti
  O: ordii
  S: spectabilis
  V: venustus
  P: panamintinus
  I: ingens

                         H    M    A    D    O    S    V    P    I
  -----------------------------------------------------------------
  Large intestine       432  290  464  397  237  413  374  419  430

  Small intestine       165  126  220  195  131  228  207  255  274

  Percent of small to
    large intestine    38.2 43.4 47.5 49.2 55.2 55.3 55.4 60.9 63.7
  -----------------------------------------------------------------


From the differences noted in the skeleton, in the entire visceral mass,
and in the shape and position of the liver it appears that as a saltator
becomes more specialized skeletally, there is a concurrent compacting
and aligning of the viscera into a more or less bilaterally balanced
mass. It seems that this alignment is for a stabilization in leaping. It
seems reasonable that the individual that has a loose and unconsolidated
visceral mass, or in which the viscera or at least the heaviest part of
the viscera is relatively unilateral, would be thrown slightly off
balance at the end of the jump. This would place the animal at a slight
disadvantage before being able to make the next jump. Howell (1944:40)
comments on the fact that kangaroo rats often land off balance, "owing
apparently to clumsy use of the tail." Possibly the unilaterality of the
visceral mass plus a shorter tail and a more clumsy use of that organ
accounts for the off balance landings which Howell has observed.

The skeleton, particularly of the appendages, shows the most
modification, ranging from a relatively generalized to a specialized
condition. Skeletal indices, as established by Howell (1944:199) have
been used in estimating the amount of such specialization.

These indices are obtained by dividing the length of one segment of a
limb by the length of another segment and are expressed in percentages.
The Femorotarsalmetatarsal and Cranial indices are not from Howell
(_loc. cit._).

The Humeroradial index (radius/humerus ×100) in the generalized animal
is theoretically 100 because the humerus and radius are of the same
length. In kangaroo rats, which are saltators, the index rises to more
than 100 owing to the lengthening of the radial component.

The Intermembral index (humerus and radius/femur and tibia ×100) in a
generalized animal is theoretically 100, but, as Howell (1944:205)
points out, the index in generalized mammals is probably nearer 75. If
the hind leg elongates at the expense of the forelimb the animal will be
a better saltator and the skeletal elements will yield a lower
intermembral index.

The Femorotibial or Crural index (tibia/femur ×100) expresses the
development of the tibia as an adaptation to the saltatorial habit and
in generalized animals would be expected to be 100. As an adaptation to
saltation the tibia would elongate at the expense of the femur and the
index would be more than 100. The degree of divergence from 100 would be
an expression of the degree of saltatorial ability.

The Tibioradial index (radius/tibia ×100) in the generalized animal also
would be expected to approximate 100 but it is doubtful if any living
mammals, except brachiating kinds, yield an index of more than 75. In
saltators, the index is low because of the elongation of the hind
appendages, whereas the forelimbs do not change their length or are
shortened.

The Femorotarsalmetatarsal index (tarsometatarus/femur ×100) in the
generalized condition would be less than 50 and an index approaching 100
would indicate a specialization for saltation owing to the elongation of
the tarsometatarsal elements.

The Cranial index (breadth across bullae/length of skull ×100) reflects
the development of the auditory or mastoid region of the skull as an
adaptation for more acute hearing and possibly for more delicate
balance. In heteromyids, the generalized condition would be represented
by an index of 50 or less, and as the width across the bullae increases,
the index rises toward 100.

[Illustration
    FIGS. 2-10. Showing the compacting of the visceral mass; liver at
    the top, small intestine and caecum at the bottom. All figures
    approximately × 1.

    FIG. 2. _Dipodomys ordii inaquosus_, [M], adult, no. 23365, KU; 7
    mi. W Fallon, Churchill County, Nevada; trapped 27 October, 1945.

    FIG. 3. _Dipodomys panamintinus mohavensis_, [M], adult, no.
    22094, KU; 1-1/2 mi. N Mojave, Kern County, California; 3
    February, 1948.

    FIG. 4. _Dipodomys heermanni morroensis_, [M], adult, no. 22082,
    KU; S side Morro Bay, 4 mi. S Morro, San Luis Obispo County,
    California; 25 January, 1948.

    FIG. 5. _Dipodomys ingens_, [F], adult, no. 22069, KU; 25 mi. SW
    Mendota, San Benito County, California; 2 February, 1948.

    FIG. 6. _Dipodomys agilis perplexus_, [F], adult, no. 22091, KU;
    1-3/10 mi. N Monolith, Kern County, California; 3 February, 1948.

    FIG. 7. _Dipodomys venustus sanctiluciae_, [M], adult, no. 22071,
    KU; 1-1/2 mi. S Jolon, Monterey County, California; 26 January,
    1948.

    FIG. 8. _Dipodomys spectabilis spectabilis_, [F], adult, no.
    22110, KU; 5 mi. NE Willcox, Cochise County, Arizona; 19 January,
    1948.

    FIG. 9. _Dipodomys merriami merriami_, [F], adult, no. 23366, KU;
    E side Carson Lake, Churchill County, Nevada; 2 October, 1945.

    FIG. 10. _Dipodomys deserti deserti_, [M], adult, no. 23364, KU;
    15 mi. WSW Fallon, Churchill County, Nevada; 3 November, 1945.]


                            TABLE 3

    RELATIVE SPECIALIZATIONS OF THE SPECIES FOR EACH INDEX


    Column headings:

    A: Humeroradial
    B: Intermembral
    C: Crural
    D: Tibioradial
    E: Femorotarsalmetatarsal
    F: Cranial
    G: Average

    ==============================================
                     A   B   C   D   E   F    G
    ----------------------------------------------
    ordii            5   1   1   1   1   5   2.33
    microps          1   2   4   5   4   2   3.0
    panamintinus     6   3   3   3   3   1   3.1
    agilis           7   4   5   6   6   4   5.3
    heermanni        3   6   7   9   5   3   5.5
    ingens           4   7   2   8   2  10   5.5
    spectabilis      2  11   6  11   7   8   7.5
    phillipsii      11   5  10   2  11   7   7.6
    merriami        10   9   9   4  10   6   8.0
    nitratoides      9   8   8   7   9   9   8.5
    deserti          8  10  11  10   8  11   9.6
    ----------------------------------------------

     The figure 1 represents the least specialized condition for the
     index, while the figure 11 represents the most specialized
     condition. The remainder of the numbers indicate the relative
     degree of specialization of each species for each index.

The species that have been examined are listed in Table 3 in increasing
order of specialization from top to bottom.

Usually animals of extreme morphological specialization are much
restricted environmentally. Attempts to correlate the relative
evolutionary position of the various species, as indicated by the degree
of specialization interpreted from the indices with that of habitus has
proven unsuccessful. For example, _Dipodomys merriami_, which is third
from the top in the list as arranged above, is neither restricted to
loose sandy soil as is _D. deserti_ nor to brush as are _D. agilis_ and
_D. venustus_. _D. merriami_ does, nevertheless, inhabit a variety of
habitats from loose sandy soils to rather hard rocky ground. Throughout
the genus there is, however, a general trend toward increased
specialization as the animals adopt the more open desert environment, as
is indicated by the elongation of the tail and hind appendage and
increase in size of the auditory region of the skull. A marked
difference is noted in the size of the pinna of the ear in the various
species. Generally, those species having small pinnae inhabit open
desert country while those with large pinnae inhabit brushy country.
This is in direct contradistinction to the hares and rabbits in which
the small-eared kinds are brush dwellers whereas the large-eared kinds
are inhabitants of open country. Three possible explanations for hares
and rabbits having this specialization of the pinnae are: (1) To enable
the open-dwelling animals with the larger pinnae to hear more readily
the approach of an enemy when it is yet far away, while the brush-living
forms, which rely for escape on a short dash into cover, do not need so
large a "funnel"; (2) large pinnae have been developed by those animals
which live in the open desert as an aid in dissipating the body heat;
(3) large pinnae in brush-dwelling animals would be a decided
disadvantage in rapid movement through the brush. Grinnell (1922:20)
points out that animals with large pinnae usually have small auditory
bullae and conversely, animals with small pinnae have large bullae. This
compensatory factor, implying an auditory function, appears to be
inoperative in _D. panamintinus mohavensis_ which has small ears and
small bullae and in _D. elephantinus_ which has large ears and large
auditory bullae. Grinnell (_loc. cit._) suggests that several additional
factors enter into the problem, such as the amount of digging each
species must do to gain safety, the texture of the soil for burrowing,
the extent of forage area and the type of cover in connection with the
mode of attack of predators. Of these factors, perhaps the most
important are the two first mentioned.

[Illustration: FIGS. 11-15. Ventral views of skulls showing the degree
of development of the auditory bullae and the configuration of the
pterygoid fossae. All figures approximately × 1.

    FIG. 11. _Dipodomys ordii compactus_, [M], adult, no. 646, TCWC;
    19 mi. S Port Aransas, Mustang Island, Nueces County, Texas;
    24 April, 1939.

    FIG. 12. _Dipodomys ordii oklahomae_, [F], adult, no. 265456,
    USBS; 2-1/4 mi. S Norman, Cleveland County, Oklahoma; 21 March,
    1934.

    FIG. 13. _Dipodomys ordii richardsoni_, [F], adult, no. 15995, KU;
    1 mi. S Lamar, Prowers County, Colorado; 8 September, 1945.

    FIG. 14. _Dipodomys ordii nexilis_, [F], adult, no. 149941, USBS;
    5 mi. W. Naturita, Montrose County, Colorado; 20 July, 1907.

    FIG. 15. _Dipodomys deserti deserti_, [F], adult, no. 18670, KU;
    14 mi. WSW Fallon, Churchill County, Nevada; 3 November, 1945.]

[Illustration: FIGS. 16-20. Dorsal views of skulls showing the degrees
of inflation of the auditory bullae and the correlation of large bullae
with small interparietal. All figures approximately × 1.

    FIG. 16. _Dipodomys ordii compactus_, for data see Fig. 11.

    FIG. 17. _Dipodomys ordii oklahomae_, for data see Fig. 12.

    FIG. 18. _Dipodomys ordii richardsoni_, for data see Fig. 13.

    FIG. 19. _Dipodomys ordii nexilis_, for data see Fig. 14.

    FIG. 20. _Dipodomys deserti deserti_, for data see Fig. 15.]

Wood (1935:155), on the basis of structure of the teeth, listed the
species which he examined in the following increasing order of
specialization: _Dipodomys compactus_ (now _Dipodomys ordii compactus_),
_D. nitratoides_, _D. merriami_, _D. ordii_, _D. agilis_, _D.
herrmanni_, _D. spectabilis_, and _D. deserti_. This arrangement is at
variance with that of Grinnell (1922) who listed the species in order of
increasing specialization as: _Dipodomys herrmanni_, _D. panamintinus_,
_D. ingens_, _D. spectabilis_, _D. merriami_, _D. nitratoides_, _D.
ordii_, _D. agilis_, _D. venustus_, _D. microps_ and _D. deserti_. As
noted, the only agreement between the two arrangements is the placing of
_D. deserti_ as the most specialized. Relying on skeletal indices alone,
I would accord the same position to _D. deserti_ but would not arrange
the other species as have either Wood or Grinnell.

In this study, the amount of specialization of each species, as
indicated by the skeleton, was determined by assigning consecutive
numbers from 1 to 11 to each species in its place in each index, and
then totaling and averaging these arbitrary numbers (Table 3). It will
be noted that there is a tendency for each species to occupy the same
relative position in each of the indices.

It is felt, however, that a more nearly correct arrangement, according
to degree of specialization, is obtained by using the six skeletal
indices plus the information obtained from the study of the viscera. On
this basis the species may be arranged from least to most specialized as
follows: _Dipodomys ordii_, _D. microps_, _D. panamintinus_, _D.
agilis_, _D. herrmanni_, _D. ingens_, _D. spectabilis_, _D. phillipsii_,
_D. merriami_, _D. nitratoides_ and _D. deserti_.

Grinnell (1922:95-96) arranged the Recent species of _Dipodomys_ in nine
groups. Davis (1942:332) also proposed an arrangement of nine groups in
which he combined the Compactus and Ordii groups of Grinnell,
established a new Elator group by removing _Dipodomys elator_ from
Grinnell's Phillipsii group, and in linear arrangement, Davis shifted
the Spectabilis and what remained of the Phillipsii groups to new
positions. Burt (1936:152) arranged Grinnell's groups into three
(unnamed) groups solely on the basis of the structure of the baculum. In
the arrangement proposed by Grinnell, two of his nine groups contained
only one species each, one other, the Microps group, has since been
shown to contain only one species and another, the Compactus group,
contained only kinds which are, by me, regarded only as subspecies of
_Dipodomys ordii_. To my mind neither Davis nor Burt added to or
fundamentally changed the basic concepts as set forth in 1922 by
Grinnell. Owing to the paucity of material at that time, especially
from areas of intergradation, Grinnell's groupings and arrangement were
as nearly natural as could be expected. With the accumulation of
additional material and with the knowledge that certain kinds treated by
Grinnell as full species are in actuality subspecies, it is felt that
the several species of kangaroo rats can best be arranged in six groups
which, from the least to the most specialized, are as follows:

    ORDII GROUP.--Composed of the subspecies of _Dipodomys ordii_ and
    _Dipodomys microps_. Grinnell placed these two species in separate
    groups; Burt on characters of the baculum alone placed _D. microps_
    with _Dipodomys deserti_ and _Dipodomys spectabilis_. Within the
    single species _D. ordii_, I find that the difference in shape and
    size of the baculum between the subspecies of _D. ordii_ is as
    great as the difference which Burt (1936:154-155) found between the
    full species _D. agilis_ and _D. microps_. The characters of the
    baculum are an aid, but not in and of themselves an adequate basis,
    for determining the natural relationships of the groups of species.
    Certainly the remainder of the morphological differences between
    _D. deserti_ and _D. microps_ are so great that I doubt that the
    similarity in the baculum is significant, at least in this one
    instance. The chisel-shaped lower incisors of _D. microps_ appear
    to be a specialization. They may enable _D. microps_ to utilize
    more woody types of vegetation than can _D. ordii_. Both species
    occupy the same territory over much of their geographic range,
    probably because they eat different kinds of food.

    PANAMINTINUS GROUP.--Composed of all the now known subspecies of
    _Dipodomys panamintinus_ and the species _Dipodomys stephensi_, if
    the latter is a full species. This group was included by Grinnell
    in the Heermanni group, with which it agrees in broadness of the
    maxillary arches and the configuration of the penis bone, but on
    the basis of the degree of specialization, as indicated by the
    indices (see Table 1), I feel that the Panamintinus group is more
    properly placed after the Ordii group and should be separated from
    the Heermanni group. Actually, animals in the Panamintinus group
    are intermediate between those of the Ordii and Heermanni groups.

    HEERMANNI GROUP.--Composed of the subspecies of _Dipodomys
    heermanni_ and _Dipodomys agilis_, the species _Dipodomys ingens_,
    _Dipodomys venustus_ and _Dipodomys elephantinus_. _D._ _ingens_
    even though larger in linear measurements than any of the other
    kinds included in this group, has almost the same degree of
    specialization as does _D. heermanni_. _D. agilis_, even though
    somewhat less specialized than the other kinds placed in this
    group, by the general nature of the indices, by the form of the
    visceral mass and to some degree by the shape of the baculum, shows
    itself properly to belong with this group. The species _D.
    venustus_, judged by characters of the visceral anatomy, also
    belongs here rather than with some other group or as a separate
    group. From the appearance of the visceral mass, _D. venustus_ is
    somewhat more specialized than either _D. heermanni_ or _D.
    agilis_, but _D. venustus_ does show its affinities with this
    group. The species _D. elephantinus_ has not been examined as
    thoroughly as have the other species but the external morphology
    and the configuration of the cranium place it with this group.

    SPECTABILIS GROUP.--Composed of the subspecies of _Dipodomys
    spectabilis_. In two of the six indices, _D. spectabilis_ shows a
    high degree of specialization toward saltation, but in the other
    four indices it shows a relatively low degree of specialization or
    is average for the genus. Burt (1936:155) placed _D. spectabilis_
    with _D. deserti_ on the basis of the baculum alone. I have not
    examined _D. nelsoni_ but place it with this group as did also
    Grinnell and Davis.

    MERRIAMI GROUP.--Composed of the subspecies of _Dipodomys
    merriami_, _Dipodomys nitratoides_ and _Dipodomys phillipsii_, and
    the species _Dipodomys platycephalus_, _Dipodomys margaritae_,
    _Dipodomys insularis_, _Dipodomys mitchelli_, _Dipodomys ornatus_
    and _Dipodomys elator_. I have not examined five of these species.
    However, the indices and characters of the viscera indicate that
    the three species first mentioned are closely allied. Owing to the
    lack of known intergradation between the three, I judge that they
    should be retained as full species, but the difference in degree
    of morphological specialization is no more than would be expected
    between subspecies. I have examined no specimens of _Dipodomys
    elator_ but from what I know of its morphology, I think that
    Grinnell better indicated its relations in allying it with _D.
    phillipsii_ than did Davis in erecting a new group for it on the
    basis of linear measurements.

    DESERTI GROUP.--Composed of _Dipodomys deserti_ which has only two
    subspecies. In all morphological respects, _D. deserti_ is the
    most specialized species in the genus as shown by the reduced
    number (4) of toes on the hind foot, the bilateral arrangement of
    the viscera, the extreme development of the auditory region of the
    skull and by developing, early in life, the hiatus in the enamel
    wall of each molariform tooth.

The parallel arrangement below emphasizes the differences and
similarities between Grinnell's (1922) arrangement and the one proposed
in the present paper.


      Grinnell's arrangement               Present arrangement

         HEERMANNI GROUP                    HEERMANNI GROUP
  _Dipodomys heermanni_                  _Dipodomys heermanni_
  _Dipodomys morroensis_                 _Dipodomys agilis_
  _Dipodomys mohavensis_                 _Dipodomys ingens_
  _Dipodomys leucogenys_                 _Dipodomys venustus_
  _Dipodomys panamintinus_               _Dipodomys elephantinus_
  _Dipodomys stephensi_
  _Dipodomys ingens_

         SPECTABILIS GROUP                  SPECTABILIS GROUP
  _Dipodomys spectabilis_                _Dipodomys spectabilis_
  _Dipodomys nelsoni_                    _Dipodomys nelsoni_

         PHILLIPSII GROUP               NOW IN MERRIAMI GROUP BELOW
  _Dipodomys phillipsii_
  _Dipodomys perotensis_
  _Dipodomys ornatus_
  _Dipodomys elator_

          MERRIAMI GROUP                     MERRIAMI GROUP
  _Dipodomys merriami_                   _Dipodomys merriami_
  _Dipodomys nitratoides_                _Dipodomys nitratoides_
  _Dipodomys platycephalus_              _Dipodomys platycephalus_
  _Dipodomys margaritae_                 _Dipodomys margaritae_
  _Dipodomys insularis_                  _Dipodomys insularis_
  _Dipodomys mitchelli_                  _Dipodomys mitchelli_
                                         _Dipodomys phillipsii_
                                         _Dipodomys ornatus_
                                         _Dipodomys elator_

            ORDII GROUP                        ORDII GROUP
  _Dipodomys ordii_                      _Dipodomys ordii_
                                         _Dipodomys microps_

          COMPACTUS GROUP                NOW IN ORDII GROUP ABOVE
  _Dipodomys compactus_
  _Dipodomys sennetti_

           AGILIS GROUP                NOW IN HEERMANNI GROUP ABOVE
  _Dipodomys agilis_
  _Dipodomys venustus_
  _Dipodomys elephantinus_

          MICROPS GROUP                  NOW IN ORDII GROUP ABOVE
  _Dipodomys microps_
  _Dipodomys levipes_

          DESERTI GROUP                       DESERTI GROUP
  _Dipodomys deserti_                    _Dipodomys deserti_

  WERE IN HEERMANI GROUP ABOVE              PANAMINTINUS GROUP
                                         _Dipodomys panamintinus_
                                         _Dipodomys stephensi_


Names of the subspecies are omitted from the groups named above and only
the names of full species, as understood by Grinnell and as understood
now, have been used. It will be noted that the phylogenetic order
follows that of Grinnell rather than the one proposed herein.

The fossil record of the kangaroo rats is so scanty that one can but
speculate on the evolutionary sequence. Wood (1935) presented a
diagnosis of the early phyletic history up to and through _Cupidinimus_;
this is probably as correct as can be made. I cannot, however, share his
view that the recent species of _Dipodomys_ have originated from a
descendant of _Cupidinimus nebraskensis_; instead, I think that the
Recent species originated from some unknown ancestor in the southwest.

[Illustration: FIG. 21. Diagrammatic representation of the relationships
and history of the Recent species _Dipodomys_.]

In view of the foregoing evidence it seems best to estimate the
relationships and history of the various species and groups of species
only as far back as the early Pleistocene (see Figure 21). Inasmuch as
faunas of fossil mammals from the mid-Pleistocene contain few, if any,
Recent species (see Hibbard, 1937:193), the living species of
_Dipodomys_ have probably had a geologic history no longer than the
period of time which has elapsed since the middle Pleistocene, or at the
earliest the early Pleistocene. Of the Recent species, only _Dipodomys
agilis_ is known as a fossil; it was found in the late Pleistocene tar
pits of California. Under the heading "_Dipodomys near ingens_,"
however, Schultz (1938:206) recorded remains of kangaroo rats from the
tar seeps of McKittrick in the San Joaquin Valley of California.




DISPERSAL OF THE SEVERAL SPECIES


If we assume the region of origin and center of dispersal of a group of
animals to be the one in which the greatest numbers of the most
specialized species of a given genus are found, then the northern
Tableland of Mexico and the adjoining region of the United States in
southeastern California and southwestern Nevada is the region of origin
and the center of dispersal for the genus _Dipodomys_. _Dipodomys
deserti_, _Dipodomys merriami_, _Dipodomys panamintinus_, _Dipodomys
microps_, _Dipodomys phillipsii_ and _Dipodomys ordii_ are found in the
region mentioned. That the aforementioned region may be the center of
differentiation for this genus is further indicated by: First, the
finding, in this region, of saline deposits of Cenozoic (Miocene) age,
indicating aridity, which is thought to have been one of the essential
stimuli for the development of the saltatorial habit in the genus
_Dipodomys_; second, the recovery of the advanced heteromyids from the
Avawatz and Ricardo of the Clarendonian (Pliocene) of this same region;
and third, the present abundance and diversification of kangaroo rats in
this same geographic region which has been more or less arid since
Miocene time.

A secondary center of evolution has been the low, hot interior valleys
and adjacent foothills of central California where _Dipodomys ingens_,
_Dipodomys heermanni_, _Dipodomys venustus_, _Dipodomys agilis_,
_Dipodomys elephantinus_ and _Dipodomys nitratoides_ are now found.
Although there are as many species as in the principal center of origin,
the amount of specialization and adaptive radiation in California is not
so great. Probably during the Quaternary, when the process of mountain
building was actively under way the animals that had reached central
California from the parental center became isolated by the emergence of
the Tehachapi Mountains. This mountain range separated the California
animals from populations farther south and east. As a result, _D.
nitratoides_ was differentiated from _D. merriami_, and _D. heermanni_
underwent an evolution of its own which resulted in animals having
either four or five toes on the hind foot. At the same time _Dipodomys
ingens_ developed there and has since been undergoing an evolution
parallel to that of the large-sized species, _Dipodomys spectabilis_.
The two species have paralleled each other not only in large size but to
some extent in habits such as building large mounds that are kept free
of vegetation and in occupying areas of rather hard clayey soil.
Structurally, however, _D. ingens_ has not yet become quite so
specialized as _D. spectabilis_, probably because _D. ingens_ has had
less time in which to become so. A second species, if it is a full
species, _Dipodomys elephantinus_, has also been isolated in central
California but has not attained so high a degree of specialization as
_D. ingens_. It is interesting to note that in each of the two stocks,
two large-sized species have been evolved. In the parental stock the two
species are _Dipodomys deserti_ and _Dipodomys spectabilis_; the former
is the most specialized species in the genus. In the stock isolated in
California, however, even though two large species have been formed they
are still below the average in degree of specialization for the genus.
As noted elsewhere in this paper, the species from these low, hot
valleys, excepting _D. nitratoides_, are all closely related one to
another. _Dipodomys venustus_ and _Dipodomys elephantinus_ are either
closely related species or possibly only subspecies of one species,
_Dipodomys agilis_.

It is worthy of note that as the distance away from the center of
differentiation increases, the number of species decreases. For example,
in the northern Great Basin there are only two species (_Dipodomys
ordii_ and _Dipodomys microps_) and farther eastward, on the eastern
side of the Rocky Mountains, there is only the one species, _Dipodomys
ordii_. In north-central Texas, _Dipodomys elator_, perhaps a relict
species, is found occupying an area farther east than that occupied by
_Dipodomys ordii_ at that latitude.

_Dipodomys ordii_, _Dipodomys phillipsii_ and _Dipodomys merriami_
occupy the southern portion of the range of the genus. Instead of being
generalized at this southern part of the periphery of the range as are
the kinds found on the other parts of the periphery of the range of the
genus, these three southern kinds are notably specialized there in the
south. The subspecies _D. o. palmeri_ which occurs in the area, is the
most specialized of the species _Dipodomys ordii_; and _Dipodomys
phillipsii_ and _Dipodomys merriami_ stand high in the scale of
specialization with respect to the other species of the genus. The
reason for this is not clear.




SUBSPECIATION


_Dipodomys ordii_ is, without question, a valid species if one accepts
Mayr's (1942:120) definition that "Species are groups of actually or
potentially interbreeding natural populations, which are reproductively
isolated from other such groups." _D. ordii_ is not known to hybridize
with other species where their geographic ranges are adjacent or
overlap. The first part of the definition "actually or potentially
interbreeding populations" is substantiated by the 35 recognizable
subspecies which can be defined as "a complex of interbreeding and
completely fertile individuals which are morphologically identical or
vary only within the limits of individual, ecological and seasonal
variability. The typical characters of this group of individuals are
genetically fixed and no other geographic race of the same species
occurs within the same range" (after Rensch, 1934; from Mayr, 1942:106).
Thus we find that certain populations of individuals differ from others
and that in geographic areas between two of these populations,
individuals (intergrades) are found which resemble those of both
populations. In another instance, a population may be geographically
isolated yet in its characters it may be recognizable as a subspecies
without actual intergradation because of slight degrees of difference,
or a group may be different from another without being geographically
separated and may or may not show intergradation.

Subspeciation in _Dipodomys ordii_ almost certainly has been effected,
by means of mutations, under the influence of natural selection. Natural
selection enhanced by geographic and ~ecologic~ isolation, probably has
retained mutations of evolutionary significance, thus permitting the
development of the many recognizable subspecies.

In the subspecies of _Dipodomys ordii_ the color ranges from pale to
dark. The difference in color is as pronounced as that between the full
species _D. deserti_ and _D. heermanni_. The lightest-colored subspecies
are _Dipodomys ordii celeripes_, _D. o. extractus_ and _D. o.
compactus_; the darkest are _D. o. obscurus_ and _D. o. palmeri_.

There is a marked tendency for intergrades between a light-colored
subspecies, such as _D. o. celeripes_, and a dark-colored kind, such as
_D. o. utahensis_, to show varying degrees of blending in color. The
insular population, _D. o. compactus_, has, however, two distinct color
phases, a light phase and a slightly darker phase, and shows no tendency
toward blending. In other kinds of mammals, blending of color is known
to be the result of the action of multiple alleles, but in the insular
kangaroo rat (_D. o. compactus_) the color appears to be the result of
either a reduced multiple allelomorphic complex or even a unit factor.
The two color phases of this insular subspecies, which might be an
expression of a unit factor, more probably are specializations in which
the multiple alleles for color have been reduced. The probability that
there is either a unit factor or a reduced number of alleles at work is
suggested by the taking of more dark-colored than light-colored animals
and by the absence of blending of color. This insular population has
undoubtedly been derived from the mainland kangaroo rat, _D. o.
sennetti_, which has the usual range of variation but, to my knowledge,
there are no individuals of _D. o. sennetti_ so light as the darkest
animals of _D. o. compactus_ from the islands.

Populations from a given locality are remarkably stable in color except
the animals from Samalayuca, Chihuahua, which vary in color from
individuals almost as light as _D. o. compactus_ to animals that
approach _D. o. ordii_ in darkness of pelage.

The subspecies of _D. ordii_ show no noticeable variation in the extent
of the hip stripe, supraorbital and postauricular spots, basal white
ring of the tail, lateral stripes of the tail or the extent of white on
the venter and feet. There is, however, variation in the degree and
extent of the arietiform facial markings. In _Dipodomys ordii
utahensis_, _D. o. cupidineus_, _D. o. obscurus_ and _D. o. fuscus_
these markings are pronounced. In _D. o. celeripes_, _D. o. pallidus_,
_D. o. compactus_ and _D. o. attenuatus_ these markings are either
obliterated or nearly so.

In _Dipodomys ordii_, color does not seem to be correlated with amount
of moisture or geography, but rather with color of soil. For example,
all animals from the Bonneville Basin of western Utah, are light colored
as are the soils; animals from the San Rafael Desert of eastern Utah are
reddish, as is the soil. More striking extremes of this are shown by _D.
o. compactus_ of Padre and Mustang islands, Texas, which is pale-colored
as is the sand on which it lives, and _D. o. medius_ from east-central
New Mexico and western Texas, which is reddish as is the soil there,
which is derived from Permian rocks. In localities where alkaline soils
are present, kangaroo rats may be found with a roseaceous cast to the
pelage as a result of the action of the alkaline salts on the pigment of
the hair. The roseaceous color is lost when the animal sheds the old
pelage.

In the dorsal and ventral stripes of the tail, I find as much variation
in the species _D. ordii_ as Grinnell (1922:Fig. E, p. 14) recorded in
the whole genus. In _D. o. obscurus_, _D. o. fuscus_ and _D. o.
utahensis_ the stripes are complete to the distal end of the tail and
dark, whereas in _D. o. pallidus_ and _D. o. celeripes_ the ventral
stripe is either absent or nearly so and the dorsal stripe is pale.

Color as a taxonomic character is valuable in a broad sense, and is
useful in placing an individual or a group of individuals in the
subspecies to which they pertain. In most subspecies studied, color was
quite uniform throughout the range of the animals, but in _D. o. ordii_
and _D. o. columbianus_ color is so variable that cranial features were
relied on almost exclusively for the final diagnosis.

Among the subspecies of _Dipodomys ordii_ there is relatively little
variation in the length of the head and body. The smallest measurement
is 95.5 mm. in _D. o. idoneus_ and the largest is 118.3 mm. in _D. o.
richardsoni_. The shortest tail is found to be 112.0 mm. in _D. o.
celeripes_ and the longest is 154.7 mm. in _D. o. terrosus_. The length
of the hind foot varies from 35.0 mm. in _D. o. idoneus_ to 44.5 mm. in
_D. o. nexilis_.

Allen's Rule is not operative in the species _D. ordii_. According to
this rule, shorter tails and smaller feet in conjunction with a large
body would be expected as the more northerly limits of the species are
approached, and conversely, smaller body and larger appendages would be
expected as the southerly limits of the species are approached. This is
not the case, however, since the subspecies _D. o. terrosus_ ranges
farthest north and has the longest tail, whereas _D. o. celeripes_,
found in the central part of the range of the species, has the shortest
tail. Again, in regard to the hind foot, the shortest is found in _D. o.
idoneus_ which is at the extreme south of the range of the species,
whereas the longest hind foot is found in _D. o. nexilis_ which occupies
a nearly central position in the range.

Long tail and long hind foot would seem to be specializations for
saltation and the two would be expected to be correlated. Actually there
is no significant correlation in _D. ordii_. _D. o. celeripes_, in which
the hind foot is near the mean for the species (39.8 as opposed to the
mean of 40.7), has the shortest tail. _D. o. compactus_ has a short tail
(117.0 mm.) but a medium-sized hind foot. _D. o. nexilis_ and _D. o.
terrosus_ have both a long hind foot and long tail.

Cranial measurements vary less, probably because one person can measure
a series with a uniformly subjective error. External measurements,
however, are liable to a greater degree of subjective error. The total
length of the skull varies from 35.4 mm. in _D. o. attenuatus_ to 41.3
mm. in _D. o. terrosus_. In no one series of adults from one locality,
however, is the variation so marked as it is for the species as a whole.
The usual range of variation in length of skull in any given series is
not, as a rule, more than 2.5 mm.

Cranial indices (breadth across bullae/length of skull × 100) as
established for random samples of the different species of the genus
(exclusive of _D. ordii_) ranged from 60.8 to 67.6. In the subspecies of
_D. ordii_ the same index varies from 59.7 to 65.2 with an average of
63.4. In other words, the degree of specialization indicated by this one
index, in a few subspecies of _D. ordii_, is almost as great as that in
_Dipodomys deserti_, which on the basis of total morphology appears to
be the most specialized species in the genus. Also, on the basis of this
same index, some subspecies of _D. ordii_ are more generalized than is
any other species in the genus.

There is a general tendency for the nasals to decrease in length and the
rostrum to decrease in width as the southern limits of the range of _D.
ordii_ are approached. In ascertaining the decrease in length of the
nasals an index was obtained as follows: nasals/interorbital width × 100
(see Table 4). The width of the rostrum, however, does not decrease in
the same degree, nor at the same rate, as does the length of the nasals.
This decrease in length of the nasals and in width of the rostrum may be
correlated with the mean annual relative humidity of the environment. It
is known (Howell and Gersh, 1936:8) that desert rodents, more exactly
kangaroo rats, have a water retention mechanism in the kidneys and walls
of the urinary bladder which enables them more efficiently to conserve
metabolic water. The significance of the decrease of the area of the
nasal mucosa, which seems to be related to relative aridity, is not yet
properly understood.

In no cranial feature other than shortened nasals and narrowed rostrum,
does _Dipodomys ordii_ show a gradation such that it might be termed a
cline. Other parts of the skull that were measured do not vary greatly.

Perhaps the greatest amount of variation in the skull is in features
which are not readily measurable by the usual physical means. The shape
and size of the pterygoid fossae vary from almost round to rather ovoid
in a given series of animals from one locality; the size and
configuration of the zygomatic arches vary from slender to robust and
from straight to curved laterally; the size of the lacrimal processes
varies much in any given series, as do also the degree of expansion of
the distal end of the nasals, the convexity of the braincase and the
curvature of the upper incisors. In all instances where these features
varied much, one size or shape was more pronounced in the series than
any other size or shape. Thus, when comparisons were made, the size and
certain shapes were the criteria used in assigning the animals under
consideration to a given subspecies.

Subspeciation in _Dipodomys ordii_ seems to have been influenced by
water barriers. It is known (Grinnell, 1922:28) that kangaroo rats lack
the ability to swim. Large stable rivers such as the Colorado, Snake and
Columbia serve as effective barriers to further dispersal of kangaroo
rats. Streams that freeze over in the winter months, however, are not
efficient barriers. This is indicated by the "blending" of morphological
characters of _D. o. nexilis_ and _D. o. sanrafaeli_ along the Green
River which freezes over.

Any mountain which has vegetational belts above the Transition Life-zone
would serve as a barrier to the dispersal of these animals. The Uinta
Mountains, lying in an east-west direction, are interposed between the
ranges of _D. o. priscus_ and _D. o. uintensis_. The high Wasatch
Mountains and their associated outliers, lying in a north-south
direction in Utah, serve as an efficient barrier to the east-west
movement of kangaroo rats and as a result, the subspecies east of the
mountain mass are remarkably different from those to the west.


                              TABLE 4

                  PROPORTIONATE DECREASE OF NASALS

    ===========================================================
                  Width    Length     Least           Nasals
                    of       of    interorbital    ------------
                 rostrum   nasals    orbital       Interorbital
                                      width           × 100
    -----------------------------------------------------------
    terrosus       4.1     14.75       13.5           91.6
    luteolus       4.35    13.9        12.95          93.1
    evexus         4.3     14.35       13.75          94.8
    montanus       4.1     13.5        12.65          93.8
    ordii          3.5     13.3        13.0           97.7
    idoneus        3.7     13.2        13.75         103.5
    palmeri        3.3     12.8        13.0          101.1
    -----------------------------------------------------------

     The first three columns represent the actual measurements of the
     various elements; the fourth column is the index established.

Six different complexes (groups) of subspecies of _D. ordii_ have
probably arisen as a result of geographical separation.

The Great Plains complex consisting of _D. o. richardsoni_, _D. o.
oklahomae_, _D. o. evexus_, _D. o. terrosus_, _D. o. luteolus_, _D. o.
priscus_ and _D. o. medius_ are, with the exception of _D. o. priscus_,
inhabitants of the high plains grassland habitat. _D. o. priscus_
inhabits the red Desert of Wyoming.

The Gulf Coast complex, comprising _D. o. sennetti_ and _D. o.
compactus_ are separable from all others by small auditory bullae and
short tail. _D. o. compactus_ probably has differentiated from _D. o.
sennetti_ since the cutting off, by wave action, from the mainland, of
the islands on which _D. o. compactus_ lives.

The Mexican complex consisting of _D. o. obscurus_, _D. o. fuscus_, _D.
o. idoneus_ and _D. o. palmeri_ have probably differentiated by natural
selection acting on fortuitous variations, but I lack first hand
knowledge of the region concerned.

The southwestern complex consists of _D. o. chapmani_, _D. o.
extractus_, _D. o. attenuatus_ and _D. o. ordii_. _D. o. attenuatus_ and
_D. o. chapmani_ are subspecifically distinct owing to geographic
isolation, although both kinds show intergradation where their ranges
approach that of _D. o. ordii_.

The western desert complex, composed of _D. o. monoensis_, _utahensis_,
_cineraceus_, _columbianus_, _cinderensis_, _fetosus_, _celeripes_,
_marshalli_, _inaquosus_, _pallidus_, _panguitchensis_ and _fremonti_
was isolated from the other complexes of _D. ordii_ by the Quaternary
uplift of the Wasatch Mountain mass, consisting of the Wasatch, Fish
Lake and San Pitch mountains and the Wasatch, Aquarius, Paunsaugunt and
Kaiparowits plateaus, and the concurrent reëstablishment of drainage
systems. The drainages are those of the Colorado and Columbia rivers and
that of the Snake River from Blackfoot, Idaho, to the junction with the
Columbia. _D. o. fremonti_ has been isolated on the upper reaches of the
Fremont River which arises from the eastern side of the Wasatch Divide.
_D. o. panguitchensis_ has been isolated in Panguitch Valley as a result
of the canyons formed by the Sevier River in Utah. _D. o. cineraceus_,
although its subspecific and insular status are in doubt, appears to
have been isolated on Dolphin Island, Great Salt Lake, Utah.

The intermontane complex consisting of _D. o. montanus_, _longipes_,
_cupidineus_, _nexilis_, _sanrafaeli_ and _uintensis_, like the western
desert complex, has become separated from the remainder of the
subspecies of the species _D. ordii_ by Quaternary geologic events. _D.
o. cupidineus_ has been cut off by the gorges of the Colorado River to
the south and the Virgin River to the north. _D. o. sanrafaeli_ is
separated from _D. o. uintensis_ by the Tavaputs Plateau and by the Roan
and Book cliffs, and is separated from the range of _D. o. nexilis_ by
the Colorado River although there is intergradation between _D. o.
nexilis_ and _D. o. sanrafaeli_. _D. o. longipes_ has been separated
from the rest of this intermontane complex by the San Juan and Colorado
rivers, but to the east it intergrades freely with adjacent subspecies.
_D. o. montanus_ has been relatively isolated in the San Luis Valley of
Colorado and New Mexico, but in the southern part of its range it does
show intergradation with other subspecies.

[Illustration: FIG. 22. An arrangement, according to morphological
indices, of the subspecies of _Dipodomys ordii_.]

The complexes mentioned above are represented graphically in Figure 22,
in a way that expresses some of my ideas as to their genetic
relationships.

The indices used to determine the amount of specialization that each
complex of subspecies has undergone are as follows:

The Body index (head and body/length of tail × 100) is the expression of
the elongation of the tail as an organ of balance while the length of
the head and body remain relatively constant. As the tail elongates the
index decreases and as the tail becomes shorter the index increases.

The Pedal index (hind foot/head and body × 100) is the expression of the
development of the hind foot as an element essential for the saltatorial
habit. As the hind foot elongates the index will increase; elongation of
the hind foot is interpreted as a specialization.

The Cranial index (breadth across bullae/length of the skull × 100)
reflects the degree of development of the tympanic or mastoid region, or
both, and is thought to be an adaptation for more acute hearing and
possibly for more delicate balance. Inflation of the tympanic bullae is
thought to be a specialization. As the auditory bullae become more
inflated, the index increases toward 100.

The Bullar index (width of maxillary arches/breadth across bullae × 100)
also expresses the degree of inflation of the auditory bullae. In a
generalized mammal, at least in the heteromyids, the index would be 100,
but as the auditory bullae become larger the index will decrease from
100.

In attempting to arrange the subspecies of _D. ordii_ according to
degree of specialization, the geographic positions of the subspecies
have been considered along with the information provided by the
above-mentioned indices. These indices were used in the same way as were
the indices for the species of the genus. In Tables 5 and 6 and in the
accounts and maps the subspecies are arranged from the least specialized
to the most specialized.


                            TABLE 5

         INDICES FOR THE SUBSPECIES OF _DIPODOMYS ORDII_

    ======================================================
                     Body     Pedal    Cranial    Bullar
    ------------------------------------------------------
    richardsoni      88.85    34.35     60.95     88.25
    oklahomae        86.75    35.5      61.7      90.25
    compactus       127.7     37.25     59.75     88.35
    sennetti         94.25    34.0      62.85     85.95
    evexus           80.1     35.7      60.5      92.9

    medius           80.4     33.7      63.55     85.9
    obscurus                            62.95     86.4
    terrosus         75.25    35.05     61.6      86.85
    fremonti         80.55    34.7      62.9      85.5
    uintensis        77.2     35.3      62.3      86.0

    monoensis        85.4     36.4      63.4      85.6
    ordii            79.05    37.6      62.75     86.9
    luteolus         75.0     37.05     62.35     86.3
    extractus        83.65    34.35     64.3      84.25
    chapmani         75.05    36.35     62.9      85.65

    montanus         80.4     36.15     64.25     82.5
    cinderensis      85.1     37.2      65.15     84.75
    fetosus          81.8     38.85     63.95     83.95
    utahensis        80.2     36.95     64.45     84.35
    columbianus      78.5     37.55     64.25     84.9

    idoneus          72.3     36.6      64.2      85.0
    priscus          74.9     39.45     62.3      84.95
    celeripes        91.85    38.75     65.0      84.25
    cineraceus       75.5     39.1      63.9      84.8
    marshalli        81.5     37.3      65.2      83.0

    inaquosus        78.05    37.9      64.25     83.05
    attenuatus       73.5     37.35     64.0      83.4
    fuscus           79.8     39.0      64.3      83.2
    longipes         75.7     37.1      64.3      82.75
    pallidus         76.9     40.75     64.35     84.65

    nexilis          77.1     40.7      64.95     78.45
    cupidineus       73.15    39.1      64.1      80.85
    palmeri          72.25    37.15     65.1      80.45
    ------------------------------------------------------


                                 TABLE 6

    NUMERALS (derived from Table 5) ARE INDICATIVE OF THE RELATIVE
    DEGREE OF SPECIALIZATION OF THE SUBSPECIES OF _DIPODOMYS ORDII_

    =========================================================
                   Body     Pedal   Cranial  Bullar  Average
    ---------------------------------------------------------
    richardsoni      4        3        3        4      3.5
    oklahomae        5        8        5        2      5.0
    compactus        1       19        1        3      6.0
    sennetti         2        2       10       10      6.0
    evexus          15        8        2        1      6.5

    medius          12        1       15       11      9.75
    obscurus                          12        7     10.0
    terrosus        25        6        4        6     10.25
    fremonti        11        5       12       14     10.5
    uintensis       20        7        7        9     10.75

    monoensis        6       12       14       13     11.25
    ordii           17       23        9        5     13.5
    luteolus        27       15        8        8     14.5
    extractus        8        4       25       22     14.75
    chapmani        26       11       11       12     15.0

    montanus        13       10       23       30     19.0
    cinderensis      7       18       32       19     19.0
    fetosus          9       26       17       24     19.0
    utahensis       14       14       28       21     19.25
    columbianus     18       22       21       17     19.5

    idoneus         31       13       20       15     19.75
    priscus         28       30        6       16     20.0
    celeripes        3       25       30       23     20.25
    cineraceus      24       28       16       18     21.5
    marshalli       10       20       33       28     22.75

    inaquosus       19       24       22       27     23.0
    attenuatus      29       21       18       25     23.25
    fuscus          16       27       24       26     23.25
    longipes        23       16       26       29     23.5
    pallidus        22       32       27       20     25.25

    nexilis         21       31       29       33     26.0
    cupidineus      30       29       19       31     27.25
    palmeri         32       17       31       32     28.0
    ---------------------------------------------------------


[Illustration: FIG. 23. Distribution of subspecies of _Dipodomys ordii_.

     1. _D. o. richardsoni_
     2. _D. o. oklahomae_
     3. _D. o. compactus_
     4. _D. o. sennetti_
     5. _D. o. evexus_
     6. _D. o. medius_
     7. _D. o. obscurus_
     8. _D. o. terrosus_
     9. _D. o. panguitchensis_
    10. _D. o. uintensis_
    11. _D. o. sanrafaeli_
    12. _D. o. fremonti_
    13. _D. o. monoensis_
    14. _D. o. ordii_
    15. _D. o. luteolus_
    16. _D. o. extractus_
    17. _D. o. chapmani_
    18. _D. o. montanus_
    19. _D. o. cinderensis_
    20. _D. o. fetosus_
    21. _D. o. utahensis_
    22. _D. o. columbianus_
    23. _D. o. idoneus_
    24. _D. o. priscus_
    25. _D. o. celeripes_
    26. _D. o. cineraceus_
    27. _D. o. marshalli_
    28. _D. o. inaquosus_
    29. _D. o. attenuatus_
    30. _D. o. fuscus_
    31. _D. o. longipes_
    32. _D. o. pallidus_
    33. _D. o. nexilis_
    34. _D. o. cupidineus_
    35. _D. o. palmeri_ ]


=Dipodomys ordii=

Ord Kangaroo Rat

_Dipodomys ordii_ is a medium sized, relatively short-tailed, five-toed
species of a color about average for the genus. As in other members of
the genus, the hind legs and feet are disproportionately long as an
adaptation to the saltatorial mode of progression. The upperparts are
buffy, reddish or blackish, depending on the subspecies, but the entire
ventral surface, dorsal surfaces of the hind feet, supraorbital and
postauricular spots, forelimbs, hip stripes, lateral stripes of the tail
and the tail at the base are pure white. The skull has a relatively
short rostrum, moderate to large auditory bullae, relatively wide
interparietal, relatively wide maxillary arches and grooved upper
incisors.

The only other five-toed kangaroo rats with which _Dipodomys ordii_, at
places, shares its geographic range, are _Dipodomys panamintinus_ and
_Dipodomys microps_. _Dipodomys ordii_ can be distinguished from
_Dipodomys panamintinus_ by smaller size (for instance the hind foot is
shorter instead of longer than, 44 mm.) and narrower expanse of
maxillary arches in relation to breadth across the auditory bullae, and
from _Dipodomys microps_ by the awl-shaped, instead of chisel-shaped,
lower incisors.

The species _D. ordii_ is divisible into 35 subspecies, accounts of
which follow:


=Dipodomys ordii richardsoni= (Allen)

    _Dipodops richardsoni_ Allen, Bull. Amer. Mus. Nat. Hist., 3:277,
    June 30, 1891.

    _Dipodomys phillippi_, Knox, Trans. Kansas Acad. Sci., 4:22, 1875,
    (part--the part from Osborne, Kansas).

    _Dipodomys phillipsi ordi_, Coues and Allen, Monogr. North
    American Rodentia, p. 542, 1877 (part--the part from Ft. Cobb,
    Oklahoma).

    _Perodipus richardsoni_, Allen, Bull. Amer. Mus. Nat. Hist.,
    7:260, August 21, 1895 (part--the part from Pendennis, Kansas).

    _Cricetodipus richardsoni_, Trouessart, Catalogus Mammalium,
    1:581, 1897.

    _Perodipus montanus richardsoni_, Bailey, N. Amer. Fauna, 25:144,
    October 1905 (part--the part from Canadian, Texas).

    _Perodipus ordii richardsoni_, Goldman, Proc. Biol. Soc.
    Washington, 30:113, May 23, 1917.

    _Dipodomys ordii richardsoni_, Grinnell, Journ. Mamm., 2:96, May
    2, 1921.

    _Type._--Male, no. 3025/2345, Amer. Mus. Nat. Hist.; on one of the
    sources of the Beaver River, Beaver County, Oklahoma; obtained on
    October 26, 1887, by Jenness Richardson and John Rowley, Jr. (After
    Allen, original description, type not seen.)

    _Range._--Southwestern Nebraska, eastern Colorado, northeastern New
    Mexico, Panhandle of Texas, and western parts of Oklahoma and
    Kansas; marginal localities are: in Nebraska: Bladen, Haigler; in
    Colorado: Olney; in New Mexico: Clayton; in Texas: 6 mi. S and 1
    mi. W Quitaque, Vernon; in Oklahoma: 3 mi. S Cleo Springs; in
    Kansas: Medora.

    _Diagnosis._--Size large (see measurements). Color dark; entire
    dorsal surface Cinnamon-Buff, purest on sides and flanks, upper
    parts suffused with black; arietiform markings, pinnae of ears,
    plantar surfaces of hind feet, dorsal and ventral stripes of tail,
    blackish; in some specimens the ventral stripe of tail does not
    extend to tip of pencil. Skull large; rostrum short and wide;
    nasals long; zygomata relatively heavy; auditory bullae well
    inflated and wide; thus with short rostrum giving appearance of
    nearly equilateral triangle; upper incisors long and robust.

    _Comparisons._--From _Dipodomys ordii luteolus_, _D. o.
    richardsoni_ differs as follows: Size smaller in external
    measurements except length of body which is longer; color darker,
    except on plantar surfaces of hind feet and dorsal and ventral
    stripes of the tail which are lighter; ventral stripe of tail, in
    most specimens, continuous to end of pencil, whereas in _D. o.
    luteolus_ ventral stripe is present on only proximal two-thirds;
    skull larger in all measurements taken; zygomatic arch heavier;
    auditory bullae relatively as well as actually more inflated;
    external auditory meatus egg-shaped as contrasted to nearly round
    in _D. o. luteolus_; pterygoid fossae rounded as compared to ovate
    in _D. o. luteolus_.

    From _Dipodomys ordii oklahomae_, _D. o. richardsoni_ differs as
    follows: Size larger in all measurements taken; color darker in
    all pigmented areas; skull larger in all respects; auditory bullae
    larger and more inflated ventrally; jugal straight or nearly so
    instead of bowed laterad; pterygoid fossae smaller; nasals
    straight instead of inflated as a "bulb" distally.

    For comparisons with _D. o. montanus_ and _D. o. evexus_, see
    accounts of those subspecies.

Remarks.--This race of _Dipodomys ordii_ is readily distinguished from
_Dipodomys ordii evexus_, from the valley of the upper Arkansas River,
by larger size, larger skull and lighter color. Intergradation with
_Dipodomys ordii luteolus_ occurs rather freely in northeastern
Colorado, as indicated by specimens from 3 miles northeast of
Fitzsimmons, 6 miles east and 1 mile north of Denver and Barr Lake.
These specimens resemble _D. o. richardsoni_ in light color, greater
inflation of the auditory bullae and the shape of the pterygoid fossae
but resemble _D. o. luteolus_, to which they are here referred, in the
length of the nasals, the least interorbital width and in the external
measurements. In the southern part of the range of _D. o. richardsoni_
intergradation occurs with _Dipodomys ordii medius_, as at 6 miles
southwest of Muleshoe, Texas. Specimens from there have the long, wide
rostrum and narrow skull of _D. o. richardsoni_ but in the sum total of
their characters more closely resemble _D. o. medius_. At Texline,
Texas, the animals show intergradation in the length and shape of the
nasals and degree of convexity of the cranium but are referable to _D.
o. richardsoni_.

In fine, intergradation occurs at all points where the range of _D. o.
richardsoni_ touches that of any other geographic race. No one series of
it is as uniform as are most series of specimens of other known races.
_Dipodomys ordii richardsoni_ shows a mixture of characters.
Nevertheless, each of the populations studied has characters in most of
the animals that make this form recognizable as a taxonomic unit--a unit
that seems, as yet, not to have become stabilized even in the central
parts of its range.

Coues and Allen (1877:542) list specimens from Fort Cobb, Arkansas. It
is known that the Post Office Department, for administrative purposes,
attached certain towns and military installations in Indian Territory
(now Oklahoma) to the State of Arkansas. Thus it is apparent that Fort
Cobb, Arkansas, as recorded by Coues and Allen (_loc. cit._) is Fort
Cobb, Oklahoma. Specimens from Fort Cobb would be expected to be _D. o.
richardsoni_.

    _Specimens examined._--Total, 351, distributed as follows:

    =Nebraska=: _Adams County_: Bladen, 10 (AMNH). _Dundy County_:
    Haigler, 1 (USBS).

    =Colorado=: _Crowley County_: Olney, 1 (USBS). _Kiowa County_:
    Chivington, 3 (USBS). _Otero County_: 18 mi. S La Junta, 4 (AMNH);
    Higbee, 1 (USBS). _Bent County_: 4 mi. SE Las Animas, 4100 ft., 3
    (MVZ). _Prowers County_: Lamar, 9 (LACM); 1 mi. S Lamar, 4000 ft.,
    11 (KU). _Baca County_: Gaumes Ranch, 4600 ft., NW Corner, 1
    (USBS).

    =Kansas=: _Cheyenne County_: 23 mi. NW St. Francis, 5 (KU).
    _Rawlins County_: 2 mi. NE Ludell, 2 (KU); 1-1/2 mi. W Ludell, 1
    (KU). _Wallace County_: Lacey Ranch, 4-1/2 mi. E and 9 mi. S
    Wallace, 1 (KU); unspecified, 2 (KU). _Logan County_: 5 mi. W
    Elkader, 2 (KU); unspecified, 1 (UM). _Gove County_: unspecified,
    1 (KU). _Trego County_: Banner, 8 (USNM); Parrington Ranch, 12 mi.
    S Collyer, 2 (KU); unspecified, 8 (USNM). _Ellis County_: Ellis, 1
    (USBS). _Lane County_: Pendennis, 10 (USBS). _Hamilton County_:
    Coolidge, 2 (CNHM); 1 mi. E Coolidge, 5 (KU). _Pawnee County_: 1
    mi. S Larned, 4 (KU); 2 mi. S and 1/4 mi. W Larned, 2 (KU); 3 mi.
    S and 1-1/2 mi. W Larned, 10 (KU). _Edwards County_: Kinsley, 3
    (USBS); 3-1/2 mi. E Kinsley, 5 (KU); S side Arkansas River, 2 mi.
    S Kinsley, 1 (KU); 1 mi. W and 3-1/2 mi. S Kinsley, 9 (KU).
    _Stafford County_: Little Salt Marsh, 15 mi. N and 3 mi. E
    Stafford, 2 (KU). _Reno County_: Medora, 1 (UM); 2 mi. W and 1/2
    mi. S Medora, 4 (KU). _Kiowa County_: 5 mi. N Belvidere, 1(KU).
    _Pratt County_: Cairo, 2 (USBS). _Sedgwick County_: Wichita, 6
    (AMNH). _Morton County_: 10 mi. N and 3 mi. E Elkhart, 34-1/2
    (KU). _Seward County_: 1 mi. E Arkalon, 7 (KU); Liberal, 1 (KU);
    unspecified, 1 (KU). _Meade County_: Meade, 1 (USNM); 13 mi. SW
    Meade, 13 (6 AMNH; 7 KU); 17 mi. SW Meade, 2 (KU). _Clark County_:
    12 mi. S Ashland, 1 (UM); unspecified, 3 (KU). _Barber County_:
    Medicine Lodge, 4 (USBS); 1 mi. W Aetna, 3 (KU); 1/2 mi. W Aetna,
    2 (KU); Aetna, 3 (KU); 1 mi. SW Aetna, 1 (KU); 1-1/2 mi. SW Aetna,
    1 (KU); 1 mi. S Aetna, 5 (KU); unspecified, 2 (KU). _Harper
    County_: 4-1/2 mi. NE Danville, 12 (KU); 2 mi. NE Runnymede, 3
    (KU).

    =New Mexico=: _Union County_: Clayton, Apache Canyon, 1 (USBS).
    _Quay County_: Glenrio, 10 (LACM).

    =Oklahoma=: _Cimmaron County_: Kenton, 1 (CM). _Beaver County_:
    1-1/2 mi. N Beaver, 7 (KU); Beaver River, 8 (7 AMNH; 1 CNHM).
    _Harper County_: 3 mi. S of Englewood, Kansas, 2 (MVZ); 4-1/2 mi.
    N Laverne, 1 (UM). _Woods County_: 2 mi. W Edith, 1 (USBS); Alva,
    12 (UM); Waynoka, 18 (UM); 3 mi. SW Waynoka, 1 (USBS). _Alfalfa
    County_: 4 mi. SE Cherokee, 1 (USBS). _Ellis County_: Shattuck, 1
    (USBS). _Woodward County_: Woodward, 9 (USBS). _Major County_: 3
    mi. S Cleo Springs, 1 (USBS).

    =Texas=: _Dallam County_: Texline, 8 (USBS). _Lipscomb County_:
    Lipscomb, 8 (USBS). _Hemphill County_: 17 mi. NE Canadian, 1 (MVZ);
    1 mi. W Canadian, along Red Deer River, 12 (MVZ); 1/2 mi. W
    Canadian, along Red Deer River, 7 (MVZ); Canadian, 5 (USBS).
    _Oldham County_: Tascosa, 6 (USBS). _Wheeler County_: 1 mi. W
    Mobeetie, 2 (MVZ); Mobeetie, 8 (USBS); Wallace Ranch, SW Wheeler
    County, 1 (TCWC). _Hall County_: Newlin, 1 (USBS). _Wilbarger
    County_: Vernon, 5 (USBS). _Floyd County_: 6 mi. S and 1 mi. W
    Quitaque, 1 (UM).


=Dipodomys ordii oklahomae= Trowbridge and Whitaker

    _Dipodomys oklahomae_ Trowbridge and Whitaker, Journ. Mamm.,
    21:343, August 14, 1940.

    _Dipodomys ordii oklahomae_, Davis, Journ. Mamm., 23:332, August
    14, 1942.

    _Type._--Female, young adult, no. 265454, U. S. Nat. Mus., Biol.
    Surv. Coll. (formerly Univ. of Oklahoma, Mus. Zool., no. 14517);
    north bank of South Canadian River, 2-1/4 mi. S Norman, Cleveland
    County, Oklahoma; obtained on March 16, 1934, by H. L. Whitaker,
    original no., X-catalog no. 29312 of U. S. Nat. Mus.

    _Range._--Known only from the South Canadian River Valley west of
    Minco, Canadian County; and east to Lexington, Cleveland County,
    Oklahoma.

    _Diagnosis._--Size medium (see measurements). Color light, entire
    dorsal surface near (_c_) Vinaceous-Buff, paler on sides with
    great suffusion of white; arietiform markings, pinnae of ears,
    plantar surfaces of hind feet, proximal ventral portion of tail
    and dorsal stripe on tail, brownish. Skull of medium size; rostrum
    wide; nasals short, projecting but slightly anteriorly to
    incisors; zygomatic processes of maxillae heavy; bullae not
    greatly inflated.

    _Comparisons._--_Dipodomys ordii oklahomae_ differs from _D. o.
    richardsoni_ as follows: Size smaller; color lighter in all
    pigmented areas; ventral stripe of tail extending only one-fourth
    the length rather than three fourths or to end of tail; skull
    smaller in all measurements taken; rostrum heavier; auditory
    bullae less inflated; pterygoid fossae larger; braincase slightly
    more inflated; nasals more expanded distally; interparietal region
    wider.

    From _Dipodomys ordii ordii_, _D. o. oklahomae differs_ in: Size
    larger in all measurements taken; color lighter in all pigmented
    areas; ventral stripe of tail extending one fourth length of tail
    rather than to end; skull larger in all respects; rostrum heavier;
    zygomatic arches heavier; bullae more inflated ventrally; cutting
    edge of upper incisors wider; pterygoid fossae larger; braincase
    more vaulted; nasals more expanded distally; orbital region
    larger; interparietal region wider.

_Remarks._--Trowbridge and Whitaker named this kangaroo rat as a full
species. The diagnostic characters were the length and breadth of the
rostrum and the relatively great inflation of the auditory bullae. Also,
_Dipodomys oklahomae_ was not known to intergrade with any other named
kinds. Davis (1942:332) treated _D. oklahomae_ as a subspecies of the
earlier named species _Dipodomys ordii_. Certain characters in specimens
from the type series of both _D. o. richardsoni_ and _D. oklahomae_,
such as the shape and configuration of the nasals, the over-all
proportion of the skull, tooth pattern and body proportions through
individual variation overlap and indicate that these two groups of
animals belong to the same species, even though animals from
intermediate geographic areas are not available to show actual
intergradation. My findings corroborate Davis' conclusion that _D.
oklahomae_ should stand as _Dipodomys ordii oklahomae_. In spite of the
great similarities shown by the two groups of animals there are still
sufficient diagnostic characters between the two groups to enable them
to be segregated easily as valid subspecies.

_Dipodomys ordii oklahomae_ is, for some unknown reason, restricted to a
limited geographic range. Specimens examined from the upper reaches of
the South Canadian River, farther westward, are all referable to _D. o.
richardsoni_ rather than, as would be expected, to _D. o. oklahomae_
since the habitat for these animals is continuous from the type locality
of _D. o. oklahomae_ to the upper reaches of the South Canadian River.
In length and shape of the nasals, degree of inflation of the auditory
bullae and width of the interorbital region these specimens from the
upper reaches of the South Canadian River are intergrades between _D. o.
richardsoni_ and _D. o. medius_. The range of _D. o. medius_ lies to the
south of that of _D. o. richardsoni_ and to the southwest of that of _D.
o. oklahomae_.

The present range of _D. o. oklahomae_, as now understood, is the
most eastern part of the range of the species _Dipodomys ordii_ and
of the genus _Dipodomys_. The existence of _D. o. oklahomae_ in this
area is a precarious one since its habitat is limited in extent and is
periodically flooded.

Although no specimens are known from the area where intergradation
between _D. o. oklahomae_ and _D. o. richardsoni_ would be expected
to occur, it would seem that when animals from this region
become available, intergradation will be shown to occur.

    _Specimens examined._--Total, 8, all from Oklahoma, distributed as
    follows: _Grady County_: 4 mi. N Minco, 1 (USBS). _Cleveland
    County_: 2-1/4 mi. S Norman, 7 (6 OU; 1 USBS).


=Dipodomys ordii compactus= True

    _Dipodomys compactus_ True, Proc. U. S. Nat. Mus., 11:160, January
    5, 1889.

    _Cricetodipus compactus_, Trouessart, Catalogus Mammalium, 1:581,
    1897.

    _Perodipus compactus_, Elliot, Field Columbian Museum, Zool. Ser.,
    2:240, 1901.

    _Dipodomys ordii compactus_, Davis, Journ. Mamm., 23:332, August
    14, 1942.

    _Type._--None designated but Poole and Schantz (1942:406) assumed
    it to be a female, no. 19665/35227, only the skin found, from Padre
    Island, Cameron County, Texas. April 3, 1888. Purchased from C. K.
    Worthen.


    _Range._--Padre and Mustang islands, Cameron County, Texas.

    _Diagnosis._--Size medium (see measurements); tail short. Color
    light; entire dorsal surface Light Ochraceous-Buff, purest on
    sides and flanks, upper parts but lightly suffused with black. A
    lighter color phase has entire dorsal surface Cartridge Buff,
    purest on sides and flanks, upper parts but lightly washed with
    black. In both phases, cheeks white; pinnae of ears, plantar
    surfaces of hind feet, dorsal stripe of tail, ventral stripe of
    tail (in most specimens) present on proximal third of tail only,
    brownish. Skull small; rostrum narrow and long; nasals long;
    auditory bullae inflated, but greatest breadth across bullae only
    slightly more than breadth across zygomatic processes of maxillae;
    interparietal region wide.

    _Comparisons._--From _Dipodomys ordii sennetti_, _D. o. compactus
    differs_ in: Size slightly less; color lighter in all pigmented
    areas; skull smaller; auditory bullae slightly less inflated;
    interorbital width less; interparietal region wider; nasals
    longer.

    From _Dipodomys ordii attenuatus_, _D. o. compactus_ differs in:
    Body larger; tail shorter; normal color phase darker, and lighter
    color phase lighter; skull larger; rostrum wider and longer;
    nasals longer; interorbital region wider; auditory bullae
    relatively as well as actually less inflated; interparietal region
    wider; pterygoid fossae large and round as opposed to small and
    ovoid.

    Compared with _Dipodomys ordii medius_ and _Dipodomys ordii
    ordii_, _D. o. compactus_ is smaller, lighter in color, and has
    less inflated auditory bullae and a smaller skull.

_Remarks._--This subspecies of _Dipodomys ordii_ was originally
described as _Dipodomys compactus_ by True in 1889 and stood as a full
species until Davis (1942:332) relegated it to subspecific status under
_Dipodomys ordii_. Davis (_op. cit._) observed close resemblances in
external proportions, size of mastoid bullae, width of supraoccipital,
and size and shape of the interparietal, between _Dipodomys ordii_ and
_Dipodomys sennetti_ and therefore concluded that they were only
subspecies of one species. He observed that the difference between
_Dipodomys compactus_ and _Dipodomys sennetti_ was of approximately the
same degree as that between _Dipodomys sennetti_ and _Dipodomys ordii_.
From this he concluded that all three were subspecies of the one species
_Dipodomys ordii_.

In any sizeable sample of _Dipodomys sennetti_ there are crania closely
resembling those of _Dipodomys ordii ordii_ and others closely
resembling those of _Dipodomys compactus_. The external proportions of
both _D. sennetti_ and _D. compactus_ are duplicated in _D. ordii_ from
El Paso and conversely, specimens with the proportions of typical _D. o.
ordii_ occur in populations of _D. sennetti_ and _D. compactus_. Thus,
it appears that Davis' usage of the name _Dipodomys ordii compactus_
should stand although there may be a hiatus in geographic occurrence
between _D. ordii_ and _D. sennetti_, as of course there is between _D.
sennetti_ and _D. compactus_.

In _D. o. compactus_ there is a complete enamel ring around the occlusal
surface of each molariform tooth; in _D. o. ordii_ this ring is
incomplete lingually on each of the molariform teeth and labially on the
first three, and in some individuals of _D. o. sennetti_ the enamel ring
is complete and in others it is incomplete labially and lingually as in
_D. o. ordii_.

    _Specimens examined._--Total, 44, all from Texas, distributed as
    follows: _Nueces County_: 19 mi. S Port Aransas, Mustang Island, 27
    (17 TCWC; 10 MVZ); Mustang Island, 17 (LACM).


=Dipodomys ordii sennetti= (Allen)

    _Dipodops sennetti_ Allen, Bull. Amer. Mus. Nat. Hist., 3:226,
    April 29, 1891.

    _Cricetodipus sennetti_, Trouessart, Catalogus Mammalium, 1:581,
    1897.

    _Perodipus sennetti,_ Elliott, Field Columbian Museum, Zool. Ser.,
    2:239, 1901.

    _Dipodomys ordii sennetti_, Davis, Journ. Mamm., 23:332, August
    14, 1942.

    _Type._--Male, no. 3478/2733. Amer. Mus. Nat. Hist.; near
    Brownsville, Cameron County, Texas; obtained on March 9, 1888, by
    J. M. Priour. (After Allen, original description, type not seen.)
    Type locality recorded by Bailey (1905:145) as "Santa Rosa, 85 mi.
    SW Corpus Christi."

    _Range._--Southern Texas, south of Corpus Christi; marginal
    localities, all in Texas are: Somerset, 8 mi. NE Los Angeles, 8
    mi. E Encinal, Santa Rosa, 28 mi. E Raymondville, 2 mi. S Riviera.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface (_c_) between Pinkish Buff and Cinnamon-Buff,
    purest on sides and flanks, upper parts mixed with black;
    arietiform markings, pinnae of ears, dorsal and ventral stripes of
    tail, plantar surfaces of hindfeet, brownish-black. Skull small;
    auditory bullae but slightly inflated in relation to size of
    skull; nasals slightly flaring distally; premaxillae extending but
    slightly posterior to nasals; interorbital width relatively great;
    external auditory meatus small; rostrum relatively long and wide;
    zygomatic arches relatively heavy.

    _Comparisons._--From _Dipodomys ordii ordii_, _D. o. sennetti_
    differs in: Size smaller, tail shorter; color darker; skull
    smaller; nasals longer; rostrum wider; auditory bullae less
    inflated; external auditory meatus smaller; pterygoid fossae more
    rounded; zygomatic arches heavier.

    From _Dipodomys ordii medius_, _D. o. sennetti_ differs as
    follows: Size smaller; color darker, but with less red in pelage;
    skull markedly smaller in all respects.

    From _Dipodomys ordii compactus_, _D. o. sennetti_ differs in:
    Size somewhat less; color darker; skull with total length greater;
    orbit smaller; least interorbital width greater; braincase more
    inflated; width across auditory bullae more; interparietal region
    wider; external auditory meatus larger; medial part of audital
    portion (see Howell, 1932) of auditory bullae larger.

_Remarks._--_Dipodomys sennetti_, along with _Dipodomys compactus_,
was regarded by Davis as conspecific with _Dipodomys ordii_.
Reasons for placing these two kinds of kangaroo rats as subspecies
of _D. ordii_ are given in the account of _Dipodomys ordii compactus_.

This subspecies is known only from north of the Rio Grande
which may serve as a barrier to the spread of the animal into
northern Tamaulipas.

    _Specimens examined._--Total, 20, all from Texas, distributed as
    follows: _Atascosa County_: Somerset, 2 (TCWC). _LaSalle County_: 8
    mi. NE Los Angeles, 1 (TCWC); 8 mi. E Encinal, 1 (TCWC). _Kleberg
    County_: 2 mi. S Riviera, 9 (TCWC). _Jim Hogg County_: Hebronville,
    8 (LACM). _Brooks County_: Falfurrias, 2 (LACM). _Willacy County_:
    28 mi. E Raymondville, 2 (TCWC).


=Dipodomys ordii evexus= Goldman

    _Dipodomys ordii evexus_ Goldman, Journ. Washington Acad. Sci.,
    23:468, October 15, 1933.

    _Perodipus montanus richardsoni_ Warren, Mammals of Colorado, p.
    76, 1910 (part--the part from Salida, Colorado).

    _Type._--Male, adult, no. 150990, U. S. Nat. Mus. Biol. Surv.
    Coll.; Salida, Chaffee County, Colorado (altitude 7000 ft.);
    obtained on November 10, 1907, by Merritt Cary, original no. 1245.

    _Range._--Upper Arkansas River Valley of south-central Colorado,
    from Salida to Pueblo.

    _Diagnosis._--Size large (see measurements). Color dark, entire
    dorsal surface between (_16´´_) Pinkish Cinnamon and Cinnamon-Buff,
    purest on sides and flanks, upper parts strongly suffused with
    black; arietiform markings, pinnae of ears, plantar surfaces of
    hind feet and dorsal and ventral stripes of tail, blackish. Skull
    of medium size; rostrum short and wide; nasals short; auditory
    bullae but slightly inflated; braincase but slightly vaulted.

    _Comparisons._--From _Dipodomys ordii richardsoni_, _D. o. evexus_
    differs as follows: Size smaller in all measurements taken; color
    darker; ears darker, dorsal and ventral stripes on tail darker,
    arietiform markings darker and more distinct, plantar surfaces of
    hind feet darker; skull smaller in all measurements; length, as
    expressed in percentage of width of skull, greater in _D. o.
    evexus_ (66 per cent in _D. o. evexus_, 62 per cent in _D. o.
    richardsoni_ which gives the appearance of a long, narrow skull as
    contrasted with a rather short, wide skull); auditory bullae less
    expanded laterally, posteriorly and ventrally; interparietal
    region relatively wider in proportion to greatest width across
    auditory bullae; cutting edge of upper incisors narrower;
    pterygoid fossae smaller and more nearly circular.

    Compared with _Dipodomys ordii luteolus_, _D. o. evexus_ differs
    as follows: Size somewhat smaller in external measurements; color
    darker in all pigmented areas; skull smaller in two of the seven
    measurements taken but in the other five measurements somewhat
    larger; auditory bullae less inflated; cutting edge of upper
    incisors narrower; zygomatic arch heavier; pterygoid fossae
    smaller and more nearly circular; external auditory meatus ovoid
    as contrasted to nearly circular; paroccipital processes smaller.

    From _Dipodomys ordii nexilis_, _D. o. evexus_ differs in: Color
    darker; rostrum wider and shorter; interorbital region wider;
    breadth across maxillary arches greater; auditory bullae less
    inflated; interparietal region larger; zygomatic arches heavy and
    bowed laterad; molariform teeth smaller; cutting edge of upper
    incisors narrower.

    For comparison with _Dipodomys ordii montanus_ see account of that
    subspecies.

_Remarks._--This race of kangaroo rat, described from the upper
Arkansas River Valley, closely resembles _Dipodomys ordii luteolus_
but differs in darker color, slightly smaller body and larger skull.

No evidence of intergradation with any other race was noted. To the
south the range of _D. o. evexus_ is separated from that of _D. o.
montanus_ by a high, transverse ridge of the Rocky Mountains which is
inhospitable to these animals. Much territory inhospitable to
_Dipodomys_ intervenes also between the ranges of _D. o. evexus_ and _D.
o. luteolus_, but there are areas connecting the northern part of the
range of _D. o. evexus_ and the southwestern part of the known range of
_D. o. luteolus_, in which _Dipodomys_ may occur. If kangaroo rats occur
in these areas it is to be expected that they will show intergradation
between the two subspecies concerned.

    _Specimens examined._--Total, 24, all from Colorado, distributed as
    follows: _Chaffee County_: Salida, 10 (3 USBS; 7 AMNH). _Fremont
    County_: Canyon City, 13 (USBS). _Pueblo County_: Pueblo, 1 (USBS).


=Dipodomys ordii medius= new subspecies

    _Perodipus montanus richardsoni_, Bailey, N. Amer. Fauna, 25:144,
    October, 1905 (part--the part from Santa Rosa, New Mexico).

    _Type._--Male, no. 118526, U. S. Nat. Mus. Biol. Surv. Coll.; Santa
    Rosa, Guadalupe County, New Mexico; obtained on October 5, 1902, by
    Jas. H. Grant, original no. 565.

    _Range._--From north-central New Mexico, southeastward to
    west-central Texas; marginal localities are, in New Mexico: 15 mi.
    N Ojo Caliente, Gallina Mts., Deer Creek, San Pedro; in Texas: 20
    mi. N Monahans, Colorado, 7 mi. E Post, 6 mi. SW Muleshoe.

    _Diagnosis._--Size medium (see measurements). Color dark; entire
    dorsal surface (_14''_) between Orange-Cinnamon and Cinnamon,
    purest on sides and flanks, dorsal surface lightly washed with
    black; arietiform markings, pinnae of ears, plantar surfaces of
    hind feet, dorsal and ventral stripes of tail, brownish-black.
    Skull of medium size; nasals long; medial mastoid portion of
    auditory bullae well inflated caudad; braincase vaulted; external
    auditory meatus small; rostrum short and truncate; medial auditory
    portion of auditory bullae relatively little inflated; pterygoid
    fossae ovate; zygomatic arches slender and relatively straight;
    junction of jugal and zygomatic process of maxilla heavy.

    _Comparisons._--From _Dipodomys ordii richardsoni_, _D. o. medius_
    differs as follows: Tail longer; hind foot shorter; color darker;
    arietiform markings more distinct; white lateral stripes of tail
    narrower; ventral stripe of tail in most specimens complete to end
    of pencil; postauricular spots less pronounced; hip stripe
    narrower and in some specimens almost obliterated; skull smaller
    in all measurements taken; angle of dorsal extension of premaxilla
    with zygomatic process of maxilla more nearly 90°; braincase more
    vaulted; medial mastoid portion of auditory bullae more inflated,
    and coming to more of a point; medial auditory portion of auditory
    bullae more inflated ventrally; rostrum shorter and narrower;
    external auditory meatus smaller.

    From _Dipodomys ordii montanus_, _D. o. medius_ differs in: Color
    lighter in all pigmented areas; skull larger in all respects;
    rostrum shorter and heavier; bullae more inflated; zygomata, while
    nearly straight, are bowed slightly laterally; pterygoid fossae
    more ovate; foramen magnum larger; pterygoid foramina smaller.

    Compared with _Dipodomys ordii ordii_ and _Dipodomys ordii
    sennetti_, _D. o. medius_ is larger and darker. The skull is also
    larger in all measurements taken.

    Compared with _Dipodomys ordii longipes_, _D. o. medius_ is darker
    and smaller.

_Remarks._--This hitherto undescribed race of _Dipodomys ordii_
can readily be distinguished from any of its near neighbors by the
characters set forth under diagnosis and comparisons.

Intergradation is noted with _D. o. ordii_, _D. o. longipes_, _D. o.
montanus_ and _D. o. richardsoni_. Among named races _D. o. medius_
shows closest affinities with _D. o. richardsoni_ but the two are easily
separable. The northwestern extremity of the range of _D. o. medius_ is
an area of intergradation in which no specimens are clearly of one
subspecies or the other. In specimens from 5 miles east of Abiquiu, New
Mexico, three-way intergradation occurs. These animals are like _D. o.
medius_ in size, _D. o. longipes_ in color and their cranial proportions
are as in _D. o. montanus_. At Deer Creek, New Mexico, and at Monahans,
Texas, the animals show intergradation in size of body and agree with
_D. o. ordii_ in cranial proportions. In specimens from 6 miles
southwest of Muleshoe, Texas, intergradation with _D. o. richardsoni_ in
the shape of the skull and width of the rostrum is noted. In the sum
total of characters studied, however, these specimens are referable to
_D. o. medius_.

    _Specimens examined._--Total, 129, distributed as follows:

    =New Mexico=: _Rio Arriba County_: 2 mi. SE El Rito, 2 (KU); Rio
    Alamosa, 15 mi. N Ojo Caliente, 1 (USBS); 6 mi. E Abiquiu, 4
    (USBS); Rinconada, 5 (USBS); Espanola, 6 (USBS). _Sandoval
    County_: 12 mi. NW Alameda, 5500 ft., 3 (MVZ). _Santa Fe County_:
    Seton's Ranch, near Santa Fe, 1 (USBS); 8 mi. SW Santa Fe, 8 (KU);
    San Pedro, 3 (USBS). _San Miguel County_: Pecos, 2 (USBS); 3 mi. S
    Pecos, 2 (USBS); Rowe, 6 (LACM). _Bernallilo County_: Bear Canyon,
    Sandia Mountains, 7 (USBS); Pajarito, 3 (MVZ). _Guadalupe County_:
    Santa Rosa, 10 (USBS). _Lincoln County_: 44 mi. NW Roswell, 5
    (MVZ). _De Baca County_: 8 mi. N Fort Sumner, 9 (USBS). _Roosevelt
    County_: Kenna, 4 (LACM). _Curry County_: 4 mi. W and 2-3/4 mi. N
    Clovis, 1 (MVZ). _Chaves County_: 40 mi. N Roswell, 2 (USBS); 35
    mi. N Roswell, 2 (USBS); 15 mi. NE Roswell, 8 (LACM); Stinking
    Springs Lake, 3 (USBS).

    =Texas=: _Bailey County_: 6 mi. SW Muleshoe, 5 (UM); 9 mi. SW
    Muleshoe, 2 (UM). _Garza County_: 7 mi. E Post, 5 (UM). _Martin
    County_: Stanton, 4 (USBS). _Howard County_: 6 mi. NE Coahoma, 7
    (UM); 1 mi. S Coahoma, 1 (UM); 5 mi. W Big Springs, 2400 ft., 1
    (MVZ). _Mitchell County_: Colorado, 5 (USBS). _Winkler County_: 20
    mi. N Monahans, 1 (USBS). _Ward County_: Monahans, 1 (USBS).


=Dipodomys ordii obscurus= (Allen)

    _Perodipus obscurus_ Allen, Bull. Amer. Mus. Nat. Hist., 19:603,
    November 12, 1903.

    _Dipodomys ordii obscurus_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Type._--Male, adult, no. 20957, Amer. Mus. Nat. Hist.; Rio Sestin,
    northwestern Durango, Mexico; obtained on April 13, 1903, by J. H.
    Batty. (Type not seen.)

    _Range._--Northwestern and northern Durango, Mexico; marginal
    localities are: Rosario, Rio Sestin, Mt. San Gabriel, Rio del
    Bocas, Villa Ocampo.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface (_16''_) between Pinkish Cinnamon and
    Cinnamon-Buff, purest on sides, flanks and cheeks, upper parts
    strongly suffused with black; arietiform markings, plantar
    surfaces of hind feet, pinnae of ears, dorsal and ventral stripes
    of tail, brownish. Skull of medium size, nasals long and flared
    distally; rostrum long and narrow; interorbital region relatively
    narrow; auditory bullae less inflated than in _Dipodomys ordii
    palmeri_; interparietal region narrow; zygomatic arches heavy and
    bowed laterad; pterygoid fossae ovoid; braincase but slightly
    vaulted.

    _Comparisons._--From _Dipodomys ordii palmeri_, _D. o. obscurus_
    differs in: Size larger; color lighter; nasals shorter and more
    flared distally; interorbital width less; lacrimal processes
    larger; auditory bullae less inflated; pterygoid fossae ovoid as
    opposed to subcircular; zygomatic arches heavier; rostrum shorter
    and wider.

    From _Dipodomys ordii ordii_, _D. o. obscurus_ differs as follows:
    Size smaller; color darker; skull smaller; nasals longer; rostrum
    narrower and shorter; interorbital width greater; interparietal
    region narrower; narrower across auditory bullae; zygomatic arches
    heavier and more bowed laterally; pterygoid fossae more ovoid;
    breadth across maxillary arches greater; external auditory meatus
    smaller.

    With _Dipodomys ordii attenuatus_ and _Dipodomys ordii sennetti_,
    _D. o. obscurus_ needs no comparison since it is larger and darker
    than either of those subspecies and can readily be told from the
    latter by the greater expansion of the auditory bullae.

    For comparison with _Dipodomys ordii fuscus_ see account of that
    subspecies.

_Remarks._--_D. o. obscurus_ seemingly is not a far-ranging subspecies.
The only examples referable to it come from a relatively restricted
area of Durango, Mexico. One specimen from Rio del Bocas, Durango,
is not typical and shows the characters described for the animals
from Chihuahua City and from Casas Grandes. I have considered the
possibility that this specimen is an intergrade between _D. o.
obscurus_ and an unnamed subspecies ranging to the northeastward. The
other specimens in the series from Rio del Bocas are typical of _D. o.
obscurus_.

    _Specimens examined._--Total, 69, all from Durango, distributed as
    follows: Rosario, 20 (AMNH); Villa Ocampo, 5 (AMNH); Rio Sestin, 30
    (28 AMNH; 2 CNHM); Mt. San Gabriel, 2 (AMNH); Rio del Bocas, 11
    (AMNH); Rancho Santuario, 1 (AMNH).

[Illustration: FIG. 24. Known occurrences and probable geographic range
of the subspecies of _Dipodomys ordii_ in the southeastern fourth of the
range of the species.

    1. _D. o. richardsoni_ 2. _D. o. oklahomae_ 3. _D. o. compactus_ 4.
    _D. o. sennetti_ 6. _D. o. medius_ 7. _D. o. obscurus_ 14. _D. o.
    ordii_ 16. _D. o. extractus_ 23. _D. o. idoneus_ 29. _D. o.
    attenuatus_ 30. _D. o. fuscus_ 31. _D. o. longipes_ 35. _D. o.
    palmeri_ ]


=Dipodomys ordii terrosus= Hoffmeister

    _Dipodomys ordii terrosus_ Hoffmeister, Proc. Biol. Soc.
    Washington, 55:165, December 31, 1942.

    _Dipodomys phillipsi ordi_, Coues and Allen, Monogr. North
    American Rodentia, p. 541, August, 1877 (part--the part from
    Yellowstone River, Montana).

    _Perodipus montanus richardsoni_, Cary, N. Amer. Fauna, 49:124,
    December, 1926 (part--the part from Glendive, Montana).

    _Type._--Male, no. 93477, Mus. Vert. Zool., Univ. California;
    Yellowstone River, 5 mi. W Forsyth, 2,750 ft., Rosebud County,
    Montana; obtained on June 2, 1940, by J. R. Alcorn, original no.
    1528.

    _Range._--Extreme southwestern Saskatchewan and southeastern
    Alberta, eastern half of Montana, northern Wyoming and probably
    extreme western North Dakota; marginal localities are: 50 mi. W
    Swift Current, Saskatchewan; "near Medicine Hat," Alberta; in
    Wyoming, Sheep Creek, and 23 mi. SW Newcastle; in Montana,
    Medicine Rocks (14 mi. NE Ekalaka), and Glendive.

    _Diagnosis._--Size large (see measurements). Color dark, entire
    dorsal surface near (_c_) Ochraceous-Buff, purest on sides and
    flanks; upper parts mixed with black; arietiform markings, pinnae
    of ears, dorsal and ventral stripes of tail and plantar surfaces
    of hind feet brownish-black. Skull large; rostrum short, wide and
    deep; braincase slightly vaulted; auditory bullae markedly
    inflated ventrally; zygomatic arches heavy and bowed laterad;
    upper incisors long and robust.

    _Comparisons._--From _Dipodomys ordii priscus_, _D. o. terrosus_
    differs as follows: Size larger in all measurements taken, except
    for length of hind feet, which is less; color darker in all
    pigmented areas; skull larger in all parts measured except width
    of interparietal, which is less; auditory bullae more inflated
    ventrally; zygomatic processes of maxillae wider; rostrum deeper
    and shorter.

    From _Dipodomys ordii richardsoni_, _D. o. terrosus_ differs as
    follows: Size larger; color darker in all pigmented areas; ventral
    stripe of tail extending farther distally; skull larger except in
    width across auditory bullae, which is the same.

    For comparison with _Dipodomys ordii luteolus_ see account of that
    subspecies.

_Remarks._--As noted in the comparisons, _D. o. terrosus_ is larger and
darker than _D. o. priscus_, _D. o. luteolus_ or _D. o. richardsoni_,
its closest geographic neighbors, and does not resemble any of them, but
rather resembles _D. o. longipes_ and _D. o. evexus_ in size and
appearance, both of which are distantly removed geographically.

Like other subspecies of the species _D. ordii_, _D. o. terrosus_
prefers sandy soils to those of any other type. Two miles east and 1
mile south of Forsyth, Montana, animals were trapped on lenses of sandy
soil. These lenses alternated with areas of black loam of similar size.
It was noteworthy that burrows were found only in the areas of sandy
soil, although paths used by the rats when foraging did extend onto and
several crossed the lenses of black loam. We were not permitted to
excavate any of these burrows, but conversation with farmers of the
immediate vicinity indicated that the burrows were not deep. An
eight-inch disc would frequently plow out nests and food caches. It was
said that each of several caches contained as much as a peck of wheat.

Intergradation was noted in animals from 23 miles southwest of Newcastle
and Arvada, Wyoming. In animals from both localities the pterygoid
fossae are more as in _D. o. luteolus_ but referable to _D. o.
terrosus_. The specimens from Arvada, although immature, possessed
cranial characters which were intermediate between those of _D. o.
terrosus_ and _D. o. luteolus_ but the specimens are referable to the
former.

    _Specimens examined._--Total, 74, distributed as follows:

    =Montana=: _Petroleum County_: 24 mi. N Roundup, 8 mi. SW
    Flatwillow, 2 (UM). _Garfield County_: Jordan, 10 (1 UM; 2 MVZ; 7
    AMNH). _Dawson County_: Glendive, 9 (USNM). _Musselshell County_:
    Harvey Ranch, Melstone, 3 (MVZ). _Rosebud County_: Yellowstone
    River, 5 mi. W Forsyth, 2750 ft., 7 (MVZ); 2 mi. E and 1 mi. S
    Forsyth, 2600 ft., 8 (KU). _Custer County_: Miles City, 1 (USBS).
    _Yellowstone County_: Billings, 2 (1 USBS; 1 MVZ). _Big Horn
    County_: Fort Custer, 1 (USBS); Crow Agency, 1 (USBS). _Powder
    River County_: Powderville, 4 (USBS). _Carter County_: Medicine
    Rocks, 15 mi. N Ekalaka, 2 (USBS); Medicine Rocks, 14 mi. N
    Ekalaka, 2 (USBS); Clark's Fork, 1 (USBS).

    =Wyoming=: _Big Horn County_: Dry Creek, 10 mi. W Germania, 1
    (USBS); 3 mi. E Germania, 1 (USBS); Greybull, 2 (USBS); Bighorn
    Basin, 1 (USBS). _Sheridan County_: Arvada, 8 (USBS). _Campbell
    County_: Little Powder River, 1 (USBS). _Weston County_:
    Newcastle, 2 (USBS); 23 mi. SW Newcastle, 4 (USBS). _Fremont
    County_: Wilson's Ranch, Sheep Creek, S base Owl Creek Mountains,
    1 (USBS).

    _Additional records._--=Canada= (Anderson, 1946:131): _Alberta_:
    near Medicine Hat, 1; _Saskatchewan_: near Shackleton, 45-50 mi.
    NW Swift Current, 1; near Tompkins, 50 mi. W Swift Current, 1.


=Dipodomys ordii fremonti= Durrant and Setzer

    _Dipodomys ordii fremonti_ Durrant and Setzer, Bull. Univ. Utah, 35
    (no. 26):21, June 30, 1945.

    _Type._--Female, no. 15661, Carnegie Museum, Pittsburgh,
    Pennsylvania; Torrey, 7000 ft., Wayne County, Utah; obtained on
    July 19, 1938, by W. F. and F. H. Wood, original no. 1562.

    _Range._--Known only from the type locality.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface Cinnamon-Buff, purest on sides, flanks and cheeks;
    upper parts strongly suffused with black; arietiform markings,
    pinnae of ears, plantar surfaces of hind feet, dorsal and ventral
    stripes of tail, brownish. Skull small; upper incisors long;
    rostrum deep; jugal bowed laterally; diastema long; upper
    molariform tooth-row long.

    _Comparisons._--From _Dipodomys ordii panguitchensis_, _D. o.
    fremonti_ differs in: Color lighter in all pigmented areas,
    particularly ears which are light brown in _D. o. fremonti_ and
    black in _D. o. panguitchensis_; skull larger in all measurements
    taken; upper incisors longer; rostrum deeper; auditory bullae
    deeper; jugal bowed laterally rather than straight; diastema
    longer.

    From _Dipodomys ordii cupidineus_, _longipes_, _nexilis_,
    _uintensis_ and _sanrafaeli_, _D. o. fremonti_ can readily be
    distinguished by its smaller size and generally darker color.

_Remarks._--This subspecies of _Dipodomys ordii_ inhabits the upper
reaches of the Fremont River in west-central Wayne County, Utah.
_D. o. fremonti_ appears to be isolated and is known only from the
type locality. _D. o. fremonti_ is so remarkably different from any
other subspecies of _Dipodomys ordii_ that a long period of isolation
from the ancestral stock (which probably gave rise also to _Dipodomys
ordii utahensis_ and _Dipodomys ordii panguitchensis_) is indicated.
Although intergradation is not known to occur with other kinds,
differentiation has not progressed far enough for these animals to be
recognized as a distinct species.

The subspecies closest, geographically, to _D. o. fremonti_ is _D. o.
cupidineus_ from which _D. o. fremonti_ differs more than from any of
the other named forms.

    _Specimens examined._--Total, 9, from Utah, as follows: _Wayne
    County_: Torrey, 7000 ft., 9 (CM).


=Dipodomys ordii uintensis= Durrant and Setzer

    _Dipodomys ordii uintensis_ Durrant and Setzer, Bull. Univ. Utah,
    35 (no. 26):27, June 30, 1945.

    _Perodipus longipes_, Allen, Bull. Amer. Mus. Nat. Hist., 8:246,
    November 1896 (part--the part from Uncompahgre Indian Reservation,
    Utah).

    _Dipodomys ordii luteolus_, Moore, Journ. Mamm., 11:88, February,
    1930 (part--the part from Vernal, Utah).

    _Type._--Male, adult, no. 11634, Carnegie Museum, Pittsburgh,
    Pennsylvania; Red Creek, 6,700 ft., 2 mi. N Fruitland, Duchesne
    County, Utah; obtained on August 15, 1936, by J. K. and M. T.
    Doutt, original no. 3433.

    _Range._--Uinta basin of the White, Green and Duchesne river
    drainage in northeastern Utah; marginal occurrences are: 2 mi. N
    Fruitland, 10 mi. S Ouray, Vernal.

    _Diagnosis._--Size large (see measurements); hind foot short.
    Color dark; entire dorsal surface, near (_c_) Cinnamon-Buff,
    purest on sides and flanks, with moderate suffusion of black on
    upper parts; cheeks white; arietiform markings, pinnae of ears,
    plantar surfaces of hind feet, dorsal and ventral stripes of tail,
    brownish. Skull large; frontomaxillary suture convex mediad;
    lacrimal process large; styloid process projects, on ventral
    surface of tympanic bulla, beyond middle of external auditory
    meatus; nasals flared distally.

    _Comparisons._--From _Dipodomys ordii priscus_, _D. o. uintensis_
    differs in: Hind foot shorter; color darker; styloid process
    projects on ventral part of tympanic bulla well anterior to middle
    of external auditory meatus as opposed to projecting to middle;
    depth of foramen magnum, expressed in percentage of width across
    posterior margin of occipital condyles, greater (86 per cent in
    _D. o. uintensis_ and 81 per cent in _D. o. priscus_);
    frontomaxillary suture convex mediad as opposed to nearly
    straight; lacrimal processes larger; nasals more flared distally.

    From _Dipodomys ordii nexilis_, _D. o. uintensis_ differs as
    follows: Size smaller; color lighter; interorbital breadth greater;
    frontomaxillary suture convex mediad as opposed to concave;
    lacrimal processes larger; nasals more flared distally; narrower
    across auditory bullae; basal length greater; zygomatic arches
    bowed laterad as opposed to relatively straight.

    From _Dipodomys ordii longipes_, _D. o. uintensis_ differs as
    follows: Size smaller; color darker; auditory bullae wider, longer
    and deeper; frontomaxillary suture convex mediad as opposed to
    nearly straight; greatest breadth across auditory bullae less.

    For comparison with _Dipodomys ordii sanrafaeli_ see account of
    that subspecies.

_Remarks._--This large, rather dark race inhabits the desert valleys
of the White, Green and Duchesne rivers in northeastern Utah. The
race nearest geographically, as well as morphologically, is _Dipodomys
ordii priscus_. Intergradation occurs with the latter subspecies
at Vernal, Uintah County, in cranial measurements and in color.
On the basis of color alone _D. o. uintensis_ can be distinguished from
_D. o. sanrafaeli_, the geographic race to the south. Specimens from
Jensen are intermediate in color and cranial measurements between
_Dipodomys ordii nexilis_ and _D. o. uintensis_ but are referable to the
latter.

    _Specimens examined._--Total, 40, all from Utah, distributed as
    follows: _Duchesne County_: Red Creek, 6700 ft., 2 mi. N Fruitland,
    4 (CM); 10 mi. S Myton, 1 (UU); 20 mi. S Myton, 1 (RH). _Uintah
    County_: Vernal, 1 (BYU); 20 mi. E Ouray, 5 (CM); Junction Green
    and White rivers, 4800 ft., 2 mi. S Ouray, 5 (CM); Pariette Bench,
    5000 ft., 8 mi. S Ouray, 8 (CM); Desert Springs, 10 mi. S Ouray, 4
    (CM); Pariette Bench, 12 mi. S Ouray, 2 (CM); Jensen, 5 (BYU); E
    side Green River, 3 mi. S Jensen, 4 (CM).


=Dipodomys ordii sanrafaeli= Durrant and Setzer

    _Dipodomys ordii sanrafaeli_ Durrant and Setzer, Bull. Univ. Utah,
    35 (no. 26):26, June 30, 1945.

    _Dipodomys ordii longipes_, Stanford, Journ. Mamm., 12:360,
    November, 1931 (part--the part from King's Ranch, Utah).

    _Type._--Female, adult, no. 4612, Museum of Zoology, University of
    Utah; 1-1/2 mi. N Price, 5567 ft., Carbon County, Utah; obtained
    on June 5, 1940, by Ross Hardy and H. Higgins, original no. 1901.

    _Range._--East-central Utah, east into west-central Colorado.
    Marginal occurrences are: in Utah, 12 mi. E Price, 1-1/2 mi. N
    Price, Notom, King's Ranch, 12 mi. SW Green River, 16 mi. NW Moab;
    in Colorado, State Line and Grand Junction.

    _Diagnosis._--Size large (see measurements). Color dark, entire
    dorsal surface Cinnamon-Buff, purest on sides and flanks with but
    slight suffusion of black on upper parts; cheeks white; arietiform
    markings, pinnae of ears, plantar surfaces of hind feet, dorsal
    and ventral stripes of tail, brownish-black. Skull large;
    pterygoid fossae ovoid; lacrimal processes small; width across
    maxillary arches relatively great; auditory bullae well inflated;
    diastema short.

    _Comparisons._--From _Dipodomys ordii longipes_, _D. o.
    sanrafaeli_ differs as follows: Size smaller; color lighter, more
    cinnamon, pinnae of ears lighter; skull smaller; auditory bullae
    smaller; pterygoid fossae ovoid rather than round; wider across
    occipital condyles; narrower across zygomatic processes of
    maxillae.

    From _Dipodomys ordii cupidineus_, _D. o. sanrafaeli_ can be
    recognized by its larger size, lighter color and larger skull.

    For comparisons with _Dipodomys ordii nexilis_, _Dipodomys ordii
    priscus_ and _Dipodomys ordii uintensis_ see accounts of those
    subspecies.

_Remarks._--Intergradation between _Dipodomys ordii cupidineus_ and _D.
o. sanrafaeli_ is noted in the intermediate size of body in a single
specimen from Notom. Intergradation in color and cranial characters
occurs between _Dipodomys ordii nexilis_ and _D. o. sanrafaeli_ in
specimens from 16 miles northwest of Moab. All these specimens, however,
are referable to _D. o. sanrafaeli_.

Animals from that part of the range of _D. o. sanrafaeli_ west of the
Green River are typical while those to the east of the river are all
intergrades. Animals from 16 miles northwest of Moab, Utah, and from
three localities in Colorado, even though intergrades with _D. o.
nexilis_, are all referable to _D. o. sanrafaeli_. It appears that the
Green River does not act as a complete barrier in this area since in the
winter it occasionally freezes over, thus allowing the animals to cross.
It is thought that kangaroo rats do not hibernate but remain more or
less active throughout the winter. Man-made conveniences, such as
bridges, might also serve as means of dispersal, permitting these
animals to cross otherwise prohibitive barriers. Where there are no
bridges across the Green River, farther to the south, the rats
apparently do not cross the river; steep, rocky canyon-walls and the
lack of ice on the water in winter lessen the chances of small mammals
crossing from one side to the other.

    _Specimens examined._--Total, 30, distributed as follows:

    =Utah=: _Carbon County_: 12 mi. NE Price, 2 (CM); 3 mi. NE Price,
    1 (RH); 1-1/2 mi. N Price, 2 (1 RH; 1 UU); Wellington, 1 (RH).
    _Emery County_: "San Rafael, 21 mi. out," 1 (USAC); 12 mi. SW
    Green River, 2 (CM). _Grand County_: 1 mi. E Green River, 1 (MVZ);
    16 mi. NW Moab, 2 (CM). _Wayne County_: Notom, 1 (BYU). _Garfield
    County_: King's Ranch, 4800 ft., 3 (2 UU; 1 USAC).

    =Colorado=: _Mesa County_: State Line, 11 (MVZ); Fruita, 1 (USBS);
    Grand Junction, 2 (USBS).


=Dipodomys ordii panguitchensis= Hardy

    _Dipodomys ordii panguitchensis_ Hardy, Proc. Biol. Soc.
    Washington, 55:90, June 25, 1942.

    _Type._--Male, adult, no. 4375, Museum of Zoology, University of
    Utah; one mile south of Panguitch, 6666 ft., Garfield County,
    Utah; obtained on August 31, 1940, by Ross Hardy, original no.
    2151.

    _Range._--Known only from the type locality.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface near Olive-Brown, purest on sides and flanks, upper
    parts strongly suffused with black; cheeks white; arietiform
    markings, pinnae of ears, plantar surfaces of hind feet, dorsal
    and ventral stripes of tail which are wider than white lateral
    stripes, blackish. Skull small; rostrum relatively short and wide;
    interorbital region wide; interparietal region wide; foramen
    magnum elongate dorsoventrally; pterygoid fossae ovoid.

    _Comparisons._--From _Dipodomys ordii utahensis_, which it closely
    resembles, _D. o. panguitchensis_ differs in: Size larger; color
    darker; interparietal region wider; foramen magnum elongate
    dorsoventrally as opposed to nearly round; pterygoid fossae ovoid
    as opposed to nearly round.

    This subspecies can be distinguished from _Dipodomys ordii
    fetosus_, _Dipodomys ordii celeripes_ and _Dipodomys ordii
    cupidineus_ by its darker color and generally larger size.

    For comparisons with _Dipodomys ordii cinderensis_ and _Dipodomys
    ordii fremonti_ see accounts of those subspecies.

_Remarks._--This geographic race inhabits the upper reaches of
the Sevier River Valley in the vicinity of Panguitch, Utah. Natural
barriers to kangaroo rats, such as the Cedar Mountains to the west,
high plateau country to the south, the Paunsaugunt Plateau to the
east and the narrow canyons of the Sevier River to the north prevent
these animals from extending their range or from coming into physical
contact with any adjacent geographic races. This isolation has resulted
in a fairly stable population. Some animals, however, show characters,
such as the width of the rostrum, and the shape and length of the
nasals which are intermediate between those of topotypes of _D. o.
utahensis_ and the type series of _D. o. panguitchensis_.

    _Specimens examined._--Total, 3, all from Utah, distributed as
    follows: _Garfield County_: 1 mi. S Panguitch, 6666 ft., 3 (2 RH; 1
    UU).


=Dipodomys ordii monoensis= (Grinnell)

    _Perodipus monoensis_ Grinnell, Univ. California Publ. Zool.,
    21:46, March 29, 1919.

    _Dipodomys ordii monoensis_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Type._--Female, adult, no. 27002, Museum of Vertebrate Zoology,
    University of California; Pellisier Ranch, 5 mi. N Benton Station,
    5600 ft., Mono County, California; obtained on September 21, 1917,
    by J. Dixon, original no. 6384.

    _Range._--Northeastern Inyo and Mono counties, California, north
    to southern Pershing County and east to eastern Nye County,
    Nevada; marginal occurrences are: in California, 5 mi. N Benton
    Station and Deep Spring Valley; in Nevada, Arlemont, 2 mi. NW
    Palmetto, 1 mi. N Beatty, 5 mi. W White Rock Spring, Big Creek at
    Quinn Canyon Mts., 2-1/2 mi. S Lock's Ranch, 2 mi. S Millett P.
    O., 13-1/2 mi. NW Goldfield, Fingerrock Wash, Eastgate, 1/2 mi. NE
    Toulon, 21 mi. W and 2 mi. N Lovelock, 1/2 mi. S Pyramid Lake,
    West Walker River in Smith's Valley, and 10 mi. S Yerington.

    _Diagnosis._--Size medium (see measurements). Color pale, entire
    dorsal surface (_c_) between Pinkish Buff and Cinnamon-Buff, purest
    on sides, flanks and cheeks, with but slight suffusion of black in
    upper parts; pinnae of ears, plantar surfaces of hind feet, dorsal
    and ventral stripes of tail, brownish. Skull medium in size;
    rostrum relatively long and narrow; nasals relatively short;
    interorbital region narrow; interparietal region relatively wide;
    lacrimal processes small; auditory bullae relatively small;
    pterygoid fossae circular; zygomatic arches robust and relatively
    straight; foramen magnum nearly circular.

    _Comparisons._--From _Dipodomys ordii columbianus_, _D. o.
    monoensis_ differs as follows: Size larger; color lighter; skull
    larger; rostrum longer and narrower; interorbital region narrower;
    breadth across auditory bullae less; lacrimal processes larger;
    braincase less vaulted; auditory bullae more inflated ventrally;
    pterygoid fossae smaller; zygomatic arches more robust; cutting
    edge of upper incisors wider.

    From _Dipodomys ordii fetosus_, _D. o. monoensis_ differs in: Hind
    foot shorter; color lighter; skull smaller; rostrum shorter and
    narrower; interorbital width less; interparietal region larger;
    lacrimal processes smaller; auditory bullae less inflated.

    For comparison with _Dipodomys ordii inaquosus_ see account of
    that subspecies.

_Remarks._--This subspecies retains all of its diagnostic characters
throughout nearly all parts of its geographic range. Intergradation
occurs in animals from the southern end of Pyramid Lake, Big Smoky
Valley and near Toquima Peak, Nevada; these animals, although typical of
_D. o. monoensis_ in coloration, resemble _D. o. columbianus_ cranially.
Three-way intergradation between _D. o. columbianus_, _D. o. fetosus_
and _D. o. monoensis_ is noted in animals from east-central Nye County,
Nevada. These animals resemble _D. o. monoensis_ in size, _D. o.
fetosus_ in color and resemble _D. o. columbianus_ in certain cranial
features. These animals are referred to _D. o. monoensis_. Animals from
Toulon, Nevada, in the inflation of the auditory bullae, the vault of
the braincase, the color and the total length show intergradation with
_D. o. inaquosus_ but are referable to _D. o. monoensis_.

    _Specimens examined._--Total, 264, distributed as follows:

    =California=: _Mono County_: Pellisier Ranch, 5 mi. N Benton
    Station, 17 (7 DRD; 10 MVZ); Benton, 5639 ft., 2 (1 LACM; 1 MVZ);
    Taylor Ranch, 2 mi. S Benton Station, 5300 ft., 2 (MVZ). _Inyo
    County_: Deep Springs Valley, 1 (LACM).

    =Nevada=: _Washoe County_: 1/2 mi. S Pyramid Lake, 3950 ft., 1
    (MVZ); 1-1/2 mi. N Wadsworth, 4100 ft., 2 (MVZ). _Pershing
    County_: 21 mi. W and 2 mi. N Lovelock, 4000 ft., 2 (MVZ); 3-1/4
    mi. NNE Toulon, 3900 ft., 1 (MVZ); 3 mi. NNE Toulon, 3900 ft., 6
    (MVZ); 1/2 mi. NE Toulon, 1 (MVZ); Toulon, 3930 ft., 5 (MVZ).
    _Churchill County_: Truckee Canal, 2 mi. SW Hazen, 4000 ft., 1
    (MVZ); 1 mi. NW Soda Lake, 4000 ft., 2 (MVZ); 1 mi. S Soda Lake,
    4000 ft., 1 (MVZ); 5 mi. W Fallon, 1 (MVZ); 4 mi. W Fallon, 4000
    ft., 3 (MVZ); 1 mi. W Mountain Well, 5350 ft., 3 (MVZ); Eastgate,
    4400 ft., 13 (MVZ). _Lyon County_: 6 mi. N Fernley, 1 (MVZ); 1 mi.
    SE Wadsworth, 4200 ft., 7 (MVZ); 3/4 mi. N Fernley Underpass,
    Fernley, 1 (MVZ); 1/2 mi. N Fernley Underpass, Fernley, 1 (MVZ);
    Wilson Canyon, 8 mi. NE Wellington, 4700 ft., 1 (MVZ); West Walker
    River, Smith's Valley, 4700 ft., 4 (MVZ); 10 mi. S Yerington,
    Mason Valley, 4500 ft., 6 (MVZ). _Mineral County_: 8 mi. SE
    Schurz, 4100 ft., 18 (MVZ); Fingerrock Wash, Stewart Valley, 5400
    ft., 4 (MVZ); Cat Creek, 4 mi. W Hawthorne, 4500 ft., 1 (MVZ);
    Huntoon Valley, 5700 ft., 1 (MVZ). _Nye County_: 2 mi. S Millett
    P. O., 5500 ft., 1 (MVZ); 4 mi. SE Millett P. O., 5500 ft., 11
    (MVZ); 5 mi. SE Millett P. O., 5500 ft., 5 (MVZ); 4 mi. S Millett
    P. O., 5500 ft., 2 (MVZ); Millman Ranch, Moore Creek, 6400 ft., 19
    mi. SE Millett P. O., 9 (MVZ); Meadow Creek Ranger Station,
    Toquima Mts., 2 (MVZ); Monitor Valley, 9 mi. E Toquima Mts., 7000
    ft., 19 (MVZ); Fish Spring Valley, 1/2 mi. N Fish Lake, 6500 ft.,
    2 (MVZ); Railroad Valley, 2-1/2 mi. S Lock's Ranch, 5000 ft., 5
    (MVZ); Hot Creek Valley 3-1/2 mi. E Hot Creek, 5650 ft., 1 (MVZ);
    Hot Creek Valley, 4/5 mi. S Hot Creek, 5900 ft., 1 (MVZ); 5-1/2
    mi. NE San Antonio, 5700 ft., 1 (MVZ); San Antonio, 5400 ft., 2
    (MVZ); 9 mi. W and 3 mi. S Tybo, 6200 ft., 2 (MVZ); Ralston
    Valley, 15-1/2 mi. NE Tonopah, 5800 ft., 2 (MVZ); Railroad Valley,
    2-1/2 mi. S Lock's Ranch, 5000 ft., 5 (MVZ); Hot Creek Valley
    Creek, 5800 ft., 1 (MVZ); Ralston Valley, 34 mi. E and 1 mi. N
    Tonopah, 5650 ft., 2 (MVZ); Old Mill, N end Reveille Valley, 6200
    ft., 6 (MVZ); 1-1/2 mi. S Silverbow, Kawich Mountains, 1 (MVZ); 5
    7/10 mi. SE Kawich, 2 (MVZ); 5 mi. W White Rock Spring, 6950 ft.,
    Belted Range, 2 (MVZ); 1 mi. N Beatty, 1 (DRD). _Esmeralda
    County_: 13-1/2 mi. NW Goldfield, 4850 ft., 3 (MVZ); 7 mi. N
    Arlemont, 5500 ft., 6 (MVZ); Arlemont, 11 (MVZ); Mouth Palmetto
    Wash, 7 (DRD); 2 mi. NW Palmetto, 7 (DRD); 1 mi. NW Palmetto, 1
    (DRD); Palmetto, 7 (DRD); 1 mi. SE Palmetto, 7 (DRD); Pigeon
    Spring, 6400 ft., 1 (MVZ); Indian Spring, Mt. Magruder, 20 (DRD).


=Dipodomys ordii ordii= Woodhouse

    _D(ipodomys) ordii_ Woodhouse, Proc. Acad. Nat. Sci. Philadelphia,
    6:224, 1853.

    _Dipodomys phillipsi ordi_, Coues and Allen, Monogr. North
    American Rodentia, p. 541, 1877 (part--the part from El Paso,
    Texas).

    _Dipodops ordii_, Merriam, N. Amer. Fauna, 4:42, October, 1890
    (part--the part from El Paso, Texas).

    _Cricetodipus ordii_, Trouessart, Catalogus Mammalium, 1:581,
    1897.

    _Perodipus ordi_, Elliot, Field Columbian Museum, Zool. Ser.,
    2:238, 1901.

    _Perodipus montanus richardsoni_, Bailey, N. Amer. Fauna, 25:144,
    October, 1905 (part--the part from Carlsbad, New Mexico).

    _Perodipus ordii_, Goldman, Proc. Biol. Soc. Washington, 30:113,
    May 23, 1917.

    _Type._--None designated. Species characterized from specimens
    obtained by Dr. Woodhouse at El Paso, Texas.

    _Range._--Southeastern Arizona, southern New Mexico, western Texas
    and north-central Mexico; marginal occurrences are: in Arizona, 20
    mi. NE Calva, Oracle and Calabasas; in Sonora, Nogales; in
    Chihuahua, Casas Grandes, Corralitos and Santa Rosalia; in Texas,
    16 mi. E Van Horn and 30 mi. N Van Horn; in New Mexico, 40 mi. N
    Roswell, 40 mi. SE Corona and Mangos Valley.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface (16'') between Pinkish Cinnamon and Cinnamon-Buff,
    purest on sides and flanks, upper parts suffused with black;
    arietiform markings, pinnae of ears, plantar surfaces of hind
    feet, dorsal and ventral stripes of tail, brownish-black. Skull of
    medium size; rostrum narrow and relatively long; braincase
    flattened; auditory bullae but slightly inflated; zygomatic arches
    slender and straight; upper incisors short and narrow.

    _Comparisons._--From _Dipodomys ordii richardsoni_, _D. o. ordii_
    differs as follows: Size smaller; color somewhat lighter; dorsal
    and ventral stripes of tail brownish instead of blackish; skull
    smaller in all measurements taken.

    From _Dipodomys ordii montanus_, _D. o. ordii_ differs in: Size
    smaller; color lighter; skull narrower across bullae and rostrum;
    wider interorbitally; all other measurements taken the same, thus
    imparting to the skull, in dorsal view, a longer, narrower
    appearance.

    From _Dipodomys ordii chapmani_, _D. o. ordii_ differs in: Size
    smaller; color lighter; skull smaller; zygomatic arches narrower
    at suture of jugal and zygomatic process of maxillary; rostrum
    narrower; upper incisors smaller; nasals shorter; least
    interorbital width less.

    For comparisons with _Dipodomys ordii sennetti_ and _Dipodomys
    ordii compactus_ see accounts of those subspecies.

_Remarks._--Intergradation occurs with _Dipodomys ordii chapmani_,
_Dipodomys ordii longipes_, _Dipodomys ordii medius_ and _Dipodomys
ordii attenuatus_. Only along the Rio Grande near El Paso,
Texas, are individuals of a population uniform. On the periphery of
the range, specimens from a given locality may resemble _D. o. ordii_
or _D. o. longipes_ or may be intermediate between these two subspecies.

Animals from the Organ Mountains near Globe Springs, 20 miles
north of Cliff, New Mexico, and those labeled with reference to Van
Horn, Texas, on the average are darker, have a wider expanse across
the auditory bullae, a wider interorbital region and, in most specimens,
more distally flared nasals than the norm of other populations.
This deviation from the normal is interpreted not as intergradation
with any other subspecies but rather as individual
variation in a given population.

Specimens from 40 miles southeast of Corona and 10 miles northeast
of Socorro, New Mexico, show intergradation between _D. o.
ordii_ and _D. o. montanus_ in size of body, configuration of nasals and
cranial size. For a discussion of intergradation with _D. o. longipes_,
_D. o. medius_ and _D. o. chapmani_ see the remarks in the accounts of
those subspecies.

Specimens from Cananea and Santa Cruz, Sonora, Casas Grandes Viejo,
Chihuahua City and Colonia Diaz, Chihuahua, are not typical of _D. o.
ordii_ but rather show the influence of some race probably to the
southeast that is as yet unknown. In a series of nine specimens from
near Casas Grandes Viejo, Chihuahua, four individuals are typically _D.
o. ordii_, four resemble an apparently undescribed form and one specimen
is intermediate between _D. o. ordii_ and the unnamed subspecies. This
unnamed race differs from _D. o. ordii_ in having darker pelage, darker
dorsal stripe on tail, larger body, wider interorbital region, longer
skull, greater breadth across the bullae, less vaulted braincase, more
robust zygomatic arches and the foramen magnum more deeply notched on
both the dorsal and ventral rims. It seems that these animals mentioned
above should be referred to _D. o. ordii_ at least until such time as
material becomes available from eastern Chihuahua, northern Coahuila and
northeastern Durango.

    _Specimens examined._--Total, 451, distributed as follows:

    =Arizona=: _Gila County_: Rice, 2 (USBS). _Maricopa County_:
    Marinette, 8 (CAS). _Pinal County_: Oracle, 4 (USBS). _Graham
    County_: 20 mi. NE Calva, 5 (USBS); Fort Grant, 11 (7 USBS; 4
    MVZ). _Pima County_: Ft. Lowell, 3 (DRD); 11-1/2 mi. S Tucson, 1
    (MVZ); Continental, 20 (8 USBS; 12 DRD); La Osa, 11 (USNM);
    Babiquivari Mountains 10 mi. N International Boundary, 1 (DRD).
    _Santa Cruz County_: 2 mi. S Tumacacori Mission, 1 (DRD); 7 mi. N
    Patagonia, 4500 ft., 12 (CAS); 3 mi. N Patagonia, 1 (CAS);
    Calabasas, 7 (6 USBS; 1 USNM). _Cochise County_: 8 mi. W Bowie, 1
    (LACM); Wilcox, 4163 ft., 25 (12 USBS; 5 UM; 4 MVZ; 4 USNM); 12
    mi. SE Dos Cabezos, 2 (UM); 1 mi. WSW Chiricahua National
    Monument, 5000 ft., 1 (MVZ); Portal, 4500 ft., 2 (USBS); Fairbank,
    8 (3 AMNH; 5 CNHM); Mouth Pinery Canyon, 4 (USBS).

    =New Mexico=: _Torrance County_: Gran Quivira, Mesa Jumanes, 6
    (USBS). _Catron County_: Mangos Valley, 3 (USBS); Alma, 3 (USBS);
    Pleasanton, 7 (USBS). _Socorro County_: Gallina Mountains, 1
    (USBS); 10 mi. NE Socorro, 2 (USBS); 3 mi. N Socorro, 3 (MVZ);
    Socorro, 1 (USBS); Range, 2 mi. SW Socorro, 4700 ft., 2 (MVZ);
    Lava Mesa; S Clyde, 4300 ft., 1 (MVZ); Dry Creek, 3 (USBS); San
    Augustine Plain, 12 mi. N Monica Springs, 2 (USBS). _Lincoln
    County_: Guyo Canyon, 40 mi. SE Corona, 1 (USBS); 4 mi. W
    Carrizozo, 2 (UM). _Grant County_: Gila, 5 (USBS); Cactus Flat, 20
    mi. N Cliff, 3 (USBS); Cliff, Gila River, 4470 ft., 1 (USBS);
    Silver City, 2 (USBS); Redrock, 2 (USBS); 9 mi. N Faywood, 2
    (USBS); Hachita, 1 (USBS); Dog Spring, 11 (USNM); Deer Creek,
    Culberson Ranch, 2 (USBS). _Sierra County_: Fairview, 6500 ft., 1
    (USBS); Cuchillo, 4700 ft., 3 (USBS); Lake Valley, 5000 ft., 3
    (USBS). _Otero County_: Tularosa, 5 (USBS); 10 mi. SW Tularosa, 2
    (CNHM); Quartz Sands, SW Tularosa, 2 (MVZ); White Sands, 12 mi. W
    Alamogordo, 1 (MVZ); 2 mi. S Alamogordo, 2 (UM); 3 mi. S
    Alamogordo, 1 (UM); 5 mi. S Alamogordo, 1 (UM); 9 mi. SW
    Alamogordo, 1 (UM); 12 mi. SW Alamogordo, 2 (UM); 15 mi. SW
    Alamogordo, 1 (LACM); White Sands, 18 mi. SW Alamogordo, 7 (MVZ);
    19 mi. SW Alamogordo, 3 (UM); White Sands National Monument, 24
    (13 CNHM; 11 LACM); 1/2 mi. SW Escondido, 4000 ft., 2 (MVZ);
    Jarilla, 1 (USBS). _Hidalgo County_: 10 mi. NW Lordsburg, 6
    (LACM); 4 mi. NW San Luis Pass, 5200 ft., Animas Valley, 5 (MVZ).
    _Luna County_: Deming, 11 (USBS). _Dona Ana County_: Garfield, 4
    (USBS); 6 to 8 mi. NE Las Cruces, 1 (CAS); 15 mi. W Las Cruces, 1
    (LACM); 11 mi. W Las Cruces, 2 (CAS); Las Cruces, 3 (USBS); Organ
    Mountains, near Globe Springs, 2 (USBS); Coe's Ranch, El Paso
    Road, 35 mi. N El Paso, Texas, 2 (USBS); 1/4 mi. N Strauss, 2
    (CAS); 1 mi. E Strauss, 4100 ft., 7 (MVZ); 35 mi. W El Paso,
    Texas, 2 (USNM); 20 mi. W El Paso, Texas, 1 (USNM); 10 mi. W El
    Paso, Texas, 1 (USNM); Mexican Boundary, near monument 5, Lat. 31°
    47'; Long. 30° 15', 13 (USNM). _Eddy County_: 3 mi. NW Carlsbad, 7
    (MVZ); 2 mi. E Carlsbad, 1 (KU); Eddy, 10 (USBS).

    =Texas=: _El Paso County_: 3 mi. NE City Limits, El Paso, 3764
    ft., 15 (12 MVZ; 3 TCWC); El Paso, 3 (USBS); near El Paso, 7
    (USNM). _Hudspeth County_: 1 mi. NW old Fort Hancock, 3900 ft., 3
    (MVZ); Fort Hancock, 4 (USNM); 4 mi. NW Sierra Blanca, 1 (LACM).
    _Culberson County_: 35 mi. N Van Horn, 5 (TCWC); 30 mi. N Van
    Horn, 1 (TCWC); 16 mi. E Van Horn, 3 (TCWC); 16 mi. SE Van Horn, 5
    (TCWC); Kent, 1 (USBS). _Reeves County_: 5 mi. E Toyahvale, 1
    (USBS). _Jeff Davis County_: 14-1/2 mi. S Fort Davis, 2 (UM).
    _Presidio County_: 10 mi. NE Marfa, 1 (UM).

    =Sonora=: Nogales, 2 (USNM); Santa Cruz, 4 (USNM); 5 mi. N
    Cananea, 4750 ft., 4 (MVZ); Alamo Wash, 35 mi. NW Magdalena, 5
    (DRD); Sonora, 2 (AMNH).

    =Chihuahua=: 4.3 mi. W Casas Grandes Viejo, 5000 ft., 8 (MVZ); 1.5
    mi. W Casas Grandes Viejo, 1 (MVZ); Casas Grandes, 2 (USBS);
    Gallego, 1 (USBS); Colonia Diaz, 6 (USBS); Las Trincheras, 9 mi. S
    by road Boquillos de Condios, 4 (MVZ); Santa Rosalia, 6 (USBS);
    Chihuahua, 7 (USBS); 5 mi. SE Chihuahua, 5250 ft., 4 (MVZ);
    Corallitos, 4 (1 USBS; 3 MVZ).


=Dipodomys ordii luteolus= (Goldman)

    _Perodipus ordii luteolus_ Goldman, Proc. Biol. Soc. Washington,
    30:112, May 23, 1917.

    _Dipodomys phillipsi ordi_, Coues and Allen, Monogr. of N. Amer.
    Rodentia, p. 541, August, 1877 (part--the part from Niobrara
    River, Nebraska).

    _Perodipus montanus richardsoni_, Cary, N. Amer. Fauna, 33:141,
    August 17, 1911 (part--the part from Sterling, Colorado).

    _Dipodomys ordii luteolus_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Type._--Male, adult, no. 160408, U. S. Nat. Mus. Biol. Surv.
    Coll.; Casper, Natrona County, Wyoming; obtained on September 2,
    1909, by Merritt Cary, original no. 1690.

    _Range._--Southeastern Wyoming, northeastern Colorado,
    northwestern half of Nebraska and southwestern South Dakota;
    marginal occurrences are: in Wyoming, Casper, Sun and Ft. Steele;
    in Colorado, Loveland, Hugo and Akron; in Nebraska, Birdwood
    Creek, Neligh and Valentine; in South Dakota, Batesland and
    Buffalo Gap.

    _Diagnosis._--Size medium (see measurements). Color light, entire
    dorsal surface between Light Ochraceous-Buff and Ochraceous-Buff,
    purest on sides and flanks; upper parts but lightly washed with
    black; arietiform markings, plantar surfaces of hind feet, pinnae
    of ears and dorsal and ventral stripes of tail, blackish. Skull
    medium in size; jugal weak; braincase slightly inflated; nasals
    slightly flared distally.

    _Comparisons._--From _Dipodomys ordii terrosus_, _D. o. luteolus_
    differs as follows: Size smaller, except that tail and ear are
    longer; color lighter in all pigmented areas; skull smaller in
    every measurement taken; auditory bullae less inflated; zygomatic
    processes of maxillae smaller; cutting edge of upper incisors
    narrower; zygomatic arch weaker.

    From _Dipodomys ordii priscus_, _D. o. luteolus_ differs in: Size
    larger except hind foot which is shorter; dorsal and ventral
    stripes of tail, plantar surfaces of hind feet, arietiform
    markings and pinnae of ears, in most specimens, darker; auditory
    bullae less inflated; nasals shorter; rostrum wider; total length
    of skull shorter; zygomatic arch weaker; foramen magnum more
    ovate.

    From _Dipodomys ordii evexus_, _D. o. luteolus_ differs as
    follows: Hind foot longer; color lighter in all pigmented areas;
    auditory bullae more inflated; pterygoid fossae more expanded
    laterally; width across maxillary arches less; interorbital region
    narrower; zygomatic arch weaker; external auditory meatus almost
    round as opposed to ovoid.

    Comparison with _Dipodomys ordii richardsoni_ is made in account
    of that subspecies.

_Remarks._--_Dipodomys ordii luteolus_ resembles _D. o. priscus_ in
size and color but can readily be told from it and _D. o. richardsoni_
when specimens from the central portions of the ranges of the subspecies
are compared. At and near the periphery of the range, especially
in that part which adjoins the range of _D. o. richardsoni_,
intergradation occurs. Specimens from Kennedy, Perch and Neligh,
Nebraska, approach _D. o. richardsoni_ in the shape of the pterygoid
fossae and nasal bones, but in all other characters they resemble
_D. o. luteolus_ to which subspecies they are here referred. Specimens
from Loveland and 20 miles east of Avalo, Colorado, show intergradation
with _D. o. richardsoni_ in the width of the rostrum and size of the
zygomatic arch but are referable to _D. o. luteolus_.

No specimens here referred to _D. o. luteolus_ were found to intergrade
with _D. o. priscus_.

    _Specimens examined._--Total, 250, distributed as follows:

    =South Dakota=: _Perkins County_: 9 mi. N Bison, 8 (MVZ). _Meade
    County_: Smithsville, 2 (USBS). _Jackson County_: 20 mi. SSE
    Phillip, in Haakon County, 1 (MVZ). _Custer County_: Elk Mountain,
    1 (MHS); Buffalo Gap, 2 (USNM). _Bennett County_: Big Spring
    Canyon, Batesland, 7 (CNHM); Rosebud Indian Agency, 1 (USBS).

    =Wyoming=: _Fremont County_: 2-1/2 mi. W Shoshoni, 80 (KU);
    Granite Mountain, 1 (UM). _Natrona County_: 1 mi. NE Casper, 19
    (KU); Casper, 7 (USBS); Sun, 8 (USBS). _Converse County_: Douglas,
    2 (USBS). _Niobrara County_: Van Tassel Creek, 1 (CM). _Carbon
    County_: Fort Steele, 1 (USBS). _Goshen County_: Rawhide Butte, 1
    (USBS).

    =Nebraska=: _Sioux County_: Warbonnet Canyon, 6 (MHS); Glen, 1
    (MHS); Agate, 3 (1 UM; 2 CNHM); Jim Creek, 1 (MHS). _Box Butte
    County_: 16 mi. NE Alliance, 4 (UM). _Sheridan County_: 12 mi. S
    Gordon, 3 (MVZ); 5 mi. N Antioch, 4 (UM); 4 mi. N Antioch, 3 (UM).
    _Cherry County_: Valentine, 9 (6 USBS; 2 USNM; 1 NU); 15 mi. E
    Gordon, 1 (CNHM); Niobrara River, 3 (USBS); 18 mi. NW Kennedy, 3
    (2 USBS; 1 MHS); Valentine Lake Refuge, 1 (NU); Kennedy, 10 (3
    MVZ; 5 USBS; 2 USNM); 30 mi. S Wood Lake, 4 (CNHM); Cherry, 7
    (NU); near Clark's Canyon, 7 (USBS). _Rock County_: Perch, 12 (10
    AMNH; 2 CNHM). _Antelope County_: Neligh, 8 (1 USBS; 7 MHS).
    _Scotts Bluff County_: Mitchell, 1 (MHS). _Hooker County_: Kelso,
    5 (UM). _Thomas County_: Halsey, 1 (MHS); Dismal River, 2 (USBS).
    _Custer County_: 1 mi. NW Gavin, 6 (2 MVZ; 4 UM); Gavin, 3 (UM); 8
    mi. NW Anselmo, 1 (UM); 7 mi. NW Anselmo, 1 (UM). _Lincoln
    County_: Birdwood Creek, 2 (USBS); Brady, 4 (NU); Hackberry Lake,
    13 (UM).

    =Colorado=: _Larimer County_: Loveland, 8 (USBS). _Weld County_:
    20 mi. E Avalo, 3 (USBS); 8 mi. E Pawnee Buttes, 1 (USBS);
    Greeley, 1 (USBS). _Morgan County_: 30 mi. S Fort Morgan, 1 (UM).
    _Logan County_: Sterling, 8 (USBS). _Adams County_: Barr Lake, 4
    (CMNH); 6 mi. E and 1 mi. N Denver, 1 (CMNH); 3 mi. NE Fitzsimons,
    1 (CMNH). _Washington County_: Akron, 2 (UM). _Lincoln County_:
    Limon, 1 (USBS); Hugo, 1 (USBS). _El Paso County_: Colorado
    Springs, 2 (MVZ).


=Dipodomys ordii extractus= new subspecies

    _Type._--Male, adult, no. 76562, Museum of Vertebrate Zoology,
    University of California; 1 mi. E Samalayuca, 4500 ft., Chihuahua,
    Mexico; obtained on May 15, 1937, by William B. Richardson,
    original no. 2148.

    _Range._--Known only from the type locality.

    _Diagnosis._--Size medium (see measurements). Color pale, entire
    dorsal surface Pinkish Buff, purest on sides and flanks, dorsal
    surface but slightly suffused with black; pinnae of ears, plantar
    surfaces of hind feet, dorsal and ventral stripes of tail
    light-brownish. Skull medium in size; nasals long; rostrum
    relatively as well as actually wide; least interorbital breadth
    wide; auditory bullae relatively little inflated; braincase but
    slightly vaulted; external auditory meatus ovoid; zygomatic arches
    relatively robust and but slightly bowed laterad; pterygoid fossae
    subcircular; lacrimal processes small; foramen magnum deeply
    notched on dorsal border.

    _Comparisons._--From _Dipodomys ordii ordii_, _D. o. extractus_
    differs as follows: Size larger; color lighter; arietiform marks
    absent in _D. o. extractus_ but pronounced in _D. o. ordii_; skull
    larger; rostrum wider; nasals longer; re inflated laterally;
    braincase less vaulted; pterygoid fossae subcircular as opposed to
    circular; foramen magnum more deeply evaginated dorsally and
    ventrally.

[Illustration: FIG. 25. Known occurrences and probable geographic range
of the subspecies of _Dipodomys ordii_ in the northeastern fourth of the
range of the species.

  1. _D. o. richardsoni_   8. _D. o. terrosus_     18. _D. o. montanus_
  2. _D. o. oklahomae_    10. _D. o. uintensis_    24. _D. o. priscus_
  5. _D. o. evexus_       11. _D. o. sanrafaeli_   31. _D. o. longipes_
  6. _D. o. medius_       15. _D. o. luteolus_     33. _D. o. nexilis_ ]

    From _Dipodomys ordii obscurus_, _D. o. extractus_ differs as
    follows: Size larger; color lighter; skull larger in all respects,
    notably in least interorbital width, greatest length of skull and
    breadth across auditory bullae; zygomatic arches less robust and
    straight as opposed to robust and bowed laterally; pterygoid fossae
    subcircular as opposed to circular; auditory bullae more inflated
    ventrally.

    From _Dipodomys ordii idoneus_, _D. o. extractus_ differs in: Size
    larger; color lighter; skull larger in all measurements taken
    except least interorbital width and breadth across maxillary
    arches which are smaller; nasals longer and narrower; braincase
    less vaulted; zygomatic arches less robust and more nearly
    straight; auditory bullae less inflated ventrally.

_Remarks._--This subspecies of _Dipodomys ordii_ is the palest of
any of the known races from Mexico. It inhabits an area of light-colored
sandy soil at the type locality.

The only subspecies with which _D. o. extractus_ really needs comparison
is _Dipodomys ordii ordii_ from which it differs as described above. The
series which is herein described contains two individuals that resemble
_D. o. ordii_ cranially and three that resemble it in color although
they are somewhat paler. One specimen, MVZ no. 76560, is the palest of
any of the series, has a short tail and in these respects resembles the
pale form of _Dipodomys ordii compactus_. It is apparent from the skull
of this latter individual that it is not _D. o. compactus_ but _D. o.
extractus_.

_Dipodomys ordii ordii_ inhabits, in most of its range, dark-colored
soils, whereas _D. o. extractus_ inhabits light-colored soils. Possibly
the differentiation that has occurred is a result of an ecological
separation much as occurs with _Perognathus_ on the white sands and
black lavas of the Tularosa Basin of New Mexico (see Benson,
1933).

    _Specimens examined._--Total, 14, all from Chihuahua, as follows: 1
    mi. E Samalayuca, 4500 ft., 14 (MVZ).


=Dipodomys ordii chapmani= Mearns

    _Dipodomys chapmani_ Mearns, Bull. Amer. Mus. Nat. Hist., 2:291,
    February 21, 1890.

    _Cricetodipus chapmani_, Trouessart, Catalogus Mammalium, 1:581,
    1897.

    _Perodipus chapmani_, Elliot, Field Columbian Museum, Zool. Ser.,
    2:237, 1901.

    _Perodipus ordii chapmani_, Goldman, Proc. Biol. Soc. Washington,
    30:113, May 23, 1917.

    _Dipodomys ordii chapmani_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Cotypes._--Male, no. 2400, and female, no. 2398, Amer. Mus. Nat.
    Hist.; Fort Verde, Yavapai County, Arizona; obtained on January 26,
    1887, and October 1, 1885, respectively, by Edgar A. Mearns. (Type
    not seen.)

    _Range._--Central Arizona from the Grand Canyon of the Colorado
    River, southeastward to, and probably beyond, Fort Verde; marginal
    occurrences are: lower end Prespect Valley, Kirkland, Prescott,
    Camp Verde, Bill Williams Mountain.

    _Diagnosis._--Size medium (see measurements). Color dark; entire
    dorsal surface between (_10''_) Pinkish Cinnamon and
    Cinnamon-Buff, purest on sides and flanks, upper parts strongly
    suffused with black; arietiform markings, pinnae of ears, plantar
    surfaces of hind feet, dorsal and ventral stripes of tail,
    blackish. Skull medium in size; rostrum long and narrow; nasals
    long; auditory bullae slightly distended; braincase vaulted.

    _Comparisons._--For comparisons with _Dipodomys ordii cupidineus_,
    _Dipodomys ordii longipes_ and _Dipodomys ordii ordii_ see
    accounts of those subspecies.

_Remarks._--This subspecies of _Dipodomys ordii_ is relatively isolated
from other subspecies of the species. The Colorado River with its deep
canyons is interposed between the ranges of _D. o. chapmani_ and _D. o.
cupidineus_. A high range of mountains separates _D. o. chapmani_ from
the range of _D. o. longipes_. The only race with which _D. o. chapmani_
probably comes into contact is _D. o. ordii_ to the southeast. No
specimens are available from the southeastern part of the range of _D.
o. chapmani_. Animals from the northwestern part of the range of _D. o.
ordii_, without exception, have dark-colored pelage which is
characteristic of _D. o. chapmani_. In the shape of the nasals, vault of
the braincase, interorbital width and auditory bullae, animals from
Rice, Arizona, resemble _D. o. chapmani_, but in other characters
resemble _D. o. ordii_ to which subspecies they are referred. Animals
from 20 miles northeast of Calva, Arizona, are dark-colored and are
intermediate between the dark _D. o. chapmani_ and the pale _D. o.
ordii_ in size of the cranium and body but are referable to _D. o.
ordii_. In the northwestern part of the range of _D. o. chapmani_ the
animals are not typical in that they have a shorter, wider rostrum and a
heavier zygomatic arch than topotypes.

    _Specimens examined._--Total, 90, all from Arizona, distributed as
    follows: _Mohave County_: lower end Prospect Valley, 4500 ft.,
    Grand Canyon, 7 (USBS); Kingman, 9 (LACM). _Coconino County_:
    Aubrey Valley, 10 mi. S Pine Spring, 4 (USBS); Bill Williams
    Mountain, 1 (USNM). _Yavapai County_: 3 mi. N Fort Whipple, 11
    (USBS); Fort Whipple, 4 (2 USBS; 2 USNM); Willow Creek, 4 mi. N
    Prescott, 4 (MVZ); 1 mi. W Camp Verde, 1 (MVZ); Camp Verde, 33 (15
    USBS; 3 MVZ; 3 AMNH; 9 LACM; 3 DRD); 1/2 mi. S Camp Verde, 4 (MVZ);
    Kirkland, 9 (USBS); Turkey Creek, 3 (USBS).


=Dipodomys ordii montanus= Baird

    _Dipodomys montanus_ Baird, Proc. Acad. Nat. Sci. Philadelphia,
    7:334, April, 1855.

    _Perodipus montanus_, Merriam, Proc. Biol. Soc. Washington,
    17:140, July 14, 1904.

    _Perodipus ordii montanus_, Goldman, Proc. Biol. Soc. Washington,
    30:113, May 23, 1917.

    _Dipodomys ordii montanus_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Type._--Male, no. 490/1631, U. S. Nat. Mus.; near Fort
    Massachusetts, Costilla County, Colorado; obtained in 1853 by F.
    Kreutzfeldt (Pacific Railroad Survey).

    _Range._--The San Luis Valley of south-central Colorado and
    north-central New Mexico; marginal occurrence are: in Colorado, 22
    mi. E Mosca, Saguache, Alamosa and Antonito; in New Mexico, 4 mi.
    SW Cimmaron.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface between (_c_) Vinaceous-Buff and Avellaneous,
    purest on sides and flanks, upper parts strongly suffused with
    black; arietiform markings, pinnae of ears, plantar surfaces of
    hind feet and dorsal and ventral stripes of tail, blackish. Skull
    small; rostrum slender; interorbital width narrow; auditory bullae
    strongly inflated; braincase but slightly vaulted; interparietal
    region wide; zygomatic arch bowed laterally.

    _Comparisons._--From _Dipodomys ordii richardsoni_, _D. o.
    montanus_ differs as follows: Size smaller; color darker in all
    pigmented areas; ventral stripe of tail continuous to end of
    pencil in all specimens, whereas in _D. o. richardsoni_ the stripe
    is incomplete in most specimens. In all specimens the dorsal and
    ventral stripes of the tail are darker in _D. o. montanus_; skull
    smaller in all measurements taken; jugal straight or nearly so, as
    contrasted to bowed laterally; pterygoid fossae shallower and more
    ovoid, that is to say, wings of pterygoid flare laterally; ventral
    projection of auditory bullae more pronounced; rostrum,
    immediately in front of zygomatic process of maxilla, nearly
    parallel to median plane along long axis of skull, while in _D. o.
    richardsoni_ this union forms a decided obtuse angle; paroccipital
    processes smaller; foramen magnum smaller and more ovoid as
    opposed to larger and more circular.

    From _Dipodomys ordii evexus_, _D. o. montanus_ differs as
    follows: Size smaller in all measurements taken except width
    across auditory bullae which is greater; color darker, ventral
    stripe of tail continuous to end of pencil; least width of
    supraoccipital less (2.5 mm. in _D. o. montanus_ and 3.5 mm. in
    _D. o. evexus_); extension of premaxillae posterior to nasals
    greater; braincase more inflated dorsally; bullae relatively as
    well as actually larger and more inflated ventrally; pterygoid
    fossae narrower anteroposteriorly and wider laterally than in _D.
    o. evexus_; jugal straight or nearly so as contrasted to bowed
    laterally; lacrimal processes smaller.

    For comparison with _Dipodomys ordii medius_ see account of that
    subspecies.

[Illustration: FIG. 26. Known occurrences and probable geographic range
of the subspecies of _Dipodomys ordii_ in the southwestern fourth of the
range of the species.

  14. _D. o. ordii_   17. _D. o. chapmani_   31. _D. o. longipes_ ]

_Remarks._--This subspecies of _Dipodomys ordii_ appears to be
restricted to the San Luis Valley of Colorado and New Mexico.
Intergradation, between _Dipodomys ordii ordii_ and _D. o. montanus_, is
noted in animals from Gran Quivira, Mesa Jumanes, New Mexico. These
animals have the frontomaxillary suture and extension of the premaxilla
as in _D. o. ordii_ and the nasals and inflation of the auditory bullae
as in _D. o. montanus_. In the majority of characters they are, however,
referable to the latter. Intergradation is noted also in animals from 4
miles southwest of Cimmaron, New Mexico, in that they resemble _D. o.
richardsoni_ in the shape of the nasals and the width and length of the
rostrum but in the remainder of the characters studied resemble _D. o.
montanus_ to which they are referred.

Baird, in the original description, gives "near Fort Massachusetts" as
the type locality for this subspecies. Miller (1923) lists the type
locality as "Fort Massachusetts (now Fort Garland)." Fort Massachusetts
and Fort Garland are two different ex-army posts. Old Fort Massachusetts
was situated on what is now the Trinchera Ranch which is north of the
town of Fort Garland. Old Fort Garland is approximately one-half mile
south of the town of Fort Garland. The two abandoned army posts were no
more than twelve miles apart. In 1946, at neither abandoned post could I
find any habitat suitable for kangaroo rats.

    _Specimens examined._--Total, 148, distributed as follows:

    =Colorado=: _Saguache County_: Saguache, 1 (USBS). _Alamosa
    County_: 1.6 mi. NE Medano Springs Ranch Headquarters, 8 (MVZ);
    Great Sand Dunes National Monument, 10 (MVZ); 8 mi. S Great Sand
    Dunes National Monument, 4 (MVZ); Medano Ranch, 15 mi. NE Mosca,
    11 (2 USBS; 9 MVZ); 22 mi. E Mosca, 5 (AMNH); Alamosa, 1 (UM).
    _Conejos County_: Antonito, 1 (USBS); 7 mi. E Antonito, 3 (USBS);
    12 mi. E Antonito, 2 (USBS). _Costilla County_: 4-1/2 mi. N
    Blanca, 8100 ft., 3 (MVZ); 1 mi. NE Blanca, 7950 ft., 1 (MVZ); 3
    mi. NW Fort Garland, 6 (CMNH); 1 mi. NW Fort Garland, 3 (MVZ); 15
    mi. W Fort Garland, 7800 ft., 4 (KU); Fort Garland, 64 (31 USBS;
    28 LACM; 5 MVZ); 5 mi. SSE Fort Garland, 4 (AMNH); 5 mi. S Fort
    Garland, 2 (AMNH).

    =New Mexico=: _Colfax County_: 4 mi. SW Cimmaron, 5 (AMNH); 3 mi.
    SE Cimmaron, 8 (AMNH); 1-1/2 mi. W Philmont Ranch Headquarters, 2
    (AMNH).


=Dipodomys ordii cinderensis= Hardy

    _Dipodomys ordii cinderensis_ Hardy, Proc. Biol. Soc. Washington,
    57:53, October 31, 1944.

    _Type._--Male, no. 4611, Mus. Zool., Univ. Utah; at approximately
    4,000 ft. on sandy soil, immediately north of the northern of two
    large cinder cones in Diamond Valley, 10 mi. N St. George,
    Washington County, Utah; obtained on February 13, 1944, by Ross
    Hardy, original no. 2690.

    _Range._--Diamond Valley, Washington County, Utah, north through
    Mountain Meadows, east as far as Cedar City, Iron County, Utah,
    north through the Escalante Desert to Lund, Iron County, and west
    almost to the Utah-Nevada boundary; marginal occurrences, all in
    Utah are: 11 mi. SE Lund; N end Mountain Meadows; Diamond Valley;
    10 mi. W Cedar City; 4-1/2 mi. NW Summit and 6 mi. W Parowan.

    _Diagnosis._--Size small (see measurements). Color dark, upper
    parts near Buffy Brown, strongly suffused with black, purest on
    sides and flanks; pinnae of ears, plantar surfaces of hind feet,
    dorsal and ventral stripes of tail, arietiform markings, black.
    Skull small; rostrum narrow; auditory bullae relatively as well as
    actually well inflated; external auditory meatus small;
    interparietal region narrow.

    _Comparisons._--From _Dipodomys ordii fetosus_, _D. o.
    cinderensis_ differs in: Size smaller; color darker; skull smaller
    in all measurements taken.

    From _Dipodomys ordii panguitchensis_, _D. o. cinderensis_ differs
    as follows: Size smaller; color lighter; skull smaller except for
    auditory bullae which are larger; external auditory meatus
    smaller; maxillary tooth-row longer.

    Compared with _Dipodomys ordii longipes_ and _Dipodomys ordii
    cupidineus_, _D. o. cinderensis_ is smaller, darker and can easily
    be distinguished.

    For comparisons with _Dipodomys ordii celeripes_ and _Dipodomys
    ordii utahensis_ see accounts of those subspecies.

_Remarks._--This race confined to Utah, and inhabiting northern
Washington County and most of Iron County, is restricted almost
exclusively to areas of loose shifting sand. Intergradation with
_Dipodomys ordii fetosus_ occurs near Lund. The animals from this
locality intergrade in size of body and in color, but in the majority of
cranial characters resemble _D. o. cinderensis_. In all characters
studied _D. o. cinderensis_ appears to be more closely related to
_Dipodomys ordii utahensis_ than to any other subspecies with which it
comes into actual contact.

Animals from near Parowan have both cranial and external characters
by which they could be referred to either _D. o. panguitchensis_
or _D. o. cinderensis_. Owing to the existence of the physical barrier
(Cedar Mountains) separating the two populations, they are referred
to _D. o. cinderensis_. _Dipodomys ordii cinderensis_ is not a
well differentiated race but appears to possess characters sufficiently
diagnostic to distinguish it from contiguous forms.

    _Specimens examined._--Total, 74, all from Utah, distributed as
    follows: _Iron County_: 11 mi. SE Lund, 50 (46 RH; 4 MVZ); 4-1/2
    mi. NW Summit and 6 mi. W Parowan, 9 (RH); 10 mi. W Cedar City, 1
    (USAC); 5 mi. W Cedar City, 1 (USAC); Cedar City, 2 (BYU).
    _Washington County_: Diamond Valley, 9 (RH); N end Mountain
    Meadows, 2 (RH).


=Dipodomys ordii fetosus= Durrant and Hall

    _Dipodomys ordii fetosus_ Durrant and Hall, Mammalia, 3:14, March,
    1939.

    _Type._--Female, adult, no. 48451, Museum of Vertebrate Zoology,
    University of California; 2 mi. N Panaca, 4,800 ft., Lincoln
    County, Nevada; obtained on June 24, 1931, by Ward C. Russell,
    original no. 1658.

    _Range._--Southeastern Nevada and western Beaver and Millard
    counties, Utah; marginal occurrences in Nevada, 2 mi. SE Pioche,
    15 mi. WSW Sunnyside, 16-1/2 mi. WSW Sunnyside, 14 mi. NNE Sharp,
    8-1/2 mi. NE Sharp, 15 mi. S Groom Baldy, 10 mi. E Crystal Spring,
    Panaca; in Utah, Pine Valley, 50 mi. W Milford and 5 mi. S
    Garrison.

    _Diagnosis._--Size medium (see measurements). Color dark, entire
    dorsal surface (_16''_) between Pinkish Cinnamon and Cinnamon-Buff,
    purest on sides and flanks with strong admixture of black in upper
    parts; cheeks white; pinnae of ears, arietiform markings, plantar
    surfaces of hind feet, dorsal and ventral stripes of tail,
    blackish. Skull medium in size; rostrum wide and short;
    interorbital region narrow; braincase but slightly vaulted;
    lacrimal processes large; zygomatic arches weak and bowed
    laterally; pterygoid fossae large and subcircular.

    _Comparisons._--From _Dipodomys ordii utahensis_, _D. o. fetosus_
    differs as follows: Hind foot longer; color lighter; skull larger;
    rostrum, relatively as well as actually, shorter and wider; nasals
    longer and wider; interorbital region narrower; braincase less
    vaulted; interparietal region narrower; auditory bullae more
    inflated laterally, posteriorly and ventrally; foramen magnum
    smaller.

    From _Dipodomys ordii celeripes_, _D. o. fetosus_ differs as
    follows: Larger; color darker; arietiform markings present; skull
    larger; rostrum longer and wider; nasals longer and less inflated
    distally; interorbital region wider; auditory bullae somewhat more
    inflated; zygomatic arches more robust.

    For comparisons with _Dipodomys ordii monoensis_, _D. o.
    columbianus_, _D. o. pallidus_, _D. o. panguitchensis_ and _D. o.
    cinderensis_ see accounts of those subspecies.

_Remarks._--_Dipodomys ordii fetosus_ has a small geographic range. Hall
(1946:416) points out that the interorbital breadth in topotypes is less
than in those from any other part of the range. This feature, therefore,
is not useful in characterizing this subspecies. Intergradation with
_Dipodomys ordii columbianus_ is noted in the greater total length and
the somewhat darker color in animals from Coal Valley and Garden Valley,
Nevada. In the part of the range which lies in Utah, none of the animals
is typical and all are intergrades in color and cranial characters with
_Dipodomys ordii celeripes_.

    _Specimens examined._--Total, 136, distributed as follows:

    =Nevada=: _Nye County_: White River Valley, 15 mi. WSW Sunnyside,
    5500 ft., 26 (MVZ); White River Valley, 16-1/2 mi. WSW Sunnyside,
    5500 ft., 6 (MVZ); 14 mi. NNE Sharp, 1 (MVZ); Garden Valley, 15
    mi. NE Sharp, 1 (MVZ); Garden Valley, 14-1/2 mi. NE Sharp, 3
    (MVZ); 8-1/2 mi. NE Sharp, 17 (MVZ). _Lincoln County_: E side Coal
    Valley, 14 mi. N Seeman Pass, 4850 ft., 4 (MVZ); 2 mi. SE Pioche,
    1 (MVZ); E side Coal Valley, 10 mi. N Seeman Pass, 1 (MVZ); Desert
    Valley, 20 mi. SW Pioche, 1 (MVZ); 2 mi. N Panaca, 4800 ft., 17
    (16 MVZ; 1 CAS); Desert Valley, 21 mi. W Panaca, 10 (MVZ); Crystal
    Spring, Pahranagat Valley, 4000 ft., 2 (MVZ); 10 mi. E Crystal
    Springs, 5000 ft., 1 (MVZ); 15 mi. S Groom Baldy, 1 (MVZ).

    =Utah=: _Millard County_: 5 mi. S Garrison, 5400 ft., 12 (MVZ);
    Pine Valley, Sec. 33, T. 25 S, R. 17 W, 5000 ft., 16 (UU); Warm
    Cove, Sec. 34, T. 25 S, R. 18 W, 5500 ft., 2 (UU); Desert Range
    Experiment Station, 50 mi. W Milford, 5252 ft., 10 (9 UU; 1 BYU).


=Dipodomys ordii utahensis= (Merriam)

    _Perodipus montanus utahensis_ Merriam, Proc. Biol. Soc.
    Washington, 17:143, July 14, 1904.

    _Perodipus ordii utahensis_, Goldman, Proc. Biol. Soc. Washington,
    30:113, May 23, 1917.

    _Dipodomys ordii columbianus_, Grinnell, Journ. Mamm., 2:96, May
    2, 1921.

    _Dipodomys ordii columbianus_, Hall, Univ. California Publ. Zool.,
    37:5, April 10, 1931 (part--the part from Ogden, Utah.)

    _Type._--Male, adult, no. 55115, U. S. Nat. Mus. Biol. Surv. Coll.;
    Ogden, Weber County, Utah; obtained on July 15, 1893, by Vernon
    Bailey, original no. 4085.

    _Range._--Between Great Salt Lake and the Wasatch Mountains from
    extreme northern Utah, south to northern Sevier County, Utah;
    marginal occurrences, all in Utah, are: Promontory Point, Ogden,
    St. John, Cedar Valley, Nephi, Aurora, Spring City, Provo and 4
    mi. N Draper.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface (_a_) between Cinnamon-Buff and Clay Color, purest
    on sides, flanks and cheeks, with heavy admixture of black in
    upper parts; arietiform markings, pinnae of ears, plantar surfaces
    of hind feet, dorsal and ventral stripes of tail blackish. Skull
    small; rostrum short and narrow; interorbital region moderately
    wide; interparietal large, spatulate anteriorly; lacrimal
    processes relatively large; braincase vaulted; zygomatic arches
    robust and straight; auditory bullae relatively, as well as
    actually, greatly inflated.

    _Comparisons._--From _Dipodomys ordii marshalli_, _D. o.
    utahensis_ differs as follows: Size smaller; color darker; skull
    smaller; rostrum longer and narrower; interorbital region wider;
    lacrimal processes larger; interparietal region larger; auditory
    bullae less inflated; palate longer and narrower.

    From _Dipodomys ordii pallidus_, _D. o. utahensis_ differs in:
    Size smaller; color darker; skull smaller; rostrum shorter and
    narrower; interorbital region narrower; auditory bullae less
    inflated laterally, posteriorly and ventrally; interparietal
    region larger; lacrimal processes smaller; foramen magnum with
    ventral notch as opposed to rounded ventrally; pterygoid fossae
    circular as opposed to subcircular; palate longer and narrower.

    From _Dipodomys ordii cinderensis_, _D. o. utahensis_ differs as
    follows: Size larger, except hind foot which is shorter; color
    somewhat lighter, more reddish; skull larger; rostrum longer;
    nasals longer; braincase more vaulted; pterygoid fossae circular
    as opposed to subcircular; auditory bullae less inflated laterally
    but more inflated ventrally.

    For comparisons with _Dipodomys ordii columbianus_, _D. o.
    fetosus_, _D. o. marshalli_, _D. o. panguitchensis_ and _D. o.
    cineraceus_ see accounts of those subspecies.

_Remarks._--The systematic status of _D. o. utahensis_ has long been
in doubt. Several workers have, at various times, considered it to be
indistinguishable from _Dipodomys ordii columbianus_. Durrant and
Setzer (1945:29) recognized it as a valid subspecies and gave diagnostic
characters by which it could be distinguished from _D. o.
columbianus_.

Intergradation has been noted in specimens from the eastern and
southeastern shores of Great Salt Lake. In color and the width of the
auditory bullae these specimens are intermediate between _D. o.
utahensis_ and _Dipodomys ordii marshalli_ but in the sum total of
characters are referable to the latter. Specimens from 20 miles
southwest of Nephi and from U. B. (Yuba) Dam are darker and intermediate
in rostral width and breadth of the auditory bullae but are referable to
_Dipodomys ordii celeripes_.

    _Specimens examined._--Total, 91, all from Utah, distributed as
    follows: _Box Elder County_: Promontory Point, 1 (USNM). _Weber
    County_: Ogden, 4293 ft., 20 (7 BYU; 7 MVZ; 4 USNM); Little
    Mountain, 1 (USNM). _Davis County_: Antelope Island, Great Salt
    Lake, 4250 ft., 5 (USNM). _Tooele County_: Bauer, 4500 ft., 6 (UU);
    St. John, 4300 ft., 4 (UU); Little Valley, Sheeprock Mountains,
    5500 ft., 1 (UU); Clover Creek, Onaqui Mountains, 5500 ft., 1 (UU).
    _Salt Lake County_: Plain, 4 mi. N Draper, 4500 ft., 1 (UU). _Utah
    County_: Fairfield, Cedar Valley, 4800 ft., 15 (9 BYU; 6 UU); W
    Lake Mountains, 9 (BYU); Provo, 4510 ft., 10 (MVZ); Sand Dunes W
    Curtis Station, 4 (BYU). _Juab County_: Nephi, 2 (1 USNM; 1 MVZ); 4
    mi. W Nephi, 1 (RH). _San Pete County_: Spring City, 4 (LACM).
    _Sevier County_: 1 mi. W Aurora, 5190 ft., 6 (5 UU; 1 USNM).


=Dipodomys ordii columbianus= (Merriam)

    _Perodipus ordi columbianus_ Merriam, Proc. Biol. Soc. Washington,
    9:115, June 21, 1894.

    _Dipodomys phillipii_, Baird, U. S. P. R. R. Expl. and Surveys,
    Gen. Rept., p. 412, 1857 (part--the part from Ft. Walla Walla, O.
    T.).

    _Cricetodipus ordii columbianus_, Trouessart, Catalogus Mammalium,
    1:581, 1897.

    _Perodipus ordii columbianus_, Goldman, Proc. Biol. Soc.
    Washington, 30:113, May 23, 1917.

    _Dipodomys ordii columbianus_, Grinnell, Journ. Mamm., 2:96, May
    2, 1921.

    _Type._--Female, adult, no. 24181/31594, U. S. Nat. Mus., Dept. of
    Agriculture, Coll.; Umatilla, Plains of Columbia, Umatilla County,
    Oregon; obtained on October 18, 1890, by Clark P. Streator,
    original no. 386.

    _Range._--Southeastern Washington, eastern Oregon, southwestern
    Idaho, northwestern, northern and most of northeastern Nevada;
    marginal occurrences are: in Washington, 2 mi. SW Paterson, 4 mi.
    E Burbank and Wallula; in Oregon, 7 mi. E Madras, 2 mi. E
    Prineville and Guano Valley; in California, Eagleville, Red Rock,
    Observation Peak, 5 mi. E Litchfield, Honey Lake, Vinton; in
    Nevada, 3-1/2 mi. E Flanigan, 6 mi. S Pahrum Peak, 2-1/2 mi. E and
    11 mi. N Gerlach, 2 mi. SW Quinn River Crossing, 1 mi. SE
    Tuscarora, 5 mi. N Beowawe, 1/2 mi. S Beowawe, 2-1/2 mi. NE Smiths
    Creek Ranch, Bells Ranch, 5 mi. W Austin, 8 mi. W Eureka, 4 mi. S
    Shoshone, 5 mi. SE Greens Ranch, and 22 mi. N Deeth; in Idaho, 8
    mi. W Rodgerson, 6 mi. SW American Falls, 4 mi. NE American Falls,
    5 mi. NW Michaud, Arco, Hammett and Payette; in Oregon, Umatilla.

    _Diagnosis._--Size medium (see measurements). Color dark, entire
    dorsal surface (_16''_) between Pinkish Cinnamon and
    Cinnamon-Buff, purest on sides and flanks with strong admixture of
    black on upper parts; cheeks white; arietiform markings, pinnae of
    ears, plantar surfaces of hind feet, dorsal and ventral stripes of
    tail, blackish. Skull medium in size; rostrum relatively
    long and narrow; nasals long and expanded distally; interorbital
    region narrow; lacrimal processes small; braincase but slightly
    vaulted; auditory bullae relatively greatly inflated; pterygoid
    fossae circular; zygomatic arches robust.

    _Comparisons._--From _Dipodomys ordii utahensis_, _D. o.
    columbianus_ differs as follows: Color lighter, dorsal and ventral
    stripes of tail brownish as opposed to black; ventral stripe of
    tail, in most specimens, incomplete to end of pencil as opposed to
    complete; lacrimal processes smaller; extension of premaxillae
    dorsad wider; interparietal generally narrower, smaller,
    quadrangular and truncate anteriorly, as opposed to spatulate and
    rounded anteriorly; braincase less vaulted; zygomatic arches bowed
    laterally as opposed to straight; styloid processes larger;
    cutting edge of upper incisors narrower.

    From _Dipodomys ordii fetosus_, _D. o. columbianus_ differs in:
    Hind foot shorter; color generally darker; skull larger; rostrum
    shorter and wider; nasals somewhat shorter; braincase more
    vaulted; auditory bullae less inflated; interparietal region
    wider; ventral border of foramen magnum more rounded (less
    indented); zygomatic arches straight as opposed to bowed
    laterally.

    For comparisons with _Dipodomys ordii inaquosus_, _Dipodomys ordii
    monoensis_ and _Dipodomys ordii celeripes_ see accounts of those
    subspecies.

_Remarks._--In most subspecies of _Dipodomys ordii_ having large
geographic ranges, there is a certain amount of variation, but _D. o.
columbianus_ remains relatively stable throughout its large range. Where
extreme variation is noted in _D. o. columbianus_ it is obviously the
result of intergradation. This intergradation is noted between
_Dipodomys ordii monoensis_ and _D. o. columbianus_ in Lyon County,
Nevada, where the animals are referable to the former race cranially but
to the latter on the basis of color. Animals from Kelton, Utah, are in
color as _Dipodomys ordii marshalli_ and cranially combine characters of
_D. o. columbianus_, _D. o. utahensis_ and _D. o. marshalli_. The sum
total of their characters places them with _D. o. marshalli_. Durrant
and Setzer (1945:29), and the present writer in this account, do not
record any animals from Utah as belonging to _D. o. columbianus_.
Nevertheless, the influence of _D. o. columbianus_ is seen in the
animals from Kelton, Utah.

    _Specimens examined._--Total, 588, distributed as follows:

    =Washington=: _Benton County_: Blalock Island, 2 mi. SW Paterson,
    2 (MVZ). _Walla Walla County_: 4 mi. E Burbank, 4 (MVZ); 2 mi. SSE
    Burbank, 27 (MVZ); Wallula, 7 (4 MVZ; 3 DRD).

    =Oregon=: _Gilliam County_: Arlington, 1 (MVZ). Morrow County:
    2-1/2 mi. SW Irigon, 6 (MVZ); Cecil, 1 (MVZ). _Umatilla County_:
    Umatilla, 10 (MVZ). _Jefferson County_: 7 mi. E Madras, 2 (DRD).
    _Crook County_: 2 mi. NE Prineville, 1 (MVZ); 7 mi. W Prineville,
    8 (MVZ); 4 mi. SW Prineville, 23 (MVZ); Crooked River, at mouth of
    Bear Creek, 8 (MVZ). _Lake County_: Fort Rock, 1 (DRD); NE edge
    Alkali Lake, 8 (MVZ); 9 mi. S Adel, mouth 20 Mile Creek, 1 (MVZ);
    Guano Ranch, Guano Valley, 2 (DRD). _Harney County_: Malheur Lake,
    9 (LACM); Narrows, 1 (DRD); 1 mi. S Narrows, 3 (MVZ); 5 mi. SW
    Narrows, 19 (MVZ); Smith Creek, 10 mi. SE Diamond, 1 (MVZ); Lake
    Alvord, 1 (MVZ); 1-1/2 mi. E Denio, 4 (MVZ). _Malheur County_: 3
    mi. N Vale, 2 (MVZ); 8 mi. N Jordan Valley, 1 (MVZ); 1/2 mi. S
    Rome, 5 (MVZ); 1 mi. S Rome, 11 (MVZ).

    =Idaho=: _Payette County_: Payette, 1 (DRD). _Butte County_: Arco,
    1 (MVZ). _Elmore County_: Hammett, 1 (MVZ). _Bingham County_: 5 mi.
    E Shelley, 1 (MVZ); Blackfoot, 5 (MVZ); 3 mi. S Blackfoot, 6 (MVZ);
    Aberdeen, 1 (MVZ). _Owyhee County_: S bank Snake River, Homedale,
    13 (MVZ); Indian Cove, 4 (MVZ); 5 mi. SE Murphy, 3 (MVZ); Castle
    Creek, 8 mi. S Oreana, 1 (MVZ); S Fork Owyhee River, 12 mi. N
    Nevada line, 1 (MVZ). _Minidoka County_: Acequia, 8 (MVZ); 4 mi. N
    Rupert, 2 (MVZ). _Twin Falls County_: Salmon Creek, 8 mi. W
    Rodgerson, 7 (MVZ). _Power County_: 5 mi. NW Michaud, 4 (MVZ); 4
    mi. NE American Falls, 4 (MVZ); 6 mi. SW American Falls, 10 (MVZ).

    =California=: _Modoc County_: Eagleville, 12 (CAS); 2 mi. E
    Eagleville, 7 (CAS); 2-1/2 mi. E Eagleville, 24 (CAS); 3 mi. E
    Eagleville, 6 (CAS); 5 mi. E Eagleville, 3 (CAS). _Lassen County_:
    2 mi. W Red Rock P. O., 1 (MVZ); 1 mi. W Red Rock P. O., 4 (MVZ);
    Dransfield, 6 mi. E Ravendale, 5300 ft., 4 (CAS); 7 mi. E
    Ravendale, 1 (MVZ); 7 mi. N Observation Peak, 21 (MVZ); 6 mi. N
    Observation Peak, 7 (MVZ); Observation Peak, 31 (MVZ); Pete's
    Valley, 4 (MVZ); 5 mi. E Litchfield, 12 (MVZ); 6 mi. W Wendell,
    3975 ft., 3 (CAS); 8 mi. SW Wendell, 5 (CAS); Honey Lake, 2
    (LACM); 4-1/2 mi. WNW Stacy, 5 (MVZ); 3 mi. NW Warm Springs, 1
    (MVZ). _Plumas County_: Beckwith, 1 (DRD); 2 mi. WNW Vinton, 2
    (MVZ); Vinton, 18 (14 LACM; 4 MVZ); 1 mi. E Vinton, 7 (MVZ); near
    Vinton, 21 (DRD).

    =Nevada=: _Washoe County_: 3 mi. N Vya, 3 (MVZ); 4-1/2 mi. NE
    Painted Point, 4 (MVZ); 8-1/2 mi. E Vya, 1 (MVZ); 3 mi. E Painted
    Point, 1 (MVZ); Long Valley Ranch, 3 mi. S Vya, 1 (MVZ); 10-1/2
    mi. S Vya, 1 (MVZ); 11 mi. S Vya, 2 (MVZ); 13 mi. S Vya, 4 (MVZ);
    Hausen, 4800 ft., 8 (MVZ); 10 mi. SE Hausen, 4675 ft., 7 (MVZ);
    2-1/2 mi. E and 11 mi. N Gerlach, 4050 ft., 4 (MVZ); Smoke Creek,
    9 mi. E California line, 3900 ft., 5 (MVZ); 40° 28' N Lat., 6 mi.
    E California line, 4000 ft., 3 (MVZ); Horse Canyon, 3 mi. NW
    Pahrum Peak, 5000 ft., 1 (MVZ); Fox Canyon, 6 mi. S Pahrum Peak,
    4800 ft., 4 (MVZ); N side Sand Pass, 3950 ft., 2 (MVZ); 4 mi. NW
    Flanigan, 4200 ft., 1 (MVZ); 3-1/2 mi. NW Flanigan, 4200 ft., 1
    (MVZ); 3-1/2 mi. E Flanigan, 2 (MVZ); 2-3/4 mi. SW Pyramid, 4300
    ft., 2 (MVZ). _Humboldt County_: 1 mi. S Denio, Oregon, 4200 ft.,
    6 (MVZ); Quinn River Crossing, 4100 ft., 1 (MVZ). _Elko County_:
    Mary's River, 22 mi. N Deeth, 3 (MVZ); 1 mi. SE Tuscarora, 5900
    ft., 2 (MVZ); 5 mi. W Halleck, 5200 ft., 7 (MVZ); 3 mi. W Halleck,
    5300 ft., 2 (MVZ). _Lander County_: 1 mi. E Battle Mountain, 1
    (MVZ); Reese River Valley, 6 mi. N Austin, 2 (MVZ); Malloy Ranch,
    5 mi. W Austin, 3 (MVZ); 2-1/2 mi. NE Smiths Creek Ranch, 5800
    ft., 1 (MVZ); Campbell Creek, 6900 ft., 3 (MVZ); Campbell Creek
    Ranch, 5500 ft., 8 (MVZ). _Eureka County_: 5 mi. N Beowawe, 7
    (MVZ); 1/2 mi. S Beowawe, 1 (MVZ); Pine Creek, 2 mi. E Palisades,
    7 (MVZ); Evans, 4 (MVZ); Winzell, 3 (MVZ); 4 mi. SE Romano,
    Diamond Valley, 1 (MVZ); 8 mi. W Eureka, 12 (MVZ). _White Pine
    County_: 5 mi. SE Greens Ranch, Steptoe Valley, 1 (MVZ); Cherry
    Creek, 6600 ft., 2 (MVZ); 1 mi. E Illipah, 6100 ft., 3 (MVZ);
    5-1/2 mi. SE Ely, 6500 ft., 5 (MVZ); Spring Valley, 5900 ft., 4
    mi. S Shoshone, 6 (MVZ). _Nye County_: Bells Ranch, Reese River,
    6890 ft., 1 (MVZ).


=Dipodomys ordii idoneus= new subspecies

    _Type._--Male, adult, no. 90029, Museum of Zoology, University of
    Michigan; San Juan, 12 mi. W Lerdo, 3,800 ft., Durango, Mexico;
    obtained on March 1, 1946, by F. and F. Hammerstrom.

    _Range._--Known only from the type locality.

    _Diagnosis._--Size small (see measurements). Color pale, entire
    dorsal surface (c) between Light Ochraceous-Buff and
    Ochraceous-Buff, purest on sides, flanks and cheeks; upper parts
    but slightly washed with black; arietiform markings, lateral parts
    of pinnae of ears, plantar surfaces of hind feet, dorsal and
    ventral stripes of tail, brownish; medial part of pinnae of ears
    flesh-colored. Skull medium in size; rostrum wide and relatively
    long; braincase but slightly inflated; least interorbital width
    great; interparietal region relatively narrow; upper incisors
    strongly recurved; zygomatic arches relatively heavy and slightly
    bowed laterally; auditory bullae greatly inflated ventrally,
    laterally and posteriorly.

    _Comparisons._--From _Dipodomys ordii ordii_, _D. o. idoneus_
    differs in: Size smaller; color lighter; skull larger; nasals
    longer and somewhat more inflated distally as opposed to straight;
    interorbital width greater; breadth across maxillary arches
    greater; interparietal region narrower; auditory bullae more
    inflated posteriorly, laterally and ventrally and projecting
    anteriorly into orbit; extension of nasals anterior to upper
    incisors less; zygomatic arches heavier and more bowed laterally;
    paroccipital processes smaller; foramen magnum elongate as
    opposed to nearly circular.

    From _Dipodomys ordii obscurus_, _D. o. idoneus_ differs as
    follows: Size smaller; color lighter; skull larger, rostrum wider;
    nasals shorter and more expanded distally; interorbital region
    wider; width across maxillary arches greater; interparietal region
    narrower; auditory bullae more inflated laterally, posteriorly and
    ventrally; zygomatic arches shorter, heavier and less bowed
    laterally.

    From _Dipodomys ordii palmeri_, _D.o. idoneus_ differs in: Size
    smaller; color lighter; skull larger; rostrum shorter and wider;
    nasals shorter and more expanded distally; interorbital region
    wider; auditory bullae more inflated laterally, posteriorly and
    ventrally; zygomatic arches heavier.

    From _Dipodomys ordii fuscus_, _D. o. idoneus_ differs as follows:
    Size smaller; color lighter; skull smaller; rostrum narrower and
    shorter; interorbital width greater; braincase more vaulted;
    nasals longer; interparietal region generally wider; auditory
    bullae less inflated; breadth across maxillary arches greater;
    zygomatic arches heavier and more bowed laterally; pterygoid
    fossae ovoid as opposed to subcircular; occipital condyles more
    anterior to dorsal evagination when viewed ventrally.

    _Dipodomys ordii idoneus_ differs from _Dipodomys ordii
    attenuatus_ in larger size, generally darker color and larger
    skull.

_Remarks._--This subspecies of _Dipodomys ordii_ is paler than either of
the subspecies with adjoining geographic ranges. Measurements of the
skull, in proportion to external measurements, are larger than in any
other subspecies of _Dipodomys ordii_. Cranially, this new subspecies is
more closely allied to _Dipodomys ordii fuscus_ but in color appears to
be much closer to _Dipodomys ordii attenuatus_ from which it differs
markedly in cranial features.

    _Specimens examined._--Total, 3, all from Durango, distributed as
    follows: San Juan, 12 mi. W Lerdo, 3 (UM).


=Dipodomys ordii priscus= Hoffmeister

    _Dipodomys ordii priscus_ Hoffmeister, Proc. Biol. Soc. Washington,
    55:167, December 31, 1942.

    _Perodipus longipes_, Allen, Bull. Amer. Mus. Nat, Hist., 8:246,
    November, 1896 (part--the part from Kinney Ranch, Wyoming).

    _Perodipus montanus richardsoni_, Cary, N. Amer. Fauna, 33:141,
    August 17, 1911 (part--the part from Lay, Colorado).

    _Periodipus_ [_Dipodomys_] _ordii luteolus_, Svihla, Journ. Mamm.;
    12:262, August, 1931 (part--the part from Linwood, Utah).

    _Type._--Male, no. 89119, Mus. Vert. Zool., Univ. California;
    Kinney Ranch, 21 mi. S Bitter Creek, 7100 ft., Sweetwater County,
    Wyoming; obtained on September 16, 1939, by Donald T. Tappe,
    original no. 766.

    _Range._--Southwestern Wyoming, extreme northeastern Utah and
    northwestern Colorado; marginal occurrences are: in Wyoming, 7 mi.
    N Ft. Washakie and 10 mi. SW Granger; in Colorado, Lay and Snake
    River south of Sunny Peak.

    _Diagnosis._--Size medium (see measurements). Color light, entire
    dorsal surface between (c) Light Ochraceous-Buff and
    Ochraceous-Buff, purest on sides, flanks and cheeks; upper parts
    slightly suffused with black; arietiform markings, pinnae of ears,
    plantar surfaces of hind feet, dorsal and ventral stripes of tail,
    grayish to blackish in different individuals. Skull medium in
    size; rostrum long and narrow; nasals long; auditory bullae
    relatively narrow and skull long, giving appearance of much
    narrower skull than is actually the case; zygomata weak; upper
    incisors moderately wide at cutting edge.

    _Comparisons._--From _Dipodomys ordii uintensis_, _D. o. priscus_
    differs as follows: Hind foot longer; color lighter in all
    pigmented areas, and skull smaller in all measurements taken.

    From _Dipodomys ordii sanrafaeli_, _D. o. priscus_ differs in:
    Color decidedly less red in upper parts; ventral stripe of tail
    not continuous to end of pencil; nasals longer; auditory bullae
    less inflated.

    For comparisons with _Dipodomys ordii luteolus_ and _Dipodomys
    ordii terrosus_ see accounts of those subspecies.

_Remarks._--The characters of this subspecies are stable throughout most
of its geographic range. It is not known to intergrade with adjacent
forms. One specimen, a male, available from the Snake River, south of
Sunny Peak, Colorado, however, is not typical of _D. o. priscus_, in
that it has a wider and deeper rostrum than any other specimen from the
entire range. Between _D. o. priscus_ and _D. o. luteolus_, the skull,
but not the color, provides diagnostic differences.

The Red Desert of Wyoming is mostly sandy but there are large exposures
of rock and gravel. At the type locality of _D. o. priscus_ rockier soil
predominates but is interspersed with stabilized sand dunes where the
kangaroo rats are abundant. Traps set on the rocky soils, in a
continuous line between the dunes, yielded no kangaroo rats.

Kangaroo rats in the area of the Kinney Ranch, Wyoming, apparently form
a good source of food for owls, since many bones (jaws and limb
elements) were found in owl pellets at the bases of cliffs approximately
5 miles northeast of the ranch buildings.

    _Specimens examined._--Total, 72, distributed as follows:

    =Wyoming=: _Fremont County_: 7 mi. N Fort Washakie, 1 (USBS); Fort
    Washakie, 1 (USBS); Wind River, 1 (USBS). _Sweetwater County_:
    Eden, 1 (USBS); 5 mi. E Rock Springs, 1 (UM); 10 mi. SW Granger,
    13 (UM); Bitter Creek, 9 (6 AMNH; 3 CNHM); Kinney Ranch, 21 mi. S
    Bitter Creek, 18 (MVZ); Shell Creek, 25 mi. S Bitter Creek, 3
    (CM); 30 mi. S Bitter Creek, 3 (KU); 33 mi. S Bitter Creek, 8
    (KU). _Carbon County_: 20 mi. W Baggs, 2 (USBS).

    =Utah=: _Daggett County_: E bank Green River, 4 mi. E Linwood, 4
    (CM).

    =Colorado=: _Moffat County_: Snake River, south of Sunny Peak, 1
    (USBS); 20 mi. NW Sunbeam, 4 (CM); Bear River, Lay, 1 (USBS). _Rio
    Blanco County_: W side White River, 1 mi. N Rangely, 1 (CM).


=Dipodomys ordii celeripes= Durrant and Hall

    _Dipodomys ordii celeripes_ Durrant and Hall, Mammalia, 3:10,
    March, 1939.

    _Dipodomys ordii columbianus_, Hall, Univ. California Publ. Zool.,
    37:5, April 10, 1931.

    _Type._--Male, adult, no. 1956, Museum of Zoology, University of
    Utah; Trout Creek, 4600 ft., Juab County, Utah; obtained on May 5,
    1937, by Stephen D. Durrant, original no. 1168.

    _Range._--Eastern Nevada, western and west-central Utah, east to
    eastern Sevier County, Utah; marginal occurrences are: in Nevada,
    Tecoma, Cobre and 8 mi. SE Mt. Moriah; in Utah, E side Clear Lake,
    U. B. (Yuba) Dam, 10 mi. SW Nephi, and Trout Creek.

    _Diagnosis._--Size small (see measurements). Color pale, entire
    dorsal surface Pinkish Buff, purest on sides, flanks and cheeks,
    with but slight suffusion of black in upper parts; pinnae of ears,
    plantar surfaces of hind feet, dorsal and ventral stripes of tail,
    brownish. Skull small; rostrum relatively short and wide; nasals
    relatively short; lacrimal processes small; braincase but slightly
    vaulted; auditory bullae but little inflated; interorbital region
    narrow; styloid processes project on ventral surface of auditory
    bullae beyond middle of external auditory meatus; zygomatic arches
    robust and bowed laterally; pterygoid fossae ovoid.

    _Comparisons._--From _Dipodomys ordii marshalli_, _D. o.
    celeripes_ differs as follows: Size smaller, hind foot longer,
    tail shorter; color lighter; skull smaller; rostrum wider and
    shorter; interorbital region narrower; auditory bullae less
    inflated; lacrimal processes smaller; palate shorter; pterygoid
    fossae larger.

    From _Dipodomys ordii cinderensis_, _D. o. celeripes_ differs as
    follows: Size smaller, tail shorter; color lighter; rostrum wider
    and shorter; nasals shorter; interorbital width less; auditory
    bullae less inflated; foramen magnum wider and shorter; pterygoid
    fossae more circular.

    From _Dipodomys ordii columbianus_, _D. o. celeripes_ differs in:
    Size smaller; color lighter; rostrum wider and shorter;
    interorbital width less; interparietal region wider; auditory
    bullae, generally, less inflated; upper incisors longer and more
    robust; pterygoid fossae larger.

    For comparisons with _Dipodomys ordii fetosus_, _Dipodomys ordii
    pallidus_ and _Dipodomys ordii panguitchensis_ see accounts of
    those subspecies.

_Remarks._--It appears that wherever the range of _D. o. celeripes_
meets that of an adjoining race, intergradation occurs freely.
Practically all of the Nevadan specimens referable to this subspecies
are intergrades with _Dipodomys ordii columbianus_ in size and color.
Specimens from west of Delta, Utah, are intermediate in size between
_Dipodomys ordii pallidus_ and _D. o. celeripes_ but their cranial
characters are more as in _D. o. celeripes_. Intergrades with _Dipodomys
ordii utahensis_ are discussed under the account of that subspecies.

The characters differentiating _D. o. celeripes_ from any contiguous
subspecies are not present in every specimen even in the type series.

    _Specimens examined._-Total, 96, distributed as follows:

    =Nevada=: _Elko County_: 13 mi. N Montello, 5000 ft., 2 (MVZ);
    1-1/2 mi. N Tecoma, 4900 ft., 6 (MVZ); Tecoma, 4900 ft., 8 (MVZ);
    Cobre, 6100 ft., 3 (MVZ); Salt Springs, 4200 ft., 1 (MVZ). _White
    Pine County_: 2 mi. W Smith Creek Cave, 6300 ft., Mt. Moriah, 2
    (MVZ); Hendry Creek, 8 mi. SE Mt. Moriah, 6200 ft., 1 (MVZ).

    =Utah=: _Tooele County_: Clifton Flat, 7 mi. SW Gold Hill, 6149
    ft., 4 (UU); Parrish Ranch, 5 mi. N Ibapah, 5175 ft., 1 (UU);
    Ibapah, 5000 ft., 23 (UU). _Juab County_: Trout Creek, 4600 ft.,
    21 (19 UU; 1 USAC; 1 MVZ); 20 mi. SW Nephi, 2 (UU); U. B. (Yuba)
    Dam, Sevier River, 5000 ft., 10 (UU). _Millard County_: 4 mi. S
    Gandy, 5000 ft., 1 (MVZ); Smith Creek, 6 mi. S Gandy, 5400 ft., 2
    (MVZ); Hendry Creek, 5000 ft., 17 mi. S Gandy, 4 (MVZ); Oak City,
    5000 ft., 1 (UU); White Valley, 60 mi. W Delta, 1 (UU); 35 mi. W
    Delta, 1 (UU); East side Clear Lake, 4600 ft., 4 (3 UU; 1 USAC); 2
    mi. E Clear Lake, 4600 ft., 2 (UU).


=Dipodomys ordii cineraceus= Goldman

    _Dipodomys ordii cineraceus_ Goldman, Journ. Mamm., 20:352, August
    14, 1939.

    _Type._--Male, no. 263890, U. S. Nat. Mus. Biol. Surv. Coll.;
    Dolphin Island, Great Salt Lake, 4250 ft., Box Elder County, Utah;
    obtained on June 4, 1938, by William H. Marshall, original no. 57.

    _Range._--Dolphin Island, Great Salt Lake, Utah.

    _Diagnosis._--Size medium (see measurements). Color pale, upper
    parts near Pale Pinkish Buff, but lightly washed with black,
    purest on sides and flanks; arietiform markings, pinnae of ears,
    plantar surfaces of hind feet, dorsal and ventral stripes of tail,
    brownish. Skull medium in size; rostrum short; nasals relatively
    short; interparietal region relatively wide; auditory bullae but
    slightly inflated.

    _Comparisons._--From _Dipodomys ordii utahensis_, _D. o.
    cineraceus_ differs in: Size smaller; color lighter; nasals
    longer; auditory bullae larger; total length of skull greater.

    From _Dipodomys ordii marshalli_, _D. o. cineraceus_ differs in:
    Size smaller; color darker; skull larger in all measurements
    taken.

_Remarks._--The race _D. o. cineraceus_ along with _Dipodomys microps
russeolus_ is found on Dolphin Island, Great Salt Lake, Utah. Dolphin
Island is connected with the mainland by a bar that could allow animals
from the island to disperse onto the mainland. There are no animals from
the mainland, however, that are referable to _D. o. cineraceus_ or to
_D. m. russeolus_. The animals available from the mainland, at Kelton,
although geographically near Dolphin Island, are referable to _D. o.
marshalli_ and to _D. m. bonnevillei_. The paucity of material from the
mainland, adjacent to Dolphin Island, may be significant. Future
trapping in this area is needed before we can be certain that _D. o.
cineraceus_ is isolated.

    _Specimens examined._--Total, 2, both from Utah, as follows: _Box
    Elder County_: Dolphin Island, Great Salt Lake, 4250 ft., 2 (USNM).


=Dipodomys ordii marshalli= Goldman

    _Dipodomys ordii marshalli_ Goldman, Proc. Biol. Soc. Washington,
    50:223, December 28, 1937.

    _Type._--Female, adult, no. 262655, U. S. Nat. Mus. Biol. Surv.
    Coll.; Bird Island, Great Salt Lake, 4,300 ft., Tooele County,
    Utah; obtained on June 22, 1937, by W. H. Marshall, X-catalog no.
    27969.

    _Range._--Bird, Carrington, Badger and Stansbury islands, Great
    Salt Lake; around western edge of Great Salt Lake north to Kelton,
    Box Elder County, Utah; around southern and southeastern edge of
    the lake to mouth of the Jordan River; marginal occurrences are:
    all in Utah, Kelton, 2 mi. W Grantsville, 14 mi. W Salt Lake City
    and Bird Island, Great Salt Lake.

    _Diagnosis._--Size medium (see measurements). Color pale, entire
    dorsal surface near Pinkish Buff, purest on sides, flanks and
    cheeks with but slight suffusion of black on upper parts;
    arietiform markings, pinnae of ears, plantar surfaces of hind
    feet, and dorsal and ventral stripes of tail, brownish. Skull
    medium in size; rostrum narrow and long; pterygoid fossae ovoid;
    cutting edge of upper incisors narrow; external auditory meatus
    round and small; jugal straight or nearly so.

    _Comparisons._--From _Dipodomys ordii pallidus_, _D. o. marshalli_
    differs in: Hind foot smaller; color darker, arietiform markings
    more distinct; dorsal and ventral stripes of tail more pronounced;
    skull smaller; palate shorter and wider; jugals lighter; external
    auditory meatus smaller; cutting edge of upper incisors narrower;
    nasals shorter and less flared distally.

    From _Dipodomys ordii utahensis_, _D. o. marshalli_ differs in:
    Size smaller; color lighter; skull smaller, except least
    interorbital width and depth of auditory bullae which are greater;
    cutting edge of upper incisors narrower; nasals less flared
    distally.

    For comparison with _Dipodomys ordii celeripes_ see account of
    that subspecies.

_Remarks._--This subspecies was described from Bird Island, Great Salt
Lake, and was thought by Marshall (1940:153), who collected the
specimens, to be restricted to that island. However, specimens taken
over a period of years on the nearby mainland, by students from the
University of Utah, are referable to this subspecies. Although these
animals from the mainland are referable to _D. o. marshalli_, they have
some characteristics of _D. o. utahensis_ from the eastern and southern
mainland. Four specimens from Kelton, also on the mainland, are not
typical of _D. o. marshalli_; nevertheless, more than half of their
characters of taxonomic worth are as in _D. o. marshalli_ to which the
animals are referred.

Great Salt Lake has not been so effective in isolating the animals
living on the islands as heretofore has been thought. After these
supposedly isolated kinds of animals from Great Salt Lake were named,
some other workers have shown several of the kinds to have extensive
ranges on the mainland. Some of the kinds ranging also on the mainland
are: _Dipodomys ordii marshalli_, _Dipodomys microps subtenuis_ and
_Peromyscus crinitus pergracilis_. Of the animals named from the
islands, I suppose that those which require the semiarid habitat found
in this area will all be found to have large ranges on the adjacent
mainland and that each of the kinds of animals which do not require the
above habitat, and which lived in this region during the Pleistocene,
will be found to be restricted to the island from which it was named.

    _Specimens examined._--Total, 47, all from Utah, distributed as
    follows: _Box Elder County_: Kelton, 4300 ft., 7 (5 MVZ; 2 UU).
    _Tooele County_: 2 mi. W Grantsville, 1 (CAS); Bird Island, Great
    Salt Lake, 4300 ft., 1 (USNM); Carrington Island, Great Salt Lake,
    4300 ft., 1 (USNM); Stansbury Island, Great Salt Lake, 4300 ft., 10
    (6 UU; 4 USNM). _Salt Lake County_: 18 mi. W Salt Lake City, 4260
    ft., 16 (UU); 17 mi. W Salt Lake City, 4320 ft., 7 (UU); 16 mi. W
    Salt Lake City, 4300 ft., 3 (UU); 14 mi. W Salt Lake City, 4300
    ft., 1 (UU).


=Dipodomys ordii inaquosus= Hall

    _Dipodomys ordii inaquosus_ Hall, Proc. Biol. Soc. Washington,
    54:58, May 20, 1941.

    _Type._--Male, adult, no. 73580, Museum of Vertebrate Zoology,
    University of California; 11 mi. E and 1 mi. N Jungo, 4,200 ft.,
    Humboldt County, Nevada; obtained on July 26, 1936, by Ward C.
    Russell, original no. 5026.

    _Range._--Southeastern Humboldt and northern Lander counties,
    Nevada; marginal occurrences, all in Nevada, are: 7 mi. N
    Winnemucca, 8 mi. E and 1 mi. N Jungo, 15 mi. SW Winnemucca, 23
    mi. NW Battle Mountain, Izenhood, and 18 mi. NE Iron Point.

    _Diagnosis._--Size medium (see measurements). Color pale, entire
    dorsal surface Pinkish Buff, purest on sides and flanks with but
    slight suffusion of black on the upper parts; cheeks white;
    arietiform marks indistinct, pinnae of ears, plantar surfaces of
    hind feet, dorsal and ventral stripes of tail, brownish. Skull
    medium in size; rostrum short and wide; nasals relatively long and
    expanded distally; braincase but slightly vaulted; interorbital
    width narrow; extension of premaxillae posterior to nasals
    relatively great; interparietal relatively large; pterygoid fossae
    subcircular; foramen magnum ovoid; auditory bullae relatively
    greatly expanded ventrally.

    _Comparisons._--From _Dipodomys ordii columbianus_, _D. o.
    inaquosus_ differs as follows: Size larger; color lighter; skull
    larger; nasals longer; rostrum longer and wider; interorbital
    region narrower; braincase more vaulted; interparietal larger;
    auditory bullae more inflated ventrally; pterygoid fossae
    subcircular as opposed to nearly circular; zygomatic arches more
    robust.

    From _Dipodomys ordii monoensis_, _D. o. inaquosus_ differs in:
    Size larger; color lighter; skull larger; nasals longer; rostrum
    wider; interorbital width greater; braincase more vaulted;
    auditory bullae more inflated laterally, ventrally and
    posteriorly; interparietal region narrower; pterygoid fossae
    subcircular as opposed to circular; lacrimal processes larger;
    foramen magnum ovoid as opposed to circular.

_Remarks._--In pallor _D. o. inaquosus_ closely approaches _Dipodomys
ordii celeripes_ from eastern Nevada and western Utah. The two
populations are separated, however, by a large area inhabited by the
darker _Dipodomys ordii columbianus_. Specimens from 18 mi. NE Iron
Point, Nevada, which Hall (1946:413) refers to _D. o. columbianus_, are
intergrades in color, size and cranial characters and here are referred
to _D. o. inaquosus_ instead of to _D. o. columbianus_. Animals from
Toulon are intergrades between _D. o. inaquosus_ and _Dipodomys ordii
monoensis_ but are referable to the latter.

    _Specimens examined._--Total, 47, all from Nevada, distributed as
    follows: _Humboldt County_: 18 mi. NE Iron Point, 4600 ft., 1
    (MVZ); 7 mi. N Winnemucca, 4400 ft., 4 (MVZ); 1 mi. N Winnemucca,
    4600 ft., 8 (MVZ); 5 mi. NE Golconda, 7 (MVZ); 3 mi. SW Winnemucca,
    4500 ft., 1 (MVZ); 4 mi. SW Winnemucca, 4500 ft., 1 (MVZ); 5 mi. SW
    Winnemucca, 4600 ft., 2 (MVZ); 8 mi. E and 1 mi. N Jungo, 4200 ft.,
    6 (MVZ); 11 mi. E and 1 mi. N Jungo, 4200 ft., 7 (MVZ); 10 mi. SW
    Winnemucca, 4500 ft., 1 (MVZ); 23 mi. NW Battle Mountain, 4 (MVZ).
    _Pershing County_: 15 mi. SW Winnemucca, 1 (MVZ). _Lander County_:
    Izenhood, 2 (MVZ); 3 mi. S Izenhood, 2 (MVZ).


=Dipodomys ordii attenuatus= Bryant

    _Dipodomys ordii attenuatus_ Bryant, Occas. Papers, Museum of
    Zool., Louisiana State Univ., no. 5:65, November 10, 1939.

    _Type._--Male, no. 80429, Museum of Vertebrate Zoology, University
    of California; Mouth of Santa Helena Canyon, 2146 ft., Big Bend of
    the Rio Grande, Brewster County, Texas; obtained on November 19,
    1938, by Adrey E. Borell, original no. 5581.

    _Range._--Big Bend region of Brewster County, Texas.

    _Diagnosis._--Size small (see measurements). Color light, entire
    dorsal surface between Pinkish Buff and Pinkish Cinnamon, purest
    on sides and flanks, upper parts but lightly mixed with black;
    cheeks and narrow outer margin of ear, pure white; arietiform
    markings absent; pinnae of ears, dorsal and ventral stripes of
    tail, brownish; plantar surfaces of hind feet, blackish. Skull
    small; rostrum long and narrow; nasals short; interparietal longer
    than wide; auditory bullae longer than deep.

    _Comparisons._--Compared with _Dipodomys ordii ordii_, _D. o.
    attenuatus_ differs in: Size smaller; color lighter; skull
    smaller; nasals thinner; rostrum narrower; auditory bullae less
    inflated.

    From _Dipodomys ordii richardsoni_, _D. o. attenuatus_ differs in
    smaller size and lighter color. Skull smaller in all respects.

    For comparison with _Dipodomys ordii sennetti_ see account of that
    subspecies.

[Illustration: FIG. 27. Known occurrences and probable geographic range
of the subspecies of _Dipodomys ordii_ in the northwestern fourth of the
range of the species.

  9. _D. o. panguitchensis_ 20. _D. o. fetosus_     28. _D. o. inaquosus_
 10. _D. o. uintensis_      21. _D. o. utahensis_   31. _D. o. longipes_
 11. _D. o. sanrafaeli_     22. _D. o. columbianus_ 32. _D. o. pallidus_
 12. _D. o. fremonti_       24. _D. o. priscus_     33. _D. o. nexilis_
 13. _D. o. monoensis_      25. _D. o. celeripes_   34. _D. o. cupidineus_
 17. _D. o. chapmani_       26. _D. o. cineraceus_
 19. _D. o. cinderensis_    27. _D. o. marshalli_ ]

_Remarks._--This small race of _Dipodomys ordii_ was known formerly
only from the type locality. This study has shown it to range northward
and slightly westward. At four places, 6, 20, and 47 miles south of
Marathon and 10 miles west of San Vicente, Texas, this race can be said
to be typical, in that specimens from these places agree with those from
the type locality. At two other localities, 5 miles east of Toyahvale
and Kent, Texas, animals show an intergrading tendency toward _Dipodomys
ordii ordii_. The animals from these latter places are darker colored
and are intermediate in size and cranial characters. Since these animals
show more resemblance to _D. o. ordii_ in the majority of characters
they are referred to that race, rather than to _D. o. attenuatus_.

    _Specimens examined._--Total, 14, all from Texas, distributed as
    follows: _Brewster County_: 6 mi. S Marathon, 1 (USBS); 20 mi. S
    Marathon, 1 (USBS); Cooper's Well, 47 mi. S Marathon, 4 (MVZ); 10
    mi. W San Vicente, 1 (UM); Johnson's Ranch, Big Bend Rio Grande, 4
    (2 TCWC; 2 UM); mouth Santa Helena Canyon, 3 (1 TCWC; 2 MVZ).


=Dipodomys ordii fuscus= new subspecies

    _Type._--Male, adult, no. 93886, U. S. Nat. Mus., Biol. Surv.
    Coll.; Juamave, Tamaulipas, Mexico; obtained on June 3, 1898, by E.
    W. Nelson and E. A. Goldman, original no. 12437.

    _Range._--Nuevo León, extreme northern Zacatecas, Tamaulipas and
    northern San Luis Potosí, Mexico; marginal occurrences are:
    Coahuila, La Ventura; Tamaulipas, Tula, Juamave and Nuevo Laredo.

    _Diagnosis._--Size medium (see measurements). Color dark, entire
    dorsal surface (_a_) between Cinnamon-Buff and Clay Color, purest
    on sides, flanks and cheeks, upper parts strongly suffused with
    black; posterior surfaces and fold of pinnae of ears, white;
    arietiform markings, plantar surfaces of hind feet, inside of
    pinnae of ears, dorsal and ventral stripes of tail, blackish.
    Skull of medium size; nasals relatively short; interorbital width
    narrow; auditory bullae relatively as well as actually greatly
    inflated posteriorly, laterally and ventrally; braincase vaulted;
    zygomatic arches light and straight; pterygoid fossae ovoid;
    rostrum short and wide.

    _Comparisons._--From _Dipodomys ordii palmeri_, _D. o. fuscus_
    differs in: Size larger; color lighter; skull larger; rostrum
    shorter and wider; interorbital width less; nasals shorter;
    auditory bullae more expanded laterally, posteriorly and
    ventrally; interparietal region narrower; pterygoid fossae more
    circular; upper incisors wider at cutting edge; zygomatic arches
    straight rather than bowed laterally.

    From _Dipodomys ordii obscurus_, _D. o. fuscus_ differs as
    follows: Size larger; color lighter; skull larger; rostrum wider
    and shorter; interorbital region wider; width across maxillary
    arches greater; auditory bullae more expanded laterally,
    posteriorly and ventrally; zygomatic arches light and straight
    instead of heavy and bowed laterally; pterygoid fossae more nearly
    circular; braincase more vaulted; foramen magnum smaller.

    From _Dipodomys ordii ordii_, _D. o. fuscus_ differs in: Size
    larger; color darker; skull larger; rostrum shorter and wider;
    nasals short and more flared distally; interorbital width greater;
    auditory bullae more inflated posteriorly, laterally and
    ventrally; interparietal region narrower; width across maxillary
    arches greater; pterygoid fossae larger and more nearly circular;
    braincase more vaulted.

    From _Dipodomys ordii sennetti_, _D. o. fuscus_ can be
    distinguished by larger  size, longer tail, darker color, and
    cranially by larger auditory bullae, longer nasals, wider
    interorbital region and greater width across maxillary arches.

_Remarks._--This dark subspecies of _Dipodomys ordii_ is most closely
allied to _Dipodomys ordii palmeri_ from, which it can be distinguished
by the characters set forth under comparisons.

It seems that the Rio Grande serves as a barrier to the dispersal
southward of kangaroo rats from the north side and vice versa. _D. o.
fuscus_ ranges from the type locality to Nuevo Laredo and has not been
found on the north side of the river, being replaced there, up-river, by
_Dipodomys ordii medius_ and down-river by _Dipodomys ordii sennetti_.

    _Specimens examined._--Total, 53, distributed as follows:

    =Coahuila=: San Juan Neponuceno, 5 mi. N La Ventura, 4 (MVZ); La
    Ventura, 7 (USBS).

    =Tamaulipas=: Nuevo Laredo, 2 (USBS); Miquihuana, 14 (4 USBS; 9
    MVZ; 1 AMNH); Juamave, 8 (USBS); Tula, 5 (UM); 3 mi. N Lulú, 5
    (MVZ): Lulú, 8 (MVZ).


=Dipodomys ordii longipes= (Merriam)

    _Dipodops longipes_ Merriam, N. Amer. Fauna, 3:72, September 11,
    1890.

    _Perodipus ordii_, Allen, Bull. Amer. Mus. Nat. Hist., 5:71, April
    28, 1893 (part--the part from Bluff, Utah).

    _Cricetodipus longipes_, Trouessart, Catalogus Mammalium, 1:581,
    1897.

    _Perodipus longipes_, Elliot, Field Columbian Museum, Zool. Ser.,
    2:239, 1901.

    _Perodipus ordii longipes_, Goldman, Proc. Biol. Soc. Washington,
    30:113, May 23, 1917.

    _Dipodomys ordii longipes_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Dipodomys ordii cleomophila_ Goldman, Journ. Washington Acad.
    Sci., 23:469, October 15, 1933, type from 5 miles northeast of
    Winona, Coconino County, Arizona.

    _Type._--Male, no. 17703/24639, U. S. Nat. Mus. Dept. Agric. Coll.;
    foot of Echo Cliffs, Painted Desert, Arizona; obtained on September
    22, 1889, by C. Hart Merriam, original no. 512.

    _Range._--Southeastern Utah, northeastern Arizona to immediately
    south of the Little Colorado River, northwestern New Mexico and
    extreme southwestern Colorado; marginal occurrences are: in
    Arizona, 20 mi. NE Lees Ferry, Foot Echo Cliffs in Painted Desert,
    5 mi. NE Winona, Winslow and Holbrook; in New Mexico, 10 mi. SW
    Quemado, Riley, Laguna, Chama Canyon and Shiprock.

    _Diagnosis._--Size large (see measurements). Color dark, entire
    dorsal surface between (_16''_) Pinkish Cinnamon and
    Cinnamon-Buff, purest on sides and flanks with but slight
    suffusion of black on upper parts; cheeks white; arietiform
    markings, pinnae of ears, plantar surfaces of hind feet, dorsal
    and ventral stripes of tail, brownish. Skull large; rostrum long
    and narrow; nasals long and thin; auditory bullae greatly
    inflated; styloid processes project on ventral surface of auditory
    bullae beyond middle of external auditory meatus.

    _Comparisons._--From _Dipodomys ordii chapmani_, _D. o. longipes_
    differs as follows: Size larger; color lighter; skull larger in
    all measurements taken; auditory bullae much more inflated.

    From _Dipodomys ordii cupidineus_, _D. o. longipes_ differs in:
    Size larger; color lighter; rostrum longer and narrower; nasals
    longer; interorbital width greater; breadth across zygomatic
    processes of maxillae greater; auditory bullae more inflated;
    zygomatic arches heavier and more bowed laterally.

    For comparisons with _Dipodomys ordii medius_ and _Dipodomys ordii
    nexilis_ see accounts of those subspecies.

_Remarks._--The large reddish _Dipodomys ordii longipes_ is notably
distinct from those subspecies which have adjoining ranges. The
subspecies closest, geographically and morphologically, is _Dipodomys
ordii nexilis_ with which _D. o. longipes_ intergrades, in size of body
and color of pelage, north of the San Juan River, Utah. This
intergradation is probably the result of a migration of _D. o. longipes_
around the head waters of, or above the place in, the river where there
is constantly flowing water. It is probably impossible for these animals
to cross a constantly flowing stream as wide as the San Juan is in its
lower reaches. The San Juan River, however, in 1896, and again in 1934,
was so low that it ceased to flow below Aneth (Gregory, 1938:6, 19).
Consequently, at these times, _Dipodomys_ could have crossed the river
from one side to the other, at least above the Goosenecks.
Intergradation is noted also with _Dipodomys ordii medius_ at Chama
Canyon, New Mexico, where the color is like that of _D. o. medius_,
although the cranial characters are as in _D. o. longipes_; specimens
from Chama Canyon are referred to the latter. Ten miles southwest of
Quemado and at Riley, New Mexico, intergradation with _Dipodomys ordii
ordii_ occurs in the shape of the nasals and the intermediate size of
the skull. In color and external measurements these animals more closely
resemble _D. o. longipes_.

Goldman (1933:469) described _Dipodomys ordii cleomophila_ from 5 miles
northeast of Winona, Coconino County, Arizona, and gave as distinctive
characters "upper parts distinctly darker, ... black facial markings
more distinct; skull slightly different." These comparative statements
were made in reference to _Dipodomys ordii longipes_. While it is true
that the animals which Goldman examined are darker and show some slight
cranial differences, these animals, in my opinion, are not sufficiently
distinct to warrant their separation from _D. o. longipes_. In the
degree of expansion of the auditory bullae, the width of the rostrum,
the length of the nasals and interorbital width, animals from 5 miles
northeast of Winona (2 specimens) are within the range of individual
variation shown by _D. o. longipes_. The color is darker, being more as
in _Dipodomys ordii chapmani_. Specimens examined from 10 miles north
of Angell, Springerville, Tanner Tank and Cedar Ranch Wash, Arizona
(listed by Goldman as referable to _D. o. cleomophila_), and those from
Wupatki Ruins, Arizona, agree with _D. o. longipes_ except that the
width across the maxillary arches is greater. This greater width across
the maxillary arches and the darker color of animals from Winona and
Wupatki Ruins, in my opinion, afford insufficient basis for the
recognition of the subspecies _Dipodomys ordii cleomophila_ Goldman
which, therefore, is placed as a synonym of _Dipodomys ordii longipes_
(Merriam).

    _Specimens examined._--Total, 244, distributed as follows:

    =Utah=: _San Juan County_: 1 mi. N Bluff, 3500 ft., 1 (UU); 1/2
    mi. N Bluff, 3300 ft., 7 (UU); Bluff, 2 (UU); Johns Canyon, San
    Juan River, 5150 ft., 2 (UU).

    =Arizona=: _Coconino County_: 20 mi. NE Lees Ferry, 1 (USNM); 2
    mi. S Endische, 2 (MVZ); 2 mi. SE Endische Spring, Navajo
    Mountain, 1 (MVZ); 1/2 mi. W Navajo Spring, Echo Cliffs, 4 (MVZ);
    5 mi. S Navajo Mountain, 2 (MVZ); 7 mi. SE Navajo Mountain, 1
    (MVZ); Moa Vae, 10 (MVZ); 2 mi. S Grand Canyon Bridge, 1 (USBS);
    Tuba, 4 (1 USBS; 3 AMNH); 12 mi. above mouth of Moencopi Wash, 2
    (USBS); 14 mi. NW Cedar Ridge, 1 (USBS); 5 mi. N Cameron, 1 (MVZ);
    Painted Desert, 6 mi. NE Cameron, 1 (MVZ); 5 mi. E Little Colorado
    River on Tuba road, 2 (MVZ); Cameron, 4200 ft., 17 (8 LACM; 9
    MVZ); Wupatki Ruins, 4 (MVZ); Deadmans Flat, 6400 ft., NE San
    Francisco Mt., 3 (MVZ); 3 mi. NW Winona, 4 (USBS); 5 mi. NE
    Winona, 2 (USBS); 10 mi. N Angell, Walnut Tank, 8 (USBS); Cedar
    Ranch Wash, 3 mi. above mouth, 5 (USBS); Tanner Tank, 2 (USBS);
    Tanners Crossing, Painted Desert, 1 (USBS). _Navajo County_: Right
    fork, Segi-ot-Sosie Canyon, 11 mi. NW Kayenta, 2 (MVZ); Bat Woman
    Canyon, 13 mi. W Kayenta, 1 (MVZ); Kayenta, 4 (USBS); Segi Canyon,
    12 mi. WSW Kayenta, 1 (MVZ); Segi Canyon, 13 mi. WSW Kayenta, 1
    (MVZ); Oraibi, 6000 ft., 9 (4 USBS; 5 MVZ); Walpi, 2 (USBS); Keam
    Canyon, 12 (6 USBS; 3 USNM; 3 MVZ); Winslow, 6 (USBS); Zuni Well,
    7-1/2 mi. N Adamana, 9 (MVZ); Holbrook, 10 (USBS); Long Canyon, 3
    (AMNH); Bubbling Springs, 2 (AMNH). _Apache County_: Dinnehotso,
    5000 ft., 3 (MVZ); Lukachukai, 1 (USBS); Chin Lee, 6 (USBS); 9 mi.
    SW Chin Lee, 1 (USBS); 7 mi. from mouth, Canyon de Chelly, 1
    (USBS); Fort Defiance, 2 (USNM); Ganado, 1 (USBS); Springerville,
    2 (USBS); 3 mi. SE Springerville, 5 (USBS); unspecified, 4 (2
    USBS; 2 USNM); Trash Tank, Grand Canyon, 2 (USBS).

    =New Mexico=: _San Juan County_: Ship Rock, 4 (USBS); Fruitland, 9
    (USBS); Blanco, 1 (USBS); Chaco Canyon National Monument, 4 (MVZ).
    _Rio Arriba County_: Chama Canyon, 1 (USBS). _McKinley County_: 2
    mi. W Mariano Lake, 3 (MVZ); Gallup, 6 (USBS); Wingate, 6 (USBS);
    Thoreau, 2 (USBS); Zuni River, 1 (USBS). _Sandoval County_: Juan
    Tafoya, 1 (USBS). _Valencia County_: 8 mi. SE Grants, 7 (UM); 9
    mi. SSE Grants, 5 (UM); 2-1/2 mi. E El Morro P. O., Zuni Mts., 1
    (LACM); Laguna, 1 (USBS); Laguna Indian Reservation, 7 (LACM).
    _Catron County_: Cougar Ranch, NE Adams Diggings, 1 (CAS); 10 mi.
    SW Quemado, 1 (USBS). _Socorro County_: 1 mi. S Bernardo, 1 (MVZ);
    Riley, 1 (USBS).


=Dipodomys ordii pallidus= Durrant and Setzer

    _Dipodomys ordii pallidus_ Durrant and Setzer, Bull. Univ. Utah, 35
    (no. 26):24, June 30, 1945.

    _Type._--Male, adult, no. 3526, Museum of Zoology, University of
    Utah; Old Lincoln Highway, 18 mi. SW Orr's Ranch in Skull Valley,
    4,400 ft., Tooele County, Utah; obtained on June 6, 1940, by S. D.
    Durrant, original no. 1905.

    _Range._--Low valleys of west-central Utah in Tooele, Juab and
    Millard counties; marginal occurrences are: all in Utah, 18 mi. SW
    Orr's Ranch, 7 mi. S Fish Springs, Hinckley and Lynndyl.

    _Diagnosis._--Size medium (see measurements). Color light, entire
    dorsal surface Light Pinkish Cinnamon, purest on sides and flanks,
    with but slight suffusion of black on upper parts; cheeks white;
    arietiform markings, pinnae of ears, plantar surfaces of hind feet,
    dorsal and ventral stripes of tail, brownish. Skull large; auditory
    bullae long, wide and well inflated; external auditory meatus
    elongate with a notch on the dorsal border; nasals long and flaring
    distally.

    _Comparisons._--From _Dipodomys ordii celeripes_, _D. o. pallidus_
    differs in: Size larger; color generally darker, although some
    specimens are lighter; skull larger; nasals longer and more flared
    distally; interorbital width greater; auditory bullae larger;
    external auditory meatus larger.

    From _Dipodomys ordii fetosus_, _D. o. pallidus_ differs in: Size
    larger; color lighter; ventral stripe of tail indistinct as
    opposed to pronounced; skull larger; nasals longer and more flared
    distally; auditory bullae larger; external auditory meatus larger;
    palate shorter and broader.

    For comparisons with _Dipodomys ordii marshalli_ and _Dipodomys
    ordii utahensis_ see accounts of those subspecies.

_Remarks._--Among named subspecies of _Dipodomys ordii_, _D. o.
pallidus_ most closely resembles, morphologically, _D. a. marshalli_,
its nearest geographic neighbor to the north and east. Intergradation
with _Dipodomys ordii utahensis_ is noted in color and intermediacy of
body size of specimens from Clover Creek. The majority of cranial
characters, however, show these animals to be referable to _D. o.
utahensis_ rather than to _D. o. pallidus_. Specimens taken at Lynndyl
and Hinckley show intergradation in size of body, length and
configuration of the nasals and the degree of inflation of the auditory
bullae between _Dipodomys ordii celeripes_ and _D. o. pallidus_. The
majority of characters studied show these latter animals to be referable
to _D. o. pallidus_. Specimens from 35 and 60 miles west of Delta, in
size of body and shape and inflation of the auditory bullae, are
intermediate between _D. o. pallidus_ and _D. o. celeripes_. These
specimens are here referred to _D. o. celeripes_.

    _Specimens examined._--Total, 34, all from Utah, distributed as
    follows: _Tooele County_: Old Lincoln Highway, 18 mi. SW Orr's
    Ranch in Skull Valley, 4400 ft., 9 (UU). _Juab County_: Fish
    Springs, 4400 ft., 4 (UU); 7 mi. S Fish Springs, 4400 ft., 4 (UU).
    _Millard County_: 1 mi. N Lynndyl, 4768 ft., 5 (UU); Lynndyl, 4768
    ft., 1 (UU); Hinckley, 4600 ft., 11 (UU).


=Dipodomys ordii nexilis= Goldman

    _Dipodomys ordii nexilis_ Goldman, Journ. Washington, Acad. Sci.,
    23:470, October 5, 1933.

    _Perodipus longipes_, Warren, Mammals of Colorado, p. 77, 1910
    (part--the part from Coventry, Colorado).

    _Dipodomys ordii longipes_, Moore, Journ. Mamm., 10:260, August,
    1929 (part--the part from Monticello, Utah).

    _Type._--Male, adult, no. 149938, U. S. Nat. Mus. Biol. Surv.
    Coll.; 5 mi. W Naturita, Montrose County, Colorado; obtained on
    July 20, 1907, by Merritt Cary, original no. 1068.

    _Range._--West-central Colorado, southwest into San Juan County,
    Utah, north of the San Juan River; northwest into Grand County,
    Utah, to the  Colorado River; and westward probably as far as the
    Colorado River; marginal occurrences are: in Utah, Cisco, 18 mi. NE
    Moab, and Blanding; in Colorado, 5 mi. W Naturita, and Coventry.

    _Diagnosis._--Size medium (see measurements). Color dark, entire
    dorsal surface between (_a_) Cinnamon-Buff and Clay Color, purest
    on sides and flanks, upper parts strongly suffused with black;
    arietiform markings, pinnae of ears, plantar surfaces of hind
    feet, dorsal and ventral tail-stripes blackish. Lateral white
    stripes of tail less than one fourth of diameter of tail. Skull
    large; rostrum long and narrow; nasals long; auditory bullae
    strongly inflated; braincase not inflated; pterygoid fossae ovoid.

    _Comparisons._--From _Dipodomys ordii sanrafaeli_, _D. o. nexilis_
    differs in: Color darker; skull smaller in all measurements taken;
    auditory bullae noticeably smaller; width across zygomatic
    processes of maxillae less.

    From _Dipodomys ordii longipes_, _D. o. nexilis_ differs in: Size
    smaller; color darker in all respects; rostrum wider; breadth
    across auditory bullae less; interorbital width greater; breadth
    across zygomatic processes of maxillae less; cutting edge of upper
    incisors wider; zygomatic arch lighter and more nearly straight.

    Comparison with _Dipodomys ordii evexus_ is made in account of
    that subspecies.

_Remarks._--This animal is apparently not abundant at any place in its
range. Two different attempts, by me, to obtain topotypes were
unsuccessful. A single specimen was obtained and that was only a skull
saved from a mutilated animal that was taken away from a rattlesnake.
The habitat at the type locality is such that a person would not expect
it to be inhabited by kangaroo rats. The soil is a heavy clay with a
generous admixture of stones but in isolated spots there are light sandy
soils which should be suitable for kangaroo rats. Even so, 500 traps set
in the area of the type locality over a period of two nights yielded no
_Dipodomys_.

This subspecies of _Dipodomys ordii_, inhabiting west-central Colorado
and southeastern Utah, is darker than any other subspecies with which
its range comes in contact. The races to both the north and south are
larger, with the exception of the hind foot which is longer in _D. o.
nexilis_ than in either _D. o. sanrafaeli_ or _D. o. longipes_. The
affinities of _D. o. nexilis_ are with _D. o. longipes_ rather than with
any of the other known subspecies of _Dipodomys ordii_.

Intergradation between _D. o. nexilis_ and _D. o. longipes_ is shown by
animals from Bluff, San Juan County, Utah, which, however, are referable
to the latter. In animals from sixteen miles northwest of Moab, Grand
County, Utah, there is intergradation in size of skull and in color
between _D. o. nexilis_ and _D. o. sanrafaeli_. The specimens are
referred to _D. o. sanrafaeli_.

_D. o. nexilis_ is apparently prevented from extending its range to the
northward by the presence there of _D. o. sanrafaeli_. To the south _D.
o. nexilis_ encounters _D. o. longipes_ and the San Juan River. To the
east it is limited by the Rocky Mountains and to the west by the deep
canyons of the Colorado River.

Warren (1942:183) did not apply the name _D. o. nexilis_ to Ord kangaroo
rats in Colorado. He listed specimens from Montrose, Montezuma and Mesa
counties as being referable to _D. o. longipes_. The specimens from
Montezuma County, Colorado, probably are _D. o. longipes_ and those from
Montrose and Mesa counties (for which Warren gives no precise
localities) are _D. o. nexilis_.

    _Specimens examined._--Total, 35, distributed as follows:

    =Utah=: _Grand County_: Cisco, 4 (CM); 18 mi. NE Moab, 6000 ft., 1
    (UU). _San Juan County_: 15 mi. N Monticello, 4 (MVZ); Blanding, 1
    (UU).

    =Colorado=: _Delta County_: Hotchkiss, 1 (USBS). _Montrose
    County_: Paradox, 1 (DRD); Bedrock, 4 (AMNH); 5 mi. W Naturita, 2
    (USBS); Coventry, 3 (1 USBS; 2 AMNH).


=Dipodomys ordii cupidineus= Goldman

    _Dipodomys ordii cupidineus_ Goldman, Journ. Washington Acad. Sci.,
    14:372, September 19, 1924.

    _Type._--Male, no. 243093, U. S. Nat. Mus. Biol. Surv. Coll.; Kanab
    Wash, at southern boundary of Kaibab Indian Reservation, Arizona;
    obtained on October 12, 1922, by E. A. Goldman, original no. 23384.

    _Range._--Northeastern Arizona and south-central Utah; marginal
    occurrences are: in Utah, Escalante, near Paria and S of Virgin;
    in Arizona, 6 mi. N Wolf Hole, 20 mi. S Wolf Hole, 5 mi. S
    Trumbull Spring and 10 mi. S Jacobs Pools in Houserock Valley.

    _Diagnosis._--Size large (see measurements). Color relatively
    dark, entire dorsal surface between (_16''_) Pinkish Cinnamon and
    Cinnamon-Buff, purest on sides and flanks, upper parts washed with
    black; arietiform markings, pinnae of ears, dorsal and ventral
    stripes of tail, plantar surfaces of hind feet, blackish. Skull
    large; auditory bullae well inflated; interorbital width
    relatively narrow; rostrum long and narrow; nasals long and
    slightly flared distally; pterygoid fossae ovoid; external
    auditory meatus small and ovoid; jugal light and relatively
    straight.

    _Comparisons._--From _Dipodomys ordii chapmani_, _D. o.
    cupidineus_ differs in: Size larger; color lighter in all
    pigmented areas; skull larger; rostrum shorter and wider; nasals
    shorter; auditory bullae more inflated, particularly median
    tympanic portion; least interorbital width less.

    From _Dipodomys ordii nexilis_, _D. o. cupidineus_ differs as
    follows: Size smaller; color lighter in all pigmented areas; skull
    smaller; rostrum relatively longer and narrower; least
    interorbital width less; auditory bullae less inflated; breadth
    across maxillary arches less; foramen magnum circular as opposed
    to ovoid; cutting edge of upper incisors narrower; zygomatic
    arches lighter.

    For comparisons with _Dipodomys ordii cinderensis_, _Dipodomys
    ordii panguitchensis_ and _Dipodomys ordii longipes_ see accounts
    of those subspecies.

_Remarks._-This subspecies is prevented from intergrading, to the east,
with _D. o. longipes_ by the deep canyons of the Colorado River, with
_D. o. cinderensis_ by the Virgin River and with _D. o. panguitchensis_
by a series of high mountain ranges. Intergradation does, however, occur
with _D. o. sanrafaeli_ in animals from Escalante, Garfield County,
Utah, but they are referable to _D. o. cupidineus_. The Colorado River,
farther to the north, again serves as a barrier in preventing
intergradation between _D. o. nexilis_ and _D. o. cupidineus_.

    _Specimens examined._--Total, 122, distributed as follows:

    =Utah=: _Garfield County_: Mouth of Calf Creek, Escalante River, 3
    (BYU); Ten Mile Spring, 3 (BYU); Escalante, 3 (BYU). _Washington
    County_: near Short Creek road, south of town of Virgin, 18 (RH).
    _Kane County_: near Paria, 1 (UU); Willow Tank Springs, 7 (BYU); 8
    mi. NW Kanab, 4800 ft., 1 (UU); near Sand Dunes, 7 (RH); Kanab, 15
    (12 MVZ; 2 BYU; 1 UU); 1 mi. S Kanab, 4400 ft., 2 (UU).

    =Arizona=: _Mohave County_: near S Boundary Kaibab Indian
    Reservation, 4 (MVZ); 6 mi. N Wolf Hole, 8 (MVZ); 4 mi. N Wolf
    Hole; 3 mi. NW Diamond Butte, 7 (USBS); 20 mi. S Wolf Hole, 1
    (USBS); 1 mi. W Diamond Butte, 1 (USBS); 6 mi. N Mt. Trumbull, 1
    (USBS); Nixon Springs, 6250 ft., W Base Mt. Trumbull, 6 (3 USBS; 3
    MVZ); 5 mi. S Trumbull Spring, 1 (USBS). _Coconino County_:
    Fredonia, 3 (USBS); 2 mi. W Lees Ferry, 3 (MVZ); Jacobs Pools,
    4000 ft., Houserock Valley, 15 (MVZ); 10 mi. S Jacobs Pools,
    Houserock Valley, 2 (MVZ); Houserock Valley, 10 (USBS).


=Dipodomys ordii palmeri= (Allen)

    _Dipodops ordii palmeri_ Allen, Bull. Mus. Comp. Zool., 8:187,
    1881.

    _Cricetodipus ordii palmeri_, Trouessart, Catalogus Mammalium,
    1:581, 1897.

    _Perodipus ordii palmeri_, Goldman, Proc. Biol. Soc. Washington,
    30:113, May 23, 1917.

    _Dipodomys ordii palmeri_, Grinnell, Journ. Mamm., 2:96, May 2,
    1921.

    _Cotypes._--Two males, adults, nos. 5886 and 5887, Mus. Comp.
    Zool.; San Luis Potosí, Mexico; obtained on May 1, 1878, and
    September 1, 1878, respectively, by Dr. Edward Palmer. (Types not
    seen.)

    _Range._--Eastern Zacatecas, Aguascaliente, northern Jalisco, San
    Luis Potosí, Hidalgo, and probably Querétaro; marginal occurrences
    are: Zacatecas, Canitas and Berriozobal; Aguascaliente, 1 mi. N
    Chicalote; Jalisco, 9 mi. N Encarnación; Guanajuato, Celaya;
    Hidalgo, Irolo.

    _Diagnosis._--Size small (see measurements). Color dark, entire
    dorsal surface (_h_) between Cinnamon and Sayal Brown, purest on
    sides and flanks, upper parts strongly suffused with black;
    posterior surfaces and fold of pinnae of ears, white; arietiform
    markings, plantar surfaces of hind feet, inside of pinnae of ears,
    dorsal and ventral stripes of tail, blackish. Skull small; nasals
    long; rostrum long and narrow; interorbital region relatively
    wide; degree of inflation of auditory bullae about average for
    species; zygomatic arches light and bowed laterally; pterygoid
    fossae subcircular; braincase but slightly vaulted.

    _Comparisons._--From _Dipodomys ordii ordii_, _D. o. palmeri_
    differs as follows: Size somewhat larger; color darker; skull
    larger; nasals longer and flaring distally; interorbital width
    greater; narrower across auditory bullae; interparietal region
    narrower; breadth across maxillary arches greater; zygomatic arches
    bowed laterally as opposed to relatively straight; pterygoid
    fossae more nearly circular; rostrum longer and narrower.

    From _Dipodomys ordii sennetti_, _D. o. palmeri_ differs in larger
    size, darker color, longer tail and longer skull.

    For comparisons with _Dipodomys ordii obscurus_ and _Dipodomys
    ordii fuscus_ see accounts of those subspecies.

_Remarks._--Specimens from Berriozobal, Zacatecas, in the width of the
rostrum and the configuration of the nasals, are intermediate between
_Dipodomys ordii fuscus_ and _D. o. palmeri_. In color these animals are
more nearly like typical representatives of _D. o. palmeri_. The animals
from Jalisco and Guanajuato are not typical but the characters
differentiating them from _D. o. palmeri_ are merely modifications of
such slight degree that they all have been placed with that subspecies.

    _Specimens examined._--Total, 56, distributed as follows:

    =Zacatecas=: Canitas, 3 (USBS); Berriozobal, 10 (USBS).

    =San Luis Potosí=: Potrero Santa Ana, 7.6 mi. S Matehuala, 2
    (MVZ); Jesus Maria, 12 (USBS); 2 mi. NW San Luis Potosí, 8 (MVZ).

    =Aguascalientes=: 1 mi. N Chicalote, 1900 m., 4 (MVZ).

    =Jalisco=: 9 mi. N Encarnación, 1900 m., 1 (MVZ).

    =Guanajuato=: Celaya, 8 (USBS).

    =Hidalgo=: Ixmiquilpan, 1 (USBS); Irolo, 12 (USBS).




CONCLUSIONS


    1. There are thirty-five recognizable subspecies of the species
      _Dipodomys ordii_ of which four are herein, for the first time,
      recognized by name. Three subspecies, _D. o. oklahomae_, _D. o.
      sennetti_ and _D. o. compactus_, previously were regarded by most
      authors as full species.

      2. The species _Dipodomys ordii_ is divisible into six complexes,
      or groups, of subspecies on both geographic and morphological
      bases.

      3. _Dipodomys ordii_ is the most generalized Recent species of the
      genus.

      4. The extremes of geographic variation in _Dipodomys ordii_ are
      greater than in any other species of the genus.

      5. Color, at least in _Dipodomys ordii_, does not seem to be
      correlated with amount of moisture but rather with color of soil.

      6. Clinal variation, from north to south, is shown in the
      decreasing length of the nasals. This decrease in length of nasals
      and resultant decrease in size of the nasal chamber may be
      correlated with the decrease of humidity of the environment.

      7. Subspeciation has been enhanced by the late Quaternary mountain
      building which was prevalent over the western United States.

      8. In general, the most primitive kinds of _Dipodomys ordii_ occur
      at the periphery of the range of the species.

      9. Natural selection plus geographical and ecological isolation
      has undoubtedly been operative in speciation and in subspeciation.

      10. _Dipodomys deserti_ is found to be the most specialized
      species in the genus.

      11. Six, rather than nine, groups of species are recognized, on
      the basis of morphology, as comprising the genus _Dipodomys_.

      12. The center of dispersal for the genus _Dipodomys_ appears to
      have been in the southwestern United States and the adjoining part
      of Mexico. A secondary center of differentiation is apparent in
      the low, hot valleys of central California.

      13. Parallel development of species is noted between _Dipodomys_
      of the parental center and _Dipodomys_ of the isolated valleys of
      central California; _Dipodomys_ in the California center is the
      less specialized.

      14. The trend of the dipodomyines, as indicated by the fossil
      record, has been toward a saltatorial specialization with
      consequent morphological changes.

      15. The morphological change in the direction of saltatorial
      specialization is clearly evident in the compacting and aligning
      of the viscera as well as in the lengthening of the distal
      segments of the hind legs and the tail, tufting of the tail,
      enlargement of the auditory bullae, shortening of the neck and
      fusion of the cervical vertebrae for stability and other
      modifications of the skeleton.


                        TABLE 7

  MEASUREMENTS (IN MILLIMETERS) OF DIPODOMYS ORDII

  Key:

  A Total length
  B Length of tail
  C Length of hind foot
  D Greatest length of skull
  E Greatest breadth across bullae
  F Breadth across maxillary arches
  G Width of rostrum
  H Length of nasals
  I Least interorbital width
  J Basilar length

  =================+=====+=====+====+====+====+====+===+====+====+====
                   |  A  |  B  |  C |  D |  E |  F | G |  H |  I |  J
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. richardsoni_ 1-1/2 mi. N Beaver, Oklahoma (KU)
    [M] Mean (4)   |251.2|131.5|40.5|41.0|24.7|22.0|4.3|14.9|13.0|26.3
        Maximum    |256  |136  |41  |41.8|25.1|22.3|4.5|15.4|13.2|27.3
        Minimum    |243  |133  |40  |40.4|24.4|21.5|4.2|14.6|12.7|26.0
                   |     |     |    |    |    |    |   |    |    |
    [F] KU 17962   |253  |135  |42  |40.6|25.4|22.6|4.6|15.1|14.2|25.7
        KU 17963   |246  |133  |40  |39.4|24.0| ...|4.3|14.1|12.5|25.6
        KU 17964   |255  |136  |41  |41.2|25.5|22.1|4.5|15.1|13.8|26.2
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. oklahomae_ 2-1/4 mi. S Norman, Oklahoma (USBS)
    [M] Mean (4)   |239.7|130.0|39.5|39.0|23.9|21.5|4.3|13.7|13.3|24.9
        Maximum    |254  |140  |42  |40.3|24.6|22.4|4.4|14.3|13.6|25.8
        Minimum    |227  |125  |37  |38.0|23.0|20.9|4.2|13.4|12.8|23.9
                   |     |     |    |    |    |    |   |    |    |
    [F] USBS 265456|245  |133  |40  |39.1|24.5|22.0|4.4|14.4|13.5|25.3
        OU 20140   |234  |120  |39  |38.7|23.8|21.7|4.4|14.3|13.5|24.8
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. compactus_ 19 mi. S Port Aransas, Mustang Island, Texas (TCWC)
    [M] Mean (10)  |234.6|119.5|39.3|37.0|21.8|19.4|4.1|13.8|11.9|24.2
        Maximum    |251  |134  |41  |37.9|22.5|20.8|4.2|14.6|12.3|25.3
        Minimum    |228  |112  |38  |35.6|21.3|18.2|3.9|12.9|11.6|22.8
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (7)   |231.0|116.0|39.0|37.1|22.4|19.7|4.0|13.9| ...|24.2
        Maximum    |235  |120  |41  |38.2|22.9|20.5|4.1|14.7| ...|24.8
        Minimum    |224  |110  |38  |36.0|21.7|19.1|3.8|13.2| ...|23.8
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. sennetti_ 2 mi. S Riviera, Texas (TCWC)
    [M] Mean (5)   |217.6|112.2|35.8|37.2|23.4|20.1|4.0|13.6|13.1|24.2
        Maximum    |222  |115  |38  |38.2|24.1|20.7|4.3|14.4|13.2|24.6
        Minimum    |208  |104  |34  |36.3|23.0|19.4|3.8|13.0|12.6|23.8
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |218.3|112.0|36.0|37.2|23.3|20.1|4.0|13.9|13.1|24.1
        Maximum    |226  |115  |37  |37.7|23.9|20.8|4.1|14.4|13.4|24.4
        Minimum    |209  |108  |35  |36.7|22.8|19.0|3.9|13.3|12.6|23.5
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. evexus_ Salida, Colorado (AMNH)
    [M] AMNH 28802 |267.0|140.0|42.0| ...|23.0| ...|4.2| ...| ...|25.0
        AMNH 28804 |271  |156  |43  |39.3|23.5|22.1|4.4|14.6|14.0|25.8
        AMNH 28805 |252  |137  |39  | ...| ...|21.5|4.2| ...| ...|24.5
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |261.0|147.0|42.2|38.0|23.5|21.6|4.3|14.1|13.4|24.6
        Maximum    |264  |149  |43  |38.1|24.0|22.1|4.4|14.2|13.8|25.0
        Minimum    |258  |144  |42  |37.9|22.7|20.8|4.2|14.0|13.0|24.3
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. medius_ Santa Rosa, New Mexico (USBS)
    [M] Mean (6)   |258.5|143.3|38.0|39.5|25.2|21.4|4.1|14.2|12.9|24.8
        Maximum    |266  |151  |40  |40.6|25.9|22.5|4.2|15.2|13.1|25.6
        Minimum    |251  |132  |37  |38.9|24.8|20.6|4.0|13.5|12.8|24.1
                   |     |     |    |    |    |    |   |    |    |
    [F] USBS 118527|261.0|145.0|40.0|40.4|25.4|22.2|4.5|15.7|13.5|25.7
        USBS 127310|  ...|  ...| ...|38.1|24.3|20.8|4.1|13.5|13.5| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. obscurus_ Rio Sestin, Durango (AMNH)
    [M] Mean (6)   |  ...|  ...| ...|36.3|22.9|19.7|3.7|13.1|12.6|22.8
        Maximum    |  ...|  ...| ...|38.0|23.4|21.0|3.9|13.5|13.0|23.9
        Minimum    |  ...|  ...| ...|35.2|22.6|19.1|3.6|11.9|12.4|21.7
                   |     |     |    |    |    |    |   |    |    |
    [F] AMNH 20945 |  ...|  ...| ...|36.5|22.8|19.9|3.8|13.1|12.9|22.3
        AMNH 20951 |  ...|  ...| ...|36.0|22.3|19.6|3.5|13.0| ...|22.5
        AMNH 20958 |  ...|  ...| ...|35.9|22.7|19.4|3.4|12.6|12.3|22.7
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. terrosus_ Jordan, Montana
    [M] AMNH 41442 |280.0|155.0|44.0|42.7|26.5|23.6|4.0|15.2|14.5|27.0
        AMNH 41443 |267.0|155.0|40.0|40.5|24.8|21.1|4.0|14.5|13.1|25.1
        AMNH 41444 |279.0|162.0|41.0|40.8|25.7|21.6|4.4|14.6|13.4|25.9
                   |     |     |    |    |    |    |   |    |    |
    [F] AMNH 41441 |265.0|149.0|40.5|41.4|25.4|22.2|4.3|14.7|13.0|26.8
        MVZ 25658  |273.0|154.0|41.0|41.3|25.1|22.4|4.0|14.9|13.8|26.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. fremonti_ Torrey, Utah
    [M] CM 15663   |250.0|141.0|40.0|37.0|23.3|19.3|3.6|13.5|12.0|23.2
        CM 15670   |248.0|136.0|38.0|37.3|23.8|19.8|3.8|13.7|11.6|23.5
                   |     |     |    |    |    |    |   |    |    |
    [F] CM 15666   |258.0|141.0|39.0|37.5|23.5|19.9|3.7|13.8|11.9|23.5
        CM 15667   |252.0|140.0|39.0|36.8|23.5|20.5|3.7|13.5|11.5|23.2
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. uintensis_ 2 mi. N Fruitland, Utah
    [M] CM 11634   |253.0|140.0|40.0|37.9|23.3|20.3|3.9|13.5|12.5|23.9
        CM 11640   |260.0|150.0|41.0|38.2|24.2|20.6|4.0|13.2|12.5|24.5
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. sanrafaeli_ 12 mi. SW Green River, Utah
    [M] CM 15649   |265.0|144.0|41.0| ...| ...| ...|...|14.1| ...| ...
                   |     |     |    |    |    |    |   |    |    |
    [F] CM 15647   |253.0|138.0|42.0| ...| ...| ...|...|13.5| ...| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. panguitchensis_ 1 mi. S Panguitch, Utah
    [M] RH 2151    |257.0|145.0|41.0| ...| ...| ...|...|13.3|12.0| ...
        RH 2152    |252.0|135.0|40.0| ...| ...| ...|...|13.5|11.9| ...
                   |     |     |    |    |    |    |   |    |    |
    [F] RH 2153    |240.0|132.0|38.0| ...| ...| ...|...|12.7|11.3| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. monoensis_ 5 mi. N Benton Station, California (MVZ)
    [M] MVZ 26993  |232.0|125.0|40.0|36.6|23.7|20.0|3.7|13.0| ...|23.4
        MVZ 26995  |240.0|125.0|39.0|36.8|23.0|19.8|3.6|13.4|11.5|23.3
        MVZ 26997  |230.0|122.0|39.0|37.2|23.2|20.1|3.6|13.4|12.0|23.9
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (5)   |228.0|125.4|38.4|36.6|23.1|19.7|3.5|13.1|11.8|23.4
        Maximum    |240.0|137.0|39.0|37.2|24.2|20.0|3.7|13.2|12.2|23.6
        Minimum    |220.0|120.0|38.0|36.0|22.6|19.3|3.4|13.0|11.5|23.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. ordii_ Near El Paso, Texas (USNM)
    [M] Mean (5)   |  ...|  ...| ...|37.1|24.1|19.6|3.7|13.0|12.7|23.5
        Maximum    |  ...|  ...| ...|38.1|24.8|20.5|3.8|13.2|13.3|24.3
        Minimum    |  ...|  ...| ...|36.3|23.4|18.8|3.5|12.8|12.1|22.4
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (6)   |235.2|128.0|37.4|37.3|24.0|19.6|3.7|13.3|12.8|23.5
        Maximum    |245.0|136.0|39.0|38.0|24.1|20.0|3.8|13.5|13.4|24.4
        Minimum    |222.0|120.0|35.0|36.3|24.0|19.1|3.6|13.0|12.4|23.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. luteolus_ 1 mi. NE Casper, Wyoming (KU)
    [M] Mean (12)  |265.6|152.2|42.2|38.9|24.1|20.8|4.3|13.9|13.0|24.6
        Maximum    |281.0|163.0|43.0|39.5|25.0|22.1|4.4|14.5|13.7|25.7
        Minimum    |254.0|145.0|42.0|37.5|23.8|19.9|4.2|13.0|12.5|24.0
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (7)   |260.7|148.0|41.0|38.6|24.2|20.9|4.3|13.9|12.9|24.7
        Maximum    |269.0|153.0|43.0|40.5|25.7|21.9|4.4|14.9|13.8|25.5
        Minimum    |250.0|139.0|40.0|37.6|23.0|20.0|4.2|13.3|12.5|24.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. extractus_ 1 mi. E Samalayuca, Chihuahua (MVZ)
    [M] Mean (11)  |235.1|128.2|37.3|37.5|24.1|20.1|3.5|13.2|13.0|23.4
        Maximum    |251.0|142.0|39.0|38.6|24.6|20.8|3.8|13.8|13.5|24.4
        Minimum    |224.0|121.0|35.0|36.2|23.2|19.3|3.3|12.6|12.4|22.3
                   |     |     |    |    |    |    |   |    |    |
    [F] MVZ 76568  |251.0|132.0|39.0|39.6|25.4|22.2|3.7|13.8|14.1|24.8
        MVZ 76569  |244.0|140.0|37.0|37.3|23.6|20.0|3.6|13.5|12.8|24.0
        MVZ 76570  |230.0|120.0|37.0|35.7|23.4|19.5|3.2|12.4|12.1|22.5
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. chapmani_ Camp Verde, Arizona (USBS)
    [M] Mean (6)   |258.0|148.0|39.0|38.9|24.2|21.1|3.8|14.2|13.5|24.3
        Maximum    |268.0|157.0|41.0|40.1|24.7|22.1|3.9|14.8|13.9|24.7
        Minimum    |244.0|138.0|38.0|38.1|23.6|20.5|3.8|13.3|13.1|24.1
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |255.4|151.0|38.2|37.1|23.9|20.1|3.8|13.4|13.5|23.3
        Maximum    |262.0|152.0|39.0|37.7|24.3|20.1|3.9|13.7|14.9|23.5
        Minimum    |245.0|144.0|37.0|36.0|23.7|20.1|3.6|13.1|12.6|23.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. montanus_ Fort Garland, Colorado (USBS)
    [M] Mean (11)  |252.0|140.5|41.0|37.7|24.2|20.1|4.1|13.6|12.8|23.8
        Maximum    |263.0|150.0|42.0|39.0|25.0|21.0|4.5|14.0|13.2|24.7
        Minimum    |233.0|131.0|39.0|36.6|23.6|19.0|3.9|12.7|12.4|23.0
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (11)  |256.0|141.0|40.8|37.2|23.9|19.6|4.1|13.4|12.5|23.7
        Maximum    |259.0|145.0|42.0|38.4|24.4|21.4|4.3|14.1|13.3|24.4
        Minimum    |237.0|132.0|40.0|36.0|23.0|18.2|3.9|12.3|11.9|22.6
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. cinderensis_ 11 mi. SE Lund, Utah
    [M] MVZ 102059 |244.0|135.0|41.0|35.7|23.2|19.2|3.6|12.2|11.2|22.7
        MVZ 102056 |237.0|130.0|41.0|36.4|23.7|20.6|3.5|13.0|12.1|23.1
                   |     |     |    |    |    |    |   |    |    |
    [F] MVZ 102057 |229.0|122.0|41.0|36.3|23.5|20.2|3.6|13.0|11.5|23.4
        MVZ 102058 |241.0|127.0|40.0|36.8|24.0|20.0|3.6|13.2|11.7|23.2
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. fetosus_ 2 mi. N Panaca, Nevada (MVZ)
    [M] Mean (4)   |242.5|133.7|42.3|37.4|23.7|20.0|3.7|13.3|11.7|23.7
        Maximum    |249.0|140.0|43.0|37.7|24.0|20.3|3.8|13.9|12.0|23.8
        Minimum    |233.0|126.0|42.0|36.8|23.2|19.5|3.7|12.7|11.5|23.6
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |229.0|125.5|40.6|35.8|23.3|19.5|3.6|12.8|11.3|22.5
        Maximum    |235.0|129.0|41.5|37.0|24.1|20.0|3.6|13.3|11.6|23.2
        Minimum    |224.0|122.0|40.0|34.3|23.0|19.0|3.6|11.9|11.0|21.9
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. utahensis_ Ogden, Utah
    [M] MVZ 44005  |243.0|133.0|40.5|35.9|23.1|19.2|3.5|12.8|12.4|22.4
                   |     |     |    |    |    |    |   |    |    |
    [F] MVZ 44006  |238.0|133.0|38.0|36.1| ...|19.8|3.7|13.5|12.2|22.9
        MVZ 44007  |240.0|137.0|39.0|35.6|22.9| ...|3.6|12.8|11.7|22.4
        MVZ 44008  |241.0|134.0|40.0|36.4|23.5|19.8|3.6|13.3|12.3| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. columbianus_ Umatilla, Oregon
    [M] MVZ 45317  |243.0|140.0|40.0|37.2|23.6|20.0|3.8|13.5|12.2|23.4
        MVZ 45318  |236.0|137.0|40.0|36.8|23.5|20.1|3.6|13.2| ...|23.4
        MVZ 45322  |240.0|132.0|40.0|36.4|23.4|19.9|3.7|13.0|12.1|23.3
                   |     |     |    |    |    |    |   |    |    |
    [F] MVZ 45314  |239.0|130.0|39.0|35.8|22.7|19.8|3.7|13.2|11.9|22.7
        MVZ 45315  |251.0|140.0|41.0|36.6|23.8|19.6|3.6|13.3|12.0|23.1
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. idoneus_ 12 mi. W Lerdo, Durango
    [M] UM 90027   |  ...|  ...|35.0|37.3|24.3|20.7|3.8|13.0|14.1|23.1
        UM 90029   |230.0|129.0|35.0|37.2|23.5|20.0|3.6|13.5|13.4|23.3
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. priscus_ 33 mi. S Bitter Creek, Wyoming (KU)
    [M] Mean (7)   |259.0|148.0|44.0|39.1|24.3|20.7|4.1|14.3|13.1|24.9
        Maximum    |265.0|152.0|45.0|40.4|25.1|21.2|4.3|15.2|13.6|25.5
        Minimum    |251.0|144.0|43.0|38.0|23.7|20.0|4.0|13.8|12.7|23.7
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |257.0|147.0|43.0|39.4|24.6|20.8|4.2|14.3|13.1|24.7
        Maximum    |264.0|152.0|45.0|40.4|25.2|21.9|4.3|14.9|13.3|25.2
        Minimum    |249.0|138.0|40.0|38.1|23.5|20.1|4.1|14.0|12.7|24.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. celeripes_ Trout Creek, Utah (UU)
    [M] Mean (4)   |208.7|109.0|40.2|35.3|22.9|19.3|3.6|12.6|11.2| ...
        Maximum    |220.0|115.0|41.0|36.6|23.6|20.2|3.8|13.5|11.5| ...
        Minimum    |203.0|100.0|39.0|34.0|22.1|18.4|3.5|11.7|11.1| ...
                   |     |     |    |    |    |    |   |    |    |
   [F] UU 1957     |219.0|110.0|39.0|35.3|23.4|19.1|3.6|11.9|11.8|22.4
        UU 1961    |223.0|120.0|40.0|37.0|23.6|20.4|3.6|13.1|12.1|23.9
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. cineraceus_ Dolphin Island, Great Salt Lake, Utah
    [F] USNM 263893|228.0|129.0|39.0|37.2|23.4|19.7|3.5|13.6|11.6|23.0
        USNM 263894|230.0|132.0|38.0|37.1|23.7|20.1|3.6|13.4|11.9|23.6
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. marshalli_ Stansbury Iland, Great Salt Lake, Utah
    [M] UU 2968    |238.0|128.0|40.0|36.4|23.5| ...|3.5|13.0|12.0|23.2
        UU 2969    |241.0|136.0|40.0|36.3|23.7|19.2|3.7|12.9| ...|23.0
                   |     |     |    |    |    |    |   |    |    |
    [F] UU 2972    |  ...|  ...| ...|35.9|23.5|19.9|3.6|12.9|11.9|23.1
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. inaquosus_ 11 mi. E and 1 mi. N Jungo, Nevada (MVZ)
    [M] Mean (4)   |243.0|137.0|40.0|36.6|23.5|19.8|3.7|13.5|11.8|23.1
        Maximum    |247.0|140.0|40.5|36.8|24.0|20.0|3.8|13.8|12.1|23.5
        Minimum    |238.0|131.0|39.0|36.4|23.3|19.5|3.6|13.1|11.5|23.0
                   |     |     |    |    |    |    |   |    |    |
    [F] MVZ 73577  |242.0|139.0|40.5|36.4|23.9|19.2|3.7|13.2|11.4|22.9
        MVZ 73579  |231.0|130.0|40.5|36.3|23.2|19.0|3.5|12.7|11.0|23.2
        MVZ 73582  |254.0|138.0|41.0|38.2|23.9|20.0|3.6|13.9|12.2| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. attenuatus_ Johnson's Ranch, Texas
    [M] TCWC 3633  |235.0|126.0|41.0|37.3|24.1|20.1|3.7|13.7| ...|23.4
        TCWC 3634  |237.0|136.0|37.0|35.5|22.1|18.8|3.5|13.2|12.2|22.3
        UM 79121   |245.0|143.0|37.3|35.7|22.3|19.1|3.6|12.4|12.9|23.3
                   |     |     |    |    |    |    |   |    |    |
    [F] UM 79122   |238.0|140.0|38.0|34.6|22.5|18.5|3.5|11.9|13.0|21.9
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. fuscus_ Juamave, Tamaulipas (USBS)
    [M] Mean (4)   |248.0|149.0|38.5|37.6|24.1|20.2|3.6|12.6|12.7|23.6
        Maximum    |254.0|152.0|40.0|38.3|24.7|20.4|3.7|13.1|12.9|23.7
        Minimum    |241.0|146.0|38.0|37.0|23.5|19.7|3.6|12.3|12.5|23.6
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |244.7|146.2|38.5|37.4|24.1|19.9|3.4|12.9|12.7|23.2
        Maximum    |254.0|155.0|40.0|37.7|24.5|20.5|3.6|13.0|12.9|23.4
        Minimum    |240.0|138.0|38.0|37.2|23.7|19.2|3.3|12.7|12.4|23.2
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. longipes_ Kayenta, Arizona
    [M] USBS 247915|255.0|145.0|41.0|39.3|25.5|20.7|3.9|13.8|13.0|24.3
        USBS 247916|242.0|138.0|40.0|38.4|25.4|20.6|3.8|13.3|12.7|24.6
                   |     |     |    |    |    |    |   |    |    |
    [F] USBS 247552|255.0|135.0|40.0|39.9|25.7|21.2|4.0|13.8| ...|25.4
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. pallidus_ 18 mi. SW Orr's Ranch, Utah (UU)
    [M] Mean (4)   |236.6|131.3|42.3|37.6|24.2|20.4|3.8|13.4|11.8|23.6
        Maximum    |240.0|134.0|43.0|37.9|24.6|20.9|4.0|13.6|12.1|24.2
        Minimum    |230.0|128.0|41.0|37.0|23.7|19.8|3.7|12.9|11.5|23.4
                   |     |     |    |    |    |    |   |    |    |
    [F] UU 3528    |229.0|132.0|40.0|36.6|23.5|20.0|3.7|12.5|12.0| ...
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. nexilis_ 5 mi. W Naturita, Colorado
    [M] USBS 149940|261.0|156.0|44.0|38.7|25.1|18.9|4.1|13.8|11.4|24.6
                   |     |     |    |    |    |    |   |    |    |
    [F] USBS 149941|265.0|142.0|45.0|40.5|26.3|21.5|4.2|14.4|13.1|25.3
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. cupidineus_ Houserock Valley, Arizona (USBS)
    [M] Mean (6)   |239.0|138 0|39.8|36.9|24.1|19.3|3.8|12.8|12.0|23.6
        Maximum    |244.0|146.0|41.0|37.5|24.9|20.1|4.0|13.0|12.6|24.3
        Minimum    |225.0|130.0|38.5|36.3|23.5|18.7|3.6|12.6|11.7|23.2
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (4)   |244.7|141.0|40.0|37.4|24.2|19.7|3.8|13.2|12.3|23.9
        Maximum    |247.0|147.0|40.5|37.7|24.4|20.0|3.9|13.5|12.6|24.6
        Minimum    |240.0|137.0|39.5|37.1|23.9|19.5|3.7|12.9|12.0|23.7
  -----------------+-----+-----+----+----+----+----+---+----+----+----
  _D. o. palmeri_ Jesus María, San Luis Potosí (USBS)
    [M] Mean (6)   |242.0|141.6|37.6|36.7|23.6|20.0|3.3|12.9|12.9|22.6
        Maximum    |255.0|157.0|39.0|37.3|24.4|20.8|3.6|13.6|13.4|23.0
        Minimum    |229.0|129.0|35.0|35.9|23.2|19.4|3.0|12.5|12.6|22.0
                   |     |     |    |    |    |    |   |    |    |
    [F] Mean (6)   |239.5|139.6|37.1|36.4|23.8|19.9|3.4|12.8|13.1|22.7
        Maximum    |252.0|148.0|38.0|37.3|23.9|20.0|3.6|13.3|13.2|23.5
        Minimum    |225.0|128.0|36.0|35.9|23.7|19.5|3.3|12.2|13.0|22.0
  -----------------+-----+-----+----+----+----+----+---+----+----+----




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  _Transmitted May 15, 1948._


                                  22-6114




Transcriber's note:

Gesperrt text is indicated by ~swung dashes~.