closely resembles _Z. h. campestris_. From topotypes of _Z. h.
campestris_, _Z. h. preblei_ differs as follows: Upper parts generally
dull, averaging lighter, less black-tipped hair; dorsal band less
distinct; sides duller; averaging smaller in most cranial measurements
taken; least interorbital constriction narrower; auditory bullae
smaller, less well inflated; incisive foramina narrower, not truncate
posteriorly; frontal region usually more inflated.
From _Zapus hudsonius pallidus_, _Z. h. preblei_ differs as follows:
Upper parts generally duller (less ochraceous); dorsal band less
distinct; sides paler (not bright Ochraceous-Buff); zygomatic arch less
widely bowed; least interorbital constriction narrower; occipitonasal
length averaging greater; distance from incisors to postpalatal notch
averaging less; incisive foramina longer, proportionally less widely
bowed; auditory bullae longer; pterygoid fossae averaging broader.
_Remarks._--No evidence of intergradation with any other geographic race
was noted. To the east the range of _Z. h. preblei_ is separated from
that of _Z. h. pallidus_ (western Kansas and southwestern Nebraska), by
several hundred miles of mixed and short grass prairie. Much of this
area is unsuitable to jumping mice but local marshy places might be
inhabited. Much territory inhospitable to _Zapus_ intervenes also
between the ranges of _Z. h. preblei_ and _Z. h. campestris_. This area
(northern Platte, Goshen, eastern Converse, Niobrara, and southern
Weston counties, Wyoming) is chiefly rolling hills and short grass
prairie and, like that to the east, is only locally suitable for
_Zapus_. If jumping mice do occur in suitable places in these
intervening areas it is to be expected that they will show
intergradation between the subspecies concerned.
_Zapus hudsonius preblei_, on the basis of 11 specimens, agrees most
closely in size and color with _Z. h. campestris_; there is much less
resemblance between _Z. h. preblei_ and _Z. h. pallidus_.
An adult from Springhill, 12 mi. N Laramie Peak, is typically _Z. h.
preblei_ as is one from Cheyenne.
Although specimens of _Z. h. preblei_ are few (4 adult, 7 non-adults),
the differences between this and neighboring named kinds is
considerable.
_Specimens examined_: Total, 11, distributed as follows:
COLORADO: _Boulder County_: 3 mi. E Boulder, 1 (UCM); _5 mi. E Boulder_,
1 (UCM); _south of Boulder_ (no exact locality), 1 (UCM). _Jefferson
County_: Semper, 1. _Larimer County_: Loveland, 2 (USBS).
WYOMING: _Albany County_: Springhill, 12 mi. N Laramie Peak, 6300 ft., 3
(USBS). _Laramie County_: Cheyenne, 1 (USNM). _Platte County_:
Chugwater, 1 (Clev. MNH).
_Marginal records._--Wyoming: Springhill, 12 mi. N Laramie Peak, 6300
ft.; Chugwater; Cheyenne. Colorado: Loveland; Semper.
=Zapus hudsonius tenellus= Merriam
_Zapus tenellus_ Merriam, Proc. Biol. Soc. Washington, 11:103,
April 26, 1897.
_Zapus hudsonius tenellus_, Hall, Univ. California Publ. Zool.,
40:377, November 5, 1934.
_Zapus hudsonius hudsonius_, Baker, Univ. Kansas Publ., Mus. Nat.
Hist., 5:111, November 28, 1951 (part--the part from E side
Minaker River, 1 mi. W Trutch and 3 mi. N Fort St. John,
British Columbia).
_Type._--Female, young adult, skin and skull, No. 66932 U. S. Nat. Mus.,
Biol. Surv. Coll.; Kamloops, British Columbia; obtained on August 25,
1894, by Clark P. Streator, original No. 4196.
_Range._--British Columbia. See fig. 47. Zonal range: Canadian and
Hudsonian.
_Description._--Size medium; back from near Clay Color (brighter) to
near Cinnamon-Buff with admixture of black tipped hairs forming a weakly
defined dorsal band; sides lighter than back from near dull
Ochraceous-Buff to near Cinnamon-Buff frequently with admixture of
dark-tipped hairs; lateral line usually distinct, of clear
Ochraceous-Buff; belly white sometimes with slight suffusion of
Ochraceous-Buff; tail bicolored, brownish to brownish-black above, white
or grayish-white to yellowish-white below; ears dark, edged and flecked
on inner surface with color of sides; feet grayish-white above; auditory
bullae relatively narrow, moderately inflated, elongate when viewed from
below, anterior edge slightly concave; incisive foramina relatively
short; braincase relatively narrow; vertical depth of skull at junction
of frontals and nasals relatively great; nasals relatively narrow;
pterygoid fossae moderately broad; zygomata relatively short.
_Comparisons._--For comparisons with _Zapus hudsonius hudsonius_ and
_Zapus hudsonius alascensis_ see accounts of those subspecies.
_Remarks._--Merriam (1897a:103) named this jumping mouse as a full
species, mentioning that the skull is similar in size and characters to
that of _Zapus hudsonius_ but that externally these animals differed in
coloration and length of the tail. Hall (1934:377) treated _Z. tenellus_
as a subspecies of _Z. hudsonius_. He observed that the difference
between _Z. tenellus_, _Z. h. alascensis_, and _Z. h. hudsonius_ was of
the same degree, and, even though intergrading material was not known to
him, he considered _tenellus_ only subspecifically distinct from _Z.
hudsonius_. Hall (_loc. cit._) tentatively referred to _Z. h. tenellus_
specimens from Indianpoint Lake, 15 mi. NE Barkerville, Cottonwood P.
O., and Hazelton, British Columbia. I have seen and compared with the
type of _Z. tenellus_ all specimens examined by Hall and agree with him
that they are best referred to _Z. h. tenellus_. Since 1934, several
additional localities in British Columbia have yielded specimens. Those
from Minaker River and Fort St. John are intermediate in dorsal
coloration and in size and shape of the auditory bullae between _Zapus
hudsonius hudsonius_ and _Z. h. tenellus_ but in all other characters
are most nearly like _Z. h. tenellus_ to which they are here assigned.
These intergrades constitute additional evidence that _Z. tenellus_ and
_Z. hudsonius_ are only subspecies of a single species.
_Specimens examined._--Total, 17, all from British Columbia, distributed
as follows: east side Minaker River, 1 mi. W Trutch, 1; Hazelton, 959
ft., 2 (MVZ); 5 mi. W and 3 mi. N Fort St. John, 1; _Indianpoint Lake,
15 mi. NE Barkerville_, 5 (MVZ); Cottonwood P. O., 3 (MVZ); S end Swan
Lake, Vernon, 1200 ft., 2 (MVZ); Kamloops, 3 (USBS).
_Marginal records._--British Columbia.--E side Minaker River, 1 mi. W
Trutch; 5 mi. W and 3 mi. N Fort St. John; S end Swan Lake, Vernon, 1200
ft.; Kamloops; Hazelton, 959 ft.
TABLE 5.--Cranial Measurements (in Millimeters) of Zapus.
Column headings:
Col. A: Number examined, [M][M] plus [F][F]
Col. B: Breadth of braincase
Col. C: Condylobasal length
Col. D: Interorbital breadth
Col. E: Mastoidal breadth
Col. F: Length of maxillary tooth-row
Col. G: Occipitonasal length
Col. H: Palatal length
Col. I: Zygomatic breadth
Col. J: Zygomatic length