f pairs," and _modestus_ had a
larger foramen magnum in 6 of 6 pairs (Confidence Limit .97) and larger
first upper molar teeth in 5 of 6 pairs (C. L. .75).

A comparison of topotypes of _pullatus_ with _modestus_ shows a similar
difference in the teeth, _modestus_ being larger, but in the size of
the foramen magnum there is no difference. A comparison of the
measurements of _pullatus_ (Bitterroot Valley), _pullatus_ (near
topotypes), and _modestus_ (topotypes) shows that the two series of
topotypes differ significantly in condylobasilar length (of borderline
significance), zygomatic breadth and lambdoidal breadth (both of which
vary greatly with age), and length of molar series; the specimens from
the Bitterroot Valley agree with _pullatus_ rather than _modestus_ in
all of these characters. The specimens from the Bitterroot Valley are
smaller than _pullatus_ (topotypes) in total length; they more closely
resemble _modestus_ in length of tail, and the hind foot is shorter
than in either _modestus_ or _pullatus_ (which do not differ
significantly). Specimens from western Montana resemble _modestus_ in
certain respects but in most respects resemble topotypes of _pullatus_
and are referred to _pullatus_. Specimens from Coeur d'Alene, Idaho,
and from Blackfoot, Montana (marginal records of _modestus_, Hall and
Cockrum, 1953:410) may be referred to _drummondi_. Marginal records of
_pullatus_ in Montana to my knowledge are: Florence, Ravalli Co.;
Highwood Mtns., Chouteau Co.; 7 mi. NE Hilger, Fergus Co.; 10 mi. NW
Park City, Stillwater Co. (all represented by specimens in the USBS).
The line separating _pullatus_ and _drummondi_ is tentatively drawn as
shown in Figure 1.

_Specimens examined._--Total 256. _Wyoming_: YELLOWSTONE NATIONAL
PARK: Mammoth Hot Springs, 17 (USNM). PARK CO.: 3-1/5 mi. E, 3/5
mi. S Cody, 5020 ft., 15. TETON CO.: _Whetstone Creek_, 4 (Mich); 5
mi. N Moran, 13 (Mich); _Moran and environs_ (_4 localities within
4 miles of Moran_), 6200 ft., 54; Teton Park, Trappers Lake, 3
(Mich); _Teton Park, Jenny Lake_, 1 (Mich); _Teton Park, String
Lake_, 1 (Mich); Sheep Creek, 1 (Mich); _Jackson and environs_, 115
(Mich 113, USBS 1). SUBLETTE CO.: 34 mi. N, 4 mi. W Pinedale, 7950
ft., 2; Kendall, 5 (Mich). LINCOLN CO.: 9-1/2 mi. N, 2 mi. W Afton,
6100 ft., 1; _9 mi. N, 2 mi. W Afton_, 3; _7 mi. N, 1 mi. W Afton_,
11; _15 mi. N, 3 mi. E Sage_, 6100 ft., 1; _12 mi. N, 2 mi.