hed at
base of rostrum, interorbital constriction more posterior;
supraorbital ridges concave laterally (in contrast to
straight, diverging); interparietal shorter in median line,
more widely spreading and rectangular; zygomatic arches more
widely spreading and heavier; upper incisors wider; and molars
larger. _N. m. scopulorum_ differs from _inopinata_ also in
paler upper incisors and less prominent basicranial ridges.

_N. m. scopulorum_ is paler than _N. m. pinetorum_. The skulls
of these two subspecies are of about the same size, but the
subspecies differ in other respects as _scopulorum_ differs
from _fallax_ and _inopinata_.

Judging from the description and photograph of _mexicana_ in
Goldman's revision of the genus _Neotoma_ (N. Amer. Fauna, 31:
54-56, Pl. IV, 19 October 1910), _scopulorum_ differs from _N.
m. mexicana_ in: larger skull; longer nasals and dorsal
branches of premaxillae; more posterior interorbital
constriction (supraorbital ridges more concave laterally);
wider upper incisors; and larger molars.

_Measurements._--Mean and extreme measurements in millimeters
of 6 males and 5 females from 3 mi. NW Higbee and the vicinity
of Two Buttes are, respectively, as follows: total length, 357
(345-368), 345 (310-379); length of tail, 147 (140-158), 159
(138-178); length of hind foot, 35 (32-38), 36.4 (35-38);
length of ear, from notch, 25.5 (25-26), 25.7 (25-27); weight
(in grams), 234 (213-253), 206 (161-246); basilar length, 37.9
(36.8-38.9), 36.2 (34.5-38.6); length of nasals, 19.0
(18.2-20.0), 17.9 (16.4-19.6); zygomatic breadth, 23.9
(23.0-24.5), 23.3 (22.3-24.0); interorbital breadth, 5.3
(4.9-5.6), 5.1 (5.0-5.3); breadth of rostrum, 7.2 (6.8-7.7),
6.8 (6.7-6.9); diastema, 12.8 (12.3-13.3), 12.2 (11.1-13.7);
alveolar length of maxillary tooth-row, 9.5 (9.2-9.8), 9.4
(9.0-9.7); length of incisive foramina, 9.7 (9.2-10.2), 9.2
(8.6-10.2); length of palatal bridge, 8.8 (8.4-9.2), 8.5
(8.0-8.9).

_Measurements of the type._--Total length, 348; length of
tail, 143; length of hind foot, 35; length of ear, from notch,
25; weight (in grams), 230; basilar length, 38.1; length of
nasals, 18.8; zygomatic breadth, 24.2; interorbital
constriction, 5.5; breadth of rostrum, 7.2; diastema, 13.0;
alveolar length of