Adult in worn pelage taken in May at Two Buttes peak: no molt in evidence; pelage thinner and rougher than in adults of same tooth wear taken in February in unworn pelage (described above); upper parts duller, less heavily overlaid with black; sides less richly yellowish, slightly more pinkish in hue; underparts with no fur white to base (as usual for the species). The skull of this rat has narrower nasals than other adults from Two Buttes and a longer interparietal with a posterior median angle. Subadult taken in April at Regnier: completing postjuvenal (first) molt; new pelage fairly long and thick everywhere except on neck and upper back, where covered by remaining juvenal pelage; upper parts of new pelage duller than in adults, sides less buffy, more grayish; juvenal pelage grayer than new pelage; new pelage indistinguishable from same pelage (second pelage of first year) of _N. m. fallax_. _Comparisons._--_N. m. scopulorum_ is extremely variable in color but averages lighter and richer in color than _N. m. fallax_, and about the same as _N. m. inopinata_. _N. m. scopulorum_ can be separated from either by the following cranial differences: skull larger, more strongly arched 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.