Type.—Male, adult, skull, skin, and baculum, No. 20105 Univ. Kansas Mus. Nat. Hist.; from ½ mi. E and 3 mi. S Ward, 9,400 ft., Boulder County, Colorado; obtained on August 1, 1947, by E. L. Cockrum; original No. 721.
Diagnosis.—Size large; sides Clay Color; antipalmar and antiplantar surfaces of feet Cinnamon-Buff; baculum as in E. u. umbrinus.
Description.—Color pattern: Crown Raw Sienna mixed with gray; upper facial stripe and ocular stripe black mixed with Sepia; submalar stripe Snuff Brown mixed with black; ear black or Sepia, anterior margin Ochraceous-Tawny, posterior margin and postauricular patch grayish white; hairs inside posterior part of pinna Cinnamon-Buff; median dorsal dark stripe black with Sayal Brown along margins; lateral dark stripes black mixed with Sayal Brown; outermost dorsal dark stripes obsolete, Sayal Brown mixed with black; median pair of dorsal light stripes Pale Smoke Gray mixed with Clay Color; outer pair of dorsal light stripes creamy white; sides Clay Color; rump and thighs Neutral Gray; dorsal surface of tail black mixed with Cinnamon-Buff; ventral surface of tail Ochraceous-Tawny; hairs around margin of tail Cinnamon-Buff or Ochraceous-Tawny; antipalmar and antiplantar surfaces of feet Cinnamon-Buff; underparts creamy white with dark underfur. Skull: Large; zygomata strong; braincase well inflated. Baculum: As in E. u. umbrinus.
Comparisons.—From E. quadrivittatus quadrivittatus, the subspecies and species to the south, E. u. montanus differs in: General tone of upper parts darker; braincase significantly narrower; baculum shorter and markedly wider at base.
From E. u. umbrinus, the subspecies from the Uinta and northern Wasatch Mountains, E. u. montanus differs in: General tone of upper parts brighter (less tawny); sides more tawny; skull slightly larger.
From E. u. sedulus, the subspecies from the Henry Mountains of Utah, E. u. montanus differs in: Sides darker; general tone of upper parts darker.
From E. u. fremonti, the subspecies from the mountains of western and northwestern Wyoming, E. u. montanus differs in: General tone of upper parts lighter; hairs around outermost edge of tail tawnier.
Remarks.—Howell (1929:83) stated that the specimens of E. quadrivittatus quadrivittatus (= E. umbrinus montanus) from Estes Park, Long's Peak, and Gold Hill, all in Colorado, "average somewhat darker on the back and sides than typical quadrivittatus; the light dorsal stripes are also somewhat duller and the dark stripes less blackish, thus showing an approach to the characters of umbrinus." Now there are more specimens of E. u. montanus from the mountains of north-central Colorado than were available to Howell. He was not aware of the striking difference between the bacula of E. quadrivittatus and E. umbrinus, and the constancy of this difference between all the subspecies of one species and those of the other.
Although the geographic range of E. u. umbrinus is closer to the ranges of E. u. fremonti and E. u. montanus than to the geographic range of E. u. adsitus, E. u. umbrinus seems to be more closely related to E. u. adsitus than to E. u. fremonti or E. u. montanus. This observation may be explained by the presence of continuous habitat for E. umbrinus between the ranges of E. u. umbrinus and E. u. adsitus, whereas E. u. fremonti and E. u. montanus are each separated from E. u. umbrinus by areas unsuitable for occupancy by E. umbrinus. It must be noted, however, that no actual intergrades between E. u. umbrinus and E. u. adsitus are known.