When Bailey (_loc. cit._) named the red-backed mouse from Wrangell Island, Alaska, he characterized it as "A large, dull-colored species entirely distinct from any known form," and remarked: "In no way does _E._ [= _Clethrionomys_] _wrangeli_ show a close relationship to any other American species. In size and relative proportions it comes closest to _E. dawsoni_, from which it differs widely in coloration and more widely in cranial characters. With the long-tailed species south and east of its range there is no need of comparison." Swarth (Univ. California Publ. Zool., 24:173, June 17, 1922) reported that three specimens from Flood Glacier and 23 from Great Glacier, British Columbia, and four from Sergief Island, at the mouth of the Stikine River, Alaska, were: "All _E. wrangeli_, indistinguishable from specimens at hand from Wrangell Island." Swarth further reported that, although he found no intergradation between _Clethrionomys wrangeli_ from Flood Glacier and the nearly adjacent _Clethrionomys rutilus dawsoni_, "the two species, however, resemble each other so closely in form, and in some pelages in color also, that _wrangeli_ would seem to be a coastal offshoot of _dawsoni_...." Davis (The Recent Mammals of Idaho, The Caxton Printers, p. 306, April 5, 1939) and Orr (Jour. Mamm., 26:69, February 12, 1945) more recently have shown that _Clethrionomys wrangeli_ is not a member of the _rutilus_ group (to which _C. dawsoni_ belongs) but is a member of the _gapperi_ group. Our comparisons of a series of eight topotypes of _wrangeli_ (all in the Biological Surveys Collection) with several subspecies of _Clethrionomys gapperi_ (including _phaeus_, _saturatus_, _galei_, _brevicaudus_, and others) reveal that the differences seen in _wrangeli_ are of the kind and degree that serve to separate subspecies. The red-backed mouse from Wrangell Island, then, should stand as _Clethrionomys gapperi wrangeli_ (Bailey). _Specimens examined._--Total, 31, distributed as follows: Alaska: Wrangell, Wrangell Island, 27 (19 MVZ., 8 USBS); Sergief Island at mouth of Stikine River, 4 (MVZ). Clethrionomys gapperi solus, new subspecies _Type._--Male, adult, skin and skull, No. 74939, Biological Surveys Collection, United States National Museum; from Loring, Revillagigedo Island, Alaska; obtained on September 22, 1895, by C. P. Streator; original No. 4980. _Range._--Known only from two localities on Revillagigedo Island, Alaska. _Diagnosis._--A short-tailed, dark-colored member of the _gapperi_ group. Dorsal stripe wide, between Chestnut and Bay (capitalized color terms after Ridgway: Color Standards and Color Nomenclature. Washington, D. C., 1912), with slight mixture of black-tipped hairs; sides and venter heavily washed with Ochraceous-Tawny. Skull flattened; rostrum proportionately short and wide; auditory bullae relatively uninflated.