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1910] Heller—Mammals: Alaska Expedition, 1908. 339 
A specimen taken September 14 at Valdez Narrows is in the 
thick winter pelage. This one is heavily lined dorsally with 
black, the gray of the nape and the fulvous rump being much 
less conspicuous than in worn summer pelage. A few days 
after this specimen was secured snow fell heavily on the region 
above timber-line, causing the species to go into hibernation. 
Evotomys dawsoni orca Merriam. Orca Red-backed Mouse. 
Represented by 59 specimens, covering four island and five 
mainland localities. Of these specimens, 27 are fully adult, the 
remainder being immature. The island material agrees fairly 
well with the Cordova series, but the few adults in it are in 
worn pelage. Hyotomys is confined to the forest, and is much 
rarer on the islands than elsewhere. The specimens secured on 
Knight Island have considerably darker colored underparts, but 
only one fully adult specimen was taken. Localities represented 
by specimens: Cordova 12; head of Cordova Bay 7; Hoodoo 
Island 7; Latouche Island 3; Knight Island 8; Chenega Island 
6; Port Nell Juan 13; Ellamar 1; Valdez Narrows 3. 
Evotomys dawsoni insularis, new subspecies. 
Island Red-backed Mouse. 
Typr.—Male adult; no. 557, Univ. Calif. Mus. Vert. Zool. ; 
Canoe Passage, Hawkins Island, Prince William Sound, Alaska; 
June 20, 1908; collected by E. Heller; orig. no. 79. 
CHARACTERS.—Similar in size and proportions to EHvotomys 
dawsoni orca Merriam (Proe. Wash. Acad. Sei., 11, March, 1900, 
p. 24), but dorsal coloration much brighter rufous; tail dor- 
sally similar to the back in coloration; coloration of underparts 
much lehter, grayish without any yellowish suffusion. The 
skull has conspicuously larger audital bullae than orca and is 
wider zygomatically. 
CoLoration.—Above ferruginous-rufous from snout to base 
of tail; sides yellowish to level of ears; belly and feet lght 
erayish without any yellowish suffusion; a concealed whitish 
spot at base of ear; tail bicolor, above reddish like the back, 
below tawny brownish. 
