101 
than S. h, streatori, and paler than S. h, vancouverensis and S. h. picatus. In skull sharp 
indentation in orbital arch between lachrymal and postorbital process mentioned by 
Osgood in his original description (North American Fauna, vol. 19, 1900, p. 27) may differ- 
entiate subspecies from vancouverensis , but it is a character shared by other interior forms 
to some extent. 
7. Castor canadensis Kuhl. Beaver 
Beaver cuttings (willow) more or less fresh, observed on Teal pond 
in May and June, but July 21 when woodcutter met here. Tracks seen 
earlier two or three times, on river mud at edge of woods, showed that 
animal had been prowling in spring remote from habitable water. Old 
male at Teal pond — sex judged from fact that he was building scent mounds 
— proved very tame and was studied for several hours by daylight, when both 
still photos and movies made of him. His house in bank, his door half 
submerged, end of tunnel being built up and roofed considerably. Much 
submerged material indicated that he had wintered here. 
On first meeting full of curiosity only, swimming up to within 50 
feet, where he gave exhibitions of diving and tail-splashing. When worried 
by too much attention, always went ashore on opposite bank of lakelet and 
sat in sun. One long, under-water swim where he could be watched 
for some time estimated to cover a distance of about 200 yards. When on 
August 6 a visit made here to collect him, pond vacant. Nearest suitable 
water for him at least half a mile off through timber. 
Capt. Hubrick of McCarthy informed writer that a few years earlier 
he had found a large beaver colony well hidden among the islands farther 
down the Chitina, beyond Barnard glacier. 
No specimens secured, but from geographical reasons form found here probably Alaska 
beaver, Castor canadensis belugae Taylor, type locality “Beluga river, Cook Inlet region, 
Alaska,” range “probably from Alaskan mountains on north to central British Columbia”; 
specimens recorded from Stuart lake, B.C. (Univ. Calif. Publ. Zool., vol. 12, 1916, p. 429). 
8. Cleithrionomys dawsoni dawsoni (Merriam) Dawson Red-backed 
Mouse 
Commonest mouse at river-level, but never numerous. Brush-piles 
about tent best trapping grounds, but a few caught along river bank and 
in a swampy draw down river, a single specimen taken August 7, above 
timber in haunts of Yakutat vole. On June 9, in a clump of Shepherdia 
on lower end of Chitina moraine, three or four of what were taken to be 
these same red-backed mice, seen working at midday. A shot from 
•32 auxiliary barrel failed in execution and they refused to come out again. 
Immature specimens taken commonly. This mouse had widest range of 
any found here. 
Specimens: Twelve. 
May 20, <? Kubrick’s camp, Chitina river. 
May 21, 9 
June 19, d* 9 “ “ 
June 26, d” ad. “ “ 
June 27, d* juv. “ “ 
July 22, d” d” juvs. “ “ 
August 7, d” 9 ad., <? juv. Hubriek’s camp, Chitina river. 
May specimens still in full winter pelage with distinct bright reddish area on back, 
sides yellowish and underparts white. June specimens have thinner hair, are duller ana 
darker in colour above, and underparts washed with buffy. July and August specimens 
longer-haired, with richer reddish colour on back, and underparts generally more whitish. 
Alaska specimens of this widely-ranging species average slightly smaller than animals 
from Yukon and Northwest Territories, and none of specimens from Chitina valley as 
light in colour as specimens from near Bering sea and Arctic coast. 
