At both localities where specimens were taken, Alcorn noted first their characteristic droppings. At Summit Pass, droppings were found in a rock slide at the upper limit of timber line; one rat was taken. At the trapping station five miles west and three miles north of Fort St. John, droppings were found in and under an old abandoned building; four young (two prepared) and one adult were obtained. Synaptomys borealis dalli Merriam Northern Bog Lemming _Synaptomys_ (_Mictomys_) _dalli_ Merriam, Proc. Biol. Soc. Washington, 10:62, March 19, 1896. (Type from Nulato, Alaska.) _Synaptomys borealis dalli_ A. B. Howell, N. Amer. Fauna, 50:24, (June 30) August 5, 1927. _Specimens examined._--Total 6, as follows: _Alaska_: E side Deadman Lake, 1800 ft., 15 mi. SE Northway, 1. _Yukon Territory_: McIntyre Creek, 2250 ft., 3 mi. NW Whitehorse, 5. _Remarks._--The northern bog lemming is evidently not generally distributed along the Alaska Highway but may be locally numerous in cover of grass and sedge especially in marsh and bog habitat. Five specimens were obtained in a grassy area 30 feet wide by 60 feet long which was approximately 50 feet from McIntyre Creek in the Yukon Territory. In 22 mouse traps set the first night in this locality, three _Synaptomys_, six _Microtus_ and one _Sorex_ were taken. One additional _Synaptomys_ was taken on each of the following two nights in the same area. At Deadman Lake, Alaska, one _Synaptomys_ was taken in heavy sedge bordering a small pond. Clethrionomys rutilus dawsoni (Merriam) Dawson Red-backed Mouse _Evotomys dawsoni_ Merriam, Amer. Nat., 22:650, July, 1888. (Type from Finlayson River, a northern source of the Liard River, lat. 61° 30' N, long. 129° 30' W, Yukon, Canada.) _Clethrionomys rutilus dawsoni_ Rausch, Jour. Washington Acad. Sci., 40:135, April 21, 1950. _Specimens examined._--Total 126, as follows: _Alaska_: Chatanika River, 700 ft., 14 mi. E and 25 mi. N Fairbanks, 17; 1 mi. SW Fairbanks, 440 ft., 1; N side Salcha River, 600 ft., 25 mi. S and 20 mi. E Fairbanks, 15; 25 mi. S and 20 mi. E Fairbanks, 3; Yerrick Creek, 21 mi. W and 4 mi. N Tok Junction, 32; Tok Junction, 1600 ft., 1; E side Deadman Lake, 1800 ft., 15 mi. SE Northway, 9; 1 mi. NE Anchorage, 100 ft., 9; Glenn Highway, 6 mi. WSW Snowshoe Lake, 1; E side Chilkat River, 100 ft., 9 mi. W and 4 mi. N Haines, 2; 1 mi. S Haines, 5 ft., 2. _Yukon Territory_: Jct. Grafe Creek and Edith Creek, 2; 6 mi. SW Kluane, 2250 ft., 4; 2 mi. NNW Whitehorse, 2100 ft., 2; W side Lewes River, 2150 ft., 2 mi. S Whitehorse, 6; SW end Desadeash Lake, 15. _British Columbia_: Stonehouse Creek, 5½ mi. W jct. Stonehouse Creek and Kelsall River, 1; S side Toad River, 10 mi. S and 21 mi. E Muncho Lake, 2; Summit Pass, 4500 ft., 10 mi. S and 70 mi. W Fort Nelson, 2.