For the loan of comparative mammalian material, grateful acknowledgment is made to officials of the following institutions: California Academy of Sciences; Biological Surveys collection of the U. S. National Museum; Provincial Museum, Victoria, B. C.; National Museum of Canada. The promptness of officials of the game commissions of the provinces and territories concerned, in providing permits for collecting also is acknowledged. A part of the funds for field work was made available by a grant from the Kansas University Endowment Association. Elevations above sea level are given in feet. Capitalized color terms refer to those in Ridgway, Color Standards and Color Nomenclature, Washington, D. C., 1912. [Illustration: Fig. 1. Map showing localities where J. R. Alcorn collected mammals in Alaska, Yukon Territory, British Columbia, and Alberta, in 1947 and 1948.] COLLECTING LOCALITIES SHOWN IN FIGURE 1. Alaska 1. Circle. 2. Twelve Mile Summit, Steese Highway. 3. Chatanika River, 14 mi. E and 25 mi. N Fairbanks. 4. 1 mi. SW Fairbanks. 5. North side Salcha River, 25 mi. S and 20 mi. E Fairbanks. 6. Richardson Highway, 32 mi. S and 4 mi. W Big Delta. 7. Yerrick Creek, 21 mi. W and 4 mi. N Tok Junction. 8. Tok Junction. 9. Fish Creek, 5 mi. N and 1 mi. E Paxson. 10. East side Deadman Lake, 15 mi. SE Northway. 11. Glenn Highway, 6 mi. WSW Snowshoe Lake. 12. 1 mi. NE Anchorage. 13. East side Chilkat River, 9 mi. W and 4 mi. N Haines. 14. 1 mi. S Haines. Yukon Territory To avoid undue crowding, or overlapping, of symbols, two or more collecting localities, in some instances, are represented by a single symbol (solid circle) in figure 1. 15. Junction Grafe and Edith Creeks. 16. 6 mi. SW Kluane. 17. East side Aishihik River, 17 mi. N Canyon. 18. 25 mi. NW Whitehorse. 19. { 2 mi. NNW Whitehorse. { McIntyre Creek, 3 mi. NW Whitehorse. { 1 mi. NE Whitehorse. { ½ mi. W Whitehorse. 20. West side Lewes River, 2 mi. S Whitehorse. 21. { Marshall Creek, 3 mi. N Dezadeash River. { Champagne, North side Dezadeash Lake. { SW end Dezadeash Lake. 22. { 5 mi. W Teslin River, 16 mi. S and 53 mi. E Whitehorse. { 2 mi. W Teslin River, 16 mi. S and 56 mi. E Whitehorse. { West side Teslin River, 16 mi. S and 58 mi. E Whitehorse. { East side Teslin River, 16 mi. S and 59 mi. E Whitehorse. 23. { Unahini River, 5 mi. N and 1 mi. E Dalton Post. { Unahini River, 3 mi. N and 1 mi. E Dalton Post. 24. 1½ mi. E Tatshenshini River, 1½ mi. S and 3 mi. E Dalton Post. British Columbia 25. 1 mi. NW junction of Irons Creek and Liard River. 26. Screw Creek, 10 mi. S and 50 mi. E Teslin. 27. { 15 mi. NW Kelsall Lake. { Stonehouse Creek, 5½ mi. W junction Stonehouse Creek and { Kelsall River. 28. 14 mi. N Fort Halkett, West side Smith River.