_Remarks._--This geographic race is notably stable and retains most of its diagnostic characters throughout nearly all parts of its range. Intergradation occurs with _Zapus princeps idahoensis_ at various localities in Montana, as is described in more detail in the account of _idahoensis_. Crowe (1943:406) gives evidence of intergradation between _Zapus princeps idahoensis_ and _Z. p. minor_ in specimens from Entrance in western Alberta. Crowe (_loc. cit._) described these individuals as intermediate in color (lateral line present, under parts washed with buff, sides and dorsal stripe rich in ochraceous), and in cranial characters (smaller skulls, anteriorly narrower nasals, shorter more deflected rostrum, and higher cranium); but he considered them closer to _Z. p. minor_. A skin without skull from Kananaskis Valley, Alberta, shows intergradation between _Z. p. idahoensis_ and _Z. p. minor_. This individual is like _Z. p. idahoensis_ in dorsal and lateral coloring, but is nearer _Z. p. minor_ in ventral coloring and in the presence of a distinct lateral line. External measurements provide basis for tentatively assigning the skin to _Z. p. minor_. _Specimens examined._--Total, 118, distributed as follows: ALBERTA: 4 mi. N Marinville, 2; Blindman River, 1 (USBS); Camrose, 1 (ROM); Red Deer River, 1 (USBS); Didsbury, Little Red Deer River, 1 (ROM); Kananaskis Valley, 7000 ft., 1 (ROM); High River, 2 (ROM); Lodge Creek, 2 (NMC). MANITOBA: Shoal Lake, 6 (NMC); Oak Lake, 4 (NMC); Aweme, 7 (6 ROM; 1 USBS). MONTANA: _Chouteau County_: Eagle Creek, 25 mi. SE Big Sandy, 3 (UM). _Hill Co._: Fort Assiniboine, 1 (USBS); _Bear Paw Mt's, 20 mi. SE Fort Assiniboine_, 4 (USBS); _head Eagle Creek, Bear Paw Mt's_, 7 (UM). _Valley Co._: Glasgow, 1 (USBS). NORTH DAKOTA: _Benson Co._: 4 mi. W Leeds, 1400 ft., 2; _2 mi. W Fort Totten, 1400 ft._, 13; Fort Totten, 4 (USBS). _Bottineau Co._: 4-8/10 mi. N Bottineau, 2100 ft., 2; _3-1/2 mi. N Bottineau, 1920 ft._, 2; _2-1/10 mi. N Bottineau, 1800 ft._, 3; _Bottineau_, 1 (USBS). _Dickey Co._: Oakes, 3 (USBS). _Grand Forks Co._: Larimore, 3 (USBS). _Montrail Co._: 6 mi. N Lostwood, 2 (USBS). _Nelson Co._: Stump Lake, 1 (USBS). _Richland Co._: _Lidgerwood_, 1 (USBS); 4 mi. S Blackner, (USBS). _Rolette Co._: St. John, 1 (USBS). _Sargent County_: _7-1/5 mi. E and 1-1/5 mi. S Oakes, 1200 ft._, 6; _3 mi. W Cayuga, 1000 ft._, 2. _Walsh Co._: Grafton, 2. _Ward Co._: _Minot_, 3 (CMNH). _Williams Co._: Grinnell, 2 (USBS); Buford, 2 (USBS). SASKATCHEWAN: Wingard, near Carlton House, 2 (USBS); Fort Carlton, 1 (MVZ); Indian Head, 2 (USBS); Cypress Hills, N Maple Creek, 18 (NMC); _Battle Creek_, 1 (NMC). SOUTH DAKOTA: _Day Co._: Webster, 1 (Chic. AS).