_Remarks._--The coloration in _Z. p. oregonus_ varies somewhat from north to south. In the northern part of the range the average coloration of the upper parts is darker with more ochraceous on the sides. To the southward the upper parts are progressively paler and the sides are near Light Pinkish-Cinnamon. Because of this variation of color, and because of the small samples available to workers in the past, three populations of this subspecies have been named as distinct. However, with the large amount of additional material now available, the supposed diagnostic characters of these "forms" prove to be within the range of individual variations of each of several populations of which large samples are available. _Zapus major_ Preble (1899:24) was described as having zygomata short, palate broad and long, incisive foramina large and elliptical, and color dark. Some specimens of _Z. p. oregonus_, from nearly all parts of its geographic range, show these same characters. Resemblances in anteriorly divergent tooth-rows, broad interorbital region, small auditory bullae, and posteriorly narrow nasals, are additional reasons for placing _Z. major_ as a synonym of _Z. p. oregonus_. _Zapus nevadensis_ Preble (1899:25), here considered a synonym of _Z. p. oregonus_, was described as having: auditory bullae small, posterior border of the palate usually convex anteriorly, palatal bridge long, and color pale. These characters, however, are within the range of individual variation of _Zapus p. oregonus_. Similarities such as tooth-rows diverging anteriorly, nasals narrow posteriorly, interorbital region broad, and incisive foramina enlarged posteriorly are added reasons for placing _Z. nevadensis_ as a synonym of _Z. p. oregonus_.