_Remarks._--Preble (1899:16) had available for study five specimens of _Zapus hudsonius hudsonius_ from Hudson Bay. Four were preserved in alcohol and one as an incomplete skin (prepared from an alcoholic specimen). All were unreliable for comparative purposes owing to the effects of the preservative. Preble, therefore, (_loc. cit._) selected as a fairly typical sample a series of specimens from Tower, St. Louis County, Minnesota; these formed the basis of comparison between _Z. h. hudsonius_ and other subspecies of _Zapus hudsonius_. Now that additional material (well prepared skins and skulls) is available from the Hudson Bay region and from other localities in northern and western Canada it is evident that the specimens from Tower, although here considered to be _Z. h. hudsonius_, are not typical _Z. h. hudsonius_ but are intergrades between _hudsonius_ and specimens of _Zapus hudsonius intermedius_. Comparisons made in the present account are based on specimens from the vicinity of Hudson Bay (Fort Severen, Ontario, York Factory, Shamatawa River, and Robinson Portage, Manitoba). These individuals are considered typical of this subspecies. With these new data available the range of _Z. h. hudsonius_ is now understood to include all of the region from eastern Alaska to the northern parts of Minnesota, Wisconsin, and Michigan. Intergradation between _Zapus hudsonius canadensis_ and _Z. h. hudsonius_ is noted in specimens from 30 mi. NE Port Arthur and also in those from Silver Islet, Thunder Cape, Ontario. These individuals resemble _Z. h. canadensis_ in size and shape of the auditory bullae and in the shape of the nasals, but in their darker coloration, broadly rounded incisive foramina, and relatively narrow pterygoid fossae they are more nearly like _Z. h. hudsonius_ to which they are here referred. Specimens from Minaki, Ontario, are tending toward _Zapus hudsonius intermedius_ in lighter coloration but in the size and shape of the auditory bulla, size and shape of the incisive foramina, and in the width of the pterygoid fossae they are more nearly like _Z. h. hudsonius_ to which they are here referred. Specimens from various localities in Menominee County, Michigan, are like _Z. h. intermedius_ in shape of the incisive foramina and shape of the postpalatal notch, but in color of pelage, size and shape of the auditory bullae, and breadth of the pterygoid fossae they closely resemble _Z. h. hudsonius_. In Wisconsin, intergradation occurs in color and in cranial characters in specimens from Mercer, Solon Spring, and in a single individual from Basswood Lake. All these specimens, however, are best referable to _Z. h. hudsonius_.