During the course of a microclimatic study of small mammal habitats in the vicinity of UMBS, near Cheboygan, Cheboygan, County, Michigan, a series of 31 specimens of the masked shrew (Sorex cinereus cinereus Kerr) was collected from one study plot in a trapping period of six consecutive nights, from July 9 through 14, 1951. This study plot was at the north end of Burt Lake, in a portion of the extensive white cedar and spruce swamp known locally as Reese’s Bog. These shrews were taken in 100 Museum Special traps gridded over the 300 x 400 foot study plot.