The fact has already been established by bottom fauna studies (Adamstone, 1924; Rawson, 1930; Neave, 1932) that lake dwelling species of Hexagenia are inhabitors of soft, organic muds of deeper-water areas contiguous to the shallower sandy or rocky littoral region. Although specimens may be found on a sandy bottom or on a bottom of fine sand and mud intermixed, by far the greater numbers occur on bottoms of a distinctly soft, muddy character. As no investigations have been made on the ability of Hexagenia to burrow in various kinds of bottom, and since the character of the bottom is considered by the writer to be of primary importance as a factor influencing distribution of these nymphs as found in Douglas Lake, Cheboygan County, Michigan, a series of experiments was conducted.