Through the courtesy of Mr. Dan Stevens, we were able to spend several days during July, 1968, collecting bryophytes on Summer Island located in the channel between the Garden Peninsula, Michigan, and the Door Peninsula, Wisconsin. ... The Niagara escarpment is a prominent physiographic feature across much of this region. Dry or moist Thuja occidentalis stands, often containing Abies balsamea, fringe the island. Inland these give way to deciduous forest dominated by Acer saccharum and Fagus grandifolia, but with some Tsuga canadensis and other tree species. ... Until our visit, apparently no one had collected bryophytes on the island. ... We report here 130 species of bryophytes, including 35 hepatics and 95 mosses, all of which were found during our stay on the island. ... Among the material we collected are two species that evidently have not been reported before from Michigan: Eucladium verticillatum & Lophozia collaris.