When an ecosystem such as Douglas Lake is intensively studied over a period of time, lists of the local flora and fauna are usually generated as one facet of the investigations. Such is the case with our recent studies (Stoermer, 1977; Andresen, 1974, 1976). We consider it appropriate to present this list as a summary of taxa encountered to date so that others working on this lake may benefit by having some reference to the extent of the diatom flora. With Stoermer’s work on post-Pleistocene assemblages and Andresen’s work on recent sedimentary assemblages, we believe we have encountered a substantial fraction of taxa which have existed in the lake. Previous works on Douglas Lake which contain references to diatoms have been consulted (Chandler, 1937; Neel, 1948; Stoermer & Yang, 1971; Tucker, 1957; Young, 1945), and the taxa listed have been checked against our composite list.