I propose in this paper to furnish a list of the marine Turbellaria of Plymouth Sound and the neighbourhood, including all species that have hitherto been recorded from this locality. That such an attempt is in some respects premature I am only too well aware, but I have written it for the convenience of those who are working at, or are interested in, the fauna of Plymouth, and it may serve as a starting-point in our knowledge of the Turbellaria of the Sound. The synonymy and descriptions of the species are given by v. Graff, Lang, Jensen, and recently, together with figures of the new species and the literature, by myself.