Close serial sampling and quantitative analyses of the non-marine molluscan fauna of a tufa at Totland Bay, Isle of Wight, has doubled the number of species known. Several locally extinct forms, notably Spermodea lamellata, Leiostyla anglica and Pisidium tenuilineatum, were present. There was little stratigraphical change in faunal composition, although Vertigo genesii, V. geyeri and Succinea oblonga were detected only in the basal samples. The land fauna is one of closed forest. By comparison with other sites described from southern Britain it is suggested that it belongs to the Flandrian climatic optimum (c.7500 – c. 3000 BP).