A fossil assemblage containing molluscs, ostracodes, and fish has been recovered from lacustrine sediments from near Connersville, southeastern Indiana. The reversed remanent magnetic signature of the sediments and the extent of isoleucine epimerization in molluscan shell protein indicate a pre-Illinoian age for the fossils. The fauna includes four taxa of fish, Coregonus sp., cf. Prosopium sp., cf. Thymallus arcticus, and Catostomus sp.; four taxa of ostracodes, Cytherissa lacustris, Candona caudata, Cyclocypris ampla, and Candona sp.; and 28 taxa of molluscs. Elements of the aquatic molluscs, fish, and ostracodes suggest a cool-water lake (8° to 16°C). The terrestrial molluscs include boreal species that now reach the southern limits of their range in the Great Lakes region near the north shore of Lake Superior and imply average summer temperatures of about 15°C near the lake margins. The lake may have been formed when West Lebanon ice advanced into the Anderson-New Castle Buried Valley system which drained northwest as a tributary of the Lafayette Bedrock Valley System.