Ceramic cross-dating indicates the La Playa site was occupied by people of the Trincheras Culture ca. A.D. 800-1100. Pisidium, Helisoma, and lymnaeids discussed in a previous report are believed to be of this time. Other molluscs, succineid snails, may represent both earlier Cochise and later Trincheras times. Molluscs of common genera occurring in Southwestern sites are discussed.