San Nicolas Island
More than 10 endemic molluscs are known only from San Nicolas Island. These are "Binneya notabilis", "Catinella rehderi", "Haplotrema duranti duranti", "Micrarionta feralis", "Micrarionta micromphala", "M. opuntia", "M. sodalis", "Nearctula rowellii longii", "Sterkia clementina", and "Xerarionta tyroni" (ssp. "tyroni" and "hemphilli").