REDESCRIPTION OF PALUDINA-INTEGRA SAY, 1821, TYPE SPECIES OF GENUS CINCINNATIA (GASTROPODA, HYDROBIIDAE)

We present evidence that Paludina integra Say, 1821, an early describe d species of North American freshwater snail which has been previously placed in either of two families (Hydrobiidae, Viviparidae), is the h ydrobiid snail known as Cincinnatia cincinnatiensis (Anthony, 1840). W e provide a description for this snail, which is the type species of t he genus Cincinnatia Pilsbry, 1891, and select a neotype to ensure nom enclatural stability. Features of genitalia (including a second female bursal duct which has not been recorded previously for members of the family Hydrobiidae) distinguish this species from all other members o f the North American subfamily Nymphophilinae. At the present time, in sufficient data are available to support allocation of other species t o Cincinnatia. Paludina cincinnatiensis Anthony, 1840, Amnicola scarbo roughi Tryon, 1870, Amnicola peracuta Pilsbry & Walker bz Pilsbry, 188 9, Amnicola judayi Baker, 1922, and Cincinnatia cincinnatiensis chicag oensis Baker, 1930 are junior synonyms of Cincinnatia integra (Say, 18 21).