Marstonia is a genus of freshwater snails with a gill and an operculum, aquatic gastropod molluscs in the family Hydrobiidae.

Species in the genus Marstonia are distributed in springs, streams and lakes in eastern North America.

[3] The freshwater gastropod genus Marstonia is composed of 15 small (shell height < 5.0 mm), ovate- to elongate-shelled species.

[3] Marstonia differs from the other eight North American nymphophiline genera in that the (female) oviduct and bursal duct join well in front of (instead of behind) the posterior wall of the pallial cavity.

[3] Eastern North American species of Pyrgulopsis[4] are considered to be in separate genus Marstonia according to Thompson & Hershler (2002).