Hydrobiidae, commonly known as mud snails, is a large cosmopolitan family of very small freshwater and brackish water snails with an operculum; they are in the order Littorinimorpha.
Bythinella is a genus of very small freshwater snails, an aquatic gastropod mollusk in the family Bythinellidae.
Bythiospeum is a genus of very small freshwater snails that have an operculum, aquatic gastropod mollusks in the family Moitessieriidae.
Paladilhia is a genus of minute freshwater snails with an operculum, aquatic gastropod molluscs or micromolluscs in the family Moitessieriidae.
Platyla is a genus of very small land snails with an operculum, terrestrial gastropod molluscs or micromolluscs in the family Aciculidae.
Pseudamnicola is a genus of small brackish water snails with an operculum, aquatic gastropod mollusks in the subfamily Pseudamnicolinae of the family Hydrobiidae.
Valvata is a genus of very small freshwater snails with an operculum, aquatic gastropod mollusks in the family Valvatidae, the valve snails.
Mercuria is a genus of small brackish water snails or freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Hydrobiidae.
Parthenina is a genus of very small sea snails, pyramidellid gastropod mollusks or micromollusks.
Moitessieriidae is a family of small freshwater snails, aquatic gastropod molluscs in the superfamily Truncatelloidea.
Islamia is a genus of small freshwater snails with a gill and an operculum, aquatic gastropod mollusks in the family Hydrobiidae.
Palaospeum is a genus of minute freshwater snails with an operculum, aquatic gastropod molluscs or micromolluscs in the family Moitessieriidae.
Spiralix is a genus of very small aquatic snails, operculate gastropod mollusks in the family Moitessieriidae.
