Segmentina is a genus of small, air-breathing, freshwater snails, aquatic gastropod mollusks or micromollusks in the family Planorbidae, the ramshorn snails. Albrecht et al. (2007) have confirmed its placement in the tribe Segmentinini within subfamily Planorbinae. The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large. There are huge numbers of sea snails and sea slugs, as well as freshwater snails and freshwater limpets, and land snails and land slugs.