RhodacmeaRhodacmea is a genus of small freshwater snails or limpets, aquatic gastropod mollusks in the family Planorbidae, the ram's horn snails and their allies.Rhodacmea is the type genus of the subfamily Rhodacmeinae.AnatomyThese animals have a pallial lung, as do all pulmonate snails, but they also have a false gill or "pseudobranch". This serves as a gill, which is necessary as, in their non-tidal habitat, these limpets never reach the surface for air.SpeciesSpecies in the genus Rhodacmea include:Rhodacmea elatior – domed ancylidRhodacmea filosa – wicker ancylid, type species ''Rhodacmea hinkleyi''