The families in this clade are basically air-breathing freshwater snails including freshwater limpets. The three families with the greatest number of species are the Lymnaeidae (pond snails), the Planorbidae (ramshorn snails) and the Physidae (pouch or bubble snails). These are found in ponds, creeks, ditches, and shallow lakes nearly worldwide.
The snails in this clade have their eyes located at the base of their tentacles, rather than at the tips, as in the true land snails Stylommatophora. They have shells that are thin, translucent, and relatively colorless, and they lack an operculum.
Note: what was previously the family Ancylidae has been demoted in the new taxonomy to the status of tribe Ancylini Rafinesque, 1815 within the subfamily Planorbinae Rafinesque, 1815 of the family Planorbidae Rafinesque, 1815.
Acroloxoidea Thiele, 1931: synonym of Lymnaeoidea Rafinesque, 1815
Planorboidea Rafinesque, 1815: synonym of Lymnaeoidea Rafinesque, 1815
^ abMolluscaBase eds. (2020). MolluscaBase. Hygrophila. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=382243 on 2020-12-14
^ abJörger K. M., Stöger I., Kano Y., Fukuda H., Knebelsberger T. & Schrödl M. (2010). "On the origin of Acochlidia and other enigmatic euthyneuran gastropods, with implications for the systematics of Heterobranchia". BMC Evolutionary Biology10: 323. doi:10.1186/1471-2148-10-323.
^Saadi, Ahmed J.; Davison, Angus; Wade, Christopher M. (2020). "Molecular phylogeny of freshwater snails and limpets (Panpulmonata: Hygrophila)". Zoological Journal of the Linnean Society. 190 (2): 518–531. doi:10.1093/zoolinnean/zlz177.