Planorbis is a genus of air-breathing freshwater snails, aquatic pulmonate gastropod mollusks in the family Planorbidae, the ram's horn snails, or planorbids. All species in this genus have sinistral or left-coiling shells. Description Planorbis shells are flat-coiled and sinistral. Distribution This genus has a worldwide distribution. It is known from the Jurassic to the Recent periods. Species Species within the genus Planorbis include: Subgenus Planorbis (Jalpuchorbis) Prysjazhnjuk & Kovalenko, 1986 † Planorbis bolgradensis Prysjazhnjuk & Kovalenko, 1986 † Planorbis roshkai Prysjazhnjuk & Kovalenko, 1986 Subgenus Planorbis (Planorbis) Müller, 1773 Planorbis corinna Gray, 1850 Planorbis carinatus O. F. Müller, 1774 Planorbis moquini Requien, 1848 Planorbis planorbis (Linnaeus, 1758) Planorbis kahuica Finlay & Laws, 1931 Subgenus ? † Planorbis anceps Sacco, 1884 † Planorbis austroalpinus Harzhauser & Neubauer in Harzhauser et al., 2012 † Planorbis bouei Pavlović, 1932 † Planorbis fischeri Wenz, 1919 † Planorbis gladilini Pavlović, 1931 Planorbis intermixtus Mousson, 1874 † Planorbis kochi Pavlović, 1927 † Planorbis nisseanus Pavlović, 1931 † Planorbis petrovici Pavlović, 1931 † Planorbis striatus Serres, 1853 † Planorbis truncatocarinatus Pavlović, 1931 † Planorbis verticilloides Pavlović, 1931 † Planorbis zivkovici Pavlović, 1931 Suggenera and species brought into synonymy Subgenus Planorbis (Anisus) Studer, 1820: synonym of Anisus Studer, 1820 Subgenus Planorbis (Armiger) Hartmann, 1843 : synonym of Gyraulus (Armiger) Hartmann, 1843 represented as Gyraulus Charpentier, 1837 Subgenus Planorbis (Bathyomphalus) Charpentier, 1837: synonym of Bathyomphalus Charpentier, 1837 Subgenus Planorbis (Coretus) Gray, 1847: synonym of Planorbarius Duméril, 1805 Subgenus Planorbis (Gyraulus) Agassiz in Charpentier, 1837: synonym of Gyraulus Charpentier, 1837 † Planorbis (Gyraulus) declivis var. balizacensis Peyrot, 1932: synonym of † Anisus balizacensis (Peyrot, 1932) Subgenus Planorbis (Gyrorbis) Fitzinger, 1833: synonym of Valvata O. F. Müller, 1774 Subgenus Planorbis (Odontogyrorbis) Lörenthey, 1906: synonym of Anisus (Anisus) Studer, 1820 Subgenus Planorbis (Segmentina) Fleming, 1818: synonym of Segmentina Fleming, 1818 Planorbis acronicus Férussac, 1807: synonym of Gyraulus acronicus (Férussac, 1807) Planorbis albus O. F. Müller, 1774: synonym of Gyraulus albus (O. F. Müller, 1774) Planorbis argaeicus Sturany, 1904: synonym of Gyraulus argaeicus (Sturany, 1904) Planorbis atkinsoni Johnston, 1879: synonym of Gyraulus atkinsoni (Johnston, 1879) Planorbis biwaensis Preston, 1916: synonym of Gyraulus biwaensis (Preston, 1916) Planorbis borealis Westerlund, 1875: synonym of Gyraulus borealis (Lovén in Westerlund, 1875) Planorbis campanulatus Say, 1821 accepted as Planorbella campanulata (Say, 1821) Planorbis chinensis Dunker, 1848: synonym of Gyraulus chinensis (Dunker, 1848) Planorbis contrarius O. F. Müller, 1774: synonym of Marisa cornuarietis (Linnaeus, 1758) Planorbis convexiusculus Hutton, 1849: