Kingdom Animalia Linnaeus, 1758 - animals Phylum Mollusca Linnaeus, 1758 - molluscs Class Gastropoda Cuvier, 1795 - snails and slugs Subclass Prosobranchia Milne-Edwards, 1848 - prosobranchs see Class Gastropoda Cuvier, 1795 Order Mesogastropoda Thiele, 1925 - mesogastropods see [unranked] mesogastropods Family Littorinidae Children, 1834 - periwinkles Genus Littorina FĂ©russac, 1822