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 Aciculidae Gray, 1850 Genus Watsonia Fischer, 1971, nom. illeg.