Phylum Mollusca Linnaeus, 1758 - molluscs Class Gastropoda Cuvier, 1795 - snails and slugs Subclass Opisthobranchia Milne-Edwards, 1848 - opisthobranchs see Order Opisthobranchia Milne-Edwards, 1848 Order Cephalaspidea Fischer, 1883 Superfamily Bulloidea Gray, 1827 Family Retusidae Thiele, 1925 Genus Volvulella Newton, 1891 Subgenus Paravolvulella Harry, 1967