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 Gymnosomata Blainville, 1824 - naked pteropods see Suborder Gymnosomata Blainville, 1824
         Family Clionidae Rafinesque, 1815
           1 Genus Clione Pallas, 1774 - sea-butterfly
           2 Genus Fowlerina Pelseneer, 1906
           3 Genus Paedoclione Danforth, 1907
           4 Genus Paraclione Tesch, 1903
           5 Genus Thalassopterus Kwietniewski, 1910