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 Thecosomata Blainville, 1824 [monotypic] - shelled pteropods see Suborder Thecosomata Blainville, 1824
         Suborder Euthecosomata Meisenheimer, 1905 [monotypic] see Infraorder Euthecosomata Meisenheimer, 1905
           Superfamily Spiratelloidea see Superfamily Cavolinioidea Gray, 1850 (1815)
             Family Cavoliniidae Gray, 1850 (1815)
               Subfamily Clionae van der Spoel, 1967, orth. inval. see Subfamily Clioinae Jeffreys, 1869
                 Genus Hyalocylis Fol, 1875