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 Acteonoidea d'Orbigny, 1843
           Family Hydatinidae Pilsbry, 1895, nom. illeg. see Family Aplustridae Gray, 1847
             Genus Hydatina Schumacher, 1817
               Subgenus Aplustrum Schumacher, 1817 see Genus Aplustrum Schumacher, 1817