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
               1 Subgenus Aplustrum Schumacher, 1817 see Genus Aplustrum Schumacher, 1817