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 Runcinoidea Adams & Adams, 1854
           1 Family Runcinidae Adams & Adams, 1854
           2 Family Ildicidae Burn, 1963 see Family Runcinidae Adams & Adams, 1854
           3 Family Philinoglossidae Hertling, 1932
           4 Family Plusculidae Franc, 1968 [monotypic]