living organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Superkingdom Eukaryotae see Domain Eukaryota Chatton, 1925
     Kingdom Animalia Linnaeus, 1758 - animals
       Subkingdom Eumetazoa Butschli, 1910 see [unranked] Eumetazoa Bütschli, 1910
         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 Sacoglossa Ihering, 1876 - sacoglossans
                 Family Elysiidae Forbes & Hanley, 1851 see Family Placobranchidae Gray, 1840, orth. inval.
                   1 Genus Elysia Risso, 1818
                   2 Genus Bosellia Trinchese, 1891
                   3 Genus Tridachia Deshayes, 1857
                   4 Genus Placobranchus Boïé, 1824, orth. inval. see Genus Plakobranchus van Hasselt, 1824