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
Suborder Tamanovalvina
Superfamily Julioidea
see Superfamily Oxynooidea Stoliczka, 1868 (1847)
Family Elysiidae Forbes & Hanley, 1851
see Family Placobranchidae Gray, 1840, orth. inval.
Genus Elysia Risso, 1818
1 Subgenus Tridachia Deshayes, 1857
see Genus Tridachia Deshayes, 1857
2 Subgenus Tridachiella McFarland, 1924
see Genus Tridachiella McFarland, 1924