Phylum Mollusca Linnaeus, 1758 - molluscs Conchifera Gegenbaur, 1878 see Subphylum Conchifera Gegenbauer, 1878 Cyrtosoma Class Cephalopoda Cuvier, 1795 - cephalopods 1 Nautiloidea Agassiz, 1848 see Subclass Nautiloidea Agassiz, 1848 2 †Ammonoidea see Subclass Ammonoidea Zittel, 1884 3 Coleoidea Bather, 1888 see Subclass Coleoidea Bather, 1888