[Kingdom] Animalia Linnaeus, 1758 - animals Grade Enterozoa Grade Cœlomata Phylum Mollusca Linnaeus, 1758 - molluscs Branch Eucephala Grade Echinoglossa Class Cephalopoda Cuvier, 1795 - cephalopods Grade Siphonopoda Order Tetrabranchia Genus Nautilus Linnaeus, 1758