Kingdom Animalia Linnaeus, 1758 - animals Phylum Arthropoda Siebold, 1848 - arthropods Superclass Chelicerata Heymons, 1901 see Subphylum Chelicerata Heymons, 1901 Class Merostomata Dana, 1852 - horseshoe crabs see Class Xiphosura Latreille, 1802 Order Xiphosurida Latreille, 1802 Genus Limulus Müller, 1785 Genus †Paleolimulus Dunbar, 1923 see Genus Palaeolimulus