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 †Aglaspida (Walcott, 1911), nom. illeg. see Order Aglaspidida Walcott, 1911
           Genus †Aglaspis Hall, 1862