[Arthropoda] Siebold, 1848 - arthropods see Phylum Arthropoda Siebold, 1848
   Arachnomorpha Heider, 1913
     1 Genus †Retifacies Hou, Chen & Lu, 1989
     2.1 Genus †Emeraldella Walcott, 1912
     2.2 Genus †Aglaspis Hall, 1862
     3.1.1 Genus †Weinbergina Richter & Richter, 1929
     3.1.2.1 Genus †Sidneyia Walcott, 1911
     3.1.2.2 Genus †Nettapezoura Briggs et al., in press
     3.2.1 Genus †Leanchoilia Walcott, 1912
     3.2.2 Genus †Sanctacaris Briggs & Collins, 1988
     3.2.3.1 Genus †Dicranocaris Briggs et al., in press
     3.2.3.2 Genus †Alalcomenaeus Simonetta, 1970
     4 †Trilobitomorpha Størmer, 1944 see Superclass Trilobitomorpha Størmer, 1944