Phylum [Vertebrata] Lamarck, 1801 see Infraphylum Vertebrata Lamarck, 1801
   Class Agnatha Cope, 1889
     Subclass †Cephalaspidomorphi Kiaer & Stensiö, 1920 see Class Agnatha Cope, 1889
       Order †Osteostraci Lankester, 1868 - osteostracans see Order Cephalaspidiformes Halstead Tarlo, 1967
         1 Genus †Boreaspis Stensiö, 1927
         2 Genus †Dartmuthia Patten, 1931
         3 Genus †Hemicyclaspis Lankester, 1870
         4 Genus †Tremataspis Schmidt, 1866