Chelicerata Heymons, 1901
   †Eurypterida Burmeister, 1843 - eurypterids
     †Eurypterina Burmeister, 1843
       †Diploperculata Lamsdell, Hoşgör & Selden, 2013
         Superfamily †Adelophthalmoidea Tollerton, 1989 [monotypic]
           Family †Adelophthalmidae Tollerton, 1989
             1 Genus †Adelophthalmus Jordan, 1854
             2 Genus †Bassipterus Kjellesvig-Waering & Leutze, 1966
             3 Genus †Eysyslopterus Tetlie & Poschmann, 2008
             4 Genus †Nanahughmilleria Kjellesvig-Waering, 1961
             5 Genus †Parahughmilleria Kjellesvig-Waering, 1961
             6 Genus †Pittsfordipterus Kjellesvig-Waering & Leutze, 1966