Nemathelminthes Gegenbaur, 1859 see Phylum Nematoda Gegenbaur, 1859
   Class Nematoda Gegenbaur, 1859
     Subclass Penetrantia
       Order Enoplida Filipjev, 1929
         Suborder Tripylina Andrassy, 1974
           55 Family Odontolaimidae Gerlach & Riemann, 1974
           56 Family Aulolaimidae Jairajpuri & Hooper, 1968
           57 Family Bastianiidae De Coninck, 1935
           58 Family Prismatolaimidae Micoletzky, 1922
           59 Family Ironidae De Man, 1876
           60 Family Tobrilidae Filipjev, 1918
           61 Family Onchulidae Andrassy, 1964
           62 Family Tripylidae De Man, 1876
           63 Family Alaimidae Micoletzky, 1922