Nemathelminthes Gegenbaur, 1859 see Phylum Nematoda Gegenbaur, 1859
   Class Nematoda Gegenbaur, 1859
     Subclass Torquentia
       Order Monhysterida Filipjev, 1929
         Suborder Monhysterina De Coninck & Schuurmans Stekhoven, 1933
           37 Family Monhysteridae De Man, 1876
           38 Family Xyalidae Chitwood, 1951
           39 Family Sphaerolaimidae Filipjev, 1918