Class Nematoda Gegenbaur, 1859
   Subclass Phasmidia Chitwood & Chitwood, 1933
     1 Order Tylenchoidea
     2 Order Rhabditoidea Orley, 1880
     3 Order Strongyloidea see Order Strongylida
     4 Order Ascaridida see Order Spirurida Railliet, 1914
     5 Order Spirurida Railliet, 1914
     6 Order Camallanida see Order Spirurida Railliet, 1914