Superclass Spirotricha Bütschli, 1889 see Class Spirotrichea Bütschli, 1889
   Class Hypotrichea Stein, 1859 see Subclass Hypotrichia (Stein, 1859) Cavalier-Smith, 1993
     1 Order Hypotrichida Stein, 1859 - hypotrichs see Subclass Hypotrichia (Stein, 1859) Cavalier-Smith, 1993
     2 Order Stichotrichida Fauré-Fremiet, 1961