Kingdom Protista (Haeckel, 1866) - protists Phylum Ciliophora Doflein, 1901 - ciliates Class Polyhymenophorea - spirotrichs see Class Spirotrichea Bütschli, 1889 Subclass Spirotricha see Class Spirotrichea Bütschli, 1889 Order Heterotrichida Stein, 1859 - heterotrichs Genus Spirostomum Ehrenberg, 1834