[Kingdom] Animalia Linnaeus, 1758 - animals
   Grade Plastidozoa [monotypic]
     [Phylum] Protozoa (Goldfuss, 1818) C.T. von Siebold, 1854 see Kingdom Protozoa Goldfuss, 1818
       Grade Stomatodea
         Class Ciliata see [unranked] ciliates
           Order Heterotricha Stein, 1859 see Suborder Heterotricha Stein, 1859
             1 Genus Stentor Oken, 1815
             2 Genus Paramœcium Hermann, 1783, nom. null. see Genus Paramaecium Müller, 1773