Kingdom Animalia Linnaeus, 1758 - animals
   Phylum Mollusca Linnaeus, 1758 - molluscs
     Subphylum Cyrtosoma Runnegar & Pojeta Jr., 1974 see Phylum Mollusca Linnaeus, 1758
       Class Monoplacophora Odhner, 1940 - monoplacophorans
         Genus †Anabarella Vostokova, 1962
         Genus †Cyclocyrtonella Horný, 1962
         Genus †Cyrtonellopsis Yochelson, 1958
         Genus †Eotebenna Runnegar & Jell, 1976
         Genus †Hypseloconus Berkey, 1898
         Genus †Mellopegma Runnegar & Jell, 1976
         Genus †Stenotheca Salter, 1872
         Genus †Tropidodiscus Waagen, 1880
         1 Order †Cyrtonellida Horny, 1963
         2 Order Tryblidiida Lemche, 1957 see Order Monoplacophorida Wenz, in Knight, 1952
         3 Order †Bellerophontida Ulrich & Scofield, 1897 see Superfamily Bellerophontoidea McCoy, 1852
         4 Order †Pelagiellida Runnegar & Pojeta, 1985 see Order Pelagielliformes Runnegar & Pojeta, 1985