Kingdom [Animalia] Linnaeus, 1758 - animals
   Subkingdom Metazoa Haeckel, 1874 see Kingdom Animalia Linnaeus, 1758
     Division Eumetazoa Butschli, 1910 see Subkingdom Eumetazoa Butschli, 1910
       Subdivision Bilateralia
         Phylum Chordata Bateson, 1885 - chordates
           Subphylum Vertebrata Cuvier, 1812 - vertebrates
             Superclass Agnatha Haeckel, 1895 see Class Agnatha Cope, 1889
               Class Cyclostomata Richards
                 Subclass Petromyzones see Order Petromyzontiformes Berg, 1940
                   Family Petromyzonidae Bonaparte, 1831 see Family Petromyzontidae Bonaparte, 1832
                     Subfamily Petromyzoninae see Subfamily Petromyzontinae
                       1 Genus Geotria Gray, 1851
                       2 Genus Ichthyomyzon Girard, 1858
                       3 Genus Lampetra Bonnaterre, 1788
                       4 Genus Petromyzon Linnaeus, 1758