Metazoa Haeckel 1874 - multicellular animals see Kingdom Animalia Linnaeus, 1758
   Phylum Platyhelminthes Gegenbaur, 1859 - flatworms
     Class Trematoda Rudolphi, 1808 - flukes see Infraclass Trematoda Rudolphi, 1808
       Order Digenea Carus, 1863
         1 Suborder Gasterostomata Odhner [monotypic]
         2 Suborder Prosostomata Odhner
         3 "Cercaria" Müller, 1773, incertae sedis