Eumetazoa Bütschli, 1910 - eumetazoans [unranked] Bilateria Hatschek, 1888 see Subkingdom Bilateria Hatschek, 1888 Protostomia Grobben, 1908 see Infrakingdom Protostomia Grobben, 1908 Grade Acoelomates Hyman, 1951 Phylum Nemertea Schultze, 1851 - ribbon worms