bilaterians Hatschek, 1888 - bilaterians see Subkingdom Bilateria Hatschek, 1888 Spiralia Schleip, 1929 - spiralians see Superphylum Spiralia Schleip, 1929 Gnathifera Ahlrichs, 1995 Gnathostomulida Ax, 1956 - gnathostomulids see Phylum Gnathostomulida Ax, 1956