Genus: Ectoplasm consists of large vacuoles in one or several layres; endoplasm with numerous small vacuoles; numerous nuclei; axopodia end in the inner zone of ectoplasm (Kudo, 1966). Species: Cell body spherical, 200-1000 μm in diam.; ectoplasm vacuolated; endoplasm containing both granules and small vacuoles; several contractile vacuoles present; many nuclei located at the perphery of endoplasm.