Suborder: Paroral dikinetid shorter than other oral structures;
no ribbed wall from paroral dikinetids towards cytostome (Illustrated Guide, 1985).
Family: Ovoid to ellipsoid, usually flattened; dense ventral cilia; oral area relatively large; ~ midventral; long, prominent cytoproct.
Genus: Preoral suture prominent; anterior suture extends to right immediately forward of oral area (Illustrated Guide, 1985). Ovo-cylindroid body, dark colored; no anterior cilia; transverse ring of long cilia near anterior end; cytostome small, near anterior ring of cilia; a long caudal cilium; common in decaying vegetation (How to know the protozoa, 1979). Ovoid to cylindrical; crescentic cytostome on slightly flattened area near anterior end; a zone of cilia around body; one (or more) long caudal cilium; cytoplasm yellowish to dark brown; macronucleus ovoid; a single contractile vacuole; fresh or brackish water (Kudo, 1966).