Genus: Oral polykinetid 3 rectangular; oral area midventral (Illustrated Guide, 1985). Cytostome right of median line in posterior half; with 3-4 caudal cilia; contractile vacuole terminal (Kudo, 1966). Species:

31 μm 63 μm 94 μm; x 640

Cinetocilum margaritaceum Perty, 1852: Cell body 15-45 μm long; oral area in lower right quadrant of ventral surface; body ovoid, anterior and posterior rounded (Carey, 1992).