Order: No kinetidal specializations at oral region.
Family (Kahl): Cytostome terminal; ciliation uniform; usually encased in a pseudochitinous lorica (Kudo, 1966).
Genus: Oblong; ciliary circle around cytostome; usually one caudal cilium; with large posterior vesicle containing turbid fluid (Kudo, 1966). Easily recognizable by the transverse annulations of the body and the presence of a large protruding vacuole in posterior (Carey, 1992). Similar to Vasicola, but small and free swimming, without a lorica (How to know the protozoa, 1979).