Family: Synhymenium sparsely ciliated, extends from postoral region onto left preoral body surface; somewhat dorsoventrally flattened; thigmotactic (Illustrated Guide, 1985).
Genus: Both body surfaces ciliated (Illustrated Guide, 1985). Body ovoid or anterior projected toward left; flattened on both sides; both surface ciliated; cyrtos straight; a large macronucleus (Carey, 1992).