Family: Body box-shaped; body cilia as short segments of kinetids at front and rear.
Genus: > 4 caudal spines (Illustrated Guide, 1985). Laterally compressed; pellicle with ridges and folds; buccal cavity has a tooth-like projection on the anterior edge (Carey, 1992).
S. dentatum Lauterborn, 1908: Ovoid; 80 μm long; three macronuclei (Carey, 1992).
S. halophilum Kahl, 1930-5: Ovoid; 50 μm long; two macronuclei (Carey, 1992).