Outline broadly elliptical to slightly reniform, anteriorly and posteriorly broadly rounded; dorsoventrally flattened. "Cross-striped band" ("railroad track") along entire periphery of cell is a hollow tube kept open by numerous C-shaped structures. One macronucleus, 1 micronucleus. Four to five contractile vacuoles. Patch of orange to yellow-green granules (pigment spot) on anterior left. Right ciliary field composed of 11-18, left of 9-20 kineties; 4 postoral ciliary rows. Oral basket composed of 8-13 nematodesmal rods with a tooth, 1-2 nonciliated dikinetids each associated with a rod. One preoral and 2 circumoral kineties (perioral kineties). Thigmotactic. Size 30-150 x 15-70 µm. Usually a benthic species.
Ref.: Kahl (1931), Deroux (1974), Dragesco and Dragesco-Kernéis (1986), Bardele (1993).