(Ehrenberg, 1838) Stein, 1878. Cell outline is elongate to ovate. Cells are 15 - 30 microns long and about 8 to 11 microns wide, flattened, with squirming movement and with pellicular striations following a S-helix. Two emergent flagella are similar in width. The anterior flagellum is approximately 2 to 2.5 times the length of the cell and is longer than the posterior flagellum, which is slightly longer than the cell. The ingestion organelle may be difficult to see. The reservoir is in the left ventral side of the cell and the nucleus is in the posterior part of the cell. Refractile bodies lie under the cell surface. The cells move by gliding.