Cells are 12-25 microns long; circular in outline, slightly rounded above but flattened ventrally, except for a wide, rather deep groove in the median plane. There are two flagella, emerging on the left ventral side through a somewhat crescentic sub-terminal mouth opening into a shallow gullet. Below this also on the left side is a relatively conspicuous nucleus. The short anterior flagellum is thin, about body length; the trailer stout, about twice body length and carried straight bade. No stigma or color. Numerous inclusions, mostly small spheres, in the cytoplasm. Pellicle firm, smooth. Movement principally a steady glide forward. No observed ingestion of food. Reproduction not seen.