Dinoflagellates - Peridinium bipes
Peridinium has more ball-like cells than Ceratium and no horns. As with other dinoflagellates the cell is divided into an upper and a lower half, separated by the transverse groove. The two sides are different. One side has a broad groove running down the lower half of the cell. From this groove arises a flagellum. The other groove joins the ends of the transverse one and contains the second flagellum. The cell is about 38-90 my.
Peridinium bipes
Peridinium bipes
The cell wall is composed with plates of different forms, which are different for each species. The electron-microscope image (850 x) shows the plates and how the grooves joins. The flagella are not to be seen.