Cell wall ornamented with spines, but lacking central constriction
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Cell is covered by thick armoured plates; long, sharp horns protrude from both ends of the cell.
Ceratium -
Cell is covered by thick armoured plates; if horns are present, these are short and blunt (cf. Ceratium).
Peridinium -
Flattened cells; triangular, square, or polygonal in outline; spines often present at cell corners.
Tetraedron -
Cells not flattened; tetrahedral or polyhedral in outline; spines arising from the corners.
Polyedriopsis -
Cell ovoid, with a cluster of 3 or more short spines arising from each end.
Chodatella -
Cell ovoid, with a long straight spine extending from each end.
Diacanthos -
Cells usually single, but may be found in loose aggregates of a few cells.
Golenkinia