Genus: Colonies of a fixed number of cells, flat, circular in shape; cell body polygonal in shape, with horn-like projections; cell wall garanulated, wrinkled or notched; chloroplasts plate-like or reticular; asexual reproduction by zoospore; sexual reproduction by isogametes (Illustrations of The Japanese Fresh-water Algae, 1977). Species: Colonies of 8, 16, 32, 64 cells with large intercellular spaces; mariginal cells with two narrow, long, horn-like processes, of which apex truncated; inner cells H or X-shaped with deeply concaved sides; cell wall smooth (Photomicrographs of the fresh-water algae, 1997).

31 μm 63 μm 94 μm; x 640