Genus: Filamentous algae without branching, no rhizoids, covered with gelatinous sheath; cell body cylindrical or ellipsoidal, cells attached side by side or separated; a single chloroplast band-form, with a pyrenoid (Guide book to the "Photomicrographs of the Freshwater Algae", 1998). Species: Colonies a short lnear filament covered with a gelatinous sheath; cell body short cylindroid, 8-18 μm long, 4-8 μm wide; adjacent cells attached with each other (Illustrations of the Japanese Freshwater Algae, 1977).

31 μm 63 μm 94 μm; x 640

* Geminella minor (Nägeli) Hansgirg: Colonies a short lnear filament covered with a gelatinous sheath; cell body short cylindroid, 8-18 μm long, 4-8 μm wide; adjacent cells attached with each other (Illustrations of the Japanese Freshwater Algae, 1977).

Geminella ellipsoidea (Prescott) Smith var. ellipsoidea: Linear short filaments, free-floating, covered with a thick gelatinous sheath; cell body elliptic to ovate, 4-6 μm long, 7-9 μm in diam., transversely arranging in groups of 2 or 4 cells; a single chloroplast parietal, band-form, with a pyrenoid (Photomicrographs of the Fresh-water Algae, vol. 4 (1985).

Geminella planctonica Iyengar & Philipose: Thalli unbranched, short filaments clearly constricted at the cross wall, without mucilaginous sheath; cell body elontate cylindrical, 3-5 micron broad at the cross wall, 4-7 micron broad at the mid region of the cell; 8-24 micron long; chloroplasts a single, parietal, usually occupying the entire length of the cell; with 1-2 pyrenoids; (Photomicrog. Freshw. Alg. 13: 21, 1994)