Thalli colonial, forming 4-celled, square coenobia mostly, these sometimes up to 16-celled in compound coenobia; colonies flat, plate-like, embedded in structureless, gelatinous envelope. The coenobia are with long axes of cells in surface view. Cells oval to lunate to triangular, fitting tightly together along adjoining walls and leaving small to conspicuous square, empty space in center. Cell walls smooth. Cells uninucleate; single chloroplast cup-shaped and parietal, with or without pyrenoid.

Planktonic in variety of freshwater ecosystems including rivers and lakes, mostly in eutrophic conditions; genus essentially cosmopolitan except in polar and subpolar regions.

AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 07 November 2011, Guiry M.D. in Guiry M.D. & Guiry G.M., 2011,

Mémoire sur un végétal microscopique d'un nouveau genre, proposé sous le nom de Crucigénie, et sur un instrument que l'auteur nomme Microsoter, ou conservateur des petites choses., Annales des Sciences Naturelles 20:, Morren C.F.-A., 1830, 204-226

Das Phytoplankton des Susswassers: Systematik und Biologie 7.T., Halfte. Chlorophyceae (Grunalgen), Ordnung: Chlorococcales / von J. Komarek, B. Fott., Stuttgart : E. Schweizerbart'sche Verlagsbuchhandlung, Huber-Pestalozzi G., 1983, 1044

Checklist of Baltic Sea Phytoplankton Species. Baltic Sea Environment Proceedings No. 95, Helsinki Commission Baltic Marine Environment Protection Commission, Hällfors G., 2004,