Plate XI. 
Figs. 1a, 1b, le, 1d.—Staurastrum gracile, Ralfs. 
Figs. 2a, 2b, 2c.—Staurastrum paradoxum, Mey. 
Figs. 3a, 3b.—Staurastrum sexangulare, Lund. 
Figs. 4a, 4b, 4c, 4d, 4e.—Staurastruam pygmum. 
