Plate VI. 
Fig. 1a.—Sirogonium sticticum, Kutz. Sterile cells, x 200. 
Figs. 1b, 1c, 1d, 1e—Sirogonium stictioum, Kutz. Conjugating cells, * 200 
Fig. 1f.—Sirogonium sticticum, Kutz. Zygospore, x 400. 
(In text, page 10, S. strictum should be as above. 
