(Vol. 10, 1923 



422 ANNALS OF THE MISSOtTRI BOTANICAL GARDEN 



Description of Plate 



PLATE 21 



Fig. 1. Rhabdoderma sigmoidca sp. nov. X 570. 



Fig. 2. Rh. sigmoidea forma minor X 570. 



Fig. 3. Staurastrum gracile Ralfs forma X 335. 



Fig. 4. St. paradoxum Meyen var. evolutum West X 570. 



Fig. 5. Scenedesmtis quadricauda (Turp.) Br6b. var. bicaudatu* Hansg. X 570. 



Figs. 6-8. Aster ocystis smaragdina (Reinsch) Forti; fig. 6, X 90; figs. 7, 8, X 335 



Fig. 9. Closterium eboracense Turn. X 90. 



Fig. 10. Oscillatoria janthiphora Fiorini-Mazzanti X 570. 



Figs. 11, 12. Anabaena spiroides Klebahn X 570. 



Fig. 13. Tetraedron qxiadricuspidatum (Reinsch) Hansg. X 570. 



Figs. 14-16. Stigeoclonium sp.; fig. 14, X 90; figs. 15, 16, X 570. 



Figs. 17, 18. Anabaena macrospora Klebahn var. crassa Klebahn X 570. 



