Explanation of Plate I. 



Pag. 



Fig. 1. Caloneis fasciata Lgst. ? 28 



— 2. Navicula cuspidata Ktz. var. lunceolata Grun 30 



— 3. Cymbella gracilis Rabh 29 



— 4. Gowifhonema entolejum 0.st. sp. nov 30 



— 5. Navicula eincta Ehr. var. siamensia Ost var. nov 31 



— 6. Navicula Yarrensis Grun 32 



— 7. Navicula hicontracta Ost. sp. nov 32 



— 8. Pinnularia sp 34 



— 9. Achnanthes ohloncjella Ost. sp. nov 34 



— 10. Achnanthes? (vel Navicula?) 34 



— 11. Achnanthes rostrata Ost sp. nov 35 



— 12. Epithemia Argus (Ehr.) Ktz. var 35 



— 13. Eunotia robnsta Ralfs var. bigibha Ost. var. nov 36 



— 14. Eunotia costata Ost. sp. nov 37 



— 15. Desmogonium Babenhorstianum Grun. var. crassa Ost. var. nov. . 37 



— 16. Synedra Ulna (Nitzsch) Ehr. var ampihirynchus (Ehr.) Grun 38 



— 17. Surirella linearis W. Sm. var. constricta W. Sm.? 38 



— 18. Surirella siamensis Ost. sp. nov 38 



— li). Fragilaria siamensis Ost. sp. nov 39 



All the figures are magnified 6(J0 diameters. 



