PLATE VI. [PAGE 84.] 

 FRESHWATER 



Fig. 



1. Oscillatoria aittumnalis. 



2. Oscillatoria nigra. 



3. Coscinodiscus radiatus. 



4. Nostoc minutissimum. 



5. Actinocyclus undulatus. 



6. Bacterium. 



7. Rhabdonema arcuatum. 



8. Rhabdonema arcuatum, prepared 



frustules. 



9. Melosira nummuloides. 



10. Melosira nummuloides, prepared 



frustules. 



11. a, b, Oonium pectorale : 11 c. Go- 



nimn tranquittum. 



12. Spirulina oscillarioides. 



13. Synura volvox. 



14. Synura volvox. 



16. Gyrosigma attenuatum, front view. 



Fig. 



16. Gyrosigma attenuatum, side view ; 



16 a, portion of a valve. 



17. Gyrosigma angulatum ; 17 a, por- 



tion of a valve. 



18. Volvox globator. 



19. Glozocapsa. 



20. Chara vulgaris, globule. 



21. Chara vulgaris, portion of fila- 



ment. 



22. Chara vulgaris, branch with nu- 



cule and globule. 



23. Tabellariajlocculosa. 



24. Tdbellaria flocculosa, prepared 



frustules. 



25. Palmella cruenta. 



26. Vaucheria Ungeri (sessilis). 



27. Vaucheria Ungeri, capsule. 



