Explanation of Plate. 



[FRONTISPIECE.] 



GENERA OF DESMIDS. 



Each Figure is numbered to correspond with the number of the genus. 



FIG. 



1. Gonatozygon. Omitted; the cell needs no figure. 



2. Genicularia. 



3. Hyalotheca. 



4. Bambusina. 



5. Leptozosma. Omitted; the cell needs no figure. 



6. Desmidium. 



7. Phymatodocis. 



8. Sphaerozosma. 



9. Onychonema. 



10. Mesotaenium. 



11. Spirotsenia. 



12. Penium. 



13. Closterium; three figures, showing central inflation and ends 



produced into beaks. 



14. Docidium. 



15. Triploceras; end and part of cell. 



16. Calocylindrus. 



17. Cosmarium. 



1 8. Tetmemorus. 



19. Xanthidium. 



20. Arthrodesmus; 200, front view, <, end.view. 



21. Euastrum. 



22. Micrasterias; five forms. 



23. Staurastrum; four forms; 230, front view, , end. 



24. Pediastrum; three forms. 



; 



