226 



TUFTS COLLEGE STUDIES, VOL. II, No. 3 



, Membrane of oospore smooth. 



Membrane of oospore pitted. 



Membrane of oospore spinous. 

 6. Monoecious. 

 6. Dioecious. 



Pore slightly above the middle. 



Pore almost superior. 

 8. Monoecious. 

 8. Dioecious. 



Oogonia subglobose or subdepressed-globose. 



Oogonia subglobose or subellipsoid-globose. 

 10. Monoecious. 

 Dioecious. 



10. 



8. 



ii. Oogonia manifestly swollen, 

 ii. Oogonia little if any swollen. 



12. Membrane of oospore smooth. 



12. Membrane of oospore pitted. 

 13. Monoecious. 

 13. Dioecious. 



14. Vegetative cells 12-17 // diam. 



14. Vegetative cells 20-30 /x. diam. 

 15. Monoecious. 

 15. Dioecious. 



16. Oogonia K to ^ wider than vegetative cells. 



IS- 



16. Oogonia scarcely wider than vegetative cells. 



3. Oe. Magnusii. 

 4. Oe. sue cic inn. 

 Oe. cryptoporum. 

 2. Oe. rufescens. 



7. Oe. cardiaciim. 



5. Oe. obsoletmn. 



6. Oe. plusiospormn. 



9. Oe. varians. 

 Oe. franklin ian u in . 



12. 



IS- 



13- 



13. Oe.foveolattun. 

 14. 

 ;. Oe. plagiostomum. 



10. Oe. fragile. 

 n. Oe. Vaucherii. 



14. Oe. geniculatiim. 

 16. 



Oe. capillifortne . 



16. 



17. Oogonia manifestly swollen. 

 17. Oogonia little if any swollen. 



18. Membrane of oospore smooth. 



18. Membrane of oospore ribbed or pitted 

 19. Monoecious. 

 19. Dioecious. 



20. Division of antheridial cell vertical. 



20. Division of antheridial cell horizontal 

 21. Membrane of oospore ribbed. 

 21. Membrane of oospore areolate or pitted. 



22. Ribs continuous and entire. 



22. Ribs not continuous and entire. 

 23. Monoecious. 

 23. Dioecious. 



24. Ribs composed of elongate dots. 



24. Ribs distinctly dentate. 



Oe. capillare. 

 18. 

 27. 

 19. 



21. 

 2O. 



19. Oe. rivularc. 

 17. Oe. upsaliense. 

 18. Oe. Richterianmii. 

 22. 

 25- 

 23- 

 24. 



20. Oe. paludosmn. 

 21. Oe. Boscii. 

 22. Oe. margaritiferuin. 

 23. Oe. crenulato-costaiuni. 



25. Membrane of oospore areolate. 



23. Oe. crenulato-costatum var. aureum. 

 25. Membrane of oospore pitted. 26. 



