rLOSTKIMTM. 1 1 ] 



tt Cell-wall striated. 



7. Cl. 



8. Cl. COSliif >!;,/. 



9. 67. rt'yitfiire. 



10. 67. striolatum. 



11. CL intermedium. 



12. 67. Ulna. 



13. CL j a n ci<l n in. 



SECTION B. Cells without a median girdle, the adult condition 

 being attained on the growth to maturity of the younger semicells. 

 ' Cells strongly curved, lunate. 

 t Cell- wall smooth. 



a. Ventral margin not distinctly tumid. 



14. CL Dianx. 



15. Cl. Pseudodidnse. 



16. Cl. parvulum. 



17. CL Jenneri. 



18. CL iiiciirrnni. 



19. CL Venus. 



20. Cl. calosporum. 



21. CL eboracense. 

 /3. Ventral margin distinctly tuniid. 



* 22. Cl. Leibleinli. 



23. Cl. moniliferum. 



24. CL Ekrenbergii. 

 ft Cell-wall striated. Ventral margin distinctly tumid. 



25. CL Malinvernianum. 

 ' Cells slightly curved, ventral margin almost straight or 



slightly concave. 

 t Cell-wall smooth. 



tt. Cells lanceolate, gradually attenuated to the 'p >l (> s, 

 which are usually subacute. 



26. CL a'^roKimi. 



27. CL lanceolatum. 



28. Cl.Lunula. 

 J9. CL sigmoideum. 

 30. CL SUigua. 



ol. 67. peraet'f'.t't'ni. 



32. CL littoral,.: 



33. CL tumid it in. 



34. CL Cormt. 



{3. Cells lanceolate, slightly attenuated to the poles, 

 Avhich are obtuse or truncate. 

 + Poles truncate. 



35. CL abrtip 



36. 67. toxon. 



