THE GREEN ALGAE OF NORTH AMERICA 



107 



21. Cells So M diam. or less. 

 22. Cells 150-160 /j. diain. ; chromatophores many. 



22. Cells loo-no fj. diam. ; chromatophores 4-8. 



22. Cells 90-100 M diain. ; chromatophores 3-4. 

 23. Cells less than 40 /* diam. 

 23. Cells 50-80 M diam. 



24. Chromatophores 4. 



24. Chromatophores 3, rarely 2 



25. Cells 50-65 fj. diam. 

 25. Cells 70-78 fj. diam. 



26. Spore 60-72 M diam. 



26. Spore about 50 M diam. 

 27. ' Chromatophore single. 

 27. Chromatophores two or more. 



28. Spore membrane punctate. 



28. Spore membrane smooth. 

 29. Fertile cells little if any swollen. 

 29. Fertile cells distinctly swollen. 



30. Filaments 9-23 M diam. 



30. Filaments 24-33 I* diam. 

 31. Inflation cylindrical. 

 31. Inflation rounded or tapering at the ends. 



32. Cells 9-12 fj. diam. ; 4-15 times as long. 



32. Cells 15-18 M diam. ; 3-8 times as long. 



32. Cells 18-21 /u diam. ; 10-25 times as long. 

 33. Cells 24-30 /y. diam. 



23- 



17. S. crassa. 

 13. S. setifornris. 

 12. S. jug a Us. 

 24. 

 25. 



24. S. fluviatilis. 

 plant of brackish water. 

 10. .*>. decimina var. submarina. 

 23. S. ternata. 

 26. 



ii. 5. nitida. 

 14. S. parvispora. 

 '28. 



34- 

 37. S. protecta. 



32. S. 



29. 



Weberi. 

 30. 



33- 

 34. S. groenlandica. 



32. 



28. S. tenuissima. 

 29. S. inflata. 

 30. S. Spreeiana. 

 fertile cells quadrately swollen. 



31. S. quadrata. 

 33. Cells 28-33 /* diam. ; fertile cells somewhat rounded. 



33. 5". Grevilleana. 



34. Cells 30-33 p. diam. ; chromatophores broad. 35. S. Hassallii. 

 34. Cells 39-42 /u diam. ; chromatophores slender. 36. S. insignis. 



Subgenus EUSPIROGYRA ; conjugation by means of a tube. 



Section CONJUGATA ; dissepiments plane. 



Subsection DIPLOZYGA ; each cell emitting a tube. 



i. S. LONGATA (Vauch.) Kiitzing, 1843, P- 2 79 ; Petit, 

 1880, p. 20, PL V, figs. 4 & 5; Wolle, 1887, p. 214, PI. 

 CXXXV, figs. 9 & 10 ; P. B.-A., No. 510. Filaments 20-36^ 

 diam., cells 2-10 diam. long, chromatophore single, broad, 

 bright green, making 2-5 turns in the cell; fertile cells not 

 swollen ; spores broadly ovoid with rounded ends, pale yellow 

 at maturity, twice as long as broad, entirely filling the width of 

 the cell. Mass., R. I., N. J., Colorado. Europe, So. America. 



The perfectly cylindrical form of the fertile cells, barely large 



