THE GREEN ALGAE OF NORTH AMERICA i 



38. Spore compressed oval. 17. S. crassa. 



38. Spore compressed ellipsoid ; ends pointed in edge view. 



46. 5". ellipsospora var. crassoidea. 



39. Spore compressed. 17. 5. crassa var. formosa. 



39. Spore not compressed. 40. 



40. Cells loo-no n diatn. ; chromatophores 4-8. 13. S. setiformis. 



40. Cells 90-100 /* diam. ; chromatophores 3-4. 12. S.jugalis. 



41. Cells less than 40 yu diam. 42. 



41. Cells 50-80 At diam. 43. 



42. Chromatophores four. 24. 5". fluviatilis. 



42. Chromatophores 3, rarely 2 ; of brackish water. 



10. S. submarina. 



43. Spore punctate or scrobiculate. 44. 



43. Spore smooth. 45. 



44. 3 chromatophores, making half to one turn. 48. S. propia. 



44. 3-5 chromatophores, making two and a half to four turns. 



49. S. novae-angliae. 



45. Cells 50-65 a diam. 23. S. neglecta. 



45. Cells 70-78 M diam. 46. 



46. Spore 60-72 M diam. 47. 



46. Spore about 50 /u. diam. 14. S. parvispora. 



47. Spore verrucose, ovoid. 44. S. dilula. 



47. Spore smooth, ellipsoid and tapering. n. .S. nitida. 



48. Replicate and plain walls about equal in number. 



6 r. S. fallax. 



48. Plain walls rare and exceptional. 49. 



49. Replication an entire ring. 50. 



49. Replication forming half a ring. 51. S. narcissana. 



50. Chrouiatophore single, rarely two. 52.- 



50. Chromatophores two or more. 51. 



51. Membrane reticulate. 59. S. reticulata. 



51. Membrane smooth. 64. 



52. Membrane punctate or areolate. 53. 



52. Membrane smooth. 57. 



53. Cells 30 M diam. or more. 54. 



53. Cells 24 M diam. or less. 55. 



54. Membrane areolate. 60. 5. areolata. 



54. Membrane punctate. 37. S. protecta. 



55. Chromatophores slender; cells 12 n diam. or less. 



28. 5". tenuissitna var. rugosa. 

 55. Chromatophores broad ; cells 15 M diam. or more. 56. 



56. Cells 15-18 A* diam. ; spores scrobiculate. 



29. S. inflata v&r.foveolata. 



56. Cells 22-24 ** diam. ; spores punctate or granulate. 



43. S. Goetzii. 



