THE GREEN ALGAE OF NORTH AMERICA 



61 



60. Antheridium exterior. 



60. Antheridium interior. 

 61. Oogonium opening by a pore. 

 61. Oogonium opening by a lid. 



62. Oospore globose. 



62. Oospore ellipsoid. 

 63. Pore median or slightly above. 

 63. Pore superior. 

 63. Pore inferior. 



64. Membrane of oospore smooth. 



64. Membrane of oospore spinous or ribbed. 

 65. Oogonium 30-37 n diam, 

 65. Oogonium 49-53 /* diam. 



66. Membrane of oospore ribbed. 



66. Membrane of oospore spinous. 

 67. Oogonium subdepressed-globose. 

 67. Oogonium subglobose to ellipsoid. 46. 



68. Membrane of oospore smooth. 



68. Membrane of oospore spinous. 

 69. Oogonium solitary. 

 69. Oogonia usually seriate. 



70. Spines without order. 



70. Spines arranged spirally. 

 71. Spines scanty ; oogonium subglobose. 



61. 

 84. 

 62. 

 77- 

 63- 

 73- 

 64. 

 68. 

 52. Oe. Huntii. 



65- 

 66. 



43. Oe. Braunii. 

 44. Oe. flavescens. 

 82. Oe. illinoisense. 

 67. 



45. Oe.pungens. 

 Oe. echinospermum. 

 69. 

 70. 



47. Oe. irregulare. 

 59. Oe. multisporum. 



48. 



53. 



72. 



Oe. armigerum. 



71. Spines dense ; oogonium depressed-globose. 49. Oe. echinatum. 

 72. Oogonium 51-64 /j. diam. ; veg. cells 15-35 n diam. 



50. Oe. stellatum. 

 72. Oogonium 63-78 M diam. ; veg. cells 42-59 M diam. 



51. Oe. Donne llii. 

 73. Pore median or slightly higher. 



73. Pore superior. 



74. Membrane of oospore smooth. 



74. Membrane of oospore spinous. 

 75. Membrane of oospore smooth. 

 75. Membrane of oospore ribbed. 

 75. Membrane of oospore pitted. 



76. Suffultory cell not swollen. 



76. Suffultory cell swollen. 

 77. Oospore globose. 

 77. Oospore ellipsoid. 



78. Division median. 



78. Division superior. 

 79. Suffultory cell distinctly swollen. 

 79. Suffultory cell not swollen. 



80. Terminal cell apiculate or setaceous. 



80. Terminal cell obtuse. 



74- 

 75- 



Oe. sexangulare. 

 54. Oe. Hystrix. 

 76. 



57. Or. Wollcanum. 



58. Oe. concatenatum. 



55. Oe. crassiusctdum. 



56. Oe. Borisianum. 



78. 



82. 



83. Oe. macrosporum. 



79- 



593. Oe. inonile. 

 80. 



84. Oe. praticolum. 

 81. 



