THE GREEN ALGAE OF NORTH AMERICA 227 



26. Oogonia 38-48 /u cliam. 25. Oe. pitiictatmit. 



26. Oogonia 70-83 M diam. 24. Oe. taphrosporuin. 



27. Membrane of oospore smooth. 28. 



27. Membrane of oospore pitted. 70. Oe, giganteum. 



28. Monoecious. 26. Oe. martinicense . 



28. Dioecious. 29. 



29. Oogonia 63-75 /u, diarn. 27. Oe. Landsboroughii. 



29. Oogonia 65 /u diam. or less. 30. 



30. Vegetative cells 3-9 diam. long. 31. 



30. Vegetative cells i % -3 diam. long. 31. Oe. mexicanuni. 



31. Oogonia oboviforrn. 28. Oe. oboviforme. 



31. Oogonia suboboviform to oboviform-ellipsoid. 32. 



32. Male plants stouter than female. 29. Oe. pachyandriinn. 



32. Male plants more slender than female. 30. Oe. grande. 



33. Oospores globose. 34. 



33. Oospores ellipsoid. 42. 



34. Division of oogonium median. 35. 



34. Division of oogonium superior. 36. 



35. Cells with spiral markings. 32. Oe. punctato-striatum. 



35. Cells with walls plain. 33. Oe. Howardii. 



36. Monoecious. 37. 



36. Dioecious. 38. Oe. Pringsheimii. 



37. Vegetative cells with three nodulose swellings. 



41. Oe. nodulosum. 

 37. Vegetative cells cylindrical. 38. 



38. Oogonium when inature pyriform or subpyriform. 39. 



38. Oogonium when mature oboviform-globose to subglobose. 40. 

 39. Oogonium 26-30 /j. diam. 34. Oe. Pithophorae. 



39. Oogonium 40-45 M diam. 71. Oe. pyriforme. 



40. Oogonia distinctly swollen. 41. 



40. Oogonia little swollen. 37. Oe. autuntnale. 



41. Vegetative cells 15 /x diam. or less. 35. 'Oe. crispum. 



41. Vegetative cells 16 M diam. or more. 36. Oe. obe 'sum. 



42. Membrane of oospore smooth. 43. 



42. Membrane of oospore ribbed. 42. Oe. nobile. 



43. Oogonia oblong-ellipsoid or ellipsoid. 44. 



43. Oogonia pyriform. 72. Oe. sanctae thomae. 



44. Vegetative cells 3-7 M diam. 40. Oe. gracillimum. 



44. Vegetative cells 10-18 M diam. 39. Oe. Ahlstrandii. 



45. Dwarf males pluricellular. 46. 



45. Dwarf males unicellular. 66. 



46. Antheridium exterior. 47. 



46. Antheridium interior. 64. 



47. Oogonium opening by a pore. 48.. 



47. Oogonium opening by a lid. 62. 



