20 ZYGNEMATACEAE 



32. Diameter vegetative cells 24-30 /a, 



pits 2 diameters apart 5i- ^- subcrticiatum 



33. Median wall pits 2-4/' in diameter 34 



33. Median wall pits more than 4 /a in diameter 36 



34. Receptive gametangia nearly cylin- 



dric 49. Z. vaucherii 



34. Receptive gametangia greatly en- 

 larged 45- '^- substellinum 



34. Receptive gametangia enlarged on conjugating side 35 



35. Diameter vegetative cells 18-24/A 42. Z.tenue 



35. Diameter vegetative cells 24-28 /a 50. Z. normani 



35. Diameter vegetative cells 28-38 /a 59- '^- stellinum 



36. Vegetative cells less than 24 /j. in diameter 37 



36. Vegetative cells more than 24 /a in diameter 38 



37. Diameter median wall pits 4.5-6/^..... 40. Z.extenue 

 37. Diameter median wall pits 7-9 /^ 44. Z. hausmannii 



38. Receptive gametangia inflated in- 

 ner side 51. Z. insignisporum 



38. Receptive gametangia globosely in- 

 flated 54. Z. germanicum 



38. Receptive gametangia nearly cylin- 



dric 56. Z. janicum 



38. Receptive gametangia enlarged ... 57. Z. subfanicum 



39. Median spore wall verrucose 52. Z. vaginatum 



39. Median spore wall with raised prom- 

 inences 41. Z. tholosporum 



39. Median spore wall double, inner layer 



verrucose 47- -^^ flavum 



40. Diameter vegetative cells 30-40;^ 41 



40. Diameter vegetative cells 40-50 /a. . 65. Z.neocruciatum 

 40. Diameter vegetative cells 50-60 ju.. . 66. Z.crassitisculum 



41. Median spore wall scrobiculate or pitted 42 



41. Median spore wall verrucose and wavy 62. Z.bohemicum 

 41. Median spore wall of 2 layers, inner 



reticulate -verrucose, outer thick, 



smooth 6t,. Z. mirandum 



42. Median wall with pits less than 4/^ in diameter 43 



42. Median wall with pits more than 4/x in diameter 44 



43. Spores usually globose, diameter pits 



3-4M 59. Z. stellinum 



