14. Conjugating tubes arising only or mostly from the male cell 15 



14. Conjugating tubes arising from both cells; or conjugation 

 ocurring by geniculate bending of the filaments 



without tubes being formed 17 



15. Vegetative cells 15-24m in diameter S. Collinm 



15. Vegetative cells larger 16 



16. Median spore wall punctate; spore 37-42/i in diameter S. micropunctata 



16. Median spore wall smooth; spore 44-54/x in diameter S. refbxa 



17. Median spore wall smooth 21 



17. Median spore wall decorated 18 



18. Vegetative cells 11-14^ in diameter S. porangabae 



18. Vegetative cells larger 19 



19. Median spore wall scrobiculate S. scrobiculata 



19. Median spore wall reticulate 20 



20. Spore ovate, 43-46/x in diameter S. sulcata 



20. Spore ellipsoid, 35-44m in diameter . -.. - . S. daedaleoides 



21. Spores varied in shape, ovate, ellipsoid, or irregular when seen 



from the same angle; 24-36m in diameter „ S. pratensis 



21. Spores uniform in shape when seen from the same angle 22 



22. Vegetative cells less than 15^1 in diameter — - S. flavescens 



22. Vegetative cells more than ISfj. in diameter 23 



23. Spores ovate "4 



23. Spores eUipsoid 28 



24. Spores 18-20-(35)m in diameter; vegetative cells 



26-28^ in diameter S. subsalsa 



24. Spores larger; vegetative cells mostly larger 25 



25. Spores 38-50^ in diameter - — - S. porticalis 



25. Spores smaller, (28)-33-38-(39)m in diameter 26 



26. Vegetative cells 24-26/i in diameter; spores 



24-29m in diameter _ .. S. miraoilis 



26. Vegetative cells and spores larger -27 



27. Fertile cells cyhndric S. longata 



27. Fertile cells inflated on both sides.. S. suecica 



28. Sporangia cylindric ( rarely slightly enlarged by 



the spore but not inflated) -- .- -- - -- — - 29 



28. Sporangia inflated on one or both sides 3_ 



29. Vegetative cells 48-62/x in diameter S. condensata 



29. Vegetative cells smaller 30 



30. Vegetative cells 18-26/i in diameter, relatively stout, up to 90m 



long; spores 28-33^^ in diameter S. communis 



30. Vegetative cells greater in diameter, but relatively 



more slender; up to 240m long 31 



31. Vegetative cells 24-30m in diameter, up to 125m 



long; spores 28-33m in diameter S. Juergensii 



31. Vegetative cells a\'eraging larger, 28-36-39m in diameter, up to 



246m long; spores 27-37m in diameter S. singularis 



32. Vegetative cells 40-50m in diameter S. circumlineata 



32. Vegetative cells smaller 33 



33. Vegetative cells 16-24m in diameter S. gracilis 



33. Vegetative cells larger 34 



34. Sporangia (female cell) inflated on both sides 37 



34. Sporangia inflated only on one side. 35 



[309] 



