456 University of California Fiiblications in Botany [Vol. 8 



7. Gametangia up to 40/x long 6. M. foecundum f. simplicissimum (p. 461) 



7. Gametangia over 40^ long 8 



8. Gametangia up to 65/x long and 6m broad 1. M. primarium (p. 456) 



8. Gametangia 80m long and 8m broad 9. M. foecundum f. majus (p. 463) 



9. All of the erect filaments fructiferous 10 



9. Part of the erect filaments fructiferous 12 



10. Gametangia up to 130m long 12. M. balticum f. californicum (p. 465) 



10. Gametangia up to 45m long 11 



11, Pedicels 1-3-celled 3. M. corunnae f. uniforme (p. 458) 



11, Pedicels up to 8-celled 11. M. minutissima (p. 464) 



12. Sterile filaments longer than the gametangia 13 



12. Sterile filaments not longer than the gametangia 20 



13. Gametangia all terminal 14 



13. Gametangia in part lateral on sterile filaments 19. M. setiferum (p. 470) 



14. Sterile filaments partially setiferous 15 



14. Sterile filaments not setiferous 16 



15. Erect filaments unbranched 18. M. phyllophilum (p. 469) 



15. Erect filaments branched 20. M. globosum f. alfine (p. 471) 



16. Gametangia decidedly acuminate 



2. M. primarium f. acuminatum (p. 457) 



16. Gametangia cylindrical or nearly so 17 



17. Cells of sterile filaments doliiform 17. M. attenuatum f. doliiforme (p. 468) 



17. Cells of sterile filaments cylindrical 18 



18. Creeping filaments with short subulate rhizoids ; 



15. M. hecatonematoides (p. 467) 



18. Creeping filaments without rhizoids 19 



19. Gametangia up to 45m long 16. M. attenuatum (p. 468) 



19. Gametangia up to 150m long 13. M. balticum f. pedicellatum (p. 466) 



20. Erect filaments up to 65m high 5. M. corunnae f. sterile (p. 460) 



20. Erect filaments over 65m high 21 



21. Gametangia on 1-3-celled pedicels 14. M. compsonematoides (p. 467) 



21. Gametangia on long pedicels, 7-10-celled.. .4. M. corunnae f. angulatum (p., 459) 



1. Myrionema primarium S. and G. 



Plate 55, fig. 12 



Fronds forming circular cushions 0.5-1.25 mm. diam. ; prostrate 

 portion composed of regularly radiating, closely compacted filaments ; 

 erect filaments unbranched, densely crowded, arising from every cell 

 of the creeping filaments; true hair filaments numerous, scattered 

 promiscuously in the center of the frond ; cells of erect filaments 4-4.5/j. 

 diam., quadrate below, terminal cell, 2-3 times as long when young ; 

 cells of true hairs 4-5/i, diam., 4-6 times as long; zoosporangia 

 unknown ; gametangia sessile on the creeping filaments, arising by 

 transformation of all of each erect filament, except at the margin, very 

 compact, of nearly equal length in the center of the frond, shorter 

 toward the margin, cylindrical, 55-65/i, long, 5-6ju, broad, blunt or 

 tapering slightly at the apices, terminal cell acute-conical. 



