9. Filaments 11-16^ in diameter 10 



9. Filaments smaller 11 



10. Trichomes 11-13/u, in diameter, 



usually with pseudovacuoles L. Hieronymusii 



10. Trichomes 14-16;U in diameter, without pseudovacuoles L. spirulinoides 



11. Plant mass purple or purple-red L. purpurea 



11. Plants solitary, blue-green L. Umnetica 



12. Plant mass purplish or purple-red L. purpurea 



12. Plant mass gray- or blue-green... --. 13 



13. Filaments small, 1-4- (rarely ^)ix in diameter 14 



13. Filaments 5-20^i in diameter 16 



14. Plants forming a layer of much entangled 



filaments (See also L. Diguetii below)..... L. versicolor 



14. Plants not forming a definite mass or layer; 



solitary or gregarious; epiphytic 15 



15. Filaments 1.2-2/i in diameter, lying prostrate along the host plant 

 for much of their length and then curved away to form a free 



apical portion; cells usually quadrate or shorter than wide .... L. Nordgaardii 



15. Filaments 2-3. 2m in diameter, arising directly from the host plant, 

 with little of their length prostrate; cells usually longer than wide; 

 filaments sometimes forming a plant mass, usually on Rhizoclonium 

 or Cladophora, or other filamentous algae which do not have a 

 mucilaginous outer wall layer L- Diguetii 



16. Filaments 10-20m in diameter 1" 



16. Filaments S-lO^t in diameter 18 



17. Filaments mostly straight; apical cell with a thickened outer _ 

 membrane; trichomes 11-17^ in diameter L. major 



17. Filaments much entangled; apical cell without a thickened outer 

 membrane; trichomes variable, (8)-10-20-(24)m in diameter. L. aestuarii 



18. Filaments lying parallel, forming tufts - -L. Taylorii 



18. Filaments not lying parallel and not forming definite tufts 19 



19. Trichomes small 2.8-3.4^ in diameter; filaments up to 5^ wide; 

 sheaths thick (2^); cells usually distinctly longer than wide .... L. versicolor 



19. Trichomes larger; cells shorter, 1.7-3.3|U long 20 



20. Filaments 6-1 Om in diameter; apical cell 



rotund; sheaths thick L. Martensiana 



20. Filaments 4-6^ in diameter; apical cell conical, usually capitate, 



with a thickened outer membrane - L. aerugineo-caerulea 



Lyngbya aerugineo-caerulea ( Kuetz. ) Gomont 1892a, p. 146 



PI. Ill, Figs. 10, 11 

 Plants aggregated, forming masses of curved and loosely entangled 

 filaments among other algae, or expansions on submerged substrates 

 ( solitary filaments frequently found scattered among other plants ) ; 

 filaments (4)-6-(7.5)/x in diameter; trichomes 4-7 fj. in diameter; 

 cells varying in length from a little less to longer than the width, 

 2.7-1.8fji long, not at all or but very little constricted at the cross 

 walls; apices of trichomes straight, with cone-shaped or shghtly 

 capitate terminal cells. Sheaths firm, thin, sometimes with regularly 



[498] 



