is similar to L. putealis Montagne, but that species has trichomes 

 constricted at the cross walls. Our specimens should be compared 

 also with L. major. 



Rare; in tychoplankton. Mich., Wis. 



Lynghya Nordgaardii Wille 1918, p. 32 

 [Lyngbya epiphytica Wille 1913, p. 25] 

 PI. 113, Figs. 1, 2 

 Plants solitary or forming minute patches on the. walls of larger 

 filamentous algae {Oedogonium, Rhizoclonium) , curved and vermi- 

 form, sometimes recurved from a basal attachment; trichomes gray- 

 green, not tapering at the apices, 1.2-2/t in diameter, about as long 

 as wide or a little shorter; sheaths very thin and transparent. 



On Drepanocladus from a depth of 35 feet; on filamentous algae, 

 and in tychoplankton. Wis. 



Lyngbya purpurea (Hook. & Harvey) Gomont 1892, p. 49 

 Plant mass highly mucilaginous, purphsh red; trichomes some- 

 times scattered among other algae, curved and flexuous, not con- 

 stricted at the cross walls, 1.4-1.8/x in diameter; sheath thin and 

 transparent, not stained blue by chlor-zinc-iodide; cells quadrate. 

 Mich. 



Lyngbya spirulinoides Gomont 1890, p. 355; 1892a, p. 146 



PI. 131, Fig. 1 



Plant mass planktonic, olive-green; filaments entangled, loosely 

 spiralled through most of their length (or all of it), rarely straight; 

 cells light blue-green, with homogeneous or slightly granular con- 

 tents; sheaths thin and homogeneous, sticky and colorless; trichomes 

 14-16/t in diameter, not constricted at the cross walls nor tapering 

 toward the apices; apical cell broadly rounded, not capitate, and 

 without a calyptra; cells 3.4-6.8/a long. 



Tychoplankter. Wis. 



Lyngbya Taylorii Drouet & Strickland in Strickland 1940, p. 631 



PI. 113, Fig. 3 



Plants forming tufts of parallel but flexuous filaments on sub- 

 merged substrates, or floating free. Trichomes not tapering toward 

 the apices; very httle or not at all constricted at the cross walls; 

 4-7iM in diameter. Terminal cell broadly convex. Cells quadrate, 

 about as long as wide or a little shorter; cell contents granular. 

 Sheaths thin and colorless; filaments long, 6-9/x in diameter. 



Forming a bright blue-green film on mud; tychoplankter. Wis. 



[503] 



