L. gigantea Lewis, Zirkle, and Patrick (1933), referred by Drouet 

 (1938) to Oscillatoria princeps, differs in having thin smooth 

 sheaths characteristic of the hormogonial phase of the latter. Our 

 specimens are not at all tapering at the apices, and the contents of 

 the cells are granular. 



Lyngbija Hummellii Borge (1934), a large species, differs from 

 L. latissima in its smaller size (37/*, maximum width) and in the 

 longer cells (6-11/i,). Also the sheath of Borge's species is thinner 

 and apparently not lamellated as in our specimens. 



Euplanktonic and tychoplanktonic. Wis. 



Lyngbya limnetica Lemmermann 1898d, p. 154 

 PI. 112, Fig. 7 



Plants straight, solitary, planktonic; trichomes l-2-(2.5)/x in 

 diameter, not tapering at the apices; cells 6-12//, long, not con- 

 stricted at the cross walls; cell contents coarsely granular; sheaths 

 thin and colorless; filaments 2-2.2fx wide. 



Euplankter. Wis. 



Lyngbya major Meneghini 1837, p. 12 

 PI 112, Fig. 10 



Plants solitary among other algae, or somewhat gregarious, but 

 not forming expansions or plant masses; filaments straight; tri- 

 chomes not or but very slightly tapering to the apices, which are 

 indistinctly capitate in older plants, ll-17ju, in diameter; cells %- 

 1/4 as long as wide, (2)— 3.5— 4u, in length, not constricted at the 

 cross walls, which are definitely granulose; cell contents homogen- 

 eously granular; sheaths thick (3-3.7ju,), firm, and usually lamellated, 

 becoming roughened in age; filament 22-26/* in diameter. 



Caught about Utricularia and other vegetation; widely distributed 

 in a variety of lakes, mostly hard water; tychoplanktonic. Mich., Wis. 



Lyngbya Martensiana Meneghini 1837, p. 23 

 PL 112, Fig. 11 



Plants much entangled and interwoven to form an expanded, 

 dark blue-green mass; trichomes 6— 10— (12)/* in diameter, not 

 tapering toward the apices, which are broadly convex; cells about 

 1/4 as long as wide, 2.5— 2.8/x long, not constricted at the cross 

 walls, contents homogeneous except for 1 or 2 conspicuous gran- 

 ules at the cross walls; sheaths firm, moderately thick (1.5—2/*); 

 filaments mostly 6—10/* (up to 14/*) in diameter. 



This plant is assigned here on the basis of size, lack of constric- 

 tions at the cross walls, and the tendency to form plant masses. It 



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