Lyngbya Hieronymusii Lemmermann 1905, p. 146 

 PI. 112, Fig. 4 



Plants solitary, scattered among other algae or in littoral plankton. 

 Trichomes straight and not tapering at the apices, which are broadly 

 convex; 11-13/i, in diameter. Cells 1/5-^/3 ^s long as wide (2.7-4/x 

 long); usually with pseudovacuoles; not constricted at the cross 

 walls, which are granular. Sheath rather thick, but homogeneous, 

 not lamellose. Filaments (12)-14-19/i, wide. 



This species should be compared with L. major Menegh. and L. 

 Birgei G. M. Smith. From the former it differs in the convex, non- 

 tapering apices, the homogeneous sheaths, and its failure to form 

 agglutinated masses. From the latter species it differs in size and in 

 its possession of granular cross walls. 



Tychoplankter. Mich., Wis. 



Lyngbya Lagerheimia ( Moebius ) Gomont 1890, p. 354 



PI. 112, Figs. 5, 6 

 Plants solitary or somewhat entangled, bent and twisted, some- 

 times spiral; trichomes not at all or but very slightly tapering toward 

 the apices, which are broadly conical or convex; cells 2.2-3/x in 

 diameter, 1.5-2.8/x long; cell contents coarsely granular; sheaths 

 thin; filaments 2-2.5/x wide. 



Among other algae in shallow water of lakes and in roadside 

 ponds. Mich., Wis. 



Lyngbya latissima Prescott 1944, p. 372 

 PI. 112, Fig. 9 



Plants solitary, planktonic, entangled among other floating algae; 

 trichomes straight, not tapering toward the apices; cells disc-like, 

 with contents finely and evenly granular (sometimes with coarse 

 granules in old plants), 37-40.7/a in diameter, 3.7-7. 4;u, long; sheaths 

 thick, 3.7-5/A wide, lamellated, with outer layers wrinkled and 

 roughened in age; filaments 44-58^^ in diameter. 



This species, found in but two habitats, may be a planktonic and 

 unbranched expression of Plectonenia Wollei. The plants described 

 by Prescott (1944, p. 372) are about the same diameter as this 

 large species of Plectonenia, and they have some of the same sheath 

 characteristics. The filaments are entirely unbranched and solitary, 

 however, whereas Plectonema Wollei is branched (although infre- 

 quently) and occurs in woolly mats. Lyngbya latissima should be com- 

 pared also with Oscillatoria princeps when the latter is in a hor- 

 mogonous condition and inclosed by a sheath. The sheath is not 

 thick and lamellated as in our plant, nor are the trichomes so long. 



[501] 



