brown in color; ovate or subglobose; 15.6/* in diameter, 19.5)u, long. 

 Sheaths close and firm; colorless or light olive; not lamellate. Fila- 

 ments 18-23.4/x in diameter. 



All our specimens of this plant have been collected in Sphagnum 

 bogs and soft water lakes. Wis. 



Scytonema crispum ( C. A. Ag. ) Bornet 1889, p. 156 



[S. cincinnatum Thuret] 



PL 124, Figs. 4-6 



Filaments forming dark brown or gray-brown wooly mats; seldom 



branched; coarse and wiry. Trichomes straight or somewhat bent, 



not tapering, frequently constricted and forming hormogonia. Cells 



very short, disc-like; 14-30ju in diameter, 2.4-3;u, long. Heterocysts 



spherical, frequent, olive-green or yellowish, 19/x, in diameter. 



Sheath thick (3.5/i,), firm, brown, not lamellated. Filaments 16-36 



(mostly 20-30;u,) in diameter. 



Frequent in hard water lakes. Forming tangled, brown clots 

 among filamentous algae or submerged aquatics. In sections of the 

 filament which are unbranched and in which no heterocysts occur 

 the plant has the appearance of a coarse Lyngbya. Wis. 



Scytonema mirabile ( Dillw. ) Bornet 1889, p. 155 



[S. figuratum C. A. Agardh] 



PL 124, Figs. 7, 8 



Filaments forming brown or dark green wooly tufts, either aquatic 

 or terrestrial. Trichomes with long, infrequent branches usually 

 arising singly either at the heterocysts or between heterocysts. Cells 

 quadrate in the main filaments, cylindrical in the branches; 6-12ju, 

 in diameter, 8-1 4/a long. Heterocysts quadrate-globose to cylindric; 

 about the same size as the vegetative cells. Sheaths thin and close 

 in the branches, thick and wi^ diverging lamellations in the main 

 filaments. Filaments 15-20)u, in diameter. 



One of the most common species of Scytonema found in our 

 region. It occurs in both soft and hard water lakes. Many times 

 the plants have the appearance of a Tolypothrix, especially in the 

 habit of branching. 



Mich., Wis. 



Scytonema myochrous ( Dillw. ) C. A. Agardh 1812, p. 38 

 PL 124, Fig. 9; PL 125, Figs. 1, 2 

 Filaments forming dark brovm turfy or tomentose patches. Tri- 

 chomes long and flexuous in wide sheaths. Cells quadrate to cylin- 

 dric in the older portions, disc-shaped or compressed-globose in the 



[535] 



