CL ADOPHOR A . 125 



cells of the filaments, not terminal, usually more or less 

 turgid. Cells cylindrical or more frequently somewhat 

 swollen. Cell-membrane strong and smooth ; cell contents 

 green, covering the inside of the walls. 



Diameter of stems, 50-120 /* ; 1-3 times as long. 

 Diameter of branches, 15-40 // ; 3-6 times as long. 



The following are some of the varieties enumerated by 

 Rabenhorst, which agree with forms found here. 



a. Var. NORMALIS, Eab. 



Corresponding with the diagnosis. 



b. Var. GOSSYPINA, Kg. 



Filaments long and thin, sparingly branched ; articula- 

 tions 6-10 times longer than broad, often of silky appearance, 

 loosely interwoven into large masses. Another form has the 

 articulations much shorter. 



c.--Var. HORRID A, Kg. 



Much branched, branches in most part, secund, robust, 

 articulations short, 132-3 diameters long. 

 Often in masses in limestone springs. 



d. Var. RIGIDULA, Kg. 



Green, but more frequently a dull brown or nearly black ; 

 in comparison with the last (horrida) not quite so robust; 

 articulations longer and more swollen. 



Floating masses in ponds of spring- water. 



e. Var. VIADRINA, Kg. 



Filaments elongated, numerously branched ; cells cylin- 

 drical or somewhat swollen, densely interwoven ; forms 

 largely expanded masses, which when dried have the 

 appearance of a skin or very coarse paper, 2-4 mm in thick- 

 ness. 



Frequent in pools of stagnant or sluggish, brackish water. 



Plate CVII, figs. 1, 2, filament var. normdle; figs. 3, 4, 

 escape of zoogonidia. 



Plate CVII, figs. 5, 6, filament var. gossypina. 



Plate CVIII, fig. 3, filament var. horrida. 



Plate CVIII, figs. 4, 5, filament var. rigidula. 



Plate CIX, figs. 1, 2, filament var. viadrina-, fig. 3 

 illustrates how a filament out of the water, on moist ground, 

 seeks to retain life by throwing out a sort of rootlets. 



