Ankistrodesmus falcatus var. stipitatus ( Chod. ) 

 Lemmermann 1908, p. 176 

 PI. 56, Figs. 14, 15 

 Cells lunate (rarely almost straight), attached at one pole to 

 filamentous algae or other submerged aquatics; usually gregarious, 

 forming clusters of 2-8; cells 3-4^ in diameter, 18-22/a long. 

 Plankter. Wis. 



Ankistrodesmus falcatus var. tumidus (West & West) 

 G. S. West 1904, p. 224 

 PI. 56, Fig. 9 

 Cells lunate or fusiform, the ventral margin decidedly tumid in 

 the midregion, 4.5-6.5;a in diameter, 61-73/x long. 

 Rare; in plankton. Wis. 



Ankistrodesmus fractus ( West & West) Brunnthaler 1915, p. 189 



PI. 56, Fig. 7 



Solitary, arched-fusiform or arcuate cells, the outer wall convex 

 in the median portion only, with almost straight walls extending 

 to the sharply pointed apices, the inner margin concave in the 

 median portion, straight toward the apices; cells 2.8/x in diameter, 

 40-43.5/i long; chloroplast divided into 4 portions by deep folds 

 or incisions. 



Rare; in the plankton of Sphagnum bogs. Wis. 



Ankistrodesmus spiralis (Turner) Lemmermann 1908, p. 176 



PI. 56, Figs. 11, 12 

 Cells spindle-shaped, spirally twisted into bundles of 4-16 cells; 

 cells 2-3/. in diameter, 25-35/a long; chloroplast a parietal plate 

 without a pyrenoid. 



Common in a variety of ponds and lakes; tycho- and euplanktonic. 

 Mich., Wis. 



DACTYLOCOCCUS Naegeh 1849, p. 85 



Pseudo-filamentous, consisting of ovate or fusiform-elliptic cells 

 attached end to end, filaments breaking up to form single, scattered 

 cells or small chains of cells; chloroplast a parietal plate, with or 

 without a pyrenoid. 



See G. M. Smith 1933, p. 507, for a discussion of the systematic 

 position of this genus. 



[254] 



