Dactylococcus infusionum Naegeli 1849, p. 85 

 PI. 56, Fig. 13 

 Fusiform cells, either solitary or attached pole to pole to form 

 false, branched filaments or chains; chloroplast a parietal plate, 

 sometimes with a pyrenoid; cells 2.5-3.5/x in diameter. 

 From a laboratory culture. Wis. (Smith). 



CLOSTERIOPSIS Lemmermann 1899a, p. 124 

 Cells long and needle-like, tapering to sharp points at both ends; 

 chloroplast a lobed plate extending almost the entiie lengtli of the 

 cell and containing a row of pyrenoids. 



Closteriopsis should be compared with Closterium and Ankistro- 

 desmus. It is shaped much like some of the very slender species of 

 the former genus in which, however, there are two chloroplasts, 

 one on either side of a central nucleus. It is differentiated from 

 Ankistrodesmus on the basis of its greater size, stouter proportions, 

 and the axial row of pyrenoids. 



Closteriopsis longissima Lemmermann 1899a, p. 124 



[Ankistrodesmus longissimus ( Lemm. ) Wille] 



PI. 57, Fig. 1 



Cells long and very narrowly spindle-shaped, the ends tapering 



to fine points; chloroplast a parietal, lobed plate; cells 3.5-6/x in 



diameter, 190-240-( 530)/. long. 



Rare; in the plankton of a few soft water lakes. Wis. 



Closteriopsis longissima var. tropica West & West 1905, p. 31 



PI. 57, Figs. 2, 3 

 A variety of stouter proportions than the typical plant and not 

 tapering to a fine point but bluntly tipped at the poles; cells 

 6-7.5/z in diameter, 225-370/x long. 

 Plankter. Wis. 



SCHROEDERIA Lemmermann 1898c, p. 311 

 Free-floating, unicellular, acicular, fusiform or sti'aight, tapering 

 at the poles and forming long fine setae, one of which may terminate 

 in a disc or may be bifurcated near the end to form a pair of 

 recurved, bristle-like spines; 1 parietal chloroplast covering most of 

 the cell wall, with 1-3 pyrenoids. 



Key to the Species 

 Cells as much as 20 times their diameter in length; 



spines 13-27/u long S. setigera 



Cells smaller, not more than 10 times their diameter 



in length; spines 10-16fi long S. Judaiji 



[ 255 ] 



