Phacus Swirenkoi Skvortzow 1928, p. 114 

 PI. 88, Fig. 24 



Cells orbicular in outline, slightly twisted posteriorly and extended 

 into a short, sharp caudus which turns obliquely to the right ( when 

 seen from the ventral side); broadly rounded anteriorly; periplast 

 longitudinally striated; margin of the cell entire; paramylon bodies 

 2 large circular plates; cells SSfi in diameter, 43-46ju, long. 



Common in the plankton of lakes; in tychoplankton of bays and 

 in swamps. Wis. 



Phacus tortus ( Lemm. ) Skvortzow 1928, p. 110 

 PL 88, Fig. 20 



Cells broadly fusiform or napiform, broadest in the anterior third 

 of the cell, conically rounded at the anterior end, tapering and 

 spirally twisted in the posterior portion to form a long, straight 

 (rarely slightly curved) caudus; periplast with spiral striations; 

 paramylon bodies 1 or 2 large, centrally located circular plates; 

 flagellum % the length of the cell body; cells (38)-40-50-(52)/^ in 

 diameter, 85-95- ( 112 )/x long. 



In shallow water of many swamps and in small ponds. Wis. 



Phacus triqueter (Ehrenb.) Dujardin 1841, p. 338 

 PI. 107, Figs. 4-6 



Cells broadly ovoid, usually broadest below the median line, 

 broadly rounded and bilobed anteriorly, narrowed unsymmetrically 

 posteriorly to form a prominent, slightly deflected, sharply pointed 

 caudus; the dorsal surface with a high flange, thus making the cell 

 triangular in outline when seen from the end; a deep longitudinal 

 furrow on the ventral side; periplast longitudinally striated, the 

 striations extending slightly into the caudus; paramylon bodies 2 

 to several large rings ( sometimes only 1 ) ; cells 30-45/x in diameter, 

 37-68/x long. 



Tychoplankter. Wis. 



LEPOCINCLIS Perty 1849, p. 28 



Cells ovoid, ovate, elhptical or fusiform, sometimes nearly spheri- 

 cal, with a firm and usually spirally striated periplast, round in cross 

 section; posteriorly extended into an abruptly pointed tail-piece 

 (rarely gradually tapering); a gullet in the anterior end where there 

 arises a single flagellum that is once or twice the cell in length; 

 chloroplasts numerous parietal discs; pigment-spot laterally placed 



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