smooth ?); paramylon bodies 2 large discs; chloroplasts numerous 

 ovoid bodies; cell 24-26/Lt in diameter, (25)-28-30/li long. 

 Euplanktonic and tychoplanktonic. Wis. 



Phacus helikoides Pochmann 1942, p. 212 

 PI. 87, Fig. 9 



Cells fusiform or elongate fusiform-pyriform, twisted" throughout 

 their entire length (sometimes closely so), briefly narrowed anter- 

 iorly and bilobed, the lobes appearing in 2 planes when seen from 

 the side; tapering posteriorly to a spirally twisted, long, straight 

 caudus which is about 1/2 the cell body in length; margins of the cell 

 entire but with 2 or 3 bulges; periplast longitudinally and spirally 

 striated; 1 large circular paramylon body; cells 39-(40)-54/x in 

 diameter, 70-120/a long. 



This species should be compared with P. tortus (Lemm.) Skv., 

 which is broader and is twisted only in the posterior portion of the 

 cell. 



Not uncommon in the plankton of lakes and ponds but most 

 frequently found in the tychoplankton of shallow water. Wis. 



Phacus Lemmermannii (Swir.) Skvortzow 1928, p. 114 



PI. 88, Fig. 12 



Cells broadly ellipsoid to ovoid, decidedly twisted in the posterior 

 portion (usually) and somewhat abruptly tapered to a short, sharp 

 caudus which turns to the right (when the cell is seen from the 

 ventral side); slightly retuse at the anterior pole and sometimes 

 rather narrowly rounded (in our specimens); paramylon bodies 

 either 2 moderately large rings or, more commonly, 2 larger rings 

 and many small circular plates; cell (19)-20-30/x in diameter, 

 (27)-32-45-(47)ialong. 



Plankter; in sloughs and ponds. Wis. 



Phacus longicauda (Ehrenb.) Dujardin 1841, p. 337 



PL 87, Fig. 1 

 Cells broadly ovoid to pyriform, tapering gradually posteriorly 

 to form a long, straight, sharply pointed caudus; anteriorly broadly 

 rounded; periplast longitudinally striated; flagellum shorter than 

 the cell in length; paramylon body usually in the form of a single 

 large (or small) circular plate; cells 45-70/1* in diameter, 85-170/x 

 long. 



Rather common in the euplankton and tychoplankton of lakes and 



swamps. Mich., Wis. 



[400 1 



