superior; 11-12.9/a in diameter, 10-11.2/x long. Oospores globose; 

 filling the oogonia; the wall smooth; 11-12/;. in diameter. Antheridia 

 not observed. 



This plant is similar to Oe. Hotvei Tiff., which is larger and has 

 an inferior division of the oogonium. Although numberless plants 

 were examined, the antheridia were not found. The female charac- 

 teristics are distinctive and warrant the description of a new species. 



In several soft water lakes and acid swamps. Wis. 



Oedogonium mitratum Hirn 1895, p. 22 

 PI. 44, Figs. 11, 12 

 Macrandrous; dioecious. Vegetative cells capitellate, (4)-5-10/i, 

 in diameter, 18-50- ( 80 )/x long. Oogonia solitary or 2-4 in series; 

 globose; operculate; division superior or supramedian; 18-24-(27)/i, 

 in diameter, 20-28- ( 35 )fi long. Oospores globose to subglobose, 

 with a smooth wall; nearly filling the oogonia; 17-23/t in diameter, 

 17-22- ( 23 )/t long. Antheridia 6-9^1 in diameter, 6-8/* long. 

 Attached to submerged aquatics. Wis. 



Oedogonium nanum Wittrock 1875, p. 37 

 PI. 36, Fig. 10 

 Macrandrous; dioecious. Vegetative cells usually cyhndric, 6-S- 

 (lO)iLt in diameter, (15) -18-20- (33)/. long. Oogonia sohtary or as 

 many as 3 in a series; ellipsoid; operculate; division superior; 24-28/* 

 in diameter, 30-36/* long. Oospores ovate or ellipsoid; nearly filling 

 the oogonia; wall smooth; 18-22-(27)/* in diameter, (24)-26-28- 

 (30)/* long. Antheridia 7-10/. in diameter, 8-11/* long. 

 In shallow water of swamp. Wis. 



Oedogonium paucostriatum Tiffany 1934, p. 325 

 PL 38, Figs. 1, 2 



Macrandrous; dioecious. Vegetative cells cylindric, 13-20/* in 

 diameter, (66) -106-120/* long. Oogonia sohtary; elhpsoid; opercul- 

 late; division superior; 45-48-(52)/* in diameter, (76)-79.8-88/t 

 long. Oospores ellipsoid; not filling the oogonia; middle wall ribbed 

 with about 20 longitudinal costae; (44) -45-47/* in diameter, 53-55- 

 (70)/* long. Antheridia 17-20/* in diameter, 8-12/* long. 



This species should be compared with the slightly larger Oe. 

 paucocostatum Transeau. 



Attached to reeds in a lake of medium hard water. Wis. 



[185] 



