slender, making I/2 to 1 turn. Conjugation by tubes from both 

 gametangia; fertile cells cylindric. Zygospores ovate or laterally 

 flattened, the poles broadly rounded; median spore wall finely 

 pitted and brown; (80)-120-140/x in diameter, 166-175/x long. 

 Forming dark green masses of coarse filaments in quiet water of 

 bogs and pooled streams; apparently specific for hard water habitats. 

 Mich., Wis. 



Spirogyra daedaleoides Czurda 1932, p. 180 

 PI. 72, Figs. 9-11 



Filaments of rather stout cylindrical cells, 30-35/a in diameter, 

 70-148-(240)/i, long, with plane end walls; chloroplast solitary, 

 making 3 to 4 turns. Conjugation scalariform by tubes from both 

 gametangia, or lateral; fertile cells becoming inflated. Zygospores 

 ellipsoid or ovate-ellipsoid; median spore wall coarsely reticulate 

 and brown; 35- (44)//, in diameter, (46)-59-77|U long. 



In hard water lakes. Mich., Wis. 



Spirogyra decimina ( Mueller ) Kuetzing 1843, p. 280 



Filaments of rather stout cylindric cells, 34-40/x in diameter, 

 60-125- (150) /A long, with plane end walls; chloroplasts 2 (rarely 3) 

 in each cell, broad, making 2 turns. Conjugation by tubes from both 

 gametangia; fertile cells cylindric. Zygospores cylindric-ovate, rarely 

 subglobose; median spore wall smooth; 31-40jii in diameter, 31-68- 

 (75)/. long. 



Forming cloudy masses on false bottom of an alkaline bog lake. 

 Mich., Wis. 



Spirogyra dubia Kuetzing 1855, p. 8. Tab. Phyc. V 



Filaments of rather stout cylindrical cells, (40)-43-50/x in diam- 

 eter and up to 2i/^ times the diameter in length, with plane end walls. 

 Chloroplasts 2 (sometimes 3), making 1 to 3 turns. Conjugation 

 scalariform by tubes from both gametangia; fertile cells inflated. 

 Zygospores globose or ovate; median wall smooth; 40/i, in diameter, 

 up to 80/x long. 



Mich., Wis. 



Spirogyra ellipsospora Transeau 1914, p. 294 



PI. 72, Fig. 12 



Filaments of stout cylindric cells, 125-150/a in diameter, 125-230- 



(500)/i, long, with plane end walls; chloroplasts 3-8 narrow bands, 



making Vo to 5 turns. Conjugation by tubes from both gametangia; 



[313] 



