Spirogyra aequinoctialis G. S. West 1907, p. 105 

 PI. 72, Figs. 3, 4 



Vegetative cells long-cylindric, 23-29/x in diameter, up to 150/x 

 long, with plane end walls. Chloroplasts 2-3, with crenate margins 

 and large pyrenoids, making 1 to l^^ turns. Conjugation by tubes 

 from both gametangia, the receiving cells becoming symmetrically 

 inflated. Zygospores ovate or elongate-ellipsoid, with broadly 

 rounded poles; median spore wall with deep pits; ( 40 ) — 41— 50/;i 

 in diameter, ( 52 ) — 72— 77/li long. 



In shallow water of lake margins. Wis. 



Spirogyra afjinis (Hass.) Petit 1880, p. 18 

 Filaments of rather stout cylindrical cells, 27-30)Lt in diameter, 

 up to 90/A long, with plane end walls. Chloroplast solitary, making 



1 to 3 1/2 turns. Conjugation mostly lateral, but also scalariform, 

 tubes from both cells; sporangia inflated on both sides. Zygo- 

 spores ellipsoid; wall layers smooth; 28— 33/i, in diameter, 30— 50/x 

 long. 



Common in ponds and swamps. Mich., Wis. 



Spirogyra Borgeana Transeau 1915, p. 23 

 PL 77, Figs. 7, 8 

 Filaments of cylindrical cells, usually slender, 30-35/x in diameter, 

 up to 200/A long, with plane end walls. Chloroplast sohtary, making 

 1% to 5 turns. Conjugation scalariform; sporangia inflated only on 

 the outer side. Zygospores ellipsoid; wall layers smooth; 33-40/i. in 

 diameter, 54^70)a long. 

 Mich. 



Spirogyra horysihenica Kasanowsky & SmirnoflF 1913, p. 139 



Filaments of slender cylindrical cells, 30-40/a in diameter, 130-450jii 

 long, with replicate end walls; chloroplasts 3-4, making i/^ to 



2 1/2 turns. Conjugation scalariform, tubes from both cells, fertile 

 cells swollen to twice the diameter of the vegetative cells. Zygo- 

 spores ellipsoid to fusiform; median wall with papillae; 52— 63/a 

 in diameter, 100— 180/i long. 



Mich. 



Spirogyra catenaeformis ( Hass. ) Kuetzing 1849, p. 438 



Filaments of rather stout cylindrical cells, 24-27- (32) /a in dia- 

 meter and up to 5 diameters in length, with plane end walls; 

 chloroplast solitary, making 1 to 6 turns. Conjugation by tubes from 

 both gametangia; fertile cells swollen; the sporangia inflated on 

 both sides. Zygospores ellipsoid; wall layers smooth; 24-30/i, in 

 diameter, 55-90ju, long. 



Mich., Wis. ^3^^^ 



