Spirogyra circumlineata Transeau 1914, p. 293 

 PI. 74, Fig. 8 

 Filaments of rather stout cells, 40-50/^ in diameter and 3-6 times 

 their diameter in length, with plane end walls; chloroplast solitary, 

 making 4 to 8 turns. Conjugation by tubes from both gametangia; 

 sporangia inflated mostly on the inner (conjugating) side. Zygo- 

 spores ellipsoid; wall layers smooth; 40-50/a in diameter, 70-125/1, 

 long. 

 Mich. 



Spirogyra Collinsii ( Lewis ) Printz 1927, p. 372 

 PI. 77, Figs. 4-6 

 Filaments of rather slender cells, 15-24|U, in diameter, and about 

 5 times as long as broad, with plane end walls; chloroplast solitary. 

 Conjugation scalariform and lateral, the tube formed by the male 

 gametangium only; sporangia inflated slightly on both sides to 

 contain the spore; the male gametangium fonned by a partitioning 

 ofiF of one end of a vegetative cell. Zygospores ellipsoid; median wall 

 coarsely punctate; 35/x in diameter, 60fx long. 

 Mich., Wis. 



Spirogyra communis (Hass.) Kuetzing 1849, p. 439 

 Vegetative cells slender, cylindric, (18)-20-26/x in diameter, (35)- 

 65-100/>i long, with plane end walls; chloroplast solitary, making 1% 

 to 4 turns. Conjugation by tubes from both gametangia; fertile cells 

 cylindric. Zygospores ellipsoid, with narrowly rounded poles; median 

 spore wall smooth, colorless, or yellowish in age; 19-23/i, in diameter, 

 36-69/x long. 



Common in ponds and swamps. Mich., Wis. 



Spirogyra condensata (Vauch. ) Kuetzing 1843, p. 279 



PL 72, Figs. 5, 6 

 Filaments of rather stout vegetative cells, (48)-53-62/i, in diameter, 

 45-94- (120) /A long, with plane end walls; chloroplast solitary, mak- 

 ii^g ¥2 to 4 turns. Conjugation by tubes from both gametangia, or 

 lateral; fertile cells cylindric. Zygospores ellipsoid; median spore 

 wall smooth and brown; 34-38;Lt in diameter, 50-75/x long. 

 In alkaline bog lakes. Mich. 



Spirogyra crassa Kuetzing 1843, p. 280 

 PI. 72, Figs. 7, 8 



Filaments coarse, stout, feeling glassy to the touch; vegetative cells 

 cells (133)-140-160/i in diameter, quadrate or 2 times the diameter 

 in length, with plane end walls; chloroplasts 6-12 (usually 8-10), 



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