152 ZYGNEMATACEAE 



6. Spirogyra condensata (Vaucher) Kiitzing 1843. Phycologia 



Generalis, p. 279. 



Vegetative cells 45-^)0/1 x 45-1 20 m, with plane end walls; i chro- 

 matophore, making .5 to 4 turns; conjugation scalariform and lateral; 

 tubes formed by both gametangia; fertile cells cylindric or slightly 

 enlarged; zygospores ellipsoid, 34-3^/^ x 50-75 ju; median spore wall 

 yellow, smooth. (PI. XXI, Fig. 11.) 



United States: Wisconsin and Kentucky; eastward to Massachusetts 

 and New Jersey, 



Widely distributed in Europe; reported from South America. 



Characterized by its short cells and closely spiraled chromatophores. 

 Sterile cells sometimes inflated. 



7. Spirogyra variformis Transeau 1938. Amer. Jour. Bot. 25, 



pp. 526-27. 



Vegetative cells 43-50M x (70-) 108-140 (-200) m with plane end 

 walls; I chromatophore, making 2 to 5 turns in the cell; conjugation 

 scalariform; tubes formed by both gametangia and widest at the mid- 

 dle; some sterile cells inflated to 72-ioo/t; fertile cells mostly cylindric 

 but sometimes enlarged or inflated; zygospores ellipsoid or ovoid, 

 45-54 /x X 58-90 M, rarely spherical, 52-60 /u. in diameter; median wall 

 brown, smooth. (PI. XXI, Figs. 9-10.) 



Africa, Cape Town (Stephens Coll.). 



8. Spirogyra gracilis (Hassall) Kiitzing 1849. Species Algarum, 



p. 438. 



Vegetative cells 16-24/x x 50-ioo/x, with plane end walls; i chro- 

 matophore, making .5 to 4 turns; conjugation scalariform; tubes formed 

 by both gametangia; fertile cells inflated, mostly on the conjugating 

 side; zygospores ellipsoid with rounded ends, 23-30 ju. x 40-65 i^^; median 

 spore wall yellow-brown, smooth. (PI. XXI, Fig. 5.) 



United States: Colorado; Texas; Missouri; Michigan; Ohio; Massa- 

 chusetts. 



Widely distributed in Europe; reported also from China and Siam. 



9. Spirogyra fragilis Jao 1935. Sinensia. 6, p. 590, PI. 6, Fig. 64. 



Vegetative cells 24-29 jt^ x 54-160/11, with plane end walls; chromato- 

 phore I (rarely 2), making 1.5-6 turns; conjugation scalariform; tubes 

 formed by both gametangia; fertile cells slightly inflated, usually a Uttlc 

 more on the conjugating side; the female gametangia often separate 

 from each other after conjugation; zygospores ellipsoid with more or 

 less rounded ends, 22-38 /li x 36-67/1; median spore wall yellow, smooth. 

 (PI. XXI, Fig. 6.) 



United States: Texas, Johnson City, April 24, 1938 (Taft Coll.). 



