ZYGNEMA 31 



■7^^. Zygnema stagnale (Hassall) Kiitzing 1849. Species Algarum, 

 p. 444. 



Vegetative cells 9-12/^1 x 20-50 m; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia enlarged on the 

 inner side; zygospores globose to subglobose, 14-18 /a x 14-20/x; median 

 spore wall brown, punctate. 



United States: Massachusetts, North Eastham (Collins Coll.). 



England. 



37. Zygnema subtile Kiitzing 1849. Species Algarum, p. 444. 



Vegetative cells 14-20/x x 30-85 /x; conjugation scalariform or very 

 rarely lateral; zygospores in one of the gametangia; receptive gam- 

 etangia greatly enlarged or inflated on the inner side; zygospores ovoid 

 to subglobose, 20-29 m x 22-30 m; median spore wall brown, punctate. 



United States: Illinois. 



Finland; Germany; Bohemia. 



This is possibly the species figured by G. S. West (1909) as Z. spon- 

 taneum from Yan Yean Reservoir, Australia. In a collection from Calhoun, 

 Illinois, in a filament of 35 cells there were 1 1 gametangia with scalariform 

 conjugation, 2 pairs conjugating laterally, and 20 vegetative cells scattered 

 among them. 



38. Zygnema cylindrospermum (W. & G. S. West) Krieger 1941. 



Zygnemales. Rabenhorst's Kryptogamen flora. 13, p. 260. 



Vegetative cells 15-18)". in diameter; conjugation scalariform; zygo- 

 spores formed in one of the gametangia; receptive gametangia cylindric 

 or slightly enlarged; zygospores ovoid, 15-19 itx x 23-54 /x; rnedian spore 

 wall brown, punctate. (PI. IV, Fig. 16.) 



Shedands (Loch Asta); Wales (Wittrock and Nordstedt No. 750); 

 Cape Colony (Stephens Coll.). 



39. Zygnema yunnanense Li 1940. Bull. Fan Mem. Inst. Biol. 



10, p. 63. 



Vegetative cells 16-18 ju, x 50-1 04 /x; conjugation lateral; receptive 

 gametangia more or less enlarged; zygospores globose to ovoid, 32-40 /x 

 X 38-48 A^; median wall thick, deeply scrobiculate, with pits 3-4.5 /^ in 

 diameter, 2-3 /x apart, yellow at maturity. 



China, Yunnan, October i, 1938. 



40. Zygnema extenue Jao 1935. Sinensia. 6, p. 568, PL i, Fig. 8. 

 Vegetative cells 19-25 /x x 32-48^1,; conjugation scalariform and 



sometimes lateral; receptive gametangia more or less enlarged; zygo- 

 spores subglobose to ovoid, 23-32 /x x 26-39 /x; median spore wall scro- 



