32 ZYGNEMATACEAE 



biculate; pits 4.5-6.5/1 in diameter and 2-7, fi apart, yellow-brown at 

 maturity. (PI. TV, Fig. 12.) 

 China, Szechwan. 



41. Zygnema tholosporum Magnus & Wille 1884. Sydamerica 



Algflora, p. 33, Pi. I, Figs. 49-52. 



Vegetative cells 20 /x x 20-40//.; conjugation scalariform; zygospores 

 in one of the gametangia; receptive gametangia inflated; zygospores 

 globose, 36 /i in diameter; median spore wall brown, with numerous 

 circular prominences (umbonate). (PI. IV, Fig. 13.) 



Uruguay, Montevideo. 



42. Zygnema tenue Kiitzing 1849. Species Algarum, p. 445. 



Vegetative cells 18-24 /t x 20-70 ju-; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia greatly enlarged 

 or inflated toward the middle; zygospores globose to ovoid, often some- 

 what compressed, 25-30 /x x 25-40 as median spore wall brown, scrobic- 

 ulate; pits 2-3/A in diameter, 3-4/i. apart. (PI. IV, Figs. 14-15.) 



United States: Illinois; Oklahoma. 



Europe, widely reported; North and South Africa; China; Ceylon. 



43. Zygnema leiospermum de Bary 1858. Untersuchungen iiber 



die Familie der Conjugaten, p. 77, PL i, Figs. 7-14. 



Vegetative cells 20-24/1 x 20-40/1; conjugation scalariform; zygo- 

 spores in one of the greatly enlarged or inflated gametangia; zygospores 

 globose to ovoid, 2^-30/1 x 23-32 /t; median spore wall brown, smooth; 

 aplanospores similar, but smaller in diameter. 



United States: Minnesota and Illinois to the east coast. 



Greenland; Iceland; British Isles; continental Europe. 



44. Zygnema hausmannii (De Notaris) Czurda 1932. Siisswasser- 



flora Mitteleuropa. 9, p. 121, Fig. 125. 



Vegetative cells 21-23/1 x 34-72/1; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia enlarged mostly 

 on the inner side; zygospores globose or slightly compressed, 32-34/t x 

 28-34/1; median spore wall yellow-brown, pitted; pits 7-9/1 in diam- 

 eter; equatorial suture distinct. (PI. IV, Figs. 17-18.) 



Austria; northern Italy; southern Australia. 



45. Zygnema substellinum Taft 1934. Trans. Amer. Micros. Soc. 



53, p. 212, PI, 17, Fig. 10. 

 Vegetative cells 22-24/1 x 50-70/1; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia greatly enlarged, 

 becoming nearly globose; zygospores globose, filling or nearly filling 



