ZYGNEMA 33 



the gametangia, 42-46 ,«, in diameter; median spore wall yellow-brown, 

 scrobiculate; pits 3/"- in diameter. (PI. V, Fig. i.) 



United States: Oklahoma, Bartlesville, April 25, 1932. 



This species is remarkable for the large size of the zygospores as com- 

 pared with the size of the vegetative cells. 



46. Zygnema luteosporum Czurda 1932. Siisswasser flora Mittel- 



europa. 9, p. 122, Fig. 225. 



Vegetative cells 22-24/^1 x 45-80 /x; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia cylindric or 

 slightly enlarged; zygospores ovoid, 26^ x 38 /a; median spore wall 

 yellow, thick, scrobiculate, with pits widely spaced. (PI. V, Fig. 2.) 



Bohemia. 



47. Zygnema flavum Taft 1946. Trans. Amer. Micros. Soc. 65, 



p. 24. 

 Vegetative cells 22-27 /a x 48-68 a^; conjugation scalariform; zygo- 

 spores formed in one of the gametangia; receptive gametangia cyhndric 

 or slightly enlarged; zygospores cylindric-ovoid to ovoid, 24-29 m x 

 35-51 fi; outer spore wall thin and smooth; median spore wall of 2 

 layers, the outer thick and smooth, the inner irregularly verrucose; both 

 layers light yellow; innermost spore wall thin, smooth. (PI. V, Fig. 3.) 



United States: Texas, Eden, April 13, 1938. In this collection some of 

 the vegetative cells contained 4 chromatophores. 



48. Zygnema calosporum Jao 1935. Sinensia. 6, p. 568, Pi. i. 



Fig. 7. 



Vegetative cells 23-26 ju x 16-48 /x; conjugation scalariform; recep- 

 tive gametangia shortened and greatly enlarged; zygospores globose to 

 subglobose, 29-35 m ^ 32-35 m; median spore wall densely scrobiculate; 

 pits 1.5-2.5 M^ in diameter, 1-1.5/'. apart, yellowish-brown at maturity. 

 (PI. V, Fig. 4.) 



China, Szechwan. 



Differs from Z. substellinum Taft in greater diameter of the vegetative 

 cells and smaller spores; from Z. vaucherii in shorter vegetative and repro- 

 ductive cells, and in denser scrobiculations of the median spore wall. 



49. Zygnema vaucherii Agardh 1824. Systema Algarum, p. 77. 



Vegetative cells 24-28 a"- x 50-180^1; conjugation scalariform; zygo- 

 spores in one of the gametangia; receptive gametangia gradually or 

 abruptly inflated toward the middle; zygospores ovoid, 24-36 ju. x 26-45 /x; 

 median spore wall brown, scrobiculate; pits 2-3 /x in diameter. (PI. V, 

 Fig- 5-) 



