ZYGNEMOPSIS 57 



23-50 Ai, with a more or less prominent suture, yellow and scrobiculate, 

 with pits 2-3 M in diameter. (PI. IX, Figs. lo-ii.) 

 India, Fyzabad, U.P., February to April. 



20. Zygnemopsis decussata Transeau 1934. Trans. Amer. Micros. 



Soc. 53, p, 214. Includes Zygnema pseudodecussatum 

 Czurda 1932. 



Vegetative cells 16-20/t x 24-50 /.i; chromatophores as in Zygnema, 

 each with i pyrenoid; conjugation scalariform; zygospores extending 

 far into each gametangium, ovoid to quadrate-ovoid, and irregular, 

 24-30 /A X 30-48 ju., the angles rounded, retuse, or produced; aplan- 

 ospores unilaterally ovoid, the plane of the convex side changing in 

 successive cells, 17-25 i", x 20-40 ^u.; parthenospores 15-20;^, x 20-30 ^u.; 

 median wall in all the spores scrobiculate; akinetes with smooth, heavy 

 walls, 1 8-20 /i x 20-36 iU,. (PI. IX, Figs. 12-15.) 



United States: Oklahoma; Iowa; Arkansas; Illinois; Kentucky; Mich- 

 igan. 



Canada, Ontario; Europe, Bohemia; China, Szechwan. 



Some collections have only aplanospores, others only scalariform con- 

 jugation and zygospores, still others have filaments with both zygospores 

 and aplanospores. In Illinois the size of the filaments was regularly 18-20M 

 in diameter, but I have a collection sent me by Dr. Li from Amoy, China, in 

 which some of the conjugating filaments have diameters as low as 12/x. 

 The zygospores, however, are of the usual dimensions. 



21. Zygnemopsis spiralis (Fritsch) Transeau 1934. Trans. Amer. 



Micros. Soc. 53, p. 214. 



Vegetative cells 18-25/U- x 26-60 /x, with 2 stellate chromatophores; 

 conjugation scalariform; gametangia sometimes elongating to 130/^; 

 zygospores quadrately ovoid, 28-36 /^ x 48-56^1.; outer wall thin or thick, 

 transparent, usually separated from the median wall and sometimes 

 covered internally with granules; median wall punctate or finely scro- 

 biculate. (PL IX, Fig. 16.) 



United States: Wisconsin; Michigan (Prescott Coll.). 



South Africa, Table Mountain, wet rock on slope, luly 19, 1908; Latvia 

 (Skuja Coll.). 



22. Zygnemopsis fertilis (Fritsch & Rich) Transeau 1934. Trans. 



Amer. Micros. Soc. 53, p. 216. 



Vegetative cells 20-22 /j. in diameter; slight constrictions between 

 the cells; chromatophores 2, stellate; zygospores unknown; sporogenous 

 cells distended in the center; aplanospores compressed-ovoid, 31-32 /j- x 

 41-49 /x; median spore wall with 3 (or more) longitudinal ridges; 

 spores immature. (PI. IX, Fig. 17.) 



South Africa. 



