ZYGNEMOPSIS 53 



22-25 jLi X 25-30 /"-; outer spore wall hyaline; median wall thick, choco- 

 late brown, smooth; aplanospores more abundant than zygospores, 

 asymmetrically ovoid to globose, sometimes with the 2 ends slightly 

 produced, 18-20/J. x 18-31 /x. (PI. VIII, Figs. lo-ii.) 



United States: Michigan, Douglas Lake region (Taft Coll.). 



India, Fyzabad, U.P., March, 1937. 



6. Zygnemopsis desmidioides (W. & G. S. West) Transeau 1934. 



Trans. Amer. Micros. Soc. 53, p. 215, Fig. 25. 



Vegetative cells 8-1 i/x x 19-56 m, constricted at the ends; chroma- 

 tophore an axial plate with 2 pyrenoids; filaments fragment readily; 

 "conjugation between free cells" scalariform; zygospores formed in the 

 broad conjugating tubes and extending somewhat into both gam- 

 etangia; spores quadrangular with straight, concave, or slightly convex 

 sides and rounded angles, 14-18 m x 18-24 jw; median spore wall golden- 

 brown, thick, finely punctate. (PI. VIII, Figs. 12-14.) 



United States: Wisconsin. 



England; Latvia. 



The statement by West that conjugation takes place between free cells 

 is probably incorrect. Fragmentation of filaments occurs during and after 

 conjugation in several other species. The filaments of Z. desmidioides have 

 a pectic sheath. When conjugation occurs this sheath passes into solution 

 and, as the gametangia become distended with pectic compounds, the ends 

 become rounded and separate. 



7. Zygnemopsis columbiana Transeau 1934. Trans. Amer. Mi- 



cros. Soc. 53, p. 215, Figs. 27-29. 



Vegetative cells (8-) 9.5-11.5/x x 40-ioo/x, with 2 pillow-shaped 

 chromatophores, each with a central pyrenoid; conjugation scalariform; 

 zygospores formed in the wide conjugating tubes and extending far 

 into each gametangium; spores quadrate-ovoid, 23-32 /a x 23-34 jU-, with 

 angles rounded, produced, or retuse; median spore wall with a prom- 

 inent suture, finely punctate, chestnut brown; aplanospores ellipsoid to 

 ovoid, 1 8-20 /x X 25-30^1, otherwise similar. (PI. VIII, Figs. 15-17.) 



Canada, British Columbia (W. R. Taylor Coll.). 



8. Zygnemopsis Americana Transeau 1934. Trans. Amer. Micros. 



Soc. 53, p. 215. 

 Vegetative cells 9-12 /a x 27-100 /x; 2 compressed-ovoid chromato- 

 phores; conjugation scalariform; zygospores formed in the broad con- 

 jugating tubes and extending far into both gametangia; spores ovoid to 

 quadrate-ovoid, 20-40 /a x 30-40 /a; parthenospores 15-20 ft x 20-30 ju., 

 unilaterally ellipsoid with retuse ends; median spore wall minutely 



