20. Vegetative cells 18— 23w. in diameter; 



zygospores globose to ovate M. micropora 



20. Vegetative cells 24— 29^ in diameter; zygospores ovate-ellipsoid, 



with flattened ends M. pulchella 



21. Zygospores 20— 30— (36) w in diameter; ovate 



to broadly ellipsoid: pyrenoids in 1 row M. laevis 



21. Zygospores 35— 41jLt in diameter, ovate to 



subglobose; pyrenoids scattered M. robusta 



22. Zygospore wall smooth 23 



22. Zygospore wall decorated 29 



23. Vegetative cells 4— Sy. in diameter 24 



23. Vegetative cells (8)-9-24m in diameter 26 



24. Vegetative cells 4— 5m in diameter 25 



24. Vegetative cells 6-8w in diameter M. viridis 



25. Zygospores irregularly quadrate, the angles extended M. americana 



25. Zygospores cruciate-quadrate, with concave 



margins, the comers rounded M. elegantula 



26. Zygospores globose, or angular-globose M. calcarea 



26. Zygospores ovate or quadrangular 27 



27. Zygospores ovate to subglobose; vegetative 



cells 19-24/x in diameter M. sphaerocarpa 



27. Zygospores quadrate; vegetative cells 8— 19— (21) w. in diameter 28 



28. Cell sap purplish M. capucina 



28. Cell sap not purplish M. virescens 



29. Vegetative cells (8)— 13— 16m in diameter; 



wall of zygospore punctate 30 



29. Vegetative cells 5— 8.5u in diameter; wall of 



zygospore scrobiculate or verrucosa 31 



30. Zygospores cruciate-quadrate, sides concave, 18— 29m in 

 diameter, 30— 38m long; vegetative cells 8— 10m 



in diameter M. punctata 



30. Zygospores quadrate, sides straight, 28— 40m in diameter; 



vegetative cells (8)-14-16m in diameter M. quadrangulata 



31. Zygospores quadrate with tumid margins, wall 



minutely scrobiculate M. tumidula 



31. Zygospores quadrate, with concave margins, wall 



minutely verrucosa M. gracilima 



Mougeotia abnormis Kisselew 1927, p. 301 



[M. notabilis Hassall 1842, p. 46] 



PL 70, Figs. 3, 4 



Filaments forming sparse entanglements; vegetative cells long- 

 cylindric, 10-21;a in diameter, 50-1 ll-( 250 )/x long; chloroplast filling 

 the length of the cell. Zygospores formed almost entirely within the 

 conjugation tube but extending into and filling one of the gametan- 

 gia; triangular or quadrate-ovate, with margins concave and median 

 spore wall smooth; 24-26/i, in diameter, 26-36/a long. 



Our specimens are referred to M. abnormis on the basis of their 

 agreement with the published partial description. 



Among other algae in ponds and lake margins. Wis. 



[ 299 ] 



