252 zygnemataceaf: 



PL ATI-. IV 



ZvGNhMA 



Figs. 1-2. — Z. synadelphuin, zygospores and vegetative cells enclosed by 

 pectic sheath with prominent structural lines. Figure i from Latvia, after 

 Skuja; Fig. 2 from Douglas Lake, Michigan. Figs. 3-4. — Z. coirulvum , 

 zygospores and gametangia, and spore wall pattern, trom Bohemia. After 

 Czurda. Fig. 5. — Z. }{iangsiense, zygospores and gametangia from China. 

 After L. C. Li. Fig. 6. — Z. ralfsii, conjugation pattern after G. S. West. 

 Fig. 7. — Z. micropunctatum , zygospore and gametangia from Douglas Lake, 

 Michigan. Figs. 8-9. — Z. circumcarinatum , zygospore and details of spore 

 wall from Bohemia. After Czurda. Fig. 10. — Z. paivhusl{ae, gametangia 

 and zygospores from Oklahoma. After Taft. Fig. ii. — Z. carina turn, zygo- 

 spores and gametangia from Oklahoma. Fig. 12. — Z. extenuc, zygospores 

 and beginning of lateral conjugation from Szechwan, China. After Jao. 

 Fig. 13. — Z. tholosporum, zygospore from Uruguay. After Magnus and 

 Wille. Figs. 14-15. — Z. tenue, zygospores, gametangia, and details of spore 

 wall from China. After Jao. Fig. 16. — Z. cylindrospermum , zygospores and 

 gametangia from the Shetland Islands. After W. & G. S. West. Figs. 17- 

 18. — Z. hausmannii, zygospores and gametangia from Austria. After 

 Czurda. 



