THE GREEN AUJAE OF NORTH AMERICA 7 



Page 102, for Key to the Species of Zygneraa substitute, 



i. Spore formed in the tube. Sect. PECTINATA. 2. 



i. Spore usually formed in one of the cells. 6. 



2. Spore with thick, lamellate membrane. 2. Z. pachydermum. 



2. Spore without thick, lamellate membrane. 3. 



3. Spore bluish. 3. Z. cyanospermum. 



3. Spore brownish. 4. 



4. Spore smooth. 14. Z. ericetorum. 



4. Spore pitted. 5. 



5. Cells 30-50 n diam. i. Z. pedinatum. 



5. Cells 18-25 M diam. 9- Z. decussatum. 



6. Spore with smooth median membrane. Sect. L,EIOSPERMA. 7. 



6. Spore with pitted median membrane. Sect. SCROBICUI.ATA. 10. 

 7. Vegetative filaments 20-22 n diam. 5. Z, leiospermum. 



7. Vegetative filaments over 26 M diam. 8. 



8. Vegetative filaments 35-54 M diam. 



7. Z. cruciatum forma leiospermum, 



8. Vegetative filaments 26-33 V- diam. 9. 



9. Zygospores unknown ; aplanospores cylindric, filling the cell. 



ii. Z. cylindricum. 

 9. Zygospores globose or broadly ovoid, 30-32 M diam. 6. Z. insigne. 



10. Spore bluish. n. 



10. Spore brown. 13. 



ii. Fertile cells not swollen. 7. Z. cruciatum var. coeruleum. 



ir. Fertile cells swollen on the inner side. 12. 



12. Spore globose to oblong, 26-40 n diam. and length; aplanospores 

 cylindric-oblong, 18-24 A* diam. ; both with large pits. 



13. Z. Collinsianum . 



12. Spore subglobose, 33 /x diam., no aplanospores ; spore finely scro- 



biculate. 10. Z. peliosporum. 



T 3- Vegetative cells 35-54 M diam. 7. Z. cruciatum. 



13. Vegetative cells 22-36 M diam. 14. 



14. Spore produced by union of contiguous cells in a filament through 

 the partition wall. 12. Z. rhynchonema. 



14. Conjugation scalariform. 8. Z. stellinum. 



Page 103, after description of Z. PECTINATUM, insert, 



Var. CRASSUM Transeau, 1915, p. 21. Vegetative cells 

 30-40 /A diam., spores 40-55 X 50-60 /A. 111. 



Var. CONSPICUUM (Hass.) Kirchner, 1878, p. 127; Tynda- 

 ridea conspicua Hassall, 1845, p. 164, PI. XXXIX, figs. 1-2. 

 Vegetative cells 18-27 P- diam ; membrane thick and lamellose. 

 111. 



Page 104, cancel No. 4, Z. CHALYBEOSPERMUM. 



After description of Z. CRUCIATUM, insert, 



