87 



7. Sex-organs may occur; thickness of filaments 

 usually less than 10 /j, cells usually 5 — 8 diam. 

 long, sporangia sessile or on unicellular branch- 

 lets on the inner side of the branches 6. Ch. Thuretii. 



7. Without sex-organs; filaments 9 — 12// thick, cells 

 2 — 4 diam. long; sporangia-bearing branchlets 



repeatedly branched, often in the axils 7. Ch. Dauiesii. 



6. Branches partly opposite 8. Ch. attenuata. 



5. Erect filaments unbianched, bearing only numerous 

 sporangia-bearing branchlets, nearly from the base 



to the top 9. Ch. stricta. 



4. Erect filaments numerous, rather short (up to 300 fj) to 

 very short or wanting; pyrenoid axile. 

 5. Erect filaments up to ca. 300 /i long, branched. 



6. Filaments 7— 10 // thick, sporangia tetrasporous 12. Ch. polyblasta. 

 6. Filaments 3 — irj. thick, sporangia monosporous 14. Ch. leptonema. 

 5. Erect filaments up to ca. 60 fji long, usually unbranched, 

 sporangia monosporous. 



6. The cells of the creeping filaments give off 2 — 3 

 erect filaments bearing terminal and lateral spor- 

 angia 13. Ch. huinilis. 



6. The cells of the creeping filaments bear one sessile 



or stalked sporangium 15. Ch. reducta. 



3. Basal layer first a parenchymatous disc, later growing out 

 into radiating filaments; pyrenoid axile {Ch. leptonema). 



4. Erect filaments 1 — 2 mm. long 10. Ch. inrgatula. 



4. Erect filaments very short or wanting; sporangia sessile 



on the basal disc or terminal on the erect filaments.. 11. Ch. Macula. 

 1. Frond partly or entirely endophytic or endozoic. Group III. 

 2. Vegetative part partly endophytic. 



3. Epiphytic creeping filaments present. 



4. Endophytic filaments intracellular 16. Ch. cytophaga. 



4. Endophytic filaments intercellular 17. Ch. Dumoniia;. 



3. Epiphytic creeping filaments wanting 18. Ch. Nemalionis. 



2. Vegetative part entirely endophytic or endozoic. 



3. Vegetative filaments endozoic, giving off short free, spor- 

 angia-bearing filaments 19. Ch. endozoica. 



3. Filaments entirely endophytic. 



4. Filaments creeping in the outer cell- wall of Polysiphonia; 



sporangia entirely free, short-stalked, single 20. Ch. emergens. 



4. Filaments intercellular; sporangia partly or entirely 

 immersed in the host. 



