87 
7. Sex-organs may occur; thickness of filaments 
usually less than 10 y, 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. Daviesit. 
6. Branches partly opposite ..................... 8. Ch. attenuata. 
5. Erect filaments unbranched, bearing only numerous 
sporangia-bearing branchlets, nearly from the base 
LOMUNCE LO Dirac tie ae iets RUN OU cs ie nie abe aU er NE 9. Ch. stricta. 
4. Erect filaments numerous, rather short (up to 300 y) to 
very short or wanting; pyrenoid axile. 
5. Erect filaments up to ca. 300 # long, branched. 
6. Filaments 7—10y thick, sporangia tetrasporous 12. Ch. polyblasta. 
6. Filaments 3—4 y thick, sporangia monosporous 14. Ch. leptonema. 
5. Erect filaments up to ca. 60 4 long, usually unbranched, 
sporangia monosporous. 
6. The cells of the creeping filaments give off 2—3 
erect filaments bearing terminal and lateral spor- 
BA EH So ie d OS LOC CR APT BOLD 3 CET SOS CEC DUC cuban 13. Ch. humilis. 
6. The cells of the creeping filaments bear one sessile 
orsstalkedEsporansiuml er Reel 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. virgatula. 
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. Dumontie. 
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. 
