276 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



eluded here which have little resemblance to the more typical 

 genera, but for which no more appropriate place could be found. 



KEY TO THE GENERA OF CHAETOPHORACEAE. 



i. Fronds erect with differentiated base and apex. 2. 



i. Fronds creeping or expanded, no differentiated base and apex. 5. 

 2. Fronds less than i mm. high, tips not acute nor setiferous. 



22. MlCROTHAMNION. 



2. Fronds larger, tips generally acute or setiferous. 3. 



3. Filaments united in gelatinous thalli of definite form. 



23. CHAETOPHORA. 

 3. Filaments practically free. 4. 



4. Fascicled ramuli different in character from stem. 



25. DRAPARXALDIA. 

 4. Stem, branches and ramuli little differentiated. 



24. STIGEOCLONIUM. 

 5. Filaments originally creeping, producing short, erect branches, 



closely packed into a thin layer. 6. 



5. No dense layer of vertical filaments distinct from basal layer. 8. 



6. Fresh water. 7. 



6. Marine. 21. PILINIA. 



7. Cells of filaments seldom over 10 ,u diam.; sporangia little if any 



larger than vegetative cells. 20. CHLOROTYLIUM. 



7. Cells of filaments seldom under 20 M diam.; fructification in swollen 



terminal cells. 19. GOXGROSIRA. 



8. Filaments more or less united laterally. 9. 



8. Filaments not united. 18. 



9. Forming an irregular loose incrustation. 9. PSEIDENDOCLONIUM. 



9. Forming a definite disk. 10. 



10. Disk mouostromatic. u. 



10. Disk polystromatic. 14. 



ii. Setae or hairs more or less abundant. 12. 



ii. No setae or hairs. 13. 



12. Radiating filaments turning up at the end. 10. ENDOCLONIUM. 



12. Radiating filaments not turning up at the end. 



15. OCHLOCHAETE. 

 13. Disk formed by filaments radiating from a center. 



14. PRINGSHEIMIA. 

 13. Disk formed by the union of irregular filaments. 



13. EPICLADIA. 



14. Setae or hairs present. 16'. 



14. No setae or hairs. 15. 



15. On shells of turtles. n. DERMATOPHYTOX. 



15. On algae, stones, etc.; marine. 12. ULVELLA. 



16. Hairs gelatinous. 16. CHAETOPELTIS. 



16. Setae not gelatinous. 17. 



