279 
Pl. cell. aph. 1 . HYDROPHYTE. 
Thallus mostly branched ; branches blad- 
dery Vaucheria. 10. 
Thallus entangled, in a determinate form; 
branches clublike Codium. II. 
E. Thallus jointed , filamentous ; filaments flat , brittle . 
Diatomidese. 
Joints not banded; sporidia in transverse 
lines Fragilaria. 12. 
Joints banded transversely, with a cen- 
tral spot Biddulphia. 13. 
Joints banded longitudinally Diatoma. 14. 
F. Thallus jointed , filamentous ; filaments cylindrical , 
coupling . Conjugatidese. 
Filaments parallel; granules spiral .. . Conjugata. 15. 
Fil. parallel; granules 2-dotted Zygnema. 16. 
Fil. bent; granules scattered; 
sporce elliptical, in the joint Choaspes. 17. 
Fil. bent ; granules scattered ; 
sporce cruciform, in the contracted joint . . . Agardia. 18. 
Fil. bent ; granules scattered ; 
sporce round, in the transverse tubes . . . Serpentina. 19. 
G. Thallus cylindrical , anastomosing , neilike . Hydro- 
dictyanidese. 
Filaments anastomosing; sporce netlike 
Hydrodictyon. 20. 
H. Thallus cylindrical , simple , or branched , not couplings 
nor anastomosing. Confervideoe. 
Thallus from a common base ; 
branches pointed, pellucid Myriodactylon. 22. 
Thallus from a common base ; 
branches obtuse, clublike Leathesia. 23. 
Thallus from a common axis Ch^etophora. 21. 
Thallus uniform, simple or branched . . Conferva. 25. 
Thallus difform; branches pencil- 
shaped, jointed Draparnaldia. 24. 
