PLATE 4.— Confervoidese. 



Figure 



1 . Aphanizomenon Flos-aquce, Morr. a, ordinary filaments ; b, filaments with 



spermatic cells ; c, filament with a vesicular cell {heterocyst) . 



2. Trichormiis muscicola, n. sp. a, filament with vesicular cell ; h, ditto, with 



adjoining spermatic cells ; c and d, fragments treated with acid to render the 

 membrane and contents distinct; e andy, spermatic cells similarly treated. 



3. Sphcei'ozyga elastica, Ag. 



4. Cylindrospermiim catenatum, Ralfs. 



5. Spermosira littoralis, Harv. 



6. DoUchospermiim Ralfsii, Thwaites. 



7. Nostoc commune, Vauch. a, ordinary filaments ; b, a single filament in its 



gelatinous sheath ; c and d, fragments with a vesicular cell. 



8. Oscillatoria autiimnalis, Ag. «, fragment escaped from a sheath b. 



9. Microcoleus repens, Harv.; b, fragments showing the single sheaths; c,d, frag- 



ments treated with sulphuric acid and iodine. 



10. a, by lAjngbya muralis, Ag. 



11. Dasyglcea amorpha, Berk. 



12. «, h, Hassallia ocellata, Berk. 



13. Schizosiphon WarrenicB, Caspary. a, tuft of filaments; b, c, fragments; d, e, 



decomposing sheaths. 



14. Tolypothrix distorta, Kiitz. 



15. a, Ainactis calcarea, Kiitz. ; b, fragment showing the spiral sheath. 



16. Euactis atra^ Kiitz. 



17. Schizothrix Creswellii, Harv. 



18. Rivularia Botyana, Kiitz. 



19. Scytonema Myochrous, Ag. 



20. Arthronema cirrhosum, Hass. 



21. Petalonema alatumy Berk. {Arthrosiphon Grevilliiy Kutz.). a, end of a filament ; 



b, cross section. 



22. a, Calothrlx mirabilisy Ag. ; by junction of filaments. 



