256 EXPLANATION OF THE PLATES. 



Figs. 4 and 4 6. Scytonema corlex, Wood. Portions of filaments, magnified 750 diameters. 

 Fig. 5. Piece of a small twig with a well-formed and also a very young frond of Chaetophora 

 elegans, Ag., growing upon it, magnified a few diameters. 



PLATE VII 



Fig. 1. A perfect trichoma of Scytonema cataractwm, Wood. 

 Fig. 16. A terminal part of a filament, magnified 250 diameters. 



Fig. 2 ffl. A portion of a filament of Scytonema immemum, Wood, magnified 750 diameters. 

 Fig. 2 b. Nearly a whole filament or trichoma, amplified 260 diameters. 



Fig. 3. Rhaphidium polymorphum, Wood, different forms, magnified 150 diameters. 



Fig. 4. Protococcus of undetermined species. 



Fig.' 4 a. The largest and most mature form, probably the hibernating or Winter cell. 

 Fig. 4 b. The same, commencing its active life. 



Fig.. 4 d. Colony cells believed to have been developed out of the cell represented by fig. 4 6, 

 magnified 150 diameters. 



Figs. 4 and 4 c. The motile state of the species. 



PLATE VIII. 



Fig. 1 6. Portion of the frond of Tolypothrix distorta (Miiller), magnified 500 diameters. 

 Fig. 1 a. Heterocysts magnified 800 diameters. 



Fig. 2. Portion of a frond of Sirosiphon pellucidulus, Wood, magniBed 260 diameters. - 

 Fig. 2 a. End of the branch. 



Fig. 3. Portion of a frond of Sirosiphon compactus (Ag.), magnified 260 diameters. 



Fig. 3 a. End of a filament, magnified 160 diameters. 



Fig. 3 c. Portion of a filament showing the heterocyst magnified 460 diameters. 



Fig. 4. Portion of a frond of Sirosiphon neglectus, Wood. 



Fig. 5. Frond of Sirosiphon guttula, Wood. 



Fig. 5 b. End of a branch, magnified 460 diameters. 



Fig. 6. Portion of a frond of Scytonema Nsegelii, Ktz. 



Pig. 7. Different forms of Oloeocapsa sparsa, Wood, magnified 700 diameters. 



Fig. 8. Merismopedia nova, Wood, magnified 400 diameters. 



PLATE IX. 



Fig. 1. Fragment of a frond of Sirosiphon scytenematoides, Wood. 



Figs. 2 and 2 c. Portions of fronds of Sirosiphon lignicola, Wood, magnified 260 diameters. 

 Fig. 2. The end of a branch of the same, magnified 460 diameters. 



Fig. 3 a Portion of a very old frond of Sirosiphon argillaceus, Wood, magnified 460' diameters. 

 Fig 8 6.. A terminal branch of a growing frond of the same. 



Fig. 4 a. A frond of Stigonema Bavenelii, Berkeley, magnified 125 diameters ; also a fragment 

 of the same plant, magnified 450 diameters. 



