260 EXPLANATION OF THE PLATES. 



Fig. 2. A matured froud of Hydrogaslrum yranulatum (Linu.), enlarged 90 diameters. 



Fig. 2 a. A resting spore of the same, enlarged ICO diameters ; also a minute, very young frond, 

 magnified 90 diameters. 



Fig. 4. A branch of a Stigeoclonium, emitting zoospores, enlarged 4GO diameters. 



Fig. 5. Bulbotrichia albida, Wood, magnified 460 diameters. 



Fig. 6 a. A fertile branch of Bulbochaete Ccmbyii, Wood, showing the matured spore, magnified 

 2(50 diameters. 



Fig. 66. A young plant. 



Fig. 6 c. A branch with young male plants, and a forming zoosporangium, magnified 260 

 diameters. 



Fig. 6 d. The empty cup left after the discharge of the oospore. 



Fig. 6 e. Outline of sporangium. 



Fig. 9. A young plant of Stigeoclonium. 



The globular figures in the lower part of the plate are separate cells of Porphrydium magnificum, 

 Wood, magnified 760 diameters. The numbering of the figures at the bottom of the plate are 

 wrong, fig. 3 should read fig. 4, 4, 5, &c. 



PLATE XVII. 



Fig. 1 a. The basal portion of an old frond of Sohizomeris Leibleinii, Ktz., ? magnified 120 

 diameters. 



Fig. 16. A filament emitting zoospores, magnified 250 diameters. 



Fig. I c. A perfected zoospore. 



Figs. 1 d, 1 e, 1 c. Young plants formed by the germination of the zoospore, magnified 450 

 diameters. 



Fig. 2 a. The distal end of a filament of (Edogo>.iium Huntii, Wood. 



Fig. 2 6. Cells showing the formation and growth of a new cell. 



Fig. 2 c. A portion of filament containing spores in different conditions of maturity. 



Fig. 2 d. A young female plant with attached dwarf plant. 



Fig. 2f. Cells emitting a zoospore, magnified 250 diameters. 



Fig. 2 g. The perfected zoospore. 



Fig. 2 h. Outline sketch of a young male plant, magnified about 1200 diameters. The arrows 



are meant to represent cyclotic currents. 



Fig. 3. A fertile filament of (Edogonium multispora, Wood, showing spores in different states of 

 maturity, and dwarf male plants. 



Fig. 4 e. Sterile cells of Spirogyra dubia, Ktz., enlarged 260 diameters. 



Figs. 4 and 4 d. Outline sketches of cells containing spores, magnified 260 and 160 respectively. 



Figs. 5 a and 5 b. Sterile cells of Spirogyra rivularis (Hassall), magnified 260 diameters. 

 Fig. 5 c. Outline sketch of conjugating cells with spore similarly amplified 



PLATE XVIII. 



Fig. 1 a. A young female plant of Pringsheimia insequale, Wood, magnified 250 diameters. 



Fig. 1 b. A portion of an adult female plant, containing immature spores, and showing in out- 

 line in the upper sporangium the orifice through which the spermatozoa enter, magnified 250 dia- 

 meters. 



Fig. 1 c. The supposed young male plant, magnified 450 diameters. 



Fig. 2. (Edogonium mirabile, Wood. A portion of a filament with a partially matured spore. 



