EXPLANATION OP THE PLATES. 261 



Fig. 2 a. A portion of a female plant, showing the beginning of the development of the female 

 germ, i. e. the formation of a very large cell. 



Fig. 2 6. A further stage of the process, showing the cell divided into an upper and lower por- 

 tion, with the outline of the attached male plant. 



Pig. 2 c. A fertile filament containing a matured spore. All of these figures are magnified 160 

 diameters. 



Fig. 2d. A couple of cells, one of which has divided into four daughter-cells, each of which 

 contains a nearly perfected androspore, magnified 460 diameters. 



Pigs. 2 b and 2 g. Different views of dwarf male plants discharging spermatozoids, the first figure 

 offering a profile view of the cap, the second a view from behind, magnified 400 diameters. 



Pig. 2 e. A three-celled dwarf male plant, magnified 460 diameters. 



Pig. 3. Matured spore of CEdogonium echinatum, Wood, uncolored and magnified WO diameters. 



Fig. 4. Spores in sporangia of a Florida CEdogonium of undetermined species. 



Fig. 5. Bulhochaete ignota, Wood. 



Pig. 5 a. Branches of a frond, showing different stages in the early development of the female 

 germs. 



Pig. 5 6. Sporangium containing a nearly matured spore. All magnified 460 diameters. 



Pig. 6 a. Part of a frond of Bulbochaete dumosa, Wood, with female germs and dwarf male plants 

 in different stages of development, magnified 260 diameters. The fine markings on the spores have 

 not been reproduced in the chromo-lithograph from my drawing. 



Pig. 6 b. Male plant discharging spermatozoid, magnified 750 diameters. 



Fig. "I a. Part of a sterile filament of a Conferva of unknown species. 



Fig. t b. The same discharging zoospores. 



Fig. 1c. A cluster of germinating zoospores. 



Pig. *l. A young plant. All these figures are magnified 500 diameters. 



PLATE XIX. 



Fig. 1. Stigeoclonium, showing chaetophoroidal stage. 



Fig. 2. Portion of a fertile filament of Chantransia expansa, Wood, magnified 125 diameters. 

 Fig. 2 &. A fragment of a fertile branch, magnified 260 diameters. 



Pig. 3. A portion of a fertile filament of Ghanlransia macrospora, Wood, magnified 460 

 diameters. 



Pig. 4 a. Outline of some fertile cells of Spirogyra quinina, Ag. 

 Pig. 4 6. Filaments in an advanced stage of conjugation. 

 Pin-s. 4 c and 4 e. Fragments of sterile filaments. 



PLATE XX. 



Fig. 1. Stigeoclonium, found near Philadelphia. 



Pig. 2. Arthrodesmus quadridens, Wood, as viewed from the end, and magnified 259 diameters, 

 Etlso a front view of similar amplification. 



Figs. 3 and 3 a. Different forms of fructification of Vaitcheria polymorpha, Wood, showing the 

 emptied antheridia and fertile sporangium. 



Fig. 3 6. An immature antheridium. 



Fig. 3 c. Spore of same species. 



Fig. 4. Section through fertile node of Lemanea (orulosa (Roth). 



