EXPLANATION OF THE PLATES. 261 



Fig. 2 a. A portion of a fomale plaat, showing the beginning of the dfvclopnicnt of ibu fomalu 

 n-urm, 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 j)or- 

 tion, with the outline of the attached male plant. 



Fio- 2 c. A fertile filament coutaiuiug a matured spore. All of these figures are magnified ICO 

 diameters. 



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

 contains a nearly perfected androspore, magnified 400 diameters. 



Figs. 2 b and 2 g. Different views of dwarf male plants discharging spermatozoid,«, the first figure 

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



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



Fig. 3. Matured spore of CEdogonium echinatum, Wood, uncolored and magnified 750 diameters. 



Fig. 4. Spores in sporangia of a Florida (Edogoniumof undetermined species. 



Fig. 5. Bulbochaete ignola, Wood. 



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

 germs. 



Fig. 5 b. Sporangium containing a nearly matured spore. All magnified 4G0 diameters. 



Fig. 6 a. Part of a frond of Bulhochsete dumosa, Wood, with female g-erms 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. 



Fig. 6 b. Male plant discharging spermatozoid, magnified 150 diameters. 



Fig. 7 a. Part of a sterile filament of a Conferva of unknown species. 



Fig. 7 b. The same discharging zoospores. 



Fig. 7 c. A cluster of germinating zoospores. 



Fig. 7. A young plant. All these figures are magnified 500 diameters. 



PLATE XIX. 



Fig. 1. Stigeoclonium, showing chaatophoroidal stage. 



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

 Fig. 2 6. A fragment of a fertile branch, magnified 260 diameters. 



Fig. 3. A portion of a fertile filament of Chantransia macrospora, Wood, magnified 460 

 diameters. 



Fig. 4 a. Outline of some fertile cells of Sp'irogyra qninina, Ag. 

 Fig. 4 b. Filaments in an advanced stage of conjugation. 

 Fisrs. 4 c and 4 e. Fragments of sterile filaments. 



TLATE XX. 



Fig. L Stigeoclonium, found near Philadelphia. 



Fig. 2. Arlhrodesmus quadridens, Wood, as viewed from the end, and magnified 259 diameters, 

 also a front view of similar amplification. 



Figs. 3 and 3 a. Different forms of fructification of Vauchcria pobjmorpha, Wood, showing the 

 emptied antheridia and fertile sporangium. 

 Fig. 3 b. An immature antheridium. 

 Fig. 3 c. Spore of same species. 



Fig. 4. Section through fertile node of Lcvianca lorulosa (Roth). 



