48 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



except for the chloroplast, which is in the shape of a trans- 

 verse band. The filaments are furnished more or less densely 

 with alternate or opposite, tufted branches. These are com- 

 posed of smaller, green, fertile cells, the end cell often a color- 

 less spine. From one to four zoogonidia, with four cilia apiece, 

 arise from each cell of the lateral branches. Usually all the 

 cells of one tuft form zoogonidia at the same time, and the 

 whole process occupies but a few minutes. A gelatinous 

 sheath, soft and slippery, covers the whole. Found in clear 

 streams, attached to stones or water-plants. 



D. plumosa (Vauch.) Ag., Figs. 83, 84. 



D. glomerata (Vauch.) Ag., Fig. 217. 



[D. acuta (Ag.) Kutz.] 



FAMILY III. CYLINDROCAPSACE^E. 



Filamentous green Algae, without branches or roots, living 

 either in water or air. The filaments are covered with a thick, 

 lamellose sheath, and the cells are lamellose and are in a 

 single series. 



In an ordinary vegetative cell the contents mass together to 

 form one oosphere. The antherozoids, which change from 

 green to red or orange are each provided with two short 

 cilia. After the oosphere is fertilized, it also changes to red or 

 orange, and lies resting for some time before it germinates. 



Cylindrocapsa Reinsch. With the characters of the 

 family. They are at first attached, then floating. 



FAMILY IV. ULOTRICHACE.E. 



Filaments simple, composed of cylindrical or of rounded 

 cells. The cell wall is always colorless, though of varying 

 thickness. Each cell contains a single parietal chloroplast 

 with irregular margins and one pyrenoid. Asexual reproduc- 

 tion takes place in various ways. Both motile and non-motile 

 .spores are produced; of the former some are large (macro- 

 zoogonidia) and some small (microzoogonidia). The plants 

 also multiply by dismemberment of the filament into single 

 cells or series of cells. Sexual reproduction by isogamous 

 gametes. 



