HOW TO KNOW THE FRESH-WATER ALGAE 

 24a Cells with 4 flagella 25 



24b Cells with 2 flagella 26 



25a Cells flattened when seen from the side or from the top. Fig. 20. 

 PLATYMONAS 



Fig. 20. Platymonas elliptica G. 

 drawn from Smith.) 



M. Smith. (Re- 



Although usually found in brackish water, this 

 genus contains at least one species that appears 

 in freshwater. To make identification the cells 

 should be seen from the top or side to determine 

 whether they are flattened. 



Figure 20 



25b Cells round when seen from the side or from the top. Fig. 21.. . . 

 CARTERIA 



Fig. 21a. Carteria cordiformis (Carter) Dies.; 

 b, Carteria *Klebsii Dill. 



Like Platymonas (Fig. 20) this genus is 

 characterized by having four flagella but the 

 cells are round when seen in end view. The 

 chloroplast is variable in shape and may not 

 appear as shown in the illustration. It may 

 be a thin plate along the wall, cup-shaped 

 and covering most of the wall except at the 

 anterior end, or H-shaped. 



Figure 21 



26a Cell wall with lateral, wing-like margins or flanges 



27 



31 



