HOW TO KNOW THE FRESH-WATER ALGAE 



245a Endophytic in walls of other algae 246 



245b Not endophytic in walls of other algae 247 



246a Cells bearing setae which are sheathed at the base. See Fig. 150. 

 COLEOCHAETE 



246b Cells not bearing setae. Fig. 175 ENTOCLAD1A 



.2^ 



Fig. 175. Entocladia polymorpha 

 (G. S. West) G. M. Smith. 



Figure 175 



This genus includes only 2 

 known species in the United 

 States. Although probably very 

 common it is easily overlooked 

 because the thalli are small and 

 grow inconspicuously within the 

 walls of larger algae. 



247a (245) Some cell walls bearing setae with a sheathed base; terminal 



cells of branches not tapering to form hairs. See Fig. 150 



COLEOCHAETE 



247b Cells with setae that are not sheathed at the base, or if without, 

 ends of branches tapering to form hairs 248 



248a Setae and terminal hairs multicellular 249 



248b Setae one-celled 



250 



249a Multicellular setae arising from lateral walls of the cells. Fig. 176. 

 PSEUDOCHAETE 



Fig. 176. Pseudochaete gracilis West 

 <& West. 



This species is rarely found, growing 

 partly prostrate, partly erect on sub- 

 merged plants or other substrates. The 

 branched filaments taper at both ends. 

 Some of the lateral branches form long, 

 narrow and finely tapering hairs. Some 



authorities regard Pseudochaete as a form of Stigeoclonium. See Fig. 



177. 



Figure 176 



112 



