HOW TO KNOW THE FRESH-WATER ALGAE 



30b Cell wall without protuberances 



31 



31a Gelatinous envelopes shaped similarly to the protoplasts. Fig. 27. 



CHLAMYDOMONAS 



Fig. 27a. Chlamydomonas polypyrenoi- 

 deum Presc; b, Chlamydomonas 

 sphagnicola Fritsch & Takeda, a spe- 

 cies with bipapillate protrusions at 

 the anterior end of the sheath. 



Whereas this common genus is repre- 

 sented by approximately 175 described 

 species, it is doubtful that they are all 

 distinct. Unless specimens are given 

 careful study they may be confused 

 with other minute biflagellate green 

 cells belonging to other genera, or with 

 zoospores. Variations of the same spe- 

 cies may be described under different names. The species of this genus 

 are encountered more frequently than any other members of the Volvo- 

 cales and are to be found in a great variety of habitats, from the plank- 

 ton of lakes to the green water of rain barrels. A favorable place for 

 them is the barnyard pool or watering trough. C. nivalis (Bauer) Wille 

 produces red snow at high altitudes. 



Figure 27 



31b Gelatinous envelope and protoplast different in shape from one 

 another. Fig. 28 SPHAERELLOPS1S 



Fig. 28. Sphaerellopsis fluviatilis Pascher. 



This genus probably should be classi- 

 fied under Chlamydomonas although spe- 

 cialists separate its 2 species on the basis 

 of the very wide gelatinous sheath be- 

 ing different in shape from that of the 

 protoplast. It occurs in the tychoplanktor 

 of small lakes, and in pools. 



Figure 28 



34 



