HOW TO KNOW THE FRESH-WATER ALGAE 



20a Cells fusiform with sharply pointed lateral processes or extensions 

 of the protoplast. Fig. 16 STEPHANOSPHAERA 



Fig. 16. Stephanosphaera pluvi- 

 alis Cohn. Oval colony with 

 organisms forming a median 

 band. The cells commonly 

 show 2 pyrenoids (starch- 

 storing bodies). 



Like Pascheriella (Fig. 11) this 

 plant occurs in small, tempo- 

 rary pools; is easily identified 

 by its irregularly shaped cells 

 forming a transverse belt in a 

 compressed, spheroidal gelatin- 

 ous sheath. 



Figure 16 



20b Cells round or ovoid, without lateral processes 21 



21a Cells all the same size within the colony. Fig. 17 EUDORINA 



Figure 17 



Fig. 17. Eudorina elegans Ehr. 

 In this species the cells have 

 a tendency to arrange them- 

 selves in transverse bands or 

 tiers. Occurs along with 

 Volvox (Fig. 15) and Pleo- 

 dorina (Fig. 18). 



Unlike Pandorina (Fig. 14) the 

 cells are round or oval and 

 rather evenly spaced within 

 the colonial mucilage. Eudo- 

 rina unicocca G. M. Smith is 

 another species which has been 

 reported from the United States, 

 differentiated by the colony 

 showing a slight polarity with 

 the sheath forming lobes at the 

 posterior end. 



29 



