HOW TO KNOW THE FRESH-WATER ALGAE 

 99b Cells shaped or arranged otherwise 



100 



100a Cells globose, in clumps of 4-8, the groups held together by loop- 

 like fragments of old mother-cell wall. Fig. 81 WESTELLA 



Fig. 81. Westella botryoides 

 de Wild. 



(W. West) 



Figure 81 



This plant should be compared with 

 Dictyosphaerium (Fig. 53) which it may 

 resemble superficially at times. Westella 

 has no gelatinous envelope and although 

 there are strands left by the old mother- 

 cell wall they do not produce the regular 

 radiate structures as in Dictyosphaerium. 



100b Cells appearing oval and bean-shaped in the same colony, in 

 clusters at the ends of radiating, branched strands. See Fig. 52. 



D1MOHPHOCOCCUS 



101a (98) Cells pear-shaped, bean-shaped, or somewhat crescent- 

 shaped, the outer free wall bearing 2 to 4 stout spines; cells ar- 

 ranged at the ends of radiating, stout, gelatinous strands to form 

 a globular colony. Fig. 82 SORASTRUM 



Fig. 82. Sorasfrum americanum (Bohlin) Schmidle. 



There are only 2 species of this genus report- 

 ed from the United States, of which S. spinulosum 

 Naeg. is probably the more common in the 

 plankton. This species has relatively stout 

 short spines and the basal pedicel is scarcely 

 developed so that the colony appears as a 

 compact cluster. 



Figure 82 



101b Cells not so arranged, without spines or with spines different 

 than above 102 



60 



