Scenedesmus 



Schizogonium 



Schizochlamys 



Schizomeris 



Sciadium 



Scytonema 



Sirogonium 



Sirosiphon 



Sorastrum 



Sphseroplea 



Sphaerozosma 



Sphaerozyga 



Spirogyra 



Spirotaenia 



Spirillum 



Spirulina 



Staurastrum 



Staurogenia 



Staurospermum 



Stephanosphaera 



Stigeoclonium 



Symphyosiphon 



Symploca 



Synechoccocus 



T. 



U. 



V 



117 



Page. 



94 



54 

 37 



65 

 86 



37 



45 



55 



48,' 49 

 49 



95 



61 

 61 



