-A PLANT INJURIOUS TO DRINKING WATER. 

 . — Elongated colouy. 

 . — Spherical colony — ordinary form. 

 -Encysted state. 



-Disintegrating zooids — oil globules escaping. 

 -Zooids flattened under the cover-glass, showing 

 oil-globules. 

 Fig. 6. — Zooids flattened under the cover-glass — a variety 

 with crenulated margin. Not common. 



