ACHNANTHES 

 MINUTISSIMA 



SYNEDRA 

 RADIANS 



GOMPHONEMA 

 OLIVACEUM 



E4 



^ 3 



8' 



^ 4 



o 



Jan. Apr. June Sept. Jan. Apr. June Sept. Jan. Apr. June Sept. 



4r 



3 



2 



j I I 



J L 



Jan. Apr. June Sept. Jan. Apr. June Sept. Jan. Apr. June Sept. 



f- / 



J L 



Jan_. Apr. June Sept. Jan. Apr. June Sept. Jan. Apr. June Sept. 



-I L 



Jan. Apr. June Sept. Jan. Apr. June Sept. Jan. Apr. June Sept 



Fig. 201 Distribution of diatoms on slides suspended at different 

 depths at different seasons of the year off two types of shore. (After 



Godward.) 



(2) Those typical of other habitats : 



(a) Species more abundant in streams. 



(b) Species more abundant on inorganic stony shores. 



(c) Species more abundant in the outer parts of highly 

 evolved reed-swamp and throughout the less evolved 

 reed swamp. 



A very definite gradation or succession can be traced in the algal 

 flora as one passes from the inner to the outer reed swamps, from the 

 latter to the open water or stony inorganic shores and finally to the 

 mouth of streams. In other words a progressive change in the algal 

 flora is associated with a bottom that becomes less and less organic 

 in nature or as one passes from eutrophic to oHgotrophic conditions. 



370 



