- 89 



The other Diatoms, that plav an important part in the pond, 

 are epiphytic fonns, and one would therefore expect that the 

 mosl important déterminant will be the présence of a suitable 

 substratum. Before we turn to consider this matter however 

 attention m ay bedràwn to the fact that ail the marked maxima 

 of Synedra radians and Eunotia lunàris i'all into the cold 

 part of the year, with the exception of the •• rallier coramon » 

 of the latter Diatom in Àugust 1906, for which we are unable 

 to account. 



Table to show occurrence of principal Diatoms in 

 Bartons pond, 1906-1909 (1) . 



•Tan. 



Fel.. 



Mar. 



Apr. 



May .Tune Julv 



Au--. 



Sept. 



Xo\ 



Dec. 



«S i 



rr. 

 rc. 

 vr. 



rr. 

 r. 

 r. 



rr 

 vr. 



rr. 



rc. 



r. 

 rc. 

 rr. 

 r. 



(1) Regarcling the symbols, see lbotnote 1 on p. 54, 



