— 01 



Eunotia lunaris of February and March 1908 was noticed 

 especially on Microspor a. Ourdataon thèse points are how- 

 ever inadéquate, and we hope to return to the matter in a later 

 communication. But there certainly seems évidence both from 

 direct observation and from a considération of the relative fre- 

 quency of the two epiphytes that their degree of représentation 

 in a given vear is dépendent on the extent of development of a 

 particular host. 



Table to show relation, between représentation of epiphytic 



Diatoms and Microspora, Conferva and Oedogonium 



in Bartons pond, W06-190V. 



Unlike the three Diatoms hitlierto considered, the species of 

 Navicula show no especial préférence for the colder montlis of 

 tlie vear; in fact they were almost regularly observed in some 

 quanti ty in August, although certainly also at their best in the 

 colder months (December to March). Particularly the small 

 species of Navicula (like the N. lanceolata and N. exilis with 

 which we are specially concerned) are well known to hâve a 

 préférence for water rich in organic substance and the amount 

 of the slight summer-maximum in Barton's pond appears to bear 

 a direct relation to tins. Thus taking the total decreases of 



