44 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



by a total of over 166 millions for the eight hauls in May. 

 Chaetoceras decipiens and Biddulphia mobiliensis were the only 

 two diatoms that were never completely absent from the 

 Bay plankton of the ten months. Guinardia flaccida, Rhizoso- 

 lenia shrubsolii and R. semispina were the most conspicuous 



Fig. 6. Plankton showing Biddulphia mobiliensis and B. sinensis. 

 diatoms in the summer maximum. It was estimated that 

 3 millions of the first and over 17 millions of the second were 

 present in the nine hauls of the June plankton. The diatom 

 minimum occurred in August. Only three species were 

 observed in the nine collections and the total number of 

 individuals was 3,420. 



Ceratium tripos was present throughout the ten months. 

 The maximum of the Dinoflagellata was reached in May 

 with nearly 300,000 in eight hauls. Noctiluca appeared to 

 have been unusually abundant this year. It was present every 

 month except August. It was estimated that the plankton 



