208 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



example of B. sinensis. Our B. mohiliensis undoubtedly 

 approaches the form " regia," regarded as a distinct 

 though allied species by Ostenfeld (Medd. Kom. 

 Havunders., Plankton, Bd. I. 6, 1908). Gran, in the 

 Diatomacea of the Nordisches Plankton, unites these two 

 forms as B. mohiliensis. 



In our district B. sinensis is of more elongated form 

 than is shown in Ostenfeld' s figures. Most of our 

 specimens of B. sinensis are very distinct and easily 

 distinguishable from the mobiliensis-regia group by 

 the shape and the position of the spines, but we have 

 found one or two specimens during this last year where 

 one end of the cell bore the characters of sinensis, while 

 the other had the appearance of mohiliensis. Until, 

 however, we get further specimens we do not propose to 

 base any opinion as to the species upon this possibly 

 abnormal form. We are watching the fresh material of 

 B. sinensis carefully in the present year (1912), and may 

 return to the subject in our next report. 



DlNOFLAGELLATA. 



The monthly averages for Ceratium and Peridinium 

 throughout 1911 were as follows: — 



1911. 



Ceratium 

 tripos. 



Peridinium 

 spp. 



1911. 



Ceratium 

 tripos. 



Peridinium 

 spp. 



January . . . 

 February ... 



March 



April 



3,402 

 1,815 

 1,820 

 505 

 9,131 

 28,811 



44 











2 



6,522 



14,335 



July 



17,942 

 1,385 



8,478 

 8,422 

 6,382 

 4,866 



864 



August 



September 

 October ... 

 November... 

 December . . . 



125 

 33 

 12 



May 



47 



June 



11 







We have taken, in the case of Ceraftium, the 

 familiar form commonly known as C. tripos, without 

 discriminating between the sub-species or varieties which 



