38 



TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



haul of the fine net, taken during the month of the 

 Diatom maximum. 



Date. 



May 



June 



1 



4 



10 



13 



16 



19 



22 



25 



29 



1 



3 



5 



Quantity in c.c. 



Total Diatoms 



2-5 



43,360 



1-0 



10,610 



6-5 



525,68C 



30-2 



19,118,000 



60-2 



54,141,500 



54-5 



34,447,500 



30-5 



27,775,000 



8-3 



2,504,500 



14-8 



22,023,100 



11-3 



4,620,000 



24-7 



13,132,000 



12-7 



2,143,000 



On July 5th Port Erin Bay was invaded by an 

 exceptional swarm of the Copepod Calanus helgolandicus 

 (fig. 14), such as for some years now has always appeared 

 for a few days about this part of the summer. In 1909 

 there was an enormous Calanus swarm on July 17th 

 to 19th. 



After being absent or rare during July, August and 

 most of September Diatoms made their appearance 

 again, for the Autumn visitation, towards the end of 

 September, and were very abundant in all the 

 gatherings during the first week of October. They 

 continued to be present in quantity during October, the 

 high numbers keeping up longer than usual. Both species 

 of Biddulphia (B. mobiliensis and B. sinensis, see fig. 15) 

 occurred in quantity in October, and occasionally in 

 September, an unusually early appearance for B. sinensis, 

 which seems to be in very vigorous condition this year. 

 Readers may be reminded that this is the species from the 

 Far East, which made its appearance in European seas 

 eight years ago, and is rapidly spreading along our 



