388 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



when we have no records of its presence in Port Erin Bay 

 being April. The numbers usually vary from a few 

 hundreds to a few thousands. On the whole, Noctiluca 

 seems to be least plentiful in spring and early summer 

 (February, March, April and May), and to become more 

 abundant in autumn. Our largest haul is 16,400 on 

 October 7th, and the next is 4,600 on November 16th, 

 after which the numbers diminish to the end of the year. 



COPEPODA. 



We have again taken out the records of the nine 

 commonest species of Copepoda, and have obtained the 

 following results: — 



Calanus finmarchicus.* — This species is again 

 present throughout the year, and in rather larger 

 numbers than in 1911. One very high record is 50,720 

 on May 17th, and several hauls from one to over six 

 thousand were taken from April to July. In October 

 there is one large haul, namely, 2,120 on October 7th. 



Pseudo calanus elongatus. — The highest record this 

 year is 91,960 on October 21st; this is nearly twice as 

 large as the highest in 1911. There is another, smaller, 

 maximum in May to June, with 65,200 on May 20th and 

 44,500 on June 17th. Last year the maximum was in 

 July, and there was no marked autumnal increase. 



Oithona similis. — This is again the commonest 

 species in our nets. The highest monthly average is 

 36,444 in June, but the two actually largest hauls are in 

 autumn, 87,530 on September 26th and 75,400 on 



* We have sometimes in the past followed G. O. Sars in calling 

 this species C. helgolandicus, but we are now inclined to agree with 

 Wolfenden, Esterly, and others in thinking that the characters used 

 in the attempt to separate " finmarchicus " and " helgolandicus " as 

 species are too slight and inconstant — and so we return to the older 



