394 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 

 OlKOPLETJRA. 



In 1912 Oilwpleura dioica was again present in every 

 month, and was unusually abundant. The numbers 

 increased to thousands as early as March 4th, and the 

 highest record was 57,860 on March 11th. The real 

 maximum, however, appears to have been in September, 

 when the monthly average was 11,593, as against 9,709 

 in March. The species died down again in November 

 to hundreds and tens. In this there is no serious 

 departure from the records of the last few years, so it 

 may be taken as expressing in general the normal course 

 of the organism. 



Various Larvae. 



A number of different kinds of invertebrate larvae 

 occur in considerable quantity in the Bay from time to 

 time throughout the year, and must add appreciably to 

 the nutritive value of the zooplankton. We shall note 

 here only a few examples of these. 



Echinoderm larvae are absent in January, but occur 

 in numbers of between one and three thousand per haul 

 on various occasions in February, and run up to 6,000 

 in March. After early April they die off, and are 

 practically absent during the summer, but re-appear in 

 September, reaching a maximum of 3,600 on the 20th. 



Polychaet larvae are present in January, sometimes 

 up to considerable numbers (2,420 on 4th), and become 

 still more numerous in February (over 20,000 on 10th, 

 36,800 on 27th) and March (over 10,000 on 1st and 11,000 

 on 21st). In April the numbers drop to hundreds, in 

 May again there is a slight increase to a few thousands, 

 and that is the condition throughout the summer and 

 autumn — and in fact, with occasional intervals, to the 



