SEA-FISHERIES LABORATORY. 253 



We shall now discuss the occurrence of some of the 

 more important species of Copepoda separately. 



Calanus and Anomalocera. 



The two large Copepoda, Calanus helgolandicus (Claus.) 

 and Anomalocera pattersoni, Temp., are both regarded as 

 oceanic species, and are both present in fair abundance 

 in the Irish Sea. They are two of the most conspicuous 

 objects in our plankton gatherings, and can readily be 

 picked out with the eye and counted. 



Calanus was present in our gatherings in 1907 during 

 every month of the year from January 8th to December 

 30th. It was represented on nearly every occasion when 

 hauls were taken, and in some cases when absent from 

 one net it was taken in another gathering made on the 

 same day, showing that the apparent absence was due to 

 some imperfection in the sampling of the sea. When, 

 then, we find that a species like this is not recorded from 

 a particular haul at a time of year when gatherings are 

 being taken once a week only, one is inclined to suspect 

 from the appearance of the records at other times when 

 the observations were more frequent, that if another haul 

 had been taken that day or on an adjoining day the species 

 would have been represented. The numbers as a rule are 

 not large. They are low at the beginning of the year, and 

 rapidly increase during April. We quote a few of what 

 seem to us representative catches from each month. They 

 are all from the surface nets when not otherwise stated : — 



Shear net. 



Jan. 8 



Feb. 26 



Mar. 26 



April 1 



2 



11 



13 



16 



S 



Surface Nets. 



0-10 full 



14 

 3 



— 



2 



20 45 



400 



330 150 



6 



100 260 



220 



135 150 



3G0 



20 75 



2,000 



