OF DIATOMS AND COPEPODA IN THE IRISH SEA. 



121 



species in our records are : — 45,530 on July 11th, 1916 ; 43,800 on June 11th, 

 1913 ; and 34,665 on July 26th, 1910. The average for this species per 

 haul throughout the ten years is 1234. 



Temora (fig. 19) is characteristic of coastal as opposed to Atlantic water, 

 and is the only " neritic " form in our series. The other five are all usually 

 classed as "oceanic,"' but as I have pointed out above most of them are 

 really present throughout the year in the Irish Sea. 



Temora longicornis is on occasions one of the most abundant of our 

 Copepoda in the Irish Sea and must be of considerable importance as a food 

 for fish and especially for the herring in summer. In the latter part of July 

 and the first half of August, 1917, the shoals of herring to the west of the 

 Isle of Man came unusually close to land and even penetrated into baj-s and 

 creeks ; and during this time they were feeding mainly, if not wholly, on 



Fig. 20. — Temora longicornis from the " red patches." From a 

 photo-micrograph by A. Scott. 



Temora. Late in July this Oopepod was so abundant that its presence 

 caused large patches of a red colour on the surface of the sea off Port Erin and 

 around the Calf Island. These red patches were noticed by the fishermen, 

 and were spoken of amongst them as being " fish-food " or " spawn." A 

 large jarful from such a red patch, obtained by one of the fishermen, was 

 brought to the laboratory and found to be swarming with small Copepoda, 

 which on examination proved to be almost wholly Temora longicornis (fig. 20). 

 About one-fourth part of the contents of the jar was preserved, and on being 

 counted later on was found by Mr. Andrew Scott to amount to 50 c.c. 

 of Copepoda, consisting of 33,340 Temora and 2 Calanus. Mr. Scott 

 estimated the oil present in 9 c.c. of the dried Temora at 2 - 47 per cent, of 

 the weight, which was - 925 gramme. 



During this same time the men were catching herring in quantity unusually 

 close inshore in the neighbourhood of the red patches, and on examining, in 



