68 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



quently, it may be of interest that I should print here a few 

 paragraphs from an article that was drawn up for last year's 

 report on the Lancashire Sea Fisheries scientific investigations 

 for the purpose of showing what was known of the connection 

 between plankton distribution and the occurrence of fisheries. 



Many of the older naturalists worked at marine plankton 

 qualitatively, and even connected the prevalence of certain 

 organisms with the prosperity of sea-fisheries ; but modern 

 instruments and methods of precision, such as might be 

 expected to prove quantitatively the influence of variations in 

 the type and amount of plankton, at different seasons and 

 depths, upon the movements and abundance of fishes, have 

 only been employed of recent years, and it is still too early to 

 expect much in the way of demonstrated result. However, 

 some data have been obtained which are full of promise for the 

 future. 



Many commercial fishes feed upon plankton during at least 

 some portion of their life. The Loch Fyne herrings are fre- 

 quently, at the time of a fishery, found to have their stomachs 

 filled with Nyctiphanes, Euchaeta or Calanus. In some parts 

 of the Hebridean seas the herrings have their stomachs filled 

 with the Pteropod Limacina retroversa, and other oceanic 

 organisms which may be carried in swarms into our coastal 

 waters. Many other similar cases could be quoted, and are 

 known to biologists. 



Then as to demersal fish — young plaice, after their meta- 

 morphosis, feed chiefly on Copepoda, while in younger stages 

 the larval plaice feeds upon Diatoms. We have found at Port 

 Erin the post-larval plaice with its stomach shining through of a 

 golden-brown colour from the Diatoms with which it was filled, 

 and we have watched in a shallow pond the metamorphosed 

 small plaice darting backwards and forwards pursuing, catching 

 and devouring the individual Copepoda. Then again it has 

 been shown that these Copepoda in their turn feed on 



