344 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY- 



THE PLANKTON ON THE WEST COAST OF 

 SCOTLAND IN RELATION TO THAT OF 

 THE IRISH SEA.— Part III.* 



By W. A. Herdman, F.R.S., and Wm. Riddell, M.A. 



In continuation of our attempt to trace the 

 planktonic conditions in the sea lying to the West of 

 Scotland and North of Ireland in relation to those in 

 the Irish Sea, a series of further observations were 

 taken from the S.T. " Runa " during August, 1912. 

 It will be remembered that in several previous summers 

 we obtained at certain localities considerable hauls of 

 phy to- plankton such as are not to be found in the 

 Irish Sea at that time of year, and the suggestion was 

 made that the vernal phyto-plankton, which ceases in 

 our more southern seas some time about May, persists 

 to a later period in the more northern waters — especially 

 in the more land-locked fjords and between the islands, 

 where possibly it is not brought into competition with 

 invasions of oceanic organisms. 



A further point of interest which seemed to call for 



investigation was the distribution of the oceanic 



plankton, and its connection with the physical conditions 



in a wide sense. During the first few summers 



(1907-10) we had worked among the inner islands and 



sea-lochs, from the Clyde Sea-Area to Skye; while last 



year (1911) we extended the observations as far North as 



was possible in the time — to Lerwick in the Shetlands. 



This year (1912) our object was to work still further to 



the West, along the line of the Outer Hebrides, and to 



sample the open Atlantic water to the South of Barra 



* Parts I and II were printed in the Fisheries Laboratoiy Eeports 

 for 1910 and 1911. 



