240 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The main points of difference between this year's 

 hauls and those of former years are off Ardmore at the 

 north end of the Sound of Mull, and in the sea around 

 the Small Isles. In both places the phytoplankton 

 formerly present is now replaced by zooplankton. More- 

 over, round the Small Isles the Diatoms are now mainly 

 of oceanic type in place of being neritic forms. Other 

 localities are much the same as in previous years ; but in 

 the new ground, further north, there is more phyto- 

 plankton than in the seas south of Skye. 



During all this time (July 8th to August 23rd) the 

 plankton at Port Erin, in the Irish Sea, was an undoubted 

 zooplankton composed chiefly of Copepoda and having 

 few or no Diatoms. 



The facts, such as they are, all seem to support the 

 suggestion, put forward last year, that the most probable 

 explanation of the presence of huge masses of Diatoms in 

 the Scottish Seas in summer is that the phytoplankton 

 remains longer and passes off more slowly as one goes 

 further north. 



