SEA-FISHERIES LABORATORY. 363 



net was worked at a depth of about 10 fathoms, a zone 

 where the larger Copepoda and Sagitta and various 

 larvae are usually more abundant than they are at or 

 near the surface where the finer nets were worked. 



These surface hauls in Loch Swen, those in the 

 Sound of Mull, those at the mouth of Loch Seaforth, and 

 those in Upper Loch Torridon and off the south end of 

 Colonsay, are the only ones in the whole series that can 

 be described as a well-marked phyto-plankton. They are 

 the only ones that are more or less comparable with the 

 green, flocculent, diatomaceous gatherings which we 

 obtained, in July, on some previous cruises on various 

 parts of the West Coast, at localities where this year 

 there was an oceanic zoo-plankton or more or less of a 

 mixture. 



Conclusions. 



No less than three masses of sea-water of different 

 origin and character may enter or affect the British seas 

 in varying quantity, viz. : — (1) Arctic water such as 

 normally surrounds Iceland, and may extend further 

 southwards and eastwards towards the Faroes and 

 Shetlands ; (2) Atlantic water which impinges on the 

 western shores of Ireland, and may flood the English 

 Channel and extend round the Shetlands or down into 

 the North Sea ; and (3) coastal water such as occupies the 

 Baltic, bathes the coasts of N.W. Europe generally, and 

 to a large extent surrounds the British Islands. 



The seas on the west coast of Scotland are on the 

 border line of the last two kinds of water, and may be 

 regarded as primarily an area of coastal water which is, 

 however, periodically invaded to a greater or less extent 

 by bodies of warmer and Salter Atlantic water carrying 

 in oceanic plankton. The variations which we find in 



