SEA-FISPIERIES LABORATORY. 225 



THE PLANKTON ON THE WEST COAST OF 

 SCOTLAND IN RELATION TO THAT OF 

 THE IRISH SEA.— PART II. 



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



Introductory Note. 



In last year's Report we pointed out that our know- 

 ledge of the plankton of the western coasts of the British 

 Islands is incomplete, by reason of a great gap extending 

 from the North of Scotland down to the Irish Sea — a gap 

 in our knowledge which neitlier the International observa- 

 tions on the one hand nor those of the Irish or Scottish 

 Authorities on the other seem to fill up. With the view 

 of obtaining data, which might in part at least bridge this 

 gap and possibly throw light upon the question of the 

 seasonal changes in the plankton of the Irish Sea, one of 

 us has for several years, during the summer vacation, 

 taken plankton hauls, l)oth vertical and horizontal, from 

 his vacht at various localities amongst the islands and sea 

 lochs of the west of Scotland as far north as Portree in 

 Skye, and as far out to the west as the Island of Barra. 

 In our paper last year we discussed these data, and were 

 able to show that the state of affairs in these Scottish seas, 

 at that time of year, is somewhat different from that in 

 the Irish Sea. At some spots in the Hebridean seas, for 

 example, large phytoplankton hauls may be taken in 

 July, at the time when in Manx waters the hauls are 

 comparatively small, and are composed of zooplankton. 

 It thus becomes of fundamental importance in connection 

 with local sea-fisheries problems to determine more accu- 

 rately the relation of the Irish Sea plankton to that of 

 neighbouring waters to the north, to the south, and in the 

 Atlantic outside. Such information may enable us to 



