226 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



estimate, for example, how far our local seasonal changes 

 in the plankton are due to migrations or invasions from 

 outside waters. 



As the region to the south of the Irish Sea, including 

 the English Channel, is being thoroughly investigated 

 under the scheme of the International Council, and the 

 necessary data will therefore naturally be available from 

 that source, it becomes all the more important to do all 

 that is possible to get information in regard to the con- 

 dition of the plankton in the seas off the north of Ireland, 

 and the west and. north-west coasts of Scotland. 



Cruise of 1911. 



During this last summer, July and August, 1911, we 

 were able to devote a longer time than in previous years 

 to a more detailed survey, from the yacht " Runa," with 

 both bottom and surface nets, of a considerable area of the 

 west and north of Scotland. Our observations extend 

 from the Irish Sea as far north as Noup of Noss in Shet- 

 land (from about 54° N. lat. to 60° N : . lat.), and as far 

 west as Castle Bay in Barra. They include 152 observa- 

 tions of the sea-temperature, and 142 of the salinity, and 

 not only sample the water at a number of points lying off 

 the Coast of Scotland, but also give us a series 

 of observations across the northern entrance to 

 the Irish Sea, as follows: — On August 22nd, 

 when crossing from the south end of Cantyre 

 to the north of Ireland, a series of nine temperature and 

 salinity observations were taken, one every hour during 

 the most important part of the traverse; and on the 

 following day when crossing from Larne in Ireland to 

 Port Erin, another series of eleven hourly observations 

 was taken. 



During these two months (July 7th to August 



