28 Proceedings of the Rot/dl Irish Academji. 



It is the river whose mouth is used as a harbour for the pollen-fishing boats, 

 and from here the plankton fishery was always carried on. 



The low banks with grasses and dense wood should be noticed. 



The remaining picture is very characteristic of the Though Xeagh shores 

 near Antrim. The shores shelve gradually to the water, and are thickly 

 wooded. The ti-ees extend almost to the water's edge, and then a margin 

 of grasses, often very prominent as in the photograph, completes the scene. 



The banks are sandy, and many rare plants — rare for such an inland 

 situation on the banks of a lake — are to be found. 



Methods Employed. 



The method adopted in the course of this work has been to make a series 

 of catches, all of which have been vertical hauls, with a well-known standard 

 plankton net, at one station on Lough Neagh. The catches have been taken 

 at close intervals throughout a year, even though this necessitated travelling 

 from Liverpool each time the investigations were made. The total number of 

 expeditions made to the lake was twenty-one. On each occasion a sailing-boat 

 was chartered from Antrim; and a line was followed until a point about 

 \\ miles S.W. of the entrance of the Six-mile Water was reached. A series 

 of marks were taken on the first expedition, so that the same position could 

 be reached each time. The depth of the water was 40 feet on the first visit 

 to the lake in 1910, but this was reduced to 38 feet after several weeks of dry 

 weather. The weather conditions were always observed, and the catches 

 were made as nearly as possible at the same time of day. Midnight catches 

 have also been taken for completeness. A sounding was always taken before 

 any net-work was carried out, and the boat was then anchored. It was 

 necessary to anchor the boat in order that no di'if ting should take place whilst 

 the net was being lowered. 



In order to obtain absolutely complete knowledge of the plankton of Lough 

 Neagh, it would be necessary to adopt the centrifuge. Such an intensive study 

 would have been far beyond the powers of the two workers, and would have 

 required the co-operation of many specialists. There is no doubt, however, 

 that many species common in the water of Lough Neagh have never been 

 captured. 



From work carried out in April, 1912, at Port Erin, in the course of which 

 sea- water was filtered first through net and then through a Chamberland 

 filter, it was seen that the very minute phytoplankton formed no small part of 

 the total plankton present in the water. These forms belonging to the 

 Nannoplanktou' must occur in Lough Neagh in great numbers, and probably 

 very many unrecorded species exist there. 



'Luhmann, Xannoplankton, 1911. 



