SOME PROBLEMS OF THE SEA. 15 



organisms at bottom, but variety not so great; Acartia 

 and Oithona common all through ; Anomalocera and 

 Centropages and Crab Zoea at surface only; Calanus, 

 Paracalanus and P seudocalanus more plentiful in the 

 deeper water than at surface." Again, on August 24th, 

 three miles west of Bradda Head, Mr. Scott remarks: — 

 " It is evident from the two (surface) collections that 

 there was a difference in the organisms even in a very 

 small space. A marked difference is discernible between 

 the surface and ten fathoms." Throughout these 

 gatherings Oithona seems to be mainly a surface Copepod 

 and Temora mainly a deeper form ; Anomalocera is chiefly 

 on the surface, and Calanus more abundant in the deeper 

 nets. Sagitta is more abundant below than at the top. 

 Although in many cases the deeper gathering was larger 

 than the surface one with the same net, this was not 

 invariably the case as the following examples show : — 



Aug. 24th. — Surface, 8 c.cm. ; 5 faths., 19 c.cm. 



Aug. 27th. — Surface, 11 c.cm. ; 5 faths., 8*5 c.cm. ; 



10 faths., 5 c.cm. 



Aug. 28th. —Surface, 13 c.cm.; 10 faths., 9 c.cm. 



Sept. 6th. — Surface, 6 c.cm. ; 10 faths., 0*5 c.cm. 



Sept. 7th. — Surface, 16 c.cm. ; 5 faths., 6 c.cm. ; 



10 faths., 3 c.cm. 



A fuller account of these details will be laid before 

 the Society on some future occasion in connection with 

 either the Port Erin Report or the Fisheries Laboratory 

 Report; but even without Mr. Scott's analysis of the 

 preserved material there was abundant evidence, to those 

 who saw the catches taken, that the plankton was very 

 unequally distributed over the depths, the localities and 

 the dates. It was clear that one net might encounter a 

 swarm of some organism which a neighbouring net 

 escaped, and that a sample taken on one day might be 



