286 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



reverse condition holds good : the annual range of tem- 

 perature therefore decreases with the distance of the 

 station from the land. The second line of Stations 5 to 

 7 lie on a line between Calf of Man and Holyhead, and 

 are nearly equidistant on either side from the land and 

 from each other. There is much more uniformity at 

 these points. Station 7 is about ten miles distant from 

 Holyhead, and is probably affected slightly by the tidal 

 stream which enters Carnarvon Bay as an indraught, and 

 sweeps out again ; but Stations 5 and 6 are probably not 

 at all affected in this way, and their annual range of 

 temperature is only about 5'5°, a value which is not much 

 greater than of the water in the Atlantic Ocean west 

 from Ireland. Midway between Isle of Man and Ireland, 

 and in an area including these three stations the physical 

 condition of the sea is probably more uniform than in 

 any other place north of Anglesey : it is here that critical 

 and really quantitative experiments would probably 

 indicate a high degree of uniformity in the distribution 

 of pelagic life. Nearer the land, on either side, the 

 physical conditions become much more complex, as the 

 sea becomes more shallow, and the influence of the tidal 

 streams becomes apparent. The annual range of tem- 

 perature at Port Erin is very much the same as that off 

 the coast of Anglesey between Carmel Head and Point 

 Lynus. There is hardly any trawling in this part of the 

 Irish Sea, nor round the south end of the Isle of Man 

 on the one hand, nor off the coast of Anglesey between 

 Point Lynus and South Stack on the other. 



The sea between Point Lynus and the Liverpool 

 North-West Light Vessel, south from about parallel 

 53° 30' N. is intermediate in physical conditions between 

 the two areas mentioned. There are few large sand- 

 banks along the coast of North Wales, and those of 



