278 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
alternate weeks at the time of the spring tides, and then 
run as strong currents past the headlands, such as 
Langness, Point of Ayre, and practically all round the 
Calf Island. It is probable that these tidal races give rise 
also to vertical currents in the water, which may bring up 
to the surface plankton from deeper zones. Some of our 
gatherings taken in these strong currents close to the cliffs. 
of the Calf Island have been exceptionally large, and 
have contained exceptional organisms, possibly as a result 
of these complex movements and the mixing of various 
waters. Our observing stations off Port Erin have been 
ae 
OFF PORT ERIN —l.a,M; 
g Sp 
Pe i S ig .. 
Kies 10: 
carefully chosen, so as to be under different tidal 
conditions :—Station I, five miles offshore, is just on the 
outer edge of the main tide running north and south; 
Station IT, ten miles out, is in the central area marked as 
having no perceptible tide; Station III, along shore to 
the north, and Station IV, alongside the Calf Island, are 
both in the inshore tides, the former in a slacker and the 
latter in a stronger current: and finally Station V, south 
of Spanish Head, is in a different tidal current which runs 
from the Chicken Rock Lighthouse towards Langness. 
