180 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
it is scarcely justifiable to class a little-known species as 
neritic simply because it is found to produce a resting- 
spore. 
Furthermore, even when dealing with species in 
regard to the oceanic nature of which there can be no 
reasonable doubt, it would be unwise to base hydro- 
graphic theories upon the occurrence of a few individuals 
upon one or a small number of occasions in perhaps a 
single locality. There are so many accidents by which 
small floating objects in the sea may be conveyed from 
place to place, even for considerable distances. Storms, 
prevalent or exceptional winds, high tides, unusual 
conjunctions of wind and tide, to say nothing of ships 
and other human agencies, may all on occasions play 
their part in helping to convey oceanic organisms (even 
one Diatom may suffice if it lives for a time and 
reproduces) into a neritic area where their presence must 
not be taken as being necessarily an indication of flooding 
with oceanic water. 
It is for these reasons that we hesitate to put 
forward in any dogmatic spirit the hydrographic 
conclusions to which a consideration of the supposed 
oceanic and neritic organisms found in our West Coast 
and Hebridean plankton catches would seem to point. 
If, then, we now proceed to classify the species into the 
two categories, and show how they may possibly in their 
distribution afford an indication of the course taken by 
marine currents, it must be considered that we are 
putting forward suggestions which may be tested by 
future work rather than laying down conclusions which 
we regard as established. 
It may be useful if we arrange the commoner species 
of the West Coast plankton in what would be regarded 
by most planktologists as their probable positions in the 
