SEA-FISHERIES LABORATORY. 295 
NERITIC AND OCEANIC SPECIES. 
We doubt the utility of attempting to divide all 
planktonic species into the two categories “ neritic ”’ 
and ‘ 
‘oceanic.’” For reasons that are expressed else- 
where in this Sea-Fisheries Report* we are of opinion 
that some at least, possibly a considerable number, of the 
so-called “‘ oceanic ’’ species, are able to live indefinitely, 
and reproduce, in our coastal waters throughout the 
year; and that therefore their presence in in-shore 
gatherings, along with neritic organisms, must not be 
taken as an indication of an inflow of oceanic water. 
The following species, usually considered to be 
oceanic, and most of them regarded as typical of named 
varieties of oceanic plankton, are commonly found 
throughout the year at Port Erin associated with neritic 
organisms : — 
Chaetoceras decipiens (typical of ‘‘ Chaetoplankton ’’). 
Coscinodiscus radiatus (not in large numbers). 
Ceratium tripos (typical of ‘‘ Triposplankton’”’). 
Sayitta bipunctata (with Northern ‘‘Styli-plankton’’). 
Acartia clausi (with Northern ‘‘ Styli-plankton ’’). 
Calanus helgolandicus (considered ‘‘ Boreal Oceanic ’’ plankton). 
Oithona similis (considered ‘‘ Boreal Oceanic ”’ plankton). 
Pseudocalanus elongatus (considered ‘‘ Boreal Oceanic” plankton), 
Oikopleura dioica (Temperate Atlantic). 
As we have already explained in the case of 
Ceratium tripos, we would prefer to call such widely 
distributed species which flourish both in the open ocean 
and in the coastal waters by some such term as 
‘“panthalassic,’’? and we consider it very doubtful 
whether it is safe to base any hydrographic conclusions 
upon their mere presence in a locality. 
We have, however, for the sake of continuity, drawn 
*Herdman and Riddell on ‘‘ Plankton of the West Coast of Scotland 
in relation to that of the Irish Sea ’’—this vol., p. 132. 
