108 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
surface layer of the sea being so thick with them that 
every bucket or bottle of water drawn at random brings up 
multitudes. These swarms may be quite local, a few 
miles away there may be none, or the surface fauna may 
have quite a different constitution; and moreover they 
may disappear from a spot very suddenly, moving off to 
another locality or sinking to a deeper layer of water. In 
all probability these changes in the surface fauna have a 
good deal to do with the movements of fish as it is well 
known that the larger Copepoda are an important article 
of food to some fishes, and even to some whales. 
At other times—frequently in winter—the surface fauna 
in our district is chiefly composed of the crystalline worm 
Sagitta; and sometimes the sea over large areas is covered 
with one or more species of the minute Dinoflagellata be- 
longing to the genera Ceratiwm and Peridimum. These 
are known to serve as food for the Sardine off the French 
coast, as many as twenty millions of Ceratuwm tripos having 
been calculated as being at oncein the stomach of a Sardine; 
and no doubt they are equally important in connection 
with our fisheries here. 
These various changes in the surface fauna which are 
indirectly of great economic importance are not matters of 
chance, but must all be due to a definite sequence of events; 
and the question is whether these events, 7.e., the con- 
ditions of the environment both animate and inanimate, 
are too complex for us to determine, or whether we can 
ever hope by accurate observations extending over some 
years to be able to account for, to predict, and even to 
regulate, the presence or absence in a particular locality of 
the food, or the food of the food, of fishes at any given time. 
At any rate the matter is well worth investigating, and I 
would propose that definite observations of the meteoro- 
logical conditions and the surface fauna be taken ~ 
