272 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
much smaller in volume since a very much smaller 
column of water was passed through the net. The 
vertical haul strained about 6 fathoms, and the surface 
net perhaps on the average about a quarter of a mile, say 
220 fathoms, or about forty times the amount. The 
volume of the surface catches is, however, not twenty 
times larger than those of the vertical net, which seems 
to indicate that there is a greater amount of plankton a 
fathom or two down than at the surface, a conclusion 
that agrees with what we found to be the case in the open 
sea In our previous work. 
Tasue IJ. Monthly Averages for Vertical Hauls, in Bay. 

Number of Average Dinoflag- Copepoda Copepoda Copepoda 
1910. single catch. Diatoms. ellates. adult. juv. nauplii. 
hauls. 
February 9 0-23 381 39 16 0 28 
March ayn... 8 0:2 2,154 15 12 4 104 
ADT ese ter es 9 3°83 246,390 57 71 39 394 
MEY Me retsents 8 3°86 96,449 642 204 253 1,276 
a UNO ae cco eeees 6 1-1 39,596 1,232 229 152 613 
JULY Oo vsnceeees 8 1-4 40,644 1,293 664 80 667 
August ...... 9 1-05 40 405 554 27 398 
September ... 9 1-4 7,587 168 630 53 $12 
October ...... 9 1-54 14,385 40 411 97 251 
November ... 8 0-51 1,698 6 150 38 29 
December ... 9 0-24 590 10 92 5 20 

These tables bring out very clearly that the main 
Diatom maximum this year was in April, whereas last 
year the large catches extended well over April, May 
and June, and were heaviest at the end. In this, as in 
some other respects, 1910 seems to agree better with 
1907, the first year of this series of observations, than 
with more recent years. The greatest monthly averages 
of both Diatoms and the total plankton are in April, the 
summer minimum of both is in July or August, after 
which in both cases there is a rise in September and 
October and then a distinct fall to the winter minimum. 

