102 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
larvae reached a maximum of 8,700 on March 25th and were 
also abundant in September. Polychaet larvae were especially 
abundant in the first half of the year; amongst the largest 
hauls were 147,600 on March Ist and 190,000 on April 9th. 
Balanus nauplii were most abundant from middle of March to 
late in April (299,230 on April 22nd), while the Cypris stage 
ranged from middle of April to the end of May. Crab zoeas 
reached their maximum at the end of March (810 on March 
28th). Molluscan larvae were present in all months, but most 
abundantly in spring, and again in the latter part of the year. 
The largest haul is 130,200 Lamellibranch larvae in April. 
Fish eggs ranged from February to August inclusive, 
with the maximum at the end of March; but the fish eggs of 
the plankton throughout the year have been discussed in a 
separate article by Andrew Scott, at p. 89. 
One conclusion that is becoming clear from our accumu- 
lated observations of the last ten years is the surprisingly 
small number of different kinds of organisms—both plants 
and animals—that make up the bulk of the plankton that is 
of real importance in relation to fish. Our food from the sea 
seems to depend, in great measure, ultimately upon compara- 
tively few species of Diatoms and Copepoda respectively. A 
very large proportion of the Diatoms in the spring plankton 
and of Copepoda in that of late summer belong in each case 
to a very few different kinds, so that one can select about 
half-a-dozen species of Copepoda which constitute by far the 
greater part of the summer zooplankton and about the same 
number of Diatoms which similarly make up the bulk of the 
spring phytoplankton year after year. These few species, 
belonging to these two very widely separated groups, thus come 
to be the most significant organisms in relation to the annual 
metabolic cycle of our seas and the food supply from our coastal 
fisheries. It is this fact that gives great economic importance 
to the attempt to determine with as much precision as possible 
