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growth of the larger forms. The range of variation for the North- 
umberland plaice may be said to be at least two inches on each side 
of the line given as the mean rate of growth. 
Fig. 1.— Diagram showing approximate average growth of plaice. 
The season during which the trawling experiments are made is 
not a convenient one for an enquiry into the size at which 
maturity is reached, but each year I have examined a certain 
number of the plaice captured, and the smallest female which was 
noted to be mature was one of 14f-in., but practically all above 
16-in. were either mature or had from all appearances spawned. 
It is still more difficult to determine during the summer if the 
males are mature, but all above 14 -in. appeared to be mature. It 
may be said then that the sexes reach maturity at 4 to 5 years. 
Fulton’s conclusion that the males attain maturity at four and the 
females at five is evidently therefore very nearly if not quite 
accurate. 
On the Northumberland coast, therefore, the small plaice of 
the sandy pools gradually pass out to the immediate slightly deeper 
waters of the bays, where they spend the immature phases of their 
lives, and do not migrate, so far as we can see, far along the coast. 
Approaching maturity impels them when 4 to 5 years old to 
