152 ON THE MIGRATIONS AND THE GROWTH OF PLAICE. 



The earlier stages were determined from a consideration of 

 a graphic analysis of the first haul, and of the results of the 

 migration experiment. I have ventured in bringing the results 

 together to continue the curve, so as to be able to state 

 approximately the growth of the larger forms. The range of 

 variation for the Northumberland plaice may be said to be 

 at least two inches on each side of the line given as the mean 

 rate of growth. 



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Fig. I. — 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 i4f-in., but 

 practically all above i6-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, 



