102 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Large-scale graphs, or curves, have been drawn to represent 

 the corrected and uncorrected data. 



An account of the statistical methods, which it is hoped 

 present some novel features with regard to treatment, has 

 been prepared. 



Age and Sexual Maturity of Plaice in Local Waters. 



About 8,000 plaice sent to the Liverpool and Piel Labora- 

 tories have each of them been measured, weighed, and dissected 

 so as to find the age and degree of sexual maturity. Tables 

 are given showing the growth-rate of male and female plaice, 

 and curves and measures of dispersion have been made from 

 the tables. 



Practically all plaice in the sea off the coasts of Lancashire 

 and Cheshire and North Wales are immature fish. Spawning 

 plaice do not occur. Large plaice come inshore for a short 

 time during the autumn. Large plaice also come into Red 

 Wharf Bay and thereabout during the winter, also for a short 

 time. 



Good series of data for the very immature plaice of the 

 Mersey shrimping grounds have been obtained. 



The Effect of different Trawl-meshes. 



Tables showing the sizes of plaice caught by trawl-nets 

 of 2", 4", 6", and 7" mesh have been compiled. 



The tables, just as they are, give little information, though 

 they give, of course, the actual observations made. Thus : — 



Largest Smallest 



fish caught. Average size. fish caught. 



4" 14f" 7}" U" 



6" 13" 8" 5" 



7" 13" 8f" 5f" 



But there were far more fish caught of sizes near the 

 averages, and we have to consider how they are clustered 



