140 TRANSACTIONS LIVERPOOL IUOLOGICAL SOCIETY. 



its geneva] appearance, bul il is obviously desirable to 

 have some measures of this quality, in order that it may 

 be accurately compared in different sum pies. The. samples 

 received represent most of the fishing districts, but fairly 

 good series were obtained only from the Barrow Channel 

 and the Mersey shallow water grounds. 



As a rule the method of weighing was to sort out the 

 fish in each sample into centimetre groups, and then to 

 take the total weight of all the fish in each group. Some- 

 times each fish was weighed separately. The weight was 

 always found to the nearest gramme, whether in a single 

 fish or a number. Mature females with ripening ovaries 

 were weighed, but the results were not made use of in 

 determining averages. The tables apply, therefore, to 

 immature females or to mature and immature males. 



The average weights themselves are not published: 

 obviously to do so would involve much space, and the 

 table of values of the coefficient k can be used to find the 

 average weight of the plaice of each fishing ground and 



season represented. The weight = -y^ k, I and the 



weight being taken in centimetres and grammes respec- 

 tively. Since the h of the table is itself an average 

 number, the weight will represent the mean for the place 

 and time in consideration. 



Fig. 19 represents the increase of weight with 

 length in the case of four typical catches of plaice. That 

 from Barrow Channel in July may be regarded as repre- 

 senting plaice in good condition; while the catch for 

 February represents the fish when in the worst condition 

 of the year. One sees that the differences are fairly 

 considerable: a 10-inch plaice in good condition weighs 

 about Gf ounces, while a fish of the same length taken at 

 the time of its worst condition weighs only •").\ ounces. 

 These July fish were in first-rate condition and were 



