IN THE RAYS OX THE SOUTH-EAST COAST OF DEVON. 



489 



Table XXVII., showing average increase in letigth of marked Plaice, 

 recorded in the preceding tahlc. 



In the above calculation, as regards the half-year's growth, it has 

 only been possible to consider the fishes liberated in October and 

 November; but for the full year's growth the records derived from 

 the autumn and spring fish have been combined. The average increase 

 in size during the first six months is seen to have been 2"3 cm, (|-inch) 

 in the case of seven fish belonging to the smaller group, and 1"4 cm. 

 (^-inch) in the case of four fishes belonging to the larger group. This 

 growth, however, included the winter period, and a reference to the 

 detailed table shows that during the summer months the rate of 

 growth was considerably higher. In the case of the fish liberated on 

 May 29th the average growth of two fishes in three months was 2-2 cm. 

 (|-inch), and of four fishes in four months 27 cm. (1|- inches). These 

 figures refer to the smaller group of fishes from 8 to 11 inches in 

 original length. During the winter period, therefore, these fishes grow 

 no more in six months than they attain in three months during the 

 summer. 



For the entire year's growth the average growth of nine fisli of the 

 smaller group was 5"9 cm. (2^ inches), and for six fishes of the larger 

 group 4-8 cm, (1|- inches). 



In each case it is seen that the larger fishes grow more slowly than 

 the smaller fishes, a result which, indeed, is shown by the averages for 

 almost every period specified in the detailed table. 



As regards the full year's growth, however, it will be seen in the 

 detailed table that several exceptionally low increases occur among the 

 records, viz, Nos. 335 (2-5 cm.), 75 (00 cm.), and 336 (2-0 cm.). As the 

 possibility of errors of measurement or identification has to be borne in 

 mind, we may omit these specimens altogether in order to get an idea 

 of the most usual growth for the twelve months' period. The averages 

 then become 6"9 cm. (2f inches) for seven fishes of the smaller group, 

 and 5-7 cm. {2\ inches) for five fishes of the larger group. If allowance 

 be made for shrinkage of the fish after death before remeasurement, the 

 full year's growth would appear to have been about 3 and 2\ inches 

 in the case of the two groups respectively. The true average growth 



