CHAPTER XIII 

 THE FLOUNDER 



Peculiarities of Flat-fishes Percoid characters of Psettodes 

 distribution of Pleuronectids the Flounder described colora- 

 tion differences from the Plaice reversed examples ambi- 

 colorate specimens albinos distribution habits breeding 

 growth and transformation value as food 



WE have already mentioned that the Perches 

 represent the highest stage in the evolution 

 of the normal fish, but that from them various 

 groups have evolved in adaptation to special modes 

 of life. Such a group is that of the Flat-fishes 

 (Pleuronectidce), which form a well-marked order 

 which has received the name Heterosomata. 



These fishes have a strongly compressed body 

 and differ from all other fishes in that they lie on 

 one side at the bottom of the sea; consequently 

 only the exposed side is coloured in such a way 

 as to render the fish inconspicuous, whilst the 

 hidden under-side is white. Still more remarkable 

 is the shifting of the eye of the under-side from 

 its original position, where it is of no use, round into 

 the light, so that both eyes appear to be on the 

 same side of the head ; thus, in Flat-fishes we can 

 distinguish between an eyed or coloured side and 



a blind or white side. 



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