THE FLAT-FISH FAMILY 213 



on the other. Figs. 100-105 are copies of the figures which this 

 naturalist published to illustrate the condition of these speci- 

 mens. He did not find that these flat -fishes were the young of 

 our common kinds, but that, on the contrary, they belonged to 

 a kind which is not taken on our coasts. These two naturalists 

 accordingly had a dispute as to the way in which the eye of the 

 lower side in a flat-fish gets to the other side, one maintaining 

 that the eye went through the head, the other that it went 

 round. The truth was that both were perfectly right, each gave 

 a correct account of what he saw, and formed a true judgment 

 upon it, and neither had any reason to throw doubt upon the 

 statement of the other. The specimens in which the eye was 

 seen on its way through the head were caught in the open 

 Atlantic Ocean by ship-captains. In the year 1878 a naturalist 

 in America actually kept alive specimens of young flat-fishes in 

 some of which the eye went round the head, and in others 

 went through. He watched the little fish while the change 

 was taking place. The facts are now thoroughly well established, 

 and the change in position of the eye in the common flounder 

 and in other kinds can be watched every spring in specimens 

 cauefht at low tide at favourable places on the coast. In the 



o * 



kind of flat-fish in which the eye goes through the head it 

 is known now that there is very little real difference in the 

 process from that which is more common. In this kind the fin 

 on the edge of the body extends forwards to the snout while the 

 eyes are still opposite to one another, and the eye of the lower 

 side simply tunnels under the fleshy part of this fin, and never 

 actually passes through the bones of the head. In the sole and 

 turbot the fin does not grow forwards to the end of the snout 

 until after the shifting of the eyes has taken place. 



The Plaice (Pleuronectes platessa). 



Distinguishing Characters. The rough bony knobs on the 

 head are on a bony ridge extending from the ridge between the 

 yes to the upper corner of the gill opening. The number of 

 fin-rays is not different from the number in the dab : there are 

 sixty-six to seventy- seven in the dorsal, fifty to fifty-seven in the 

 ventral, but the smooth minute scales and the straight lateral 



