224 FISHES FOR THE MARINE AQUARIUM. 



notice the meaning of the ochreous or yellow spots 

 distributed over the surface of one side of such fishes. 

 They simulate the bright pebbles, and help to conceal 

 the fishes from their enemies. 



In the plaice (Pleuronectes platessa), and sole (Solea 

 vulgaris), the coloured or upper surface is the right 

 side ; whilst in the turbot (Rhombus maximus] it is 

 the left. In both cases, whether the upper side be 



Fig. 154. 



The Flounder (Pleuronectes flesus). 



right or left, the eyes are turned round so as to be 

 placed on the upper side. When swimming in the 

 water the same abnormal position is adopted, the 

 fishes swimming on their sides, and not erect, after 

 the usual manner. The apparent, not real, motion of 

 the tail and whole body is also horizontal, instead 

 of being vertical. There can be no doubt whatever, 

 to the philosophical zoologist, that all the flat-fishes 

 have been, in course of time, modified from the ordi- 

 nary and more symmetrical type of fish. Even now, 



