BONY FISHES 



293 



a great disadvantage to the animal. Consequently this eye is gradually 

 shifted round over the forehead to the right side. The colour of the 

 under or " blind " side is now no longer of importance to the fish, and 

 accordingly disappears. The upper, "eye-bearing" side, on the other 

 hand, assumes so striking a resemblance to the colour of the sea-bottom 

 that it is difficult to discern a fish at rest. This colour is brown, grey or 

 black, sprinkled with reddish-yellow spots, and resembles muddy or 

 gravelly ground strewn with shells or pebbles. On moving to another 

 locality the plaice in a short time becomes lighter or darker in harmony 

 with the colour of the new ground (see p. 253). In addition to this, the 



PLAICE. (The fish in the foreground about one-tenth natural size.) 



fish has the peculiar habit of burying itself in the sand or mud, allowing 

 only its head, with the prominent and very movable eyes (importance of 

 this arrangement), to project. The plaice also swims on its side (side- 

 swimmer) ; but in spite of its very long dorsal and anal fins, which aid 

 in its progression, it is a slowly -moving creature, and accordingly 

 can only prey on the sluggish inhabitants of the sea-bottom. Its food 

 consists principally of crustaceans, molluscs and worms, which it seizes 

 with that portion of the mouth which is turned towards the bottom. 

 This part of the mouth is accordingly much stronger than the rest, and 

 equipped with sharp teeth. The inferior pharyngeal bones have the form 

 of broad plates, by means of which the fish can crush the hardest shells 



