Flat Fishes. 29 



fishes have also electric organs ; one of these is a 

 genus of river fishes Malapterurus, from the Nile 

 the other Mormyrus, also African has a very small 

 electric organ near the tail. 



Some fishes belonging to a curious marine group 

 of this sub-order the Scopelidae are remarkable not 

 only for the brilliancy of their lustre, but for the fact 

 of their possessing several pairs of accessory eyes on 

 the gill covers. One other species of physostome fish 

 Amblyopsis which inhabits the -Mammoth Cave of 

 Kentucky is remarkable for the rudimentary condition 

 of its eyes, which are covered with a layer of skin, 

 and are hence functionless. 



SUB-ORDER 2, ANACANTHINI. This subdivision 

 includes those soft-finned fishes which have either no 

 swimming-bladder or have one that has no duct. In 

 these not even the foremost fin-rays are spinous, but 

 all are soft-jointed and branched. They are for the 

 most part marine, and include many of the common- 

 est of our sea fishes, such as the cod, haddock, 

 whiting, saith, lithe, ling, &c. One interesting group 

 that of the flat fishes is remarkable for the want 

 of symmetry displayed in the body, which is ex- 

 tremely compressed, and the animal in progression 

 invariably lies on one side, swimming with one side 

 up and the other directed downwards. These fishes 

 usually keep near or on the bottom, and the upper 

 side is usually dark or coloured while the lower side 

 is white. To accommodate the structures of the 

 animal to this extraordinary habit, the eyes are twistod 

 round both to the one side of the head viz. that 

 which is uppermost so are the nostrils, and the 



