PLEIRONECTID,^. 147 



term) intermediate bones for the purpose of sustaining fin rays, 

 and which are continued to the snout — in their coiirsc restins: 

 on a thxin ridge of bone which forms a crest on the head. 

 The border of the abdomen of this fish, from the first long 

 spinous process of the vertebrae to the throat, is bounded by 

 a curved bone, the concavity of which supports the entrails; 

 and along its convexity jiass off the intermediate bones of the 

 fins. As an example of some of the differences between the 

 eyed and blind side of these fishes, we notice of the Flounder 

 that on the coloured side the masseter nrascle, which closes 

 the mouth, is strong, and sends a stout tendon to the angle 

 of the lower jaw, while on the white side there is no tendon, 

 but a well-marked nerve crosses obliquely from the head to 

 the angle of the jaw. A similar nerve on the coloured side 

 descends under the tendon, but comes out of the skull further 

 forward, and passes close below, or on the fiicial side of the 

 eye. A blood vessel accompanies this nerve in botli instances. 

 The nerve running to the palate appears to be the largest in 

 the body, and passes only on the coloured side. 



The Pleu7'onectidce are so called from their habit of swim- 

 ming flat on the side, (the lateral line of the coloured part 

 being their upper portion,) and not erect, as is the case with 

 other fishes. This curious mode of action is associated, as we 

 see above, with as remarkable a variation of shape and inward 

 structure, when compared with their fellow inhabitants of the 

 water; so that we may confidently pronounce them to be the 

 most irregular and strange of all the creatures we meet with, 

 and an exception esjjecially to other vertebrated animals. "\Ve 

 may add, that if they had been met with only in a fossil 

 condition, there is reason to believe they would have been set 

 down as having found their place on earth when the beings 

 inhabiting it were struggling to pass from an unformed to a 

 regularly organized state, without its being certain in what at 

 last the struggle might end. And yet this family of fishes 

 are perfect in themselves, and their form is well adajDted to 

 the peculiarities of their modes of life; with the reversal, 

 however, of the functions of all their fins; for even that of 

 the tail, while it serves, as in other fishes, as an organ of 

 propulsion, is still made to act horizontally, and not laterally; 

 and as thus it is .of little use in turning the body in its 



