PLEURONECTID^. 
147 
term) intermediate bones for the purpose of sustaining fin rays, 
and which are continued to the snout — in their course resting 
■>n a thin ridge of bone which forms a crest on the head. 
The border of the abdomen of this fish, from the first long 
pinous process of the vcrtebrse to the throat, is bounded by 
a curved bone, the concavity of which supports the entrails; 
and along its convexity pass 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 muscle, 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 facial side of the 
eye. A blood vessel accompanies this nerve in both instances. 
The nerve running to the palate appeal’s to be the largest in 
the body, and passes only on the coloured side. 
The Pleuronectidce 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 especially to other vertebrated animals. We 
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 adaj)ted 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 
