THE SHORES OP BRITAIN. 81 



is nol tfie least valuable part of its body, because it 

 melts almost entirely away into a clear oil, much used 

 in manufactures, and, of late years, in the medical 

 treatment of pulmonary diseases. 



There is a family of fishes familiar to us, which are 

 worthy of a moment's notice, not only on account of 

 tlieir importance as objects of commercial speculation, 

 but for their singuUir and unparalleled deviation 

 from the ordinary structure. These are the Flat- 

 fishes (Pleuronectidce), comprising the Turbot, Plaice, 

 Sole, and some others. Their form is very deep, but 

 at the same time very thin, and they are not consti- 

 tuted to swim as other fishes do, with the back upper- 

 most, but lying on one side. They reside wholly 

 upon the bottom, shuffling along by waving their 

 flattened bodies, fringed with the dorsal and anal fins ; 

 and as they are somewhat sluggish in their move- 

 ments, they need concealment from enemies. This 

 is afforded to them by the side which is uppermost 

 being of a dusky brown hue, undistinguishable from 

 the mud on which they rest ; and so conscious are 

 they where their safety lies, that when alarmed, they 

 do not seek to escape by flight, like other fishes, but 

 sink down close to the bottom, and lie perfectly 

 motionless. Even the practised eye of the turbot- 

 fisher, with his powers sharpened by interest, fails to 

 detect a fish when thus concealed ; and he is obliged 

 to have recourse to another sense, tracing lines upon 

 the mud with an iron-pointed j)ole, that the touch 

 may discover the latent fish. In the structure of the 

 head, again, there is a peculiar and very remarkable 

 provision for the wants of the creature. If the eyes 



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