THE SHORES OF BRITAIN. 93 



borough for one shilling ! The fish are brought to 

 the mouth of the Thames in stout cutters, furnished 

 with wells, in which they remain alive; hence they 

 are sent up in portions to Billingsgate by the night 

 tide. The cutters lie at Gravesend ; for if they 

 were to advance any higher up the river, the ad- 

 mixture of fresh water would kill the fish in the 

 wells. The liver of the Cod is not the least va- 

 luable part of its body, because it melts almost 

 entirely away into a clear oil, much used in manu- 

 factures. 



There is a family of fishes familiar to us, which 

 are worthy of a moment's notice, not only on ac- 

 count of their importance as objects of commercial 

 speculation, but for their singular and unparalleled 

 deviation from the ordinary structure. These are 

 the Flat-fishes (Plearonectidce), comprising the Tur- 

 bot, Plaice, Sole, and some others. Their form is 

 very deep, but at the same time very thin, and they 

 are not constituted to SAvim as other fishes do, with 

 the back uppermost, but lying upon 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 movements, they need concealment from ene- 

 mies. This is afforded to them by the side which 

 is uppermost being of a dusky-brown hue, undis- 

 tinguishable 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 



