FLAT FISHES. 



257 



not constituted to swim as other fishes do, with their back upper- 

 most, but lying on one side. They reside wholly upon the bottom, 

 shuffling along by waving their flattened bodit_s, fringed with the 

 dorsal and anal fins ; and as they are somewhat sluggish in their 

 movements, they need concealment from their 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, but sink down close 

 to the bottom and lie perfectly motionless. 



In the structure of the head, again, there is a peculiar and very 



FlC. 2;_-. -UlM'ER SIDE OF THE SOLE. 



FIG. 273. UNDER SIDE OF THE SOLE. 



remarkable provision for the wants of the creature. If the eyes 

 were placed, as in all other animals, one on each side of the head, 

 it is plain that the flat fishes, habitually grovelling in the manner 

 described, would be deprived of the sight of one eye, which being 

 always buried in the mud would be quite useless. To meet this 

 difficulty the skeleton is distorted, taking near the head a sudden 

 twist to one side; and thus the two eyes are placed on the side 

 which is kept uppermost, where both are available. The side fur- 

 nished with eyes and provided with dark colour varies in the 



17 



