MALACOPTERYGII. — PLEURONECTIDiE. 
sandy or muddy shores, and unprovided with I 
swimming-bladders, their place is close to the l| 
ground, where, hiding their bodies horizontally 
in the loose soil at the bottom, with the head | 
only slightly elevated, an eye on the under side 
of the head would be useless; but both eyes 
placed on the upper surface afford them an 
extensive range of view in those various direc- 
tions in which they may either endeavour to find 
suitable food, or avoid dangerous enemies. Light, 
one great cause of colour, strikes on the upper 
surface only ; the under surface, like that of 
UPPER SIDE OF THE SOLE. 
most other fishes, remains perfectly colourless. 
Having little or no means of defence, had their 
colour been placed only above the lateral line on 
each side, in whatever position they moved, their 
piebald appearance would have rendered them 
conspicuous objects to all their enemies. When 
near the ground, they swim slowly, maintaining 
