210 PLEURONECT1D.E. 



frequently not in the same vertical line, and often unequal 

 in size ; the position of the mouth ; the inequality of the 

 two sides of the head, and the frequent want of uniformity 

 in those fins that are in pairs, the pectoral and ventral 

 fins of the under or white side being in some species smaller 

 than those of the upper; 'and the whole of the colour of the 

 fish confined to one side, while the other side remains per- 

 fectly white, produce a grotesque appearance: yet a little, 

 consideration will prove that these various and seemingly 

 obvious anomalies are perfectly in harmony with that station 

 in nature which an animal bearing these attributes is ap- 

 pointed to fill. 



As birds are seen to occupy very different situations, some 

 obtaining their food on the ground, others on trees, and not 

 a few at various degrees of elevation in the air, so are fishes 

 destined to reside in different situations in the water : the 

 Flatfishes and the various species of Skate are, by their de- 

 pressed form of body, admirably adapted to inhabit the 

 lowest position, and where they occupy the least space, 

 among their kindred fishes. 



Preferring sandy or muddy shores, and unprovided with 

 swimming-bladders, their place is close to the ground, where, 

 hiding their bodies horizontally in the loose soil at the bot- 

 tom, 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 affords them an extensive range 

 of view in those various directions 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 most other fishes, re- 

 mains 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 



