COLOR CHANGES AND ADAPTATION IN FISHES. 



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spicuous. This is especially marked in Paralichthys "■ dentatus and P. alhiguttus, and 

 fairly prominent in Ancylopsefta quadrocellata. In Paralichthys, especially albiguttus, 

 the simulation of the background, both in color and pattern, is so accurate that in many 

 instances the animals become almost invisible, as will be shown in detail later. 



Table I. — Degreb op Adaptation to the Background in Various Fishes. 



After having made these rather superficial observations I was fully convinced that, 

 contrary to the opinion implied in the statements of Schondorff and Hess, quoted above, 

 adaptive color changes in fishes occur not only in a marked degree, but that they are 

 rather widespread. Bearing on the first of these conclusions I hope to present irre- 

 futable evidencfe. In general, these obser\'ations seem to indicate that adaptation in 

 shade is almost, if not quite, universal among fishes; that adaptation in color is much 

 more limited; and that adaptation in pattern is confined to relatively very few species. 

 It was found only in Paralichthys and Ancylopsetta. 



« The two species of Paralichthys mentioned are very nearly alike, both in form and structure, and in the shade, the color, 

 and the marking of the skin. They can, however, be readily distinguished in most cases by the difference in the number of 

 dark oscillated areas present. Albiguttus has but three such areas, while dentatus has more, the two near the posterior end of the 

 base of the fins being particularly prominent. (PI. xxxvi. fig. ro; pi. x,xxvn.) 



