for gorgeous brilliancy of coloration and variety of pattern. This gaudiness 

 of tropical fishes, so far from being, as most people have supposed, a mere 

 lavish expenditure of ornamentation, on Nature's part, is merely one more 

 beautiful evidence of universally perfected obliterative coloration. As the 

 sunlit crown of the tropical forest is full of gaudy colors, so, and more so, is 

 the sunlit upper region of tropical ocean water, about coralline and rocky 

 shores and reefs, and white sand beds. What could be more natural and 

 appropriate than that the fishes living in such places should have, in addi- 

 tion to their never-failing obliterative gradation of general shades, intensely 

 brilliant colors, in rich and varied patterns? All the 'paradisaic' tropical 

 fishes, which have so often been marveled at, are in fact merely covered 

 with average-background-pictures, working for their wearers' concealment 

 as truly as do the dull-colored and delicate patterns of the flounders and 

 northern rock fishes and rock crabs. To be sure, the background-pictures 

 worn by these 'submarine butterflies' are as a rule very much generalized, 

 for there is redundant variation in their surroundings, and some of them are 

 restless vagrants, — though seldom going far from the rocks or coral-beds. 

 Doubtless there are many kinds that ''lie close," and never wander far, — and, 

 accordingly, are equipped with more minute and definite pictures of gay cor- 

 alline and weedy backgrounds. But here our knowledge (i. e., that of the 

 present writers) is defective. Nevertheless, the kinds and degrees of oblit- 

 erative color- and pattern-adaptation among tropical fishes, even as we know 

 them, are many and various — too many and too various to be described in 

 detail here. A few more very general statements about them must sufiice. 

 Their colors (besides black and white, and all the mixed tints of gray and brown 

 and olive) include the entire range of the spectrum, — ^red, yellow, blue and 

 green being perhaps the commonest, among pure colors. These, of course, 

 are the colors of coral, seaweeds, moUusks and other lowly marine animals, 

 and of water over sand and stones, — or, in other words, colors typical of the 

 fishes' environments in fertile tropical seas. The above-named tints, with 

 very many more, occur on the fishes in all sorts of striped, banded, spotted 



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