and blotched patterns, whose effect is ' secant,' 'ruptive,' or purely and del- 

 icately background-picturing, as the case may be. Iridescent or highly change- 

 able color is not so characteristic of these gaudy ground-haunting fishes as it 

 is of the free-swimmers that spend much time very near the surface. Indeed, 

 their brightest colors are often almost lusterless — like those of toucans and 

 parrots rather than those of hummingbirds and peacocks. This, also, is in 

 evident harmony with their ways and places of life. For, down in ocean 

 water, below all the surface-agitations, the light is constant and somewhat 

 diffuse, and plays few tricks of any sort; hence strong 'dead' color, in fit 

 background-patterns, is all that is required to complete the concealment of 

 obliteratively shaded fishes when they lie motionless in that quiet realm. 

 Some of the most elaborate and beautiful of the obliterative patterns worn by 

 such fishes are on the fins, particularly the dorsal and the caudal. When the 

 fins are extraordinarily long but wwmarked, as for instance in the genus Choeto- 

 don, they sometimes bear a direct mimetic resemblance to blades of seaweed. 

 Mimetic in a similar way are also, probably, some of the tentacular excres- 

 cences of fishes — such as those of the "Angler" or "Hunting Frog" (Lophius 

 piscatorius, etc.). Indeed, the whole lumpy form of this sluggardly "angler" 

 suggests mimicry of a weed-grown rock or lump of coral, and its obliterative 

 shading is, I believe, scanty or wanting. There may, indeed, be a good 

 many cases of true mimicry among the fishes of grotesquely distorted form; 

 but we have no definite knowledge of more than one or two. On the other 

 hand, it seems that most of their excrescences and lengthened, 'painted' 

 fins are, like the corresponding developments of birds, truly obliterative, and 

 cooperant with full counter shading. The two uses however, are of course 

 constantly intervolved. Some of the pipe-fishes, and other snake-shaped 

 haunters of floating seaweed, probably bear a mimetic resemblance to flat 

 weed-blades. But being themselves cylindrical, they cannot look flat without 

 the aid of obliterative shading, which, accordingly, is here used for the attain- 

 ment of a mimetic effect. (This is a common occurrence among lepidopter- 

 ous larvae, as we shall show in a later chapter.) 



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