colors — green, olive, gray, pearl-blue, silvery, deep olive-brown, etc. These 

 tints are all components in the obliterative shading and its resultant uniform, 

 soft, water tone, and have, in general, little independent pattern-effect. The 

 bar of silvery blue on a salmon's side, for instance, does not flash out in its 

 full brilliance until the salmon, in executing some swift manoeuver, turns his 

 side upward toward the daylight for an instant. At other times, in the nor- 

 mal position, it is merely a link in the obliterative chain of graded shades, 

 looking almost uniform alike with the salmon's actually dusky back and his 

 actually white-silver belly. But any 'liquid' tinges of more vivid color 

 which these iridescent areas do superimpose on the general 'flat' and mono- 

 chrome effect, in the fish's normal position, help his apparent dissolution into 

 his watery background of slightly mutable and varied tints. They are the 

 open-water fish's markings, as it were — his pictures of vague, intermingled 

 water-tints. At and near the surface, there is more variety. Bubbles, and 

 foam, and flickering, shadowy ripples, seen from below — as well as dimmed 

 vistas, farther or nearer, of sky and clouds and sky-lit wave tops — all play a 

 part in the regular backgrounds of surface-swimming fishes, and all are re- 

 peated, more or less plainly, in their fair, sheeny coloration and faint pat- 

 terns. Most free-swimming, open-water fishes, indeed, spend much of their 

 time very near the surface (many are even wont to leap, and a few to 'fly, 

 above it — as everybody knows), and the delicate brilliance of their shimmer- 

 ing water- and sky-colors is in harmony with such habits. Another important 

 function of their lustrousness is the actual mirroring of water — one more 

 potent factor in their wonderfully efiicient concealing-equipment. All brightly 

 shiny fishes — mackerel, herrings, salmon, etc. — mirror their surroundings in 

 this way. But even this beautiful principle is wholly subservient to the 

 ■obliterative shading, and does not upset the essential balance of its working. 



'Secant' and 'ruptive' patterns are not common among these fair-colored 

 free-swimming fishes, but neither are they altogether lacking. The mackerel 

 has a seamed "lateral line" which serves as a 'secant' stripe, and many 

 wavy up-and-down stripes above it. A good many pelagic and fresh-water 



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