fishes have one or more such markings, either longitudinal or vertical. But 

 patterns of this sort seem less appropriate to an environment of water alone 

 — particularly away from the surface — than to one in which there is some 

 element of 'land'; and when they occur on free-swimming fishes they 

 may be connected with their wearers' need to haunt the bottom during the 

 breeding season. Blotchy 'ruptive' patterns are almost wholly wanting 

 among these fishes. They occur, however, on a few pelagic animals of gigan- 

 tic size, — namely, on certain whales — and possibly on some huge pelagic fishes 

 also, though we do not know of any that are thus marked. Many of the 

 giants among pelagic (free-swimming) fishes, such for instance as the sharks, 

 are colored rather dingily, lacking delicate tints and lustrousness — though 

 almost all obliteratively shaded to the full. 



We now come to the second and more composite class of daylight fishes, 

 the haunters of submerged land. That is, the fishes that spend all or the 

 greater part of their lives in close contiguity with submerged solid portions 

 of the earth — whether rocks, sand beds, coral reefs, or muddy and pebbly 

 lake and river bottoms. They are, so to speak, the sparrows and partridges 

 of the water, as the free- swimmers are the gulls and swallows. More than 

 this, the submerged-land-haunters are also the parrots, toucans, and para- 

 dise birds of the water. Man's knowledge of subaquatic life and scenery is 

 at the best pitifully inadequate, but he is able to piece out his few, fragmen- 

 tary, and imperfect observations * of wild fishes in their element by an ac : 

 quaintance with some indubitable general principles of their coloration and 

 illumination, and by a comparison of fishes removed from the water, and in 

 aquarium tanks, with terrestrial and aerial vertebrates. The conclusions 

 reached by such means must necessarily be defective — very far from com- 

 pletely rounded — but they will yet be approximately correct as far as they 

 go. To the student of obliterative coloration, who has learned to perceive 

 the exquisite correlations between animal and environment which prevail 

 among the creatures of earth and air, the examination of such ground-haunt- 



* Subaquatic photography is destined to be of great service in this direction. 



163 



