MARINE CAMOUFLEURS AND THEIR CAMOU- 

 FLAGE: THE PRESENT AND PROSPECTIVE 

 SIGNIFICANCE OF FACTS REGARDING THE 

 COLORATION OF TROPICAL FISHES. 



By W. H. Longt,ey. 



I With five plates.] 



Shortly before his death the late Col. Roosevelt wrote: 1 " In its 

 groundwork essentials the matter of animal coloration is one of 

 kindergarten simplicity." But, as a minor result of the World War, 

 knowledge is widely disseminated which shakes confidence in the 

 finality of this conclusion. 



For years our harbors have been choked with ships in bizarre 

 war paint, designed to deceive the enemy regarding their apparent 

 size, speed, and direction of motion. During the same period, tanks, 

 great guns, and other implements of war upon the battlefields of 

 the world have been painted on much the same system, with the 

 general result, paradoxical as it seems, that their visibility has been 

 diminished. But if daubing a gun with irregular patches of vivid 

 and contrastive color increases the difficulty with which it is dis- 

 covered by aerial observers, this fact, wholly opposed as it is to pre- 

 conceived opinion, may lead one to suspect, with regard to animal 

 coloration, that underlying principles may not always be obvious; 

 and to infer too, that Col. Roosevelt's plummet may not have reached 

 bottom in depths he believed he had sounded. 



The differences in color between closety related species of animals 

 are often more striking than any other marks which serve to dis- 

 tinguish them one from another. But, upon the basis of the Dar- 

 winian hypothesis, the more noteworthy the difference between two 

 forms, the more important, upon the average, should have been the 

 role of natural selection in bringing it into being. The greater 

 the difference, the greater too should be the ease with which the 

 service rendered by divergent characters of related species should be 

 demonstrated. These facts sufficiently explain the 'sustained in- 

 terest of Darwinians in animal coloration ; here, in a sense, they have 

 elected to stand and to demonstrate the existence of that general fit- 



1 American Museum Journal, vol. XVIII, 1918. 



475 



