220 A HISTORY OF FISHES 



chameleon-like activities. The director, Dr. Townsend, has 

 made a detailed study of the colour changes undergone by the 

 fishes under his charge, and he has found that fishes from the 

 coral reefs might have anything from two to seven distinct 

 normal colour phases, according to the species. These varied 

 greatly in the different forms, being most marked in the Sea 

 Perches or Groupers (Epinephelus) , but nearly always included 

 one very pale or even white phase, and another which was 

 exceptionally dark. To describe even a few of these colour 

 phases would be impossible, but Dr. Townsend's description of 

 a species of Sea Perch known as the Nassau Grouper will serve 

 as a typical example. "Eight phases of coloration are some- 

 times observed in a tank containing specimens of the Nassau 

 Grouper {Epinephelus striatus). In one the fish is uniformly 

 dark; in another creamy white. In a third it is dark above with 

 white under parts. In a fourth the upper part is sharply 

 banded, the lower pure white. A fifth phase shows dark bands, 

 the whole fish taking on a light brown coloration. While in a 

 sixth the fish is pale, with all dark markings tending to dis- 

 appear. The seventh phase shows a light-coloured fish with 

 the whole body sharply banded and mottled with black. This is 

 instantly assumed by all specimens when they are frightened 

 and seek hiding-places among the rock-work. The banded 

 phase shown here is no more the normal appearance of the 

 fish than the uniformly dark, the uniformly white, or any other 

 phase. Singularly enough, no two photographs of this banded 

 phase are quite ahke, the extent of the markings being depen- 

 dent apparently upon the degree of disturbance to which the 

 fish has been subjected." Another observer has described a 

 fish of a shining blue colour with three broad vertical bands of 

 brown, which swam into a clump of coral, emerging a few 

 minutes later "clad in brilHant yellow, thickly covered with 

 black polka-dots." 



It is, however, in the Flat-fishes {Heterosomata) that the 

 capacity for changing the coloration in harmony with the 

 surroundings reaches its height. In the Flounder (Flesus), for 

 example, the colour is generally greyish-olive, often more or 

 less marbled with brown, but this may vary from yellow to 

 almost black, and so perfect is the resemblance to the mud, 

 sand or gravel on which the fish happens to be resting, that 

 unless it moves it is wellnigh invisible. The bright orange-red 

 spots of the Plaice {Pleuronectes) will be familiar to all, but few 

 are aware that when the fish moves on to a piece of ground 



