COLORATION 229 



complete, the fish retaining patches or spots of black or brown, 

 as in the black and silver varieties of the Gold-fish (Carassius). 

 Completely albino Flat-fishes (Heterosomata) are caught from 

 time to time, and it is probable that a number of such cases 

 occur in a natural state ; but the fish are at such a great dis- 

 advantage in the struggle for existence, being visible to their 

 enemies against almost any background, that comparatively 

 few of them survive to reach maturity. 



