138 THE STORY OF LIFE IN THE SEAS. 



each class, to give an adequate idea of the 

 variety of colour met with in the Fauna of the 

 deep sea. 



It is inconceivable that each of these animals 

 can live amid surroundings of a colour similar to 

 its own, and therefore we may without much 

 hesitation believe, that the colour of deep-sea 

 animals is not, as a general rule, of use as a 

 protection. 



Next to the peculiarities of colour, the most 

 striking features of the more highly organised 

 inhabitants of the bottom of the sea are the 

 modifications of the organs of special sense. 

 The Fish, the Crustaceans and the Molluscs 

 almost invariably exhibit some remarkable 

 modifications of the eyes. In their natural 

 haunts there must be either absolute darkness, 

 or the faint and usually intermittent light 

 emitted by phosphorescent animals. How in- 

 tense this light may be it is impossible to judge. 

 The light that is emitted by animals on the deck 

 of a ship can afford no criterion of the light they 

 emit under a pressure of two tons to the square 

 inch. However, the fact that the deep-sea 

 animals have either very large eyes or no eyes 

 at all, suggests forcibly that this light is not 

 sufficient to cause a general illumination. 



Some of the Fish are quite blind, and although 

 most of these have a very small and rudimentary 

 eye, in at least one Fish, Ipnops, which is 

 peculiar to deep water, no trace of an eye is 

 to be found. 



In some genera with a very wide distribu- 

 tion, a very interesting series of stages may be 



