142 THE STORY OF LIFE IN THE SEAS. 



to have two definite spots on the body that emit 

 a phosphorescent light. 



Several of the Star-fish and Brittle-stars from 

 the abyss are known to be brilliantly phosphor- 

 escent, and there are some vivid accounts of the 

 light given off by Worms and various kinds of 

 deep-sea Polyps found in the dredge. 



It is possible that some of the more minute 

 forms of life that occur on the mud at the bottom 

 may also be phosphorescent. The Phceodaria, a 

 family of Eadiolarians peculiar to deep water, 

 provided with thick heavy shells, have a curious 

 organ in their bodies which may be capable of 

 emitting light. If this is the case, it is not 

 unreasonable to suppose that the vast tracts on 

 the bed of the ocean may be faintly luminous 

 like the surface of the sea on a calm night. 



Among the other characters must be men- 

 tioned a very prevalent deficiency in the salts 

 contained in the skeletons of these animals. 

 The skin of the Fish is usually soft and velvety 

 to the touch, the scales being either very thin and 

 few in number or altogether missing ; the bones 

 are described as being so soft that it is easy to 

 pass a needle through them. The shells of the 

 Crustaceans, although frequently drawn out into 

 numerous long and pointed spines, are usually 

 deficient in carbonate of lime. The shells of 

 the Molluscs are, when compared with those that 

 live in shallower water, thin and brittle. The 

 Corals do not seem in this respect to show 

 much variation from their shallow water rela- 

 tions. Some of the solitary forms seem to have 

 rather thinner shells, but the colonial genera 



