80 THE FAUNA OF THE DEEP SEA 



is interposed a thick layer of light reflecting 

 spicules. 



The exact part that is played by the different 

 components of these curious phosphorescent organs is 

 not yet known, but sufficient has been said to indicate 

 to the reader the degree of complexity that these 



FIG. 8. Section of the anterior sub-orbital phosphor- 

 escent organ of Pachystomias microdon (after 

 Von Lendenfeld). L, lens ; o, phosphorescent 

 gland ; P, pigment sheath. 



organs may reach in the fish of the great depths of 

 the ocean. 



But the power of emitting phosphorescent light 

 is by no means confined to the group of fishes. Some 

 of the Macrurous Decapoda among the Crustacea 

 are known to be phosphorescent. In the case of 

 Heterocarpus Alphonsi, for example, the naturalists 

 of the ' Investigator ' found that ' clouds of a pale 



