THE INDIAN OCEAN. 377 



which, while the animal is alive, are seen to dilate 

 and contract with a very rapid pulsation. The little 

 globe is propelled in any direction by a jerking mo- 



Noctilcca Mii.iaris, greatly magnified. 



tion of the tail or stem ; and as it is a restless crea- 

 ture, it is not a very easy matter to obtain a good 

 sight of it for observation. 



Several species of fishes are undoubtedly lumi- 

 nous: the Sun-fish (Cephalus mola), when seen at a 

 considerable distance below the surface in a dark 

 night, is said to glow like a cannon-ball heated to 

 whiteness. Ehrenberg found that the whole skeleton 

 of an Egyptian fish (Ileterotis Nilotlca) emitted such 

 a vivid light as he never saw equalled by any other 

 fish, alive or dead. And Mr. F. D. Bennett discovered 

 a new species of Shark, which he named Squalus 

 fulgens, from the whole surface of whose body pro- 

 ceeded a greenish light, which rendered the animal 

 the most ghastly object imaginable. But there can 

 be no doubt that the main source of oceanic efful- 



2i2 



