76 LIVING LIGHTS. 



does not state whether the light came from the entire body 

 or was confined to certain localities. MM. Eycloux and 

 Souleyet, naturalists of the French exploring ship " La 

 Bonite." noticed a small luminous crustacean, and succeeded 

 in separating the phosphorescent secretion from the animal. 

 They describe it as yellowish, viscous, and soluble in water, 

 and found that its luminous properties soon disappeared. 

 It was their opinion that certain crustaceans secreted the 

 luminous matter, and that they differed much in their 

 method of producing it. Certain small crabs, they believed, 

 could display a certain amount of light when irritated ; the 

 phosphorescence at these times appearing in jets, forming a 

 cloud or halo of light in which the animal seems to dis- 

 appear. 



In the abyssal depths of the ocean, where probably no ray 

 of sunlight reaches, the crabs are possibly all luminous. 

 Many of these deep-sea forms have a wide geographical dis- 

 tribution. Thus the Lithodes are found from the shallow 

 waters of the north and south poles to the tropics, in the 

 latter living in a region over which rests three-quarters 

 of a mile of water. Many other crustaceans live in depths 

 vastly more inaccessible than this, and under a much greater 

 pressure. Thus Oolossendeis titan, a strange creature, whose 

 stomach is prolonged to the ends of the feet, is found living 

 at a depth of about two miles and a half. These creatures, 

 a species of which is shown in Plate XIV., are the spiders of 

 the sea, resembling their not distant allies of the land, at 

 least in appearance. 



The different depths affect the inhabitants to a more or 

 less extent. In some, the eyes seem to have lost their proper 

 functions; and an instance is thus described by the Rev. 



