144 
ANIMAL CURIOSITIES 
situated upon a black globular prominence; 
but even better endowed is the pearl-side 
(Maurolicus borealis ), a small fish found in 
British waters, which has about forty-six 
pearly spots on either side of its body, these 
being set in depressions in the skin, and sur¬ 
rounded by a narrow black ring. 
The moon-fish or sun-fish, a species occa¬ 
sionally visiting British seas, and quite common 
in the Mediterranean, is also endowed with 
the power to radiate light. Mr. Holder tells 
us that at night “ they present a remarkable 
appearance, moving along like gigantic globes 
of light, or resembling the reflection of the 
moon upon the water. When numbers of 
them swim together, the huge dorsal cutting 
the water, that breaks itself into ripples of 
molten silver, the scene is described as being 
magnificent in the extreme.” 
In the majority of the light-bearing fish 
the luminosity they emit is produced by a 
mucus secreted by glandular organs which 
may be present upon the head, along the 
sides of the body and tail, or even on the back. 
In some species, however, in which these 
organs are absent, the light is transmitted 
through lens-like plates that lie in front of 
closed receptacles filled with a clear liquid 
substance. These phosphorescent plates may 
