LUMINOUS ANIMALS 
151 
West Indies. All of them emit light, the 
various species, however, differing in the 
degree of illumination they give forth, as 
well as in their manner of displaying it. In 
some of them the light emanates from the 
membrane-like joints of the segments in the 
region of the thorax, but in the majority the 
luminosity arises from two circular and slightly 
raised yellow spots situated upon the prothorax 
or region behind the head. The outer cover¬ 
ing of the spots or “ lanterns ” is of a semi¬ 
transparent and horny nature, and beneath 
each of these covers lies a little cell or vesicle 
containing a phosphorescent substance. The 
light emitted from the spots is of a yellowish- 
green tint, but, when flying, the creatures 
also produce a reddish and somewhat diffused 
light from the abdomen. 
In South America fire-flies are made use 
of by ladies as ornaments, the living creatures 
being fastened to the hair or dresses as if they 
were jewels. The natives catch the beetles 
by whirling about a glowing piece of charcoal 
after dark, the light of which attracts the 
creatures so that they fall an easy prey. 
They are then placed in small cages, and 
fed with sugar-cane, to await purchasers. 
The lantern-fly is said to be another light- 
bearer, although it must be mentioned that 
