406 EXPLANATORY INDEX. 



In many parts of Guiana the Egret is called by the name of 

 White Gauldin. 



F. 



FIG, WILD (Clusia alba). 



FINCH, RED-HEADED (Probably Passerina gularis). 



FIREFLY. In Tropical America there are so many lumi- 

 nous insects which go by the popular name of firefly that 

 no particular species can be here designated. Most of these, 

 however, are beetles belonging to the group of elaters. Many 

 species exist in England, and are well-known as skip-jack 

 beetles, spring-beetles, or click-beetles, because if laid on their 

 backs, they spring up in the air with, a smart click, and take 



EGEET ASLEEP. 



their chance of falling on their legs. The terrible wire- worm 

 is the larva of one of these beetles. 



The species which is most common is the Cucujo (Pyro- 

 phorus luminosus.) As is the case with our glow-worm, the 

 light disappears after death, and, indeed, how it is produced 

 in life is an unsolved mystery. Even the spectroscope yields 

 no information, giving only a * continuous ' spectrum, i.e. one 

 which is not crossed by lines, either dark or luminous. 



Still, the light which the insect emits is so powerful that, 

 as Waterton mentions, it will, if held over a paper at night, 



