70 



lengthen their iails proportionally, in order to breathe 

 from the surface; by adding more and more water 

 you will find they can extend their fails to the length 

 of five inches : an extremely remarkable length for a 

 creature little more than half an inch Jong. Beyond 

 five inches however they cannot go ; and if you make 

 the \vaterof a great depth, they It-ave the bottom, and 

 either travel up the sides of ihe vessel to a proper 

 height, or else swim in the water ; at the depth of five 

 inches. 



16. No species of flies is more remarkable than the 

 larger Fire-Fly of Jamaica. It is above an inch long, 

 and proportionably broad. Most of its internal parts 

 are luminous, only the thickness of the covers hinders 

 its appearing; but on forcing the rings that cover the 

 body a little asunder, light issues from all the entrails. 

 The head has two spots just behind the eyes, which 

 emit streams of strong light. But though these flow 

 naturally from the insect, yet it has a power of inter. 

 rupting them at pleasure ; and then these spots are as 

 opaque as the surface of the body. 



A person may read the smallest print by the light 

 of one of these insects, if held between the fingers, 

 and moved along the line, with the luminous spots 

 over the letters. They are seldom seen in the day, 

 but wake with the evening, and move and shine most 

 part of the night : they readily fly toward each other. 

 Hence the negroes have learned to hold one between 

 their fingers, and wave it up and down, which others 

 seeing fly direct toward it, and pitch upon the 

 hand. They are so torpid by day, it is hard to make 

 them discover signs of life ; and if they do, they pre. 

 sently relapse into the same- slate of insensibility. As 

 long as they remain awake, they emit light; but they 

 are vigorous only in the night. 



17. One more insect of the fly-kind we cannot pass 

 by unnoticed ; the Ephemeron, or fly that lives but 

 part of a day. It appears usually -about Midsummer. 



