150 INSECT ARCHITECTURE. 



form the grooves in the central piece, whereas they 

 are scooped out in the handles of the files, and play 

 upon two projecting ridges in the central piece, by 

 which means this is rendered stronger. M. Reaumur 

 discovered that the best manner of shewing the play 

 of this extraordinary instrument is to cut it off with a 

 pair of scissors near its origin, and then, taking it 

 between the thumb and the finger at the point of 

 section, work it gently to put the files in motion. 



Ovipositor,, withjile,, of Tree-hopper, mtgnifi*. 



Beside the muscles necessary for the movement 

 of the files the handle of each is terminated by a 

 curve of the same hard horny substance as itself 

 which not only furnishes the muscles with a sort of 

 lever, but serves to press, as with a spring, the two 

 files close to the central piece, as is shewn in the 

 lower figure. 



M. Pontedera, who studied the economy of the 

 tree-hoppers with some cure, was anxious to see the 



