TREE-HOPPER. 149 



where it is somewhat enlarged and angular, and on 

 both sides finely indented with teeth. A more mi- 

 nute examination of the sheath demonstrates that it 

 is composed of two horny pieces slightly curved, and 

 ending in the form of an elongated spoon, the concave 

 part of which is adapted to receive the convex end of 

 the ovipositor. 



When the protruded instrument is further examined 

 with a microscope, the denticulations, nine in number 

 on each side, appear strong, and arranged with great 

 symmetry, increasing in fineness towards the point, 

 where there are three or four very small ones, beside 

 the nine that are more obvious. The magnifier also 

 shews that the instrument itself, which appeared sim- 

 ple to the naked eye, is in fact composed of three 

 difierent pieces, two exterior armed with the teeth 

 before-mentioned, denominated by Rtaumur files, 

 (limes), and another pointed like a lancet, and not 

 denticulated. The denticulated pieces moreover are 

 capable of being moved forwards and backwards, 

 while the centre one remains stationary, and as this 

 motion is effected by pressing a pin or the blade of a 

 knife over the muscles on either side at the origui of 

 the ovipositor, it may be presumed that those mus- 

 cles are destined for producmg similar movements 

 when the insect requires them. By means of a finely 

 pointed pin carefully introduced between the pieces, 

 and pushed very gently downwards, they may be, 

 with no great difficulty, separated in their whole ex 

 tent. 



The contrivance by which those three pieces are 

 held united, while at the same time the two files can 

 be easily put in motion, are similar to some of our 

 own mechanical inventions, witli this difference, that 

 no human workman could construct an instrument of 

 this description so small, fine, exquisitely poHshed, 

 and fitting so exactly. We should have been apt to 



VOL. IV. 13* 



