STRIDULATION OF INSECTS. 359 



seeing in every degree of intensity of light. We also meet 

 with insects which' produce loud, and some which produce 

 weak, stridulation, and others which execute the stridulatory 

 movement without making any sound which we are able to 

 distinguish, from which we may conclude, that there are ears 

 for every modification of sound, and even some fitted to hear 

 silence, or rather that which to our grosser perceptions appears 

 to be so. It may at first sight seem extraordinary, that there 

 should exist eyes so organized as to see in the dark, and ears 

 which are capable of hearing during silence; but these propo- 

 sitions are, as I conceive, by no means inconsistent with the 

 theories generally adopted respecting the transmission of light 

 and sound, and, what is more to the purpose, they appear to 

 be confirmed l;y our observations of nature. 



The most noisy locust I have found at Cologne inhabits 

 thickets, and is commonly to be met with on shrubs or the 

 stalks of grasses. As I do not know its name, it will be neces- 

 sary to give a short description. It is about twenty millimetres 

 in length, and of a yellowish-brown colour; the prothorax is 

 deeply indented lengthwise, and divided by three transverse 

 lines ; the hind legs have the knees black, and the shanks red : 

 these latter are furnished with a double row of red black- 

 pointed spines ; the wings are hyaline, and as long as the 

 elytra and body. 



If we separate one of the elytra, it will be seen that the back 

 cover is brown, and reticulated by small nervures, and that 

 the extremity of the side cover is reticulated in the same man- 

 ner, but that the side cover itself is transparent, and of a hard 

 and sonorous consistence ; it is divided into two parts by a 

 strong longitudinal nervure, which is the treble-string {chante- 

 relle) accompanied above and below by two slenderer nervures. 

 Each of these two transparent spaces is divided into parts 

 having the form of a parallelogram, by small nervures per- 

 pendicular to the treble-string ; all these nervures are produced 

 above the membrane of the elytron, and a pin cannot be passed 

 over them without catching them and causing them to vibrate. 

 To this transparent portion the name of drum {tambour) may be 

 given, from its analogy to the sonorous organ of the crickets 

 and grasshoppers. Violin (violon) will perhaps, however, be 

 a more suitable name for this instrument, as it is more analo- 

 gous to a violin than a drum. 



