98 EVENINGS AT TEE MICEOSCOPE. 



heightened by the tense " drum" acting as a sounding- 

 board. 



So at least some say ; but M. G-oureau, who has 

 published some elaborate observations on the chirping 

 of insects,* asserts that the sound is chiefly owing to 

 the action of the " file" (which he calls the " bow") on 

 the longitudinally-ridged nervure, which he calls the 

 " treble-striag." 



We see in this individual, that is so obliging as to 

 produce what cook calls its "nasty noise" before us, 

 that he elevates the wing-sheaths so as to form an acute 

 angle with the body, and then rubs them together with a 

 veiy brisk horizontal motion ; but which of the nervures 

 it is that actually produces the sounds, it would require 

 a very careful and elaborate series of experimental re- 

 searches to determine. It has been asserted that the 

 legs play a part in the music by being rubbed against 

 the bows ; this, however, seems improbable from their 

 relative position. 



In the Southern United States, I have had opportu- 

 nities of seeing and of hearing a very noisy performer 

 of the Gryllus tribe, called the Katedid {PteropJiylla 

 concava), which sings through the night in the foliage 

 of the trees. The sounds, reiterated on every side, re- 

 semble a score or two of quarrelsome people with shrill 

 voices, divided into pairs, the individuals of each pair 

 squabbling with each other ; " I did ! " " Tou didn't ! " 

 " I did ! " " Tou didn't ! " the objurgation maintained 

 with the most amusing pertinacity, and without a 

 moment's intermission. Here the wing-sheaths, which 

 are large and as it were inflated, are certainly the or- 

 gans of sound. A portion of each is turned, at right- 



* Ann. Soc. Ent. de France. 



