314 TENANTS OF AJS OLD FAlUf. 



named, l)ut before we con^^ider that, lei lis look at their 

 musical organs, and compare them with those of the 

 cricket and katydid. 



'' The males alone ai'e musical, and their well-known 

 rattling buzz is a love-call to their silent mates. The 

 instruments by which the sounds are produced are a 

 pair of kettle-drums, as they may be called, situated 

 one on each side of the body. These can be plainl}' 

 seen here just behind the Avings. These drums are 

 formed of convex pieces of parchment-like membrane, 

 gathered into numerous fine plaits, and are lodged in 

 cavities on the sides of the bodies behind the thorax. 

 They are not played upon with sticks, of course, but by 

 muscles or cords fastened to the inside of the drums. 

 When these muscles contract and relax, which they 

 do with great rapidity, the drum-heads are alternately 

 tightened and loosened, recovering their natui'al con- 

 vexity by their own elasticity. Our Cicada may, there- 

 fore, be called a drummer." 



"But Mr. Mayfield," interrupted Harry, "a drum- 

 head don't tighten and loosen in that way. You 

 tighten it up, and keep it tight, or it wouldn't drum at 

 all." 



"Of course, Harry," I replied, "we can only speak 

 in figures when we compare the sound-producing or- 

 gans of insects to musical instruments of any sort. All 

 I mean is that the principle upon which the Cicada's 

 note is produced is like that upon which sounds are 

 brought out of a drum-head. Let us see if this is not 

 so. Here is a sheet of tin which I have laid upon the 



