Ivi INTRODUCTION. 



of the thoracic opercula. One is ghttering and 

 iridescent, the other is thicker and yellowish. Dr. 

 Lipori also cut away these, little by little, and found 

 that, although the sound was modified, it was not 

 extinguished ; indeed he thinks that they act princi- 

 pally as means for keeping extraneous matters out of 

 the cavities, and possibly for modifying their reso- 

 nance. 



Through an opening made down the back of the 

 abdomen, the viscera were removed, and this exposed 

 two masses of muscle. Still the insect continued to 

 sing as if nothing had been done to it ! " L'animale 

 continua a cantare, come se nulla fosse. Ma se si 

 taglia no le massa muscolari, l'animale non cantapiu." 

 If the muscle be cut on one side only, the song can 

 still be continued on the other. 



In a similar manner it was proved that the destruc- 

 tion of the corrugated membrane (membrana pieghet- 

 tata) entirely prevented all action of the stridulous 

 apparatus. 



A rapid vibratory movement can be distinguished in 

 these muscles, if viewed under a lens. Eeaumur's 

 experiment of evoking the creaking sound, by 

 scratching the drum (tamboure) with a fine needle, 

 was successfully repeated by Dr. Lipori. 



Landois urges the importance of certain meta- 

 thoracic spots (stigmi), which he thinks conduce to 

 the sound. Lipori closed these stigmata with oil, and 

 he states that, although the Cicala was incouvenienced, 

 its singing powers were not much impaired. 



Lipori could find no singing parts, even rudimentary, 

 in the females of Cicada omi, C. Juonatodes, or Tettigonia 

 pk'heia, of Eossi. Nevertheless this, of course, does 

 not disprove the assertion of certain authors, that the 

 rudiments do occur in the females of certain foreign 

 species. 



Reaumur, in his ' Memoire ' above cited, objects to 

 the opinion of old authors that the friction of the 

 scales, or, again, the vibrations of " les petits miroirs," 



