S6^ GOUREAU ON THE 



under the auricle naturally suggests the idea of an auditory 

 tube. 



Tiie thoracic cavity of the grasshopper may without violence 

 be regarded as the ear. But what is the use of the tube which 

 crosses the femur, and terminates in the small cavities of the 

 tibiae ? Have ears any connexion with legs ? So extraordinary 

 a proposition is inconsistent with all analogy ; we must how- 

 ever admit it in the case of the cricket, which does not appear 

 to possess any other organ to which we can accord this 

 property. 



All that has been said on the subject of the hearing of 

 Orthoptera, can only be considered as conjectural, inasmuch 

 as it is not sustained by anatomical considerations, or by direct 

 experiment. But if it should be the means of attracting the 

 attention of entomologists, and inciting them to researches on 

 a point so important in the physiology of insects, it will not 

 have been without utility. 



The species of the genus Tetrix are without the bow on the 

 inner surface of the femora, nor have they the treble-string on 

 the elytra. One may however distinguish on the very small 

 elytra of some species, a transparent space near their apex ; 

 but I have not succeeded in satisfying myself that this part is 

 sonorous ; I have not observed any abdominal cavity in these 

 insects; I have therefore concluded they are mute and deaf. 

 However, as the magnifying glass is the only instrument I have 

 used in these researches, it may be that the organs of voice 

 have escaped my observation on account of their minuteness. 

 I have never heard the species of Tetrix stridulate when at 

 liberty, and have not succeeded in producing audible sounds, 

 by artificially exciting the thighs, and rubbing them against 

 the elytra, or the borders of the prothorax ; and have therefore 

 failed in verifying the assertions of those authors, who say 

 that they possess the power of song. 



Cicadas. (Cicadce, Latr.) 



We have seen that all the stridulating insects of the order 

 Orthoptera, at least all those we have hitherto examined, have 

 their musical instruments situated externally, and that their 

 song is produced by rubbing certain parts against each other. 

 It appears that thii> is not the case in the sub-order Ilomoptera, 



