IN THE ANTENNA OF ANTS. 229 



ing of the tube in the short segments would make 

 little difference in its mode of action. 



Kirby and Spence were, I believe, the first to 

 notice that an insect allied to the ants (^Mutilla 

 Europcea) has the power of making a sibilant, 

 chirping sound, but they did not ascertain how 

 this was effected. Goureau ^ subsequently called at- 

 tention to the same fact, and attributed it to fric- 

 tion of the base of the third segment of the abdo- 

 men against the second. Westwood,^ on the other 

 hand, thought the sound was produced ' by the action 

 of the large collar against the front of the mesothorax. 

 Darwin, in his ' Descent of Man,' adopts the same view. 

 ' I find,' he says,^ ' that these surfaces (i.e. the over- 

 lapping portions of the second and third abdominal 

 segments) are marked with very fine concentric ridges, 

 but so is the projecting thoracic collar, on which the 

 head articulates ; and this collar, when scratched with 

 the point of a needle, emits the proper sound.' Landois, 

 after referring to this opinion, expresses himself strongly 

 in opposition to it. The true organ of sound is, he 

 maintains," a triangular field on the upper surface of 

 the fourth abdominal ring, which is finely ribbed, and 

 which, when rubbed, emits a stridulating sound. It 

 certainly would appear, from Landois' observations, 

 that this structure does produce sound, whether or not 



' Ann. de la Soc. Ent. de France, 1 837. 



* Modern Classifications of Insects, vol. ii. 



* Descent of Man, vol. i. p. 366. 



* Thierstimmen, p. 132. 



