IN THE ANTENNZE 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 
Europea) bas 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 
1 Ann. de la Soc. Ent. de France, 1837. 
2 Modern Classifications of Insects, vol, ti. 
8 Descent of Man, vol. i. p. 366. 
4 Thierstimmen, p. 132. 
