230 STPJDULATING APPAEATUS 



we consider that the friction of the collar against the 

 mesothorax may also assist in doing so. 



Under these circumstances, Landois asked himself 

 whether other genera allied to Mutilla might not 

 possess a similar organ, and also have the power of pro- 

 ducing sound. He first examined the genus Ponera, 

 which, in the structure of its abdomen, nearly resem- 

 bles Mutilla, and here also he found a fully developed 

 stridulating apparatus. 



He then turned to the true ants, 1 and here also he 

 found a similar rasp-like organ in the same situation. 

 It is indeed true that ants produce no sounds which 

 are audible by us; still, when we find that certain 

 allied insects do produce sounds appreciable to us by 

 rubbing the abdominal segments one over the other ; 

 and when we find, in some ants, a nearly similar 

 structure, it certainly seems not unreasonable to 

 conclude that these latter also do produce sounds, 

 even though we cannot hear them. Landois describes 



Fig. 8. 



Attachment of abdominal segments of Laaiutjlavut $ x 225. 



the structure in the workers of Lasius fuliginosus as 

 having 20 ribs in a breadth of 0*13 of a millimetre, 

 1 Some tropical ants are said to produce a chirping sound. 



