230 STRIDULATING APPARATUS 
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, 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 wunreasonable to 
conclude that these latter also do produce sounds, 
even though we cannot hear them. Landois describes 
Fig. 8. 
Attachment of abdominal segments of Lasius flavus % x 225. 
the structure in the workers of Lasius fuliginosus as 
having 20 ribs in a breadth of 0°13 of a millimetre, 
