xn] STRIDULATION 107 



sound, the organ is well developed in the male only, 

 being rudimentary or altogether absent in the female, 

 while in the Aviculariidae, which appear to be quite 

 deaf, both sexes possess it equally. In them its 

 function is probably to warn off its enemies a 

 purpose for which it is not at all necessary that the 

 spider itself should hear it. 



Sometimes sounds have been quite wrongly attri- 

 buted to spiders ; there is, for example, an Australian 

 species widely known among natives as the "barking" 

 or "booming" spider, for no better reason than that 

 the spider has been found in the day-time at a spot 

 where the booming was heard at night. This case was 

 investigated by Professor Baldwin Spencer, who found 

 that quails were really responsible for the sounds 

 with which the spider was credited. The creature 

 could, however, achieve a kind of whistle by rubbing 

 its palps against its mandibles. Its stridulating 

 apparatus was of the type common among the 

 Aviculariidae. Its principle is that of the musical 

 box, where nail-like projections on a barrel strike 

 against the teeth of a metal comb, except that the 

 barrel is stationary and the comb is moved up and 

 down against it. The barrel is here represented by 

 the first joint of the mandible which is beset on its 

 outer side with spines. The inner edge of the first 

 joint of the palp is furnished with " keys r which are 

 rubbed against the mandible spines when the palps 



