282 Mr. J. Wood-Mason's Note on Mygale stridulans. 



tlie sieve, smelling at it) pounced forward, possibly mis- 

 taking tlie prisoner for a mouse; but the spider, instead 

 of retreating, ran round and round inside its prison, fol- 

 lowing the movements of the cat and stridulating louder 

 than ever. When thus roused, the spider usually rested 

 on the four posterior legs, raising the other four and 

 shaking them in the air, with the thorax thrown up almost 

 at right angles to the abdomen and the chelicerse in rapid 

 motion — assumed, in fact, quite a threatening attitude. 

 The cat was much excited, and, had the spider been free, 

 would probably have seized it, while the latter would 

 equally probably have resented an attack by fastening on 

 the former's muzzle. I was so taken by the whole affair 

 that I did not kill the spider till the following night, and 

 thus' had many opportunities of verifying the foregoing 

 observations." 



The sound-producing apparatus in Mygale stridulans 

 has been found to consist of a comb, composed of a number 

 of highly elastic and indurated club-shaped chitinous rods 

 arranged close together comb-like on the inner face of the 

 basal joint of the palps, and of a scraper formed by an 

 irregular row of sharp erect spines on the outer surface of 

 the penultimate joint of the chelicerse ; and to be equally 

 well-developed in the two sexes, the first specimen met 

 with by Mr. Peal, indeed, having been a gigantic female. 



In Westring's spiders the apparatus consists "of a 

 serrated ridge at the base of the abdomen, against which 

 the hard hinder part of the thorax is rubbed, and of this 

 structure not a trace could be detected in the females." 

 From the analogy of the Orthoptera and Homoptera, we 

 may, with Mr. Darwin and Professor Westring, " feel 

 almost sure that the stridulation " made by these spiders 

 " serves either to call or to excite the female"; and if the 

 sounds serve this purpose in the Mygale also, they must 

 serve as a mutual call, the apparatus being present in both 

 sexes ; but it seems probable, from Mr. Peal's observations, 

 that they are also emitted by the spider in self-defence — to 

 render itself terrible in the eyes of its enemies, or, it may 

 be, from fear; perhaps, also, they are serviceable to the 

 animal for terrifying its prey; and, during its nocturnal 

 rambles in quest of food, for warning the creatures that 

 prey upon it of its dangerous and deadly nature, as I have 

 read suggested with regard to the porcupines {Hystrix 

 and Atherura) and, I believe, also respecting the rattle- 

 snakes, in all of which the rattle is equally well-developed 

 in the two sexes. 



