i8g 5 . MUSICAL BOXES IN SPIDERS. 49 



in justice to the memory of the late Professor Wood-Mason, we must 

 add that he never accredited his spider with such unnatural and 

 altruistic intentions. As a matter of fact, he said just what we have 

 stated above, namely, that the spider stridulates to warn animals thai 

 would prey upon it of its deadly nature, in order that they may leave it 

 in peace, from considerations of their own safety. It is true that both 

 parties to the question are benefited by the spider's rattling ; but it is 

 also true that the development of an organ like the stridulator above 

 described could only be brought about by Natural Selection through 

 the gain that the spider alone experiences from possessing it. 



But if the object of this stridulating organ be what has been 

 suggested, it may well be asked, What can be the function of the analo- 

 gous organ that is found in Thomisoides ? For, seeing that in this spider 

 the instrument is equally well developed in both male and female, and 

 that there is no evidence that either sex possesses an auditory sense, 

 the belief that the sound is used during courtship as a sexual call is 

 without foundation. Moreover, as compared with the Aviculariidae, 

 Thomisoides is a small and feeble spider, which, so far as we can see, 

 could in no sense profit, as the large spiders do, from the possession 

 of a stridulator unless there were something terrifying or repellent in 

 the sound pure and simple. Otherwise, the device would be 

 speedily seen through as a transparent fraud, and the stridulation 

 would prove detrimental to the spider by drawing the attention of 

 enemies to its whereabouts. But M. Simon has told us that when 

 discovered this spider, instead of attempting to escape by speed of 

 foot, or by lying perdu, or by showing fight, starts stridulating, and 

 that the resulting sound resembles the buzzing of a bee. This author, 

 indeed, makes no suggestion respecting the object of this resemblance; 

 but we venture to think that he has accidentally furnished us with 

 the key to the whole question. For just as many harmless flies 

 profitably mimic poisonous bees and wasps in appearance, and 

 possibly also in the nature of their buzzing, so, too, does it seem per- 

 missible to believe, in the absence of any other explanation of the 

 fact, that Thomisoides is protected from enemies by its power to imitate 

 the sounds produced by poisonous insects. 



To recapitulate — stridulating organs in spiders seem to exist for 

 two distinct and definite purposes. 



In the case of Leplithyphantes and of the species referred origin- 

 ally to Theridium, the organs are either better developed in the males 

 than in the females, or are exclusively confined to members of the 

 former sex. From this fact, coupled with the circumstance that the 

 spiders of these two kinds are, judging by analogy, possessed of 

 auditory organs, we may infer, although as yet without direct proof, 

 that the male makes use of his sounding organs during the period of 

 courtship. This, as is well known, is a time which to the male of 

 very many species is beset with exceptional difficulties and dangers, 

 owing to the irascible and voracious disposition of the more powerful 



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