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NATURAL SCIENCE. 



Jan., 



when worried by a cat, standing up the while and brandishing its 

 fore-limbs, as shown in Fig. 9. From this it seems clear that 

 the sound is emitted under the stimulus of danger. And if it be 

 asked what benefit the spider can derive from the stridulation, it 

 must be remembered that animals that are rendered noxious by the 

 possession of stings and poison-glands, or of juices distasteful to 

 others that would prey upon them, are very commonly made con- 

 spicuous by some readily-perceived character. Some, for instance, 

 like bees and wasps and many centipedes and scorpions, are brightly 

 coloured with black and yellow bands, which immediately strike the eye. 

 Others, on the contrary, like the huge black scorpions of India and 



Fig. 9. — Phormingochilus stridulating. 



rattlesnakes, possess an apparatus specially designed to make a 

 rattling sound, which is believed to be a danger-signal, warning other 

 animals to let them alone. And this, as Wood-Mason has suggested, 

 is probably the function of the stridulating organs in these large 

 poisonous spiders. 



But Dr. McCook, when criticising, somewhat sceptically it must 

 be admitted, Wood- Mason's conclusion, appears to have fallen into a 

 very popular misapprehension of the whole question. For he gravely 

 asserts that he can scarcely give credence to the theory that the 

 stridulating organs [in these spiders] , like the rattles of a rattle- 

 snake's tail, are intended to give warning to victims of their dangerous 

 and deadly nature. With this belief we most cordially agree ; but, 



