1896. HOW AND WHY SCORPIONS HISS. 25 



the little black poisonous spider of Australasia, to see the scarlet 

 badge on its back, or the cobra the pattern on its hood, in spite of 

 the fact that from the existence of these marks the existence of 

 eyes to see them is to be inferred. 



In conclusion, however, it must not be forgotten that the explana- 

 tion here given of the probable function of the stridulating organs in 

 the large spiders and scorpions is at present unsupported by any 

 direct observations as to the protective effect of the sound. As a 

 matter of fact, as Mr. Marshall informs me, the species of Opisthoph- 

 thalmus are eaten in spite of their hissing by both baboons and roller- 

 birds. But so also is the cobra killed by the mungoose, notwith- 

 standing its poison-badge, and bees are devoured by frogs and toads, 

 though decked with warning colours. Within the limits, indeed, of 

 the animal kingdom it would probably be impossible to find a single 

 instance of a protective feature serving to save its owner from the 

 attacks of enemies of all kinds. The hypothesis, therefore, that the 

 sound, like the scarlet band on the katipo, acts as a danger-signal 

 need not be rejected on the grounds that monkeys which are partial 

 to a diet of scorpions, and skilful enough to handle them without 

 damage, pay no heed to the hissing when searching beneath stones 

 for these animals and other vermin ; and since the hypothesis affords 

 both a simple and plausible explanation of the phenomenon, it may be 

 provisionally adopted as a probable approximation to the truth, at all 

 ■events until reasons can be shown for thinking that it is logically 

 untenable, or until another and a better one is put forward in its 

 place. 



R. I. POCOCK. 



