270 MR. R. I. POCOCK — MIMICRY IN SPIDERS. 



is like that of a protected species. Were this so its stridulation would comej 

 like that o£ the Aviculariidee, under the category of warning (aposematic) 

 characters. But the resemblance of the stridulation to that of a bee may be 

 pseudaposematic and suggest to would-be aggressors that the spider itself, 

 although harmless, is in reality, like a bee, dangerous to meddle with *. 



A possible and oft-quoted instance of aggressive mimicry in spiders was 

 suggested long ago by Trimen, who stated that some Salticida3 imitate 

 crawling flies in their movements and are enabled thereby to approach the 

 insects without alarming them. This view, however, is not in keeping with 

 my own observations upon the visual powers of flies ; nor do the hunting 

 methods of the Salticidee bear it out. For no sooner do they sight a fly than 

 they suspend the alleged deceptive crawling movement, and substitute stillness, 

 followed by a stealthy cat-like creep and a lightning leap over the intervening 

 space. This method would be unnecessary were Mr. Trimen''s hypothesis 

 true. If there be, as is possible, mimicry in this case, I suspect it is also 

 protective ; and that the spiders benefit by deceiving wasps which, mistaking 

 them for flies, perhaps pass them by as difficult or impossible to catch. 



EXPLANATION OF PLATE 32. 



Fig. 1. Ildihalia mutilloides, Sim., S (after Simon) (p. 260). 



2. Sphecotyims niger, Perty, § (after Simon) (p. 262). 



3. Myrmecium nigrum, Perty, S (after Simon) (p. 261). 



4. Myrmarachne plataleoides, 0. P. Cambr., S (after Simon) (p. 263). 



5. Amycicea forticeps, O. P. Oambr,, S (after Cambridge) (p. 262). 



5 a. ,, „ „ Lateral view with legs removed to show the ant- 



like profile and the eye-like spot at the end of the abdomen. 



6. Faraplectana thorntoni, Blackw. (after Simon) (p. 257). 



7. „ loalleri, Blackw. (after Simon) (p. 257). 



8. Araneus coccinella, Poc. (after Pocock) (p. 257). 



* Pocock, ' Natural Science,' vi. p. 49, 1895. 



Probably owing to his writing from memory of this suggestion as to the stridulation of 

 Sicaritts, Mr. G. A. K. Marshall unintentionally misrepresents me as believing that the 

 stridulation of Scorpions and Mygale Spiders (Aviculariidee) is pseudaposematic, recalling 

 the shrill, angry buzz of wasps (Trans. Ent. Soc. London, 1902, p. 403). As a matter of fact, 

 I have always believed, and frequently stated the belief, that the stridulation in these two 

 groups of Arachnida is aposematic in exactlj^ the same sense as is the rattle of the rattle- 

 snake. Scorpions can sting and the Aviculariidaj have a poisonous bite and urticating 

 bristles. 



