No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. 109 



particular species of ants which they prey upon. It seems as 

 though the highest point of protective benefit would have been 

 reached long before the resemblance of the spider to the ant 

 had become so close as it really is. On the other hand, it is 

 difficult to believe that ants are deceived, even by those spiders 

 which mimic them most closely, when we remember that 

 their perceptions are so keen that they discriminate not only 

 between ants of their own and different species, but even between 

 ants of their own species living in two different communities.* 



The mimicry of ichneumon flies by spiders was noted 

 some years ago by Mr. Herbert Smith. This case comes under 

 Class 3, in which one species mimics another which preys upon 

 it. Great destruction is caused by ichneumons which lay their 

 eggs on the bodies of the live spiders, and the disguise probably 

 protects the spider by leading the fly to mistake it for one of its 

 own species. 



We have no proof that spiders ever mimic ants as a 

 method of escaping from them, but it is possible that this 

 sometimes happens. We know that some ants prey upon 

 them. The foraging ants of South America destroy spiders as 

 well as many kinds of insects, and Wallace mentions a small, 

 wood-boring ant which fills its nest with small spiders.f 



If the spiders that feed upon ants deceive them by their 

 mimicry those which are preyed upon by ants would gain 

 an advantage by a similar disguise. I once placed a little ant- 

 like spider of the genus Herpyilus in a bottle with three ants no 

 larger than itself, which I had caught with it in the sweep-net. 

 In a very few minutes the ants had killed and began to de- 

 vour the spider. It may be that the resemblance was suffi- 

 ciently close to deceive them in the open, but failed when 

 spider and ants were confined together in close quarters. 



I will now give some account of an ant-like spider which 

 we have studied closely. 



* Sir John Lubbock, 

 t Tropical Naiure, p. 83. 



