2G4 MR. R. I. POCOCK — MIBIICRY IN SPIDERS. 



what sluillow ; Simonella and Synemosyna, in both of which the carapace is 

 deeply constricted, the abdomen being evenly oval in the latter and very long 

 and deeply subdivided in the former. The species of these genera are said 

 to show special resemblance to ants of the genus Pseudomyrmex. In addition, 

 there are the Neotropical Zuiiingia with its allied genera ; the European 

 Synaqeles and Leptorchestes ; Semora, Semorina, Bellota, &c. from Soutli 

 America, and Agorius from the Oriental Region — all of which and many 

 others exhibit in various degrees a mimetic similarity to ants, their colours 

 naturally varying in conformity with that of their models, being coppery^ 

 black, yellow, or black and red, diversified with hairs of various hues. 



A very interesting observation, perhaps throwing some light upon the 

 origin of ant-mimicry, was made many years ago by that keen naturalist 

 Burchell, who, as recorded by Prof. Poulton, affixed a MS. label to a 

 gpi(3er — one of the Salticidse — he collected in South America, stating that its 

 movements were like those of an ant. Now the spider itself, although small 

 and dark-coloured, is not ant-like. This suggests that imitation of the 

 movements of ants may have been the first modification of survival value, at 

 least in some of the many cases of ant-mimicry above recorded. 



Explanation of Ant-mimicry in Spiders. 



It has been suggested more than once that ant-mimicry in the case of 

 spiders is for purposes of aggression, the spiders being enabled by their 

 resemblance to ants to live without detection in the colony and prey upon 

 the insects, which mistake them for members of their own kind ; and 

 Mr. Shelf ord, in the paper already quoted, speaks of this explanation as the 

 true and accepted one. I cannot bring myself to believe that this is so, in 

 spite of the admitted fact that ant-like spiders have occasionally been seen to 

 kill and eat their insect models. 



Ants appear to be guided by other senses than sight in detecting friend 

 from foe ; and, as Mrs. Feckham has pointed out in this connection, are not 

 deceived when an individual of their own species, exactly resembling them so 

 far as we can see, but belonging to another colony, is introduced into a nest. 

 That the spiders are permitted to consort with the ants is a puzzling 

 phenomenon, and proves, in my opinion, that the similarity betv^een them is 

 much more deep-seated than we can perceive ; but in what the similarity 

 consists, unless it be " feel " and " smell,'' I am unable to suggest. 



It is known, moreover, that insects of various orders — Orthoptera, Homo- 

 ptera, and Lepidoptera (larvse) — mimic ants, and it cannot be claimed that in 

 these cases the mimicry is aggressive. If it is protective, as there are very 

 strong grounds for believing, similar mimicry on the part of spiders is also 

 probably protective. At all events the reasons that can be brought forward 

 in support of the view that ant-like grasshoppers, bugs, and caterpillars are 



