No. 2.] PROTECTIVE RESEMBLANCES IN SPIDERS. Ill 



useless.* The ant only moves in this way when it is hunt- 

 ing ; at other times it goes in a straight line ; but its little 

 imitator zig-zags always. 



In addition to its ant-like walk, picata holds up its second 

 pair of legs in such a way that they appear like antennae. The 

 first legs are short'Und support the anterior part of the body. 

 The second pair, although it is sometimes used, seems not to 

 be needed for locomotion. All the threatening and similar 

 movements made by other spiders with the first pair, are, with 

 picata, made with the second. 



Spiders commonly remain nearly motionless while they 

 are eating ; picata, on the other hand, acts like an ant which is 

 engaged m pulling some treasure-trove into pieces convenient 

 for carrying. I have noticed a female picata which, after get- 

 ting possession of a gnat, kept beating it with her front legs as 

 she ate, pulling it about in different directions, and all the time 

 twitching her ant-like abdomen, Pavesi says that the ant-like 

 DrassidfE and Attidce continually move their abdomens exactly 

 as ants do.f I have not noticed this habit in any of our 

 spiders excepting this species. 



Picata is found in company with several small species of 

 ants, but does not seem to resemble one more than another. It 

 does not molest, and neither is it molested by the ants, so that 

 the cause of its mimicry must be looked for in either Class 1 

 or Class 4. I should not have formed this latter class, in which 

 it is supposed that one species mimics another because it preys 

 upon a third species found with the mimicked form, but not 

 eaten by it, had it not been suggested to me by the fact that 

 when, as before related, I captured the spiders, ants and beetles 

 together, one of the spiders (picata) was engaged in eating a 

 tiny beetle. It may be that picata preys upon some small 

 beetle which is not eaten by ants — possibly one of those 

 which, undisturbed by the proprietors, inhabits their nests. In 



* Natural Selection, p. 91. 

 tioc. cit.,p. 12. 



