MIMICKY IN SPIDERS. 353 



which represent the projecting entrance of a nest of Nemesia mereclionalis 

 at Men tone. Fig. 1 shows the door closed and well disguised by re- 

 semblance to the dry olive leaves which cover the ground in the vicinity 

 of the nest. Fig. 2 shows the same tube with the door thrown open. The 

 effectiveness of this disguise is at once api)arent. It may be questioned, 

 however, whether it is made with deliberate intent at mimicry. The spi- 

 der's purpose in attaching leaves to the outer surface of its door is doubt- 

 less protective. But may it not be that, moved by ordinary self protective 

 instinct, it simply took the first available material, without regard to 

 mimetic resemblance ? 



I may illustrate this by referring to my studies of the parasol or cut- 

 ting ant of Texas. > My first experience of a formicary of these insects was 

 . discouraging. I had encamped in its vicinity on the strength of 



Ants information that it was a large and active hill ; but at a naorning 



visit it seemed utterly abandoned, not a sign of life or activity 

 anywhere present. The mound was dotted over with forest chippage, bits 

 of twigs, dried leaves from an overhanging live oak, but no entrance into 

 the nest appeared. Returning to the place in the evening I found that 

 vigorous life had succeeded the semblance of death. Numerous openings 

 appeared all over the surface of the mound, out of wliich myriads of 

 insects were pouring, streaming away into the surrounding country, engaged 

 especially in harvesting leaves from the immense live oak tree that over- 

 hung. The change was readily explained by .subsequent studies. I found 

 that the ants are in the habit of closing up their doors after their night's 

 work, and when the upper part of the tubes which lead into the main 

 formicary have been filled to the distance of about an inch with various 

 chippage and sand, piles of dry leaves and twigs are erected above the open- 

 ing. These chips form a part of the permanent property of the ants, for 

 I observed that the same pieces were used day after day. The mimicry 

 in this case was complete. The surface of the mound was made to re- 

 semble a bit of natural soil covered over with piles of dried leaves and 

 twigs. It effectually deceived me, although I was on the lookout for the 

 insects. Yet I have never thought that the ants designed to produce such 

 a mimetic harmony. They simply gathered such dry leaves and other ma- 

 terials as were convenient, and the fact that these so closely resembled the 

 surface of the mound was accidental. May it not be that some of the 

 striking resemblances in the doors of Trapdoor spiders are produced in 

 the .same way? 



Striking illu.strations of this mimetic resemblance are shown in Figs. 

 3, 4, and 5 of Plate II. Fig. 3 represents a moss covered sod, pierced by 

 the tube of the nest of Nemesia coementaria, the door of which is entirelj' 

 concealed from view, and only discovered by one who happened to cut 



' Proceedings .\cad. Nat. Sci., Phila., 1879, page 33, sq. 



