TRAP-DOOK SPIDEBS. 215 



place six days later, that a new door had been made, and that 

 the spider had mounted up to fetch moss from the undisturbed 

 bank above, planting it in the earth which formed the crown 

 of the door. Here the moss actually called the eye to the 

 trap, which lay in the little plain of brown earth made by my 

 digging. 



If an enemy should detect the trap-door and en- 

 deavour to open it, the spider frequently seizes hold of 

 its internal surface, and, applying her legs to the walls 

 of the tube, forcibly holds the trap-door shut. In the 

 double trap-door species it is surmised that the second 

 trap-door serves as an inner barrier of defence, behind 

 which the spider retires when obliged to abandon the 

 first one. In the branched tube species (which, so far as 

 at present known, only occurs in the south of Europe) it 

 is surmised that the spider, when it finds that an enemy 

 is about to gain entrance at the first trap-door, runs 

 into the branch tube and draws up behind it the second 

 trap-door. The surface of this trap-door, being overlaid 

 with silk like the walls of the tube, is then invisible ; so 

 that the enemy no doubt passes down the main tube to 

 find it empty, without observing the lateral branch in 

 which the spider is concealed behind the closed door. 



As showing that these animals are to no small extent 

 able to adapt their dwellings to unusual circumstances, I 

 shall here quote the following from Moggridge (loc. tit., 

 p. 122):- 



Certain nests which were furnished with two doors of the 

 cork type were observed by Mr. S. S. Saunders in the Ionian 

 Islands. The door at the surface of these nests was normal in 

 position and structure, but the lower one was placed at the very 

 bottom of the nest, and inverted, so that, though apparently in- 

 tended to open downwards, it was permanently closed by the 

 surrounding earth. The presence of a cai-efully constructed 

 door in a situation which forbade the possibility of its ever 

 being opened seemed, indeed, something difficult to account for. 

 However, it occurred to Mr. Saunders that, as these nests were 

 found in the cultivated ground round the roots of olive trees, 

 they may occasionally have got turned topsy-turvy when the 

 soil was broken up. The spider then, finding her door buried 

 below in the ground and the bottom of the tube at the surface, 



