TRAP-DOOR SPIDERS. 
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 pjp 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. cit n 
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 carefully 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, 
