XIV NESTS 355 
Doors of the cork type consist of alternate layers of silk and 
earth. After weaving a covering of silk, the creature brings earth 
in its jaws and lays it on the top, binding it down with a second 
layer of silk, and the process is repeated until the requisite 
thickness is attained. 
The nests are exceedingly difficult to detect, as the spiders 
take the precaution of attaching leaves, moss, or small twigs to 
the outer surface of the doors. This does not appear to be the 
result of intelligence, but a mere instinctive habit ; for if a door 
be removed and the surrounding earth denuded of moss, the 
spider will render the new door conspicuous by bringing moss 
from a distance, and thus making a green spot in the bare patch 
of earth." 
The cork doors fit with great exactness, and there is always 
to be found on their under surface a notch by which they are 
held down by the fore-legs of the spider against any attempt to 
open them from without. 
Many nests with trap-doors of the wafer type are found to 
have a second and more solid door within the tube. This serves 
to shut off the lower part of the nest as a still more secure 
retreat. This second door opens downwards, and the Spider, 
getting beneath it, is effectually shielded from an enemy which 
may have mastered the secret of the outer barrier. The nests 
of some species present still further complications in the way of 
lateral branches from the main tube. In one case (Nemesia 
congener) the burrow becomes Y-shaped, and the second door 
hangs at the fork of the Y in such a manner as to connect the 
bottom chamber either with the entrance or with the branch, 
which does not reach the surface, but ends blindly. 
Trap-door Spiders are greatly attached to their tubes, which 
they enlarge and repair at need. They begin burrowing very 
early in life, and their tiny tubes resemble in all respects those 
of their parents. Their habits are nocturnal, and little is known 
of them; an observation, however, on a species inhabiting the 
island of Tinos in the Grecian Archipelago (Cteniza ariana), by 
Erber,’ must not be omitted. This spider leaves its tube at 
night and spins a web near at hand and close to the ground. 
It carries captured insects into its tube, and in the morning 
' Moggridge, Harvesting Ants and Trap-door Spiders. London, 1873, p. 120. 
2 Verh. Ges. Wien, xviii., 1868, p. 905 (Abstract in Zool. Rec. v., 1868, ‘p. ifs) 
