WEB-SPIDERS. 
2 26 
prey. So far as the claw armature of the feet is concerned this family leads on 
to the trap-door spiders ( Ctenizidw ), famed for the perfection of their architecture. 
Although the species exhibit considerable variation in the perfection of their nests, 
the method of work appears in all cases to be substantially the same. A deep 
tunnel is first dug in the soil and then lined with silk to prevent the falling in of 
the loose earth. Then, with the object of excluding enemies such as ants and wasps, 
as well as to keep out rain, a lid, formed of layers of silk, strengthened with 
particles of soil, is built over the aperture, and attached along one side to the wall 
of the tube in such a manner that the elasticity of the silken hinge keeps the door 
normalty closed. The outer surface of the 
door is then covered, if necessary, with 
fragments of moss, or with pieces of the 
nest, so that when the door is closed it 
matches its surroundings and becomes 
practically invisible. In the genus 
Nemesia, from the shores of the Mediter¬ 
ranean and abundant in the Riviera, the 
lid is thin and light and of the so-called 
wafer type; but in the majority of cases it 
is thick and heavy, with a bevelled edge, so 
that it fits tightly into the upper end of the burrow, and is said to be of the cork- 
type. Not unfrequently the spider digs a side gallery to this burrow, and shuts 
the aperture of communication between the two by means of a second door. Then, 
in cases of emergency, when the lid of the main entrance has been forced, the 
spider retreats along the second branch and closes the door, so that the enemy, 
after exploring the main tube and finding it empty, departs, believing the burrow 
to be tenantless. In some instances, indeed, the secondary branch is made to 
communicate by a special opening with the exterior, so that even if its internal 
aperture be discovered, the spider can still beat a retreat. It is by no means, 
however, an easy matter to force open the lid in the first instance; for no sooner 
does the spider feel the attempt being made, than it seizes the inner side of the 
door with the claws of its front-legs, and, firmly planting those of its hinder limbs 
in the silken walls of the burrow, resists every effort to force an entrance. A few 
species have forsaken the ground and taken to building their nests upon the 
trunks of trees, as shown in the figure above. Some of these, like the South 
African Moggridgea, and the Mascarene Myrtale , avail themselves of natural 
irregularities in the surface and build silken tubes in the crevices; then, chipping 
oft' pieces of bark and lichen, cover the white silk, so that the tube and its door 
become invisible. The South American Pseudidiops, frequenting palm-trees at 
Bahia, appears to excavate its own grooves in the bark by means of the fangs, and 
the stout, short spines with which its mandibles are armed. 
In North Europe the only representative of this group is the genus Atypus , 
which has been found in England and Ireland. This genus belongs to the 
family Atypidce, differing from the rest of the section in possessing long maxillary 
processes on the coxae of the palp; and also in having six spinning mammillae. 
plants that grow in the vicinity of the 
PALM TRAP-DOOR SPIDER ( Pseudidiops ) AND ITS 
nest (nat. size') 
