226 



WEB-SPIDERS. 



PALM TRAP-DOOR SPIDER {Pseudicliops) AXD ITS 



nest (nat. sizel 



prey. So far as the claw armature of the feet is concerned this family leads on 

 to the trap-door spiders (Ctenizidce), 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 



normally closed. The outer surface of the 

 door is then covered, if necessary, with 

 fragments of moss, or with pieces of the 

 plants that grow in the vicinity 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 

 off pieces of bark and lichen, cover the white silk, so that the tube and its door 

 become invisible. The South American Pseudicliops, 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 1 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 mammilla?. 



