DWELLINGS 1613 



rains and their stony summits are often full of 

 spiders' nests. These subterranean dwellings are 

 shafts sunk vertically in the earth, except where some 

 stony obstruction compels the miner to deflect from 

 a downward course. The shafts are from five to 

 twelve inches in depth, and from one-half to one and 

 a half inches in diameter, depending largely upon the 

 age and size of the spider. 



When the spider has decided upon a location, 

 which is always in clay, adobe or stiff soil, he 

 excavates the shaft by means of the sharp horns at 

 the end of his mandibles, which are his pick and 

 shovel and mining tools. The earth is held between 

 the mandibles and carried to the surface. When the 

 shaft is of the required size, the spider smoothes and 

 glazes the wall with a fluid which is secreted by 

 itself. Then the whole shaft is covered with 

 a silken paper lining, spun from the animal's 

 spinnerets. 



The door at the top of the shaft is made of several 

 alternate layers of silk and earth, and is supplied 

 with an elastic and ingenious hinge, and fits closely 

 in a groove around the rim of the tube. This door 

 simulates the surface on which it lies, and is dis- 

 tinguishable from it only by a careful scrutiny. The 

 clever spider even glues earth and bits of small plants 

 on the upper side of his trap-door, thus making it 

 closely resemble the surrounding surface. 



The spider generally stations itself at the bottom 

 of the tube. When, by tapping on the door, or by 

 other means, a gentle vibration is caused, the spider 

 runs to the top of his nest, raises the lid, looks out 



