68 



Almost all spiders have the habit of lining their holes 

 with silk. Some Lycosidge dig holes a foot deep in sand, 

 linins: them with threads and fastenino^ round the rim a 

 ring of sticks and rubbish to prevent caving in. The 

 trap door spiders go a step farther and make a door of 

 web and earth fastened to the tube by a hinge at one side. 



The simplest form of web for catching insects is an 

 extension of the margin of a tube into a flat sheet made 

 of strong threads crossed by others finer and more numer- 

 ous. Of this kind are the webs of Agalena which cover 

 ffrass fields and become visible when wet with dew. Of 

 this kind also are the large webs of Tegenaria in cellars, 

 where they are often a foot in width and remain for years. 



Another kind of flat web is made by Linyphia. Here 

 a thin sheet of web is hekl in place by threads from above 

 and below and the spider stands underneath, holding on 

 by its claws. L. marginata makes its web in the shape 

 of a dome and stands under the highest part. The webs 

 of Theridion consist of irregular threads without the flat 

 sheet, but with a more closely woven portion as a little 

 tent under which the spider shelters itself. 



The most complicated cobwebs of all are those which 

 consist of threads regularly arranged, part of which are 

 adhesive. Among these we must place the webs of Dic- 

 tyna and Amamobius, the adhesive threads of which are 

 curled by a comb on the hind legs and attached to other 

 threads previously spun. Allied to these is the web of 

 Hyptiotes which consists of four radiating lines crossed 

 by several independent adhesive threads. From this we 

 pass to the web of Uloborus, the adhesive thread of which 

 is made in the same way, but arranged in a spiral on 

 threads radiating like the spokes of a wheel and at first 

 held in place by a spiral of simple thread, which is taken 

 out as it is replaced by the adhesive oue. 



