DWELLINGS. 



157 



third the actual size (except Ci and Di, which arc of 

 natural size). While A and B have only one door, C 

 and D, besides the surface door, have another a short 

 way under ground. The whole burrow as well as the 

 door are lined with silk, which also forms the hinge. 

 The great art of the Trap-door Spider lies in her 

 skilful forming of the door, which fits tightly, although 

 it opens widely when she emerges, and which she 

 frequently holds down 

 when an intruder 

 strives to enter, and in 

 the manner with which 

 the presence of the 

 door is concealed, so ,, 

 as to harmonise with*^ 

 surrounding objects. 

 Perhaps in no case is 

 the concealment more 

 complete than when 

 dead leaves are em- 

 ployed to cover the 

 door. In some cases 

 a single withered olive 

 leaf is selected, and it 

 serves to cover the 

 entrance; in other 

 cases several are woven together with bits of wood 

 or roots, as in the accompanying illustration, which 

 represents such a door when open and when shut. 



(Fig. 21.) 



The Trap-door Spider {Mygale henzn, Girard), 

 which is widely diffused in California, forms a simple 

 shaft-like burrow, but, like the European Trap-door 

 Spider, it is very skilful in forming an entrance and 



Fig. 21. 



