40 



FIRST LESSONS IN ZOOLOGY 



the hole when closed. Its upper surface is covered with 

 soil, bits of leaves, and wood, and resembles very exactly 

 the ground surface about it. We have found these trap- 

 door nests in California in moss-covered ground, and 



F[(;. 23. — Trap-duiir s]:>ider (C;ililT)rTiia) \\-\\.\\ two luirrcws, one with door 

 open, one with door cl<jseil. (Natural bize; from life and speeimeiis. ) 



here the nest lids were always covered with green, 

 growing moss. 



An English naturalist who studied the habits of these 

 spiders found that if he removed the soil and bits of bark 

 and twigs, or the moss, from the upper surface of the lid 

 the spider always recovered it. It is of course plain that 

 by means of this covering the nest is perfectl}' concealed, 

 the surface of the closed door not differing from the sur- 

 rounding ground surface. This naturalist finally removed 

 the moss not only from the surface of a trap-door, but 

 also from all the ground in a circle of a few feet about the 

 nest. The next day he found that the sjiider had brought 

 moss from outside the cleareil space and covered the 



