58 



ARACHNOIDEA. 



CASE represented 



This kind is very often overgrown by mosses. The 

 flap, or wafer-door kind made by Nemesia eleanora,is much slighter, 

 and the door not usually loaded with earth, nor has it anything grow- 

 ing on it. There was at one tin^e a doubt whether the insect did not 

 hold down the door with its claws, and some have thought that 

 they observed foot-holds on the door for this purpose. It certainly, 

 when it is near the door, and the door is then attempted to be 



Trap-door of Nemesia caementaria, overgrown 

 by moss. 



Trap-door of Nemesia eleanora, on the bare ground. 



opened, does hold it back to the best of its ability, but there 

 does not seem to be any mechanical or structural preparation for 

 such a contingency. Then it was ascertained that in Jamaica, 

 at least, the nest had sometimes two doors, a front and a back 

 door, as it were, that is, the nest was made in a raised bank which 

 it entered at one side and came out at the other. This was 

 supposed to indicate a deliberate selection of such a site, on the 

 calculation that, whichever door was forced, it could then escape 

 out at the other ; but this implies a greater stretch of foresight 

 than the circumstances warrant. It seems more likely that the 

 spider commenced its burrow in ignorance, that it would break 

 out on the other side of the bank, and that when it found it 

 had done so, its trap-door-forming instinct came into operation, 

 and led it to build a door at that opening as it had done at 



