150 



TRA P-DOOR SPIDERS. 



made excursions to catch the flies with which I supplied her, 

 but remained self-immured in her cell.^ 



It would be interesting to dit'cover whether any of the 

 spiders of this group (but which do not construct trap-door 

 nests) pass the winter in similar structures. 



H. 



On the Structure of Cork Doors. 



In order to test my theory to the effect that the trap-door 

 nests are enlarged from time to time, and that the numbers 

 of layers of silk in an undisturbed cork door should represent 

 the number of enlargements which the nest has undergone, I 

 examined the doors of twenty-eight nests of the cork type (all 

 I believe of N. ccementaria), in order to prove whether as a 

 rule the larger cork doors do contain more layers of silk than 

 the small ones, as they should on this hypothesis. 



This is, I think, fairly established by the following table : — 



* My observations on the captive spider were still in progress at the time 

 of going to print, so that the above notes must be considered as incomplete. 



