TRAP- DOOR SPIDERS. 99 



In the exceptional cases where the nests have two 

 superficial openings, one of the two surface doors 

 always appears neglected and going to decay, or is 

 covered with earth which chokes the upper part of 

 its tube. The explanation of this probably is that 

 the spider found the original entrance blocked up or 

 in some way unfitted for use, and then prolonged 

 what was the blind branch until it reached the sur- 

 face and replaced the former doorway. However this 

 may be it is certain that in the great majority of 

 nests it will be found that the branch ends in tlie 

 earth, and is a cul de sac, and this I have invariably 

 observed to be the case in the nests of very young 

 spiders of this species (fig. B, Plate IX.) 



The tube is frequently enlarged at the mouth, and 

 forms a spreading lip which the surface door is usually 

 large enough to cover (A 1, Plate IX.) 



In these branched double-door nests the upper door 

 does not fit into, but merely lies upon, the mouth of 

 the tube, the elasticity of the hinge and its own weight 

 being sufficient to keep it closed. The lower door is 

 suspended by a hinge placed at the apex of the angle 

 formed by the bifurcation of the tube, and is hung in 

 such a manner that it can either be pushed upwards 

 so as to lie diagonally across and block the main tube, 

 or be drawn back so as to fit into and close the 

 entrance to the branch. 



This will, I think, best be understood by reference 

 to the drawings of a small nest of this iy^Q given at 

 B 1 and B 2 in Plate XI. p. 105, where the second door 

 is shown in its two positions. This lower door is from 

 1 to li lines thick, channeled above, but nearly fiat 

 on the back, and of an elliptic form, with a loose ap- 



H 2 



