CTBNIZA. 61 



breakers. The covers of their burrows, instead of 

 being thick and fitting into the liole hke a stopper, 

 as is the case with those of the California trapdoor 

 spiders, are thin, covered with moss, dead leaves, or 

 whatever happens to be scattered over the ground 

 where they are, and lie loosely upon the mouth of 

 the burrow. Two or more inches down the tunnel, 

 however, is another door, hinged to one side of the 

 tube, open and hanging down when not in use ; but 

 no sooner is any attempt made to lift the upper lid, 

 than the lower one is pushed up and shut by the 

 spider under it, and then looks exactly as if it were 

 the bottom of an empty tube. 



Another species improves upon this trick by dig- 

 ging a branch tunnel from the middle of the tube in 

 a slanting direction to the surface, and hanging a door 

 at the junction of the tubes, so that it can be used to 

 close the way to either of them as occasion requires, 

 while the householder escapes to the one which has 

 not been broken into. 



The flap or lid of the tubes of all trapdoor spiders 

 is always so made that when it shuts it does not fall 

 in the slightest degree to the right or left, but comes 

 down exactly upon the opening it covers. 



Where the burrow is dug on a slope of ground, as 

 it almost always is ; the hinge is invariably uppermost, 

 so that when raised the door falls shut of itself. In i 

 the case of the American trapdoor spider, and others, 

 where the lid is thick, it is neatly beveled off in- 

 ward, so as to tightly and accurately fit the socket 

 or frame into which it falls. All others, also, where 



