42 ON THE TREE TRAPDOOR SPIDER, [Jan. 18, 



much time in smoking under one of these trees, saw an open trap, 

 and drew my attention to it, and then they could be secreted no 

 longer, for I searched every likely tree and made them my special 

 care and study for some time. 



I have in my possession two or three houses in which the doors 

 have undergone modifications to meet the size of the spiders now 

 residing in them. A small individual will sometimes take pos- 

 session of the empty house of an adult ; the new comer finds the 

 door too large, so constructs another in such a way as to form a 

 smaller opening ; thus some houses have two doors : I send you 

 a specimen. 



On attempting to Hft the doors of these houses, the spiders hold 

 them down with great firmness. Knowing that naturalists are un- 

 certain as to the means used by the ordinary Trapdoor Spiders for 

 holding down the traps, I have taken special care to observe the 

 mode adopted by those which inhabit the trees, and I find that the 

 hooks of the mandibles, which are barbed, grasp the door, and the legs 

 the side of the house. I am quite sure that this is the case, for I 

 have observed carefully, and in one instance, when the spider held 

 on tenaciously, I was enabled to fix open the door and observe with 

 a lens, and then to lift out the " fangs," which were buried deep 

 in the silken door. I have often found the doors fastened down and 

 not held. They are fastened by strong weavings of silk, which must 

 be broken before the door can be lifted ; in all such cases the spiders 

 do not appear to be active or to assist in keeping down the trap. 

 Perhaps at such times the spider is engaged in changing its skin, 

 and, in cold weather, hybernating. 



Being anxious to see the spider capture its prey, I put a few grains 

 of sugar near one of the doors. Two flies lighted on the sugar, 

 and while they were regaling, the trap was thrown open witii a slight 

 click, the spider darted out, caught one of the flies and retired ; 

 the whole transaction was done with such rapidity and dexterity 

 that the other fly, though nearly touching the captured one, was 

 undisturbed and seemed to be quite unconscious of the fate of its 

 companion. I have observed one other capture, and this also was 

 carried out with the same extreme rapidity. The spiders are 

 probably nocturnal in their habits, though I have never seen them 

 out at night, but I know that the work of building goes on during 

 the night. The captures I observed were during the day. It may be 

 that they work at night to save themselves from detection from some 

 of their enemies, and watch for prey both day and night. 



The eggs are placed in a small silken bag at the bottom of the 

 nest. When the eggs are hatched, the young live for several months 

 a free life in the home of the parent, and are thus protected from 

 the ants which infest the trees, until they are strong enough to build 

 for themselves ; this they do while they are yet very small, but not 

 until they are several months old. The greatest enemies these 

 spiders have are the ants ; but the houses are so strong and so much 

 like the natural bark that even the ants would not work them much 

 damage if they did not catch them, or enter the house accidentally. 

 On old trees I have found nearly all the houses without spiders, but 



