2CO ANIMAL LIFE 



row (Fig. 157) or cylindrical hole is closed above by a silken, 

 thick, hinged lid or door, a little larger in diameter than 

 the hole and neatly beveled on the edge, so as to fit tightly 

 into and perfectly cover the hole when closed. The upper 

 surface of the door is covered with soil, bits of leaves, and 

 wood, so as to resemble very exactly the ground surface 

 about it. We have found these trap-door nests in Cali- 

 fornia in moss-covered ground, and here the lids of the nests 

 were always covered with green, growing moss. 



An English naturalist who studied the habits of these 

 trap-door spiders found that if he removed the soil and bits 

 of bark and twigs, or the inoss, from the upper surface of 

 the lid the spider always re-covered it. It is, of course, 

 plain that by means of this covering the nest is perfectly 

 concealed, the surface of the closed door not being dif- 

 ferent from the surrounding ground surface. This natu- 

 ralist finally removed the moss not only from the surface 

 of a trap-door, but also from all the ground in a circle of a 

 few feet about the nest. The next day he found that the 

 spider had brought moss from outside the cleared space 

 and covered the trap-door with it, thus making it very con- 

 spicuous in the cleared ground space. The spider's instinct 

 was not capable of that quick modification to allow it to do 

 what a reasoning animal would have done namely, cov- 

 ered the trap-door only with soil to make it resemble the 

 cleared ground about it. 



Another interesting nest-making spider is the turret- 

 spider, that builds up a little tower (Fig. 158) of sticks and 

 soil and moss above its burrow. The sticks of which this 

 burrow are built are an inch or two in length, and are 

 arranged in such manner as make the turret five-sided. 

 The sticks are fastened together with silk, and the turret 

 is made two or three inches high. This turret-building 

 spider is one of those that carry about their egg-cocoon 

 with them. A female of this spider in captivity was ob- 

 served to pay much attention to caring for this cocoon. 



