260 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 moss, 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, coy- 
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. 
