136 ANIMAL FORMS 
for lining their burrows, or for the construction of webs of 
the most diverse patterns. 
132. The habits of spiders Many species of spiders, some 
of which are familiar objects in fields and houses, construct 
sheets of cobweb with a tube at one side in which they may 
Fig. $3.—A tarantula-spider (Zurypelma lentzii). Natural size. Photograph by 
A. L. MELanpeEr and C. T. BRUEs. 
lie in wait for their prey or through which they may escape 
in times of danger. In the webs of the common orb- or 
wheel-weavers several radial lines are first constructed, and 
upon these the female spider spins a spiral web. Resting 
in the center of this or at the margin, with her foot on 
some of the radial threads, she is able to detect the slight- 
est tremor and at once to rush upon the entangled captive. 
Some of the bird-spiders and their allies, living in trop- 
ical America, and attaining a length of two inches, con- 
struct web-lined burrows in the ground. From these they 
stalk their prey, which consists of various insects and even 
