ARACHNIDA AND MYRIAPODA 129 



sometimes becomes so angered with her mate as to kill 

 and eat him. 



The silk with which spiders work is formed by glands 

 in the abdomen, which open by two or three pairs of promi- 

 nences, the spinnerets at the posterior part of the abdomen. 

 The excretion passing out of these several orifices unites 



Fia. 148. Epeira, the common garden spider on its web. Photograph one half 

 natural size by Charles Morris. 



to form a single thread. The chief use of spiders' silk is 

 for cross hairs in telescopes. 



The wandering spiders never spin complete webs, but 

 wander about buildings and fields. Our common species 

 are rather large, and the female carries with her the small, 

 round cocoon containing the eggs or young. Most spiders 

 deposit their eggs, often numbering nearly a hundred, in 

 cocoons, where they hatch in about two weeks, and the 

 stronger young prey on the weaker for several days, so 



