THE SPIDER. 



147 



surface a number of simple eyes, variously arranged, 

 according to the species, but always embracing a very 

 large field of vision. Underneath the cephalo-thorax are 

 inserted eight legs, terminated by notched hooks ; this 

 number of feet is constant in the spiders, and distin- 

 guishes the latter from insects, all of which have six. 



The abdomen is attached to the anterior portion of 

 the body by a very thin stalk ; it is 

 soft and round. Behind it is furnished 

 with the spinning glands, which form 

 rounded eminences ; these are four or 

 six in number, and are pierced with a 

 large number of minute holes open- 

 ing, into internal canals filled with a 

 gummy matter analogous to silk. 

 This matter produces threads of ex- 

 ceeding fineness, for more than a 

 thousand would be required to make 

 the thickness of a human hair. As 

 these threads leave the spinning 

 glands the spider, by the aid of its feet, 

 notched like combs, unites them in a 

 single filament, which it draws out SPIDER WITH THE LEGS 

 from the point at which it has first T OFF - The fi * ure 



shows the union of 



attached one end by pressure of the the head and thorax 



abdomen. With these threads the 



spider weaves its web, or stretches a 



bridge from one place to another, or 



descends to the ground, as it desires. 



And with the same substance it lines 



its hiding-place, or makes the silky 



sac in which it deposits its eggs. The long white fibres 



sometimes seen floating in the air, and often called 



in one piece, forming 

 the cephalo-thorax. 

 c, chelycera; pm, 

 jaws ; pi to p 4 , the four 

 pair of feet; r, res- 

 piratory sacs; s, stig- 

 mata ; a, anus ; /, 

 spinners. 



