252 



THE ANIMAL KINGDOM. 



the Spiders, Scorpions, Centipedes, and Millipedes. The 

 Arachnida differ from insects, in having eight or more legs, 

 more than two eyes, no wings, and no head ; the Spiders 

 have four pairs of legs, and six, eight, or more, simple eyes, 

 which appear as minute spots on the upper part of the 



FIG. 31. ARACHNIDA. 



1, Spider (Epeira Diadema) ; 2, Scorpion (Scorpio). 



thorax. Spiders nearly all live by preying upon small 

 insects, which they catch in several ways, but by far the 

 most general mode is by constructing a web or net to 

 entangle them ; the threads of this web are made of a 

 fluid glutinous substance, which is secreted within the 

 abdomen, and which they project from extremely minute 

 orifices, several of which exist on the point of little projec- 

 tions called " spinnarets," this liquid dries into a solid thread 

 immediately it comes into contact with the air; it ia 

 extremely strong, and so fine that several thousand of the 

 single fibres will only make the size of a human hair. The 

 Garden Spider (Epeira diadema) is often called the Geo- 

 metrical Spider, from the regularity of its web. These 



