ARANETDA OR SPIDERS. 



115 



iii. Acarina or Mites (fig. 49) are characterised by having the 

 head, thorax, and abdomen all fused into one piece, and the legs 

 either eight or four in number. 



Fig, 47. — House Spider. 



A, Male of House Spider (Tegenw}^ cirlHs) enlarged : c, cephalothorax ; p maxillary 

 palpi ; «, abdomen, b, front of head : /, ocelli ; n, mandibles, c, under side of head : 

 m, true jaws ; I, lower lip. o, diagram of one of tlie air chambers. (After Blackwall, 

 from Nicholson.) 



Araneida or Spiders. 



The Spiders may be considered of economic importance, as 

 they are all more or less of a beneficial nature. The food of 

 spiders consists almost entirely of insects, and thus they do a 

 considerable amount of good in keeping down an access of insect 

 life which may be noxious to us. Some spiders hunt for their 

 prey ; others, and those perhaps best known to us, have the habit 



