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SYSTEMATIC ZOOLOGY 



the daylight, and feed on small insects. Though resembling 

 spiders somewhat, they differ most strikingly in having no 

 spinning glands and in the method of respiration, which here is 

 by means of the tracheae, opening usually by only a single pair of 

 stigmata on the first abdominal segment. 



Order 6. Araneida 



The Araneida (Lat. araneus, spider), or spiders, constitute a 

 large group readily distinguished from the other orders of 

 Arachnida. There is an unsegmented cephalothorax and an 

 unsegmented, rounded abdomen, the two parts being joined by 



FIG. 177. Epeira diadema, the garden spider, on its web. (After Bianchard, from Shipley 



and MacBride's Zoology.) 



a very slender stalk. The first pair of appendages is provided 

 with poison glands ; the poison of some of the larger spiders, 

 such as the tarantula, produces serious, if not fatal, results in 

 man. On the dorsal side of the head are from three to four 

 pairs of eyes, very variously arranged in different genera. The 

 spiders may be divided into two groups according to the method 





