SPIDER-LIKE ANIMALS 391 



of very characteristic construction, for the sharp curved end- 

 joint, at the tip of which a pair of poison-glands open, can be 

 folded down on the basal joint, much as the blade of a pocket- 

 knife folds down on the handle. In this way an efficient grasping 

 and holding organ is formed. The pedipalps are slender forwardly- 

 directed structures, looking something like antennae. As in 



Fig. 239. Garden-Spider [Epeira diadema] and Web. a, Female spider; b, arrangement of eyes. 



Scorpion their basal joints are provided with cutting edges, which 

 work against one another and act as jaws. The tips of the 

 pedipalps are curiously modified in the male. The four pairs 

 of legs are strong and of considerable length. Each of them is 

 provided at its tip with several toothed claws, serving as efficient 

 grasping organs. 



As regards breathing organs, the Garden- Spider combines 

 the arrangements characteristic of Scorpions on the one hand 

 and Insects on the other. There are two lung -books, which 

 open by a pair of slits on the under-side of the abdomen, near 

 its base, while farther back there is a single aperture, situated 

 in the middle, and opening into a set of air-tubes. 



One of the most striking peculiarities of an ordinary spider 

 is its power of spinning webs: indeed the word spider probably 

 means " spinner ". The silk is made by a large number of 

 spinning-glands situated in the hinder part of the body, and 



