ELEMENTARY ZOOLOGY 



the fang, which is movably articulated with the falx 

 (fig. 93 \ In the falx is a poison-sac from which poison 



FIG. 92. The dog or wood tick, Dermacentor americanus male, the most 

 common tick in the Northern States. (After Osborn.) 



flows through the hollow fang and out at its tip. The 

 legs vary in relative length in different spiders, and each 

 is made up of seven joints. The spinnerets 

 (fig. 94), which are situated at the tip of the 

 abdomen, are six in number (a few spiders 

 have only four), and are like little short 

 fingers. They have at their tips many fine 

 FIG. 93. The little spinning-tubes from each of which a 

 showh" d ^fafx ^ ne S1 *^ en thread issues when the spider is 

 and fang of a spinning. These many fine threads fuse as 

 Jenkins ^ a ^^ issue to form a single strong cable or 

 Kellogg.) sometimes a flat rather broad band. The 

 spinnerets are movable, and by their manipulation the 

 desired kind of line is produced. The silk comes from 



