GENERAL STRUCTURE 



353 



FIG. 149. Digestive tract of Argas persicus; an., anus; ch., chelicera; int. c* 

 intestinal coeca; CBS., oesophagus; ph., pharynx; sal. gl., salivary glands; st., 

 stomach. X about 20. (Adapted from Robinson and Davidson.) 



^chcl. 



FIG. 151. Tip of chelicera of a tick, 

 much enlarged; cut. p., articulated 

 FIG. 150. Head or capitulum of tick; cutting part; shaft, shaft; sh., sheath; 

 hyp., hypostome; chel., chelicera; pal., fl. t., tendon of flexor muscle; ex. t., 

 palpus; bas. p., basal piece. (Partly after tendon of extensor muscle. (After 



Banks.) 



Nuttall, Cooper and Robinson.) 



