GENERAL STRUCTURE 



353 



into 



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

 intestinal ececa; ces., oesophagus; ph., pharynx; sal. gl., salivary glands; st., 

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



'Cbel. 



Fig. 150. Head or capitulum of tick; 

 hyp-. hypostome; chel., chelicera; pal., 

 palpus; bas. p., basal piece. (Partly after 

 Banks.) 



Fig. 151. Tip of chelicera of a tick, 

 much enlarged; cut. p., articulated 

 cutting part: shaft, shaft; sh., sheath: 

 R. t., tendon of flexor muscle; ex. t., 

 tendon of extensor muscle. (After 

 Nuttall, Cooper and Robinson.) 



