OF SUCTION IN LYGUS PABULINUS. - 697 
Each of them consists ons 
(i.) an external part, projecting beyond ite head and forming 
the complementary half of the sucking tube ; 
(ii.) an internal part, separate from its complemént and going 
to one side of the pharynx. 
(i.) The external part. This tapers to a fine and curved point. 
In cross-sections it shows a groove which is divided into two 
gutters by a longitudinal ridge which runs through it, from end 
to end. In short, the whole structure looks in cross-section like 
a W, and one groove is thus divided into two small, separate, and 
non-intercommunicating groovelets. The two stylets from either 
side come together and by approximation of these groovelets form 
two complete tubes—one dorsal facing the labrum and functioning 
Text-figure 4. 
D.A. 
Lygus pabulinus. 
Nearly median longitudinal section, showing the supporting structure, the body 
of the tentorium, the pump muscles, ete. Ob. 3 & Oc. 4. 
For explanation of the lettering see p. 693. 
