276 ENTOMOLOGICAL SOCIETY 



The mandibles are here modified into two long cylindrical 

 bodies, placed side by side. They are enclosed for a part 

 of their length in scabbard-like prolongations of the labrum 

 or basal piece, in which they slide forward and backward 

 andiwhich protects them and gives them the strength necessary to 

 pierce the tough epidermis of the host. These protecting sheaths 

 are of a strong chitinous consistence and their surface is roughened 

 like a file. 



The mandibles are two-jointed ; the basal joint is much longer 

 than the apical one, of a rod-like form and chitinous structure, 

 and reaches down or back into the front part of the body, where it 

 is connected with a set of muscles by which these organs can be 

 moved fore and backward. The superior surface of this joint con 

 sists of a hard chitinous tegument which turns downward at the 

 lateral edge and leaves a free, concave space in the centre of the 

 inferior surface, which serves at the upper portion of the above- 

 mentioned channel. 



The body of the first mandibular joint is filled out by the muscles 

 which serve in the movements of the second joint ; they are visible 

 at the underside in the free space between the two upturned 

 edges of the chitinous tegument of the upper surface, which space 

 is covered by a transparent membrane. 



The second mandibular joint is of a very complicated structure. 

 It is much shorter, transparent, of a glass-like, hard consistence, 

 and movable sideways (externally) from the tip of the basal joint. 

 It is composed of two closely approximated parts, which are some 

 what blended together, the inner one being longer than the outer 

 one. Their external edge forms a series of strong, large teeth, 

 each of which is provided with a minute channel which termi 

 nates in an orifice near the tip. There are generally four of these 

 teeth, two belonging to each part, but sometimes there are five or 

 six. The fifth or sixth are, however, much smaller than the 

 others. Some of these teeth appear to have a funnel-shaped base, 

 which probably can be pressed against the wall of the wound 

 inflicted by the whole apparatus, where it may serve as a vacuum, 

 thus facilitating the flow of the blood. A membraneous, hyaline 

 sheath surrounds the base of this second mandibular joint and has 

 a part of the edge fringed out into the fine, needle-like projec 

 tions. 



