167 



The Labellae. — Attached to the end of the 

 labium by a hinge joint on either side are two 

 leaf-like processes, the labellae (Fig. 43). It is 

 through the angle made by the two labellae, that 

 the ■ stylets pass, as a billiard cue, between the 

 first and second fingers (Nuttall and Shipley). 



The labium proper stops short at the point of 

 junction of the labellae, but is continued on its 

 upper surface as a blunt point covered with fine 

 hairs (Button). We may liken it to a pen con- 

 tinued on beyond the penholder, the junction of 

 pen and penholder being the point at which the 

 labellae are hinged on. 



Duttons Membrane. — The area between the 

 end of the labium proper and the extreme tip is 

 covered by an extremely thin membrane (Button). 

 In the act of biting, when the labellae are sepa- 

 rated, this membrane is somewhat stretched, and 

 applied to the skin. 



The Escape of the Filarial Embryo 



It has been shewn by Low and James that 

 the filarial embryo occurred in the proboscis, 

 according to Low among the stylets. According 

 to Button, the embryo lies really in the tissue of 

 the fleshy labium, moreover with its head at the 

 level of the membrane described above, and 

 that it is by the rupture of this excessively thin 

 membrane that the embryo escapes. Grassi and 

 NoE think that the embryo escapes through the 

 middle of the bent- up labium through a rupture 

 at this point, but Button's explanation seems 

 more likely. 



The epipharynx is the central tube through 

 which the blood is sucked. Its point slopes off 



