they are protracted. The pimping action in the buccal cavity then 

 commences, the sphincter separating it from the pharynx being con- 

 tracted. Immediately the cavity is fall the sphincter relaxes, and the 

 pharynx dilates as the blood is socked into it from the first chamber. 

 When the air pressure is in turn exercised on the pharynx the blood 

 flows into die ruaoplngir 



The other Mood-sacking Orthorrapha, with the exception of the mos- 

 quito, which will be dealt with separately, resemble Totems in the 



structure of their month parts;, the diBuujBOLS being 



TJiJI^fJljrJr only in matters of detail. In all the proboscis is 

 relatively short, and is directed downwards from the 

 under surface of the head. The bhium functions merely as a sheath 

 for die other month parts, none of these forms having a pseudotracheal 

 like that of T*t*tm*T The mandibles are in each case 

 and blade-like, with a serrated internal edge. The serrations may, 

 as in SimmKmm* (fig. 6), be continued for a short distance on to the 

 external margin, so that the blade cuts in abduction as well as in adduc- 

 tion. Tne maxilla in Stmmfimm (fig. 6) is flattened and shaped like a long 

 and narrow triangle, with a simple armature consisting of a single row of 

 strong recurred teeth fown each edge. The blade will, therefore, cut only 

 in **&* In OrafegiM the maxilla is stout at the base, but 

 attenuated and panted at die distal end, where it is armed with a row of 

 five fine hook-like teeth, soft on the inner and thinnest edge. The maxil- 

 la of PaJeMMMB (fig. 7> is stout and rod-like, and has an armature on 

 two sides. On one side it is difficult to say which, for the blade is 

 very easily tainted there is a row of minute but stout teeth extending 

 from the distal extiemity for a short distance, and on the other a short 

 war of much nmUrr teeth commencing some distance from the tip. 

 TVe first set point towards the base of the blade and will, therefore, 

 cat dorag wim Jim ; the second set point towards the tip and cut 

 only in proUaOiom. In each case the blade of the maxilla becomes 

 cmtiaHMms at its base with the stipes, and is provided with retractor 

 and fwilm fcur anodes, of hirfc the former are always the stronger. 



In these time forms the distal ends of the lahrum-epipharynx and the 

 hrcpopoarynx are modified in a highly suggestive manner. The opening 

 at the pvestaoBum b m each case a tians\^rse slit, for the distal ends are 

 always flattened and the canal between die two parts broadened out. 

 IB ?!> MI (fig&. 14 and 13) the end of the kbrum-ptpoar>-nx is broad, 

 sclc and memfecaneons, and has on it two minute sets of three curved 

 hooks; on the dorsal aspect floe is a row of stout and long but only 



