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epipharynx raay have a single point at its tip (Mwca } Bombylius) or may end, 

 apically, in several points (Culex, and probably all Syrphidae). Tlie labrum-epi- 

 pharynx usually forms a cover for the channel of the labium below, and may be 

 separable from the labium, at the will of the insect (Cidex), or may remain always 

 tightly closed over the labium (Musca). The labrum-epipharynx is usually, second 

 to the labium, the largest mouth-part of a dipteron. Within it may contain 

 muscles and tracheal stems (Bombylius and Musca). The channel of the epi- 

 pharynx is never completely cylindrical, but is slightly open along its under side ; 

 a tube is formed by the pressing of the hypopharynx upward against this open- 

 ing ; through the tube thus formed the food is sucked up to the mouth. 



The hypopharynx is usually present in diptera (according to Menzbier absent 

 in Sargus~), and contains a tube, opening by a channel on its upper surface; this 

 channel extends back, more or less, from the tip, and is the outlet for the salivary 

 secretion. The tip of the hypopharynx may be naked and used as a lance 

 (Haematopoia, according to Menzbier), or may be hairy (Musca). The upper side 

 of the base of the hypopharynx is continuous with the lower wall of the pharynx ; 

 its under surface may entirely coalesce with the labium (Cidex, male), may join 

 the labium more or less anterior to the mouth (Musca), or, if either mandibles or 

 maxillae are present, its base may join them (Culex, female). 



The mandibles are the mouth-parts which are least developed, or most often 

 absent, in diptera. They are present in Culex, female, and, according to Menzbier, 

 in Haematopota ; they are absent in Eristalis, Bombylius, Musca, and many other 

 diptera. When present they are usually delicately lamelliform. 



The maxillae are, next to the mandibles, the oftenest absent in diptera; but 

 when both maxillae and mandibles are present (Culex, female), the maxillae are 

 more developed than are the mandibles. Maxillary palpi are usually, probably 

 always, present in diptera, usually joining the maxillae at the base; they are 

 from one-jointed (Bombylius, Eristalis, Musca) to five-jointed (species of Culex), 

 are more or less hairy, and lay outside the proboscis, attached near or at the 

 mouth. The position of the maxillary palpi in Musca has evidently created much 

 confusion in the homology of the parts of the proboscis of these insects. Their 

 location on the membranous bridge between the two upper edges of the distal 

 end of the fulcrum (in section, pi. 4, fig. 1 , /?', mp) seems to have led Gerstfeldt :i 

 to regard the fulcrum itself as chiefly made up of the maxillae. Gerstfeldt 

 described two processes extending back from the base of his hypopharynx (really 

 the epipharynx), and figured them as inside the fulcrum. These processes he 

 regarded as the basal portions, or " cardines," of the hypopharynx; a view which 



