28 



the labrum and epipharyux are not connected, as in Bombylivs, by 

 infolding delicate membranes, to mark, in section, their line of union. The basal 

 half of the labrum-epipharynx contains muscles passing obliquely upward and 

 backwards from the epipharynx to the labrum ; these muscles are only a forward 

 continuation of the system of pharyngeal muscles in the fulcrum, which the base 

 of the labrum-epipharynx joins. At its tip the labrum-epipharynx is divided into 

 six parts, as seen in h'g. 5, which represents the tip unrolled, from within, and 

 these are hairy, the rest of the labrum-epipharynx being naked. The hairs 

 on" the inner side of the outer parts of the tip have the appearance of being 

 sense-hairs, but I have only studied them superficially, and cannot therefore speak 

 with certainty of their nature. The division of the tip of the labrum into several 

 parts is regarded by Meigen 10 (Theil 3, p. 381) as a characteristic of the 

 Syrphidae, and the researches of Gerstfeldt, as well as my own examination of 

 the laftrum of about a dozen species, tends to confirm Meigen's statement. 



The hypopharynx (fig. 6 ; in cross-section, fig. 1, fi' and y', A) is lanceolate, 

 naked, and strongly chitinized. It is a rigid tube, opening apically on the upper 

 side, and is the outlet for the saliva. Its proximal end is slightly broadened, 

 and unites, with a true joint, to the under Avails of the distal end of the fulcrum, 

 or pharynx. The margins toward the tip and the tip itself of the hypopharynx 

 are transparent; the remainder of the hypopharynx is opake. 



The maxillae (fig. 4, w, and, in section, fig. 1, /?', m.r) are thin naked 

 blades of chitin, concave on their inner sides, convex on their outer sides, and 

 uniting at their bases with the maxillary palpi. The bases of the maxillae lay 

 directly outside of the labrum-epipharynx, when the proboscis is extended, but the 

 maxillae curve downward, and inward, distally, so that their tips are between the 

 hypopharynx and labium. The margins and tip of the maxillae are very trans- 

 parent, the middle a little thickened. The maxillary palpi (fig. 4 tup; fig. 1, 

 /?', tup) are cylindrical, one-jointed, hairy, a trifle longer than the maxillae, and 

 lay along the sides of the labrum-epipharynx, when the proboscis is extended 

 (fig. 1). The chitinous supports which bear the maxillae at their tips, extend 

 back along each side of the pharynx, where they can be seen, in section, at . 

 in fig. 1, 6 V and e'. 



In Enstalis hort/cola I was unable to find the least traces of the mandibles, 

 either as free rudimentary structures, or as portions united to the labium. What 

 Menzbier considered to be mandibles in St/rphm tacti/atii*, are, undoubtedly, 

 maxillae. Menzbier 8 writes (p. 60) " At the sides of the basal portion of the 

 labium and united with it, lay two thick chitinous structures, which project right 



