NO. 2 HONEY BEE — SNODGRASS 2/ 



The distance from c to rf is thus shortened, and, by reversing the 

 sequence of the movements, the approximation of c and d w^ould 

 produce the folding. In the palpiger of the bee (B) this shortening 

 results from the inward curvature of the rod {n) effected by the 

 pull of the muscle on its convex side, and the palpus automatically 

 turns over and bends backward (C). Extension of the flexed palpus 

 evidently depends on the elasticity of the palpiger, since there is no 

 extensor muscle. 



The preoral food channel. — The membranous anterior, or hypo- 

 pharyngeal, wall of the labium extends upward from the salivary 

 orifice at the distal end of the prementum to the mouth, and forms 

 the floor of a deep preoral food channel between the maxillary bases 

 (fig. 9 A, FC) that is continuous with the closed food canal of the 

 distal part of the proboscis (C, fc). The wide aperture of the mouth 

 (A, Mth) at the upper end of the channel lies behind the base of the 

 epipharynx (Ephy), and the epipharynx is covered by the projecting 

 labrum. On the floor of the mouth is the broad oral plate (fig. lo A, 

 B, opl), from which depends the large, thin, double-pointed, tri- 

 angular fold (bib) that hangs like a bib from the lower lip of the 

 mouth over the adoral hypopharyngeal surface (fig. 9 A, bib). At 

 the sides of the bib in the hypopharyngeal membrane are the slender 

 hypopharyngeal suspensory bars (s), which taper downward to the 

 sides of the prementum. 



When the proboscis is depressed or retracted, the mandibles are able 

 to close before the mouth between the labrum and the bases of the 

 maxillae. If the mandibles are spread apart when the proboscis is 

 protruded the preoral food canal is widely exposed (fig. 9 A) and 

 the lacinial lobes of the maxillae (Id) are prominently displayed on 

 the mesal margins of the stipites. When the proboscis is fully ex- 

 tended in the functional position, the mandibles are opened, allowing 

 the base of the proboscis to swing up between them, and they now 

 clasp the bases of the galeae. In this position, the proboscis extends 

 straight out from before the mouth ; the formerly vertical floor of the 

 preoral food channel becomes more nearly horizontal, and the cushion- 

 like lacinial lobes of the maxillae are pressed into the lateral con- 

 cavities of the epipharynx, with the median keel of the latter closing 

 the space between them (fig. 9B), while the labrum clamps down 

 on the epipharynx. The preoral food channel on the base of the 

 proboscis is thus converted into a closed passageway, by which the 

 food canal of the distal part of the proboscis is put into communica- 

 tion with the mouth. The approximation of the labium to the mouth 

 bows the suspensorial rods (A, s) outward and accentuates the 



