NO. 2 HONEY BEE — SNODGRASS II 



anterior wall of the hypopharynx (fig. loA, Mth). In some of the 

 Hymenoptera the mouth is guarded by a pair of long, valvelike lips, 

 the upper one being the epipharynx, the lower one a fold from the 

 lower edge of the mouth. In the bee the suboral fold hangs like a 

 bib from the lower lip of the mouth (fig. 9 A, hih). 



The fiuindibles. — The mandibles of the honey bee differ in shape 

 and relative size in the three castes (fig. 3 F, G, J). In the worker 

 (F) each mandible is elongate, thick at the base, narrowed through 

 the middle, and widened again distally in a flattened expansion. The 

 inner face of the expanded part is somewhat concave and traversed 

 obliquely by a channel (d) fringed on both sides with hairs, which 

 is continuous with a groove (e) that runs upward to the orifice of 

 the mandibular gland (/) at the base of the jaw. The mandible is 

 suspended from the lower lateral angle of the cranium (fig. i A, C), 

 and has the usual two points of articulation, one with the lower part 

 of the clypeus (fig. 3 E, c), the other {a') with the subgenal margin 

 of the cranium. The hinge line of the jaw between the two articula- 

 tions slopes downward from in front, so that when the mandible is 

 adducted its apex turns not only mesally but also posteriorly. 



Each mandible has only two muscles, an abductor and an adductor. 

 The fibers of the abductor spread over the lower part of the side wall 

 of the head behind the compound eye (fig. 3 I, 6") and converge 

 upon a stalked apodeme arising in the articular membrane at the 

 outer side of the mandibular base (E, 8Ap). The "large adductor 

 muscle (H, p) has several groups of fibers, some of which arise 

 behind the eye above the abductor fibers, others on the back of the 

 head below the level of the foramen magnum, while a small group 

 {9a), inserted on a long slender branch of the apodeme, takes its 

 origin on the top of the head. The strongly stalked adductor apodeme 

 arises from the articular membrane at the inner side of the base of 

 the mandible (fig. i C, pAp), and is closely applied to the mesal wall 

 of the mandibular gland (fig. 3 F). 



The worker bee makes various specific uses of its mandibles, in- 

 cluding the collecting and breaking of pollen grains for food, manipu- 

 lation of wax in comb-building, supporting the base of the extended 

 proboscis while feeding on liquids, and holding the flexed proboscis 

 in place when the latter is folded behind the head (fig. 3B). The 

 provision of each mandible with but two muscles gives the jaws 

 active movements of abduction and adduction only, but there is 

 sufficient flexibility at the articulations to allow of some play of the 

 mandibles on each other. When the mandibles are used to hold the 

 base of the extended proboscis, the channels on the inner surfaces 



