THE HEAD OF THE BEE AND ITS APPENDAGES. 



51 



labium (fig. 16, t). The salivary duct (SalD) bends downward in 

 the anterior part of the mentum (3It) and opens into the posterior 

 end of the pit (t). When the retractor muscles {IRMcl) of the 

 ligula pull the latter back into the mentum the lips of the salivary 

 pit must necessarily be closed. The simultaneous contraction of the 

 elevator muscle (m) attached to the roof of the horizontal part of the 

 pit must expand the latter and suck the saliva from the salivary duct. 

 When, finally, these muscles relax and the ligula is driven out by 

 blood pressure in the mentum, probably produced in part by the 

 contraction of its dorsal transverse muscles {TMcl), the saliva in 

 the temporarily formed bulb must be squirted out upon the base of 

 the tongue. Wolff (1875) calls each dorsal longitudinal muscle of 

 the mentum {IRMcl) — the two inserted upon the basal hooks (w) of 

 the glossa (fig. 15 H and fig. 16) — the retractor lingum longus. The 

 large ventral retractor muscle of each side {'BR Mel) he calls the 

 retractor linguw biceps since its anterior end divides into two parts, 

 one of which is inserted by a tendonous prolongation upon the base 

 of the glossal rod (fig. 15 H and fig. 16, r) and the other upon the 

 base of the ligula. The use of the word " lingua " in these names is 

 objectionable because, as already explained (page 45), the lingua is 

 properly the true tongue or hypopharynx. " Ligulse " should be sub- 

 stituted for " linguae." The dilator muscle (fig. 16, u) of the salivary 

 pit (t) is termed the protractor lingual by Wolff because, as he sup- 

 poses, when the ligula is pulled back into the mentum the position 

 of this muscle is reversed, so that a contraction of its fibers would 

 help to evert the ligula. 



The glands that furnish the saliva lie within the head and the 

 thorax and will be described later in connection with the alimentary 

 canal and the process of digestion. 



Fig. 1Y. — Epipharynx (Ephij) and labrum (Lm) of worker: A, ventral Tiew ; B, 



anterior view. 



5. THE EPIPHARYNX. 



The epipharynx of insects in general may be described as a dorsal 

 tongue, it being a median lobe developed on the roof of the preoral 

 cavity from the under surface of the clypeus or labrum and situated 

 opposite the hypopharynx. 



