138 Beekeeping 



The proboscis consists of the external mouth parts other 

 than the mandibles (Fig. 68, Prb, Fig. 72, A-H). This 

 group of organs serves in taking up liquid food. The name 

 "tongue" is usually given to the slender median portion 

 (Gls) but is loosely applied to the three median parts, the 

 labrum. Snodgrass (I.e. pp. 44-45) explains the relation 

 of these parts to the mouth parts of other insects and points 

 out the true homologies, at the same time showing the 

 errors into which various writers on bee anatomy have 

 fallen. The accompanying illustration (Fig. 72, A-H) 

 shows the structure of the organs of the proboscis. It 

 will be seen (Fig. 72, D) that there are three terminal pieces, 

 the central glossa (Gls) and two lateral labial palpi (LbPlp) 

 arising from the mentum (Mt\ a median basal sclerite, 

 and two maxilla?, arising from separate basal pieces, the 

 stipes (St). These in ' turn articulate with the lorum (Lr), 

 a flexible band connecting with the cardines (Cd) which 

 attach the whole proboscis to the head at the fossa of the 

 proboscis (PrbFs, Fig. 68, B), on which it is suspended. 



The maxillae (Ma;) are articulated by the cardines (Cd) 

 to the maxillary suspensoria on the side walls of the fossa 

 while the mentum (Mt) articulates with the submentum 

 (Smt) which is held in the lorum (Lr). These parts are 

 suspended in the membrane in the fossa floor, giving great 

 freedom of movement. 



The glossa (Gls) is covered with circles of hairs and the 

 tip (labellum, Lbl) is spoon-shaped. The tip is protected by 

 spiny hairs (Hr), formerly supposed to be taste organs, between 

 which is the end of the ventral groove (k) of the glossa. 



When the proboscis is not in use the labium and maxillae 

 are folded back against the mentum and stipes. When 

 in use, these parts are unfolded and held together. In 

 sucking liquid the base of the labium slides between the 

 bases of the maxillae. To acquire this motion, the sub- 

 mentum turns on the lorum and the mentum turns on 

 its articulation with the submentum. This gives the men- 

 tum a forward and backward movement and the labium 



