22 Annals Entomological Society of America [Vol. XIII, 



The Abductor of the Labium (Figs. 16 and 17, abd.lb.) is a 

 straight parallel-fibered muscle. It originates from a small 

 tubercle on the basal edge of the tentorium and is inserted at 

 the outer angle of the distal edge of the mentum. 



The Adductor of the Labium (Figs. 16 and 17, ad. lb.). The 

 two adductors are contiguous at their origin near the middle 

 of the base of the submentum, but diverge in their course. 

 They are inserted by means of small semicircular tendons into 

 the base of the ligula not far from the middle line. 



The Adductor of the Paraglossa (Fig. 17, ad.pgl.) originates 

 from the base of the ligula near the median line, and runs 

 diagonally to the base of the distal segment of the paraglossa. 



The Adductor of the Glossa (Fig. 17, ad.gl.) originates in the 

 ligula and is inserted into the lateral side of the base of the 

 glossa. 



The musculature of the labial palpi is similar to that of the 

 maxillary palpi, but the flexor and extensor arise from a narrow 

 elongate, median apodeme (Figs. 6 and 17, ap.lb.) which is 

 given off at the point where the labium and hypopharynx unite, 

 and projects backward as far as the mentum. 



The Hypopharynx. The Depressors of the Hypopharynx 

 (Fig. 6, dep.hyp.) are two muscles which originate from the 

 lower side of the central plate of the tentorium and are inserted 

 into the upper integument of the base of the hypopharynx 

 near the point at which the pharynx narrows into the 

 oesophagus. The depression of the hypopharynx at this 

 point assists in enlarging the oesophageal canal. 



The Elevator of the Hypopharynx (Fig. 6, el. hyp.) originates 

 in the face in front of the median ocellus, and is inserted on the 

 outer surface of the hypopharynx near the entrance to the 

 oesophagus. This muscle pulls the base of the hypopharynx 

 up against the roof of the pharynx, closing the entrance to the 

 oesophagus. 



The Compressor of the Hypopharynx (Fig. 6, c.hyp.) origi- 

 nates with its fellow of the opposite side from the median line 

 of the lower side of the hypopharynx at its junction with the 

 labium. The two muscles diverge, running obliquely back- 

 wards and upwards, and are inserted into the outer angles of 

 the upper side of the base of the hypopharynx in front of the 

 oesophagus. By compressing the hypopharynx these muscles 

 enlarge the pharyngeal opening. 



