PROBOSCIS OF PHORMIA REGINA — DETHIER 



165 



Epipharyngeal muscles. — These small muscles in Phormia are simi- 

 lar to their counterparts in Calliphora. They originate on the "handle" 

 of the hypopharynx and free portion of the salivary canal and are 

 inserted into the adjacent walls of air sacs of the rostrum as well as 

 on neighboring integument. As Graham- Smith surmises, they assist 

 in disposition of parts during flexion and extension. 



VENT 



HYGNG 

 PVENT Qc 



RNV 



RTOES 



A 



frcon 



Fig. 4. — Upper : Detail to show relation of insertion of the retractors of tlie 

 oesophagus to the recurrent nerve, lateral aspect. Lower : Detail of frontal 

 ganglion and its connectives, lateral aspect. 



CA, corpus allatum; CC, corpus cardiacum; FrCon, frontal ganglion connec- 

 tive ; FrGng, frontal ganglion ; HyGng, hypocerebral ganglion ; Oes, oesophagus ; 

 Pvent, proventriculus ; RNv, recurrent nerve ; RtOes, retractors of oesophagus ; 

 Vent, ventriculus. 



A, anterior ; P, posterior ; D, dorsal ; V, ventral. 



MUSCLES ARISING IN THE HAUSTELLUM 



Retractor's of the furca (fig. 5, RtFur). — These muscles arise on 

 the inner lateral surfaces of the mentum and are inserted into tubercles 

 on the lateral processes of the furca. Their action has been described 

 in detail by Graham-Smith. "Contraction of these muscles causes the 

 lateral processes, carrying the labella with them, to rotate outwards 

 on the mento-f ureal bars. Further contraction causes progressive fold- 

 ing back of the labella." Innervation is by fibers from the labial nerve. 



