172 PHILIP p. CALVERT. 



to more than balf way down on the eye-margin, inserts by a strong, flat tendon 

 into the inner side of the base of the mandible, which it draws towards the 

 middle line. 



Abductor mandibulie (extensor mandibniie Biirm.) is considerably smaller than 

 the preceding, ou the outer side of which it lies, taking origin from the rear of 

 the head near the margin of the eye and below the most external part of the 

 origin of the adductor ; it inserts by a round tendon into the outer part of the 

 base of the mandible; it draws the mandible away from the middle line. 



Adductor primus maxillx [flexor primus maxillie Burm.) is the largest of the 

 maxillary muscles; it rises by a cap like tendon from the rear of the head near 

 the posterior foramen and inserts into the cardo and the inner margin of the 

 stipes ; with the following it draws the maxilla towards the middle line. 



Adductor secundus maxillx { flexor secundus maxillse ? Burm.), a strap-like muscle, 

 arises from the rear of the head behind the adductor mandibulsp, passes within 

 the stipes, and inserts by a small, pale tendon into the inner side of the base of 

 the galea-laciuia. 



Abductor maxillae lies between the preceding and the abductor mandibulie; its 

 fibres arise from the rear of tiie head in a line running from the inner side of 

 the origin of the abductor mandibulie to the origin of the adductor secundus ; 

 they insert into the outer side of the cardo and draw the maxilla away from the 

 middle line. 



Flexor galese (Burm.) rises from the outer side of the stipes and inserts into 

 the base of the galea-lacinia. Still smaller muscles are the extensor galese- and 

 the flexor and extensor palpi. 



At least three pairs of muscles may be distinguished in the labium ; they may 

 be best examined by transmitted light in labia which have been cleared in clove- 

 oil or similar reagent. All three aid in closing the labium. 



Adductor labii (Burm.) arising from the lower margin of the posterior cephalic 

 foramen, inserts into the distal end of each half of the submentum {S7n fig. 7, 

 pi. II). 



Suhmentalis avistis from the submedian and inserts into pieces (fig. 7, i)l. II). 

 Its fibres are superficial to those of the preceding. 



Adductor ligulie arises from the submentum, distal to the origin of the submen- 

 talis and inserts into the base of piece m (fig. 7, pi. II). Its fibres are apparently 

 in the same plane as those of the adductor labri. 



Thoracic muscles. — The muscles of the legs require no special 

 notice. 



The wing-viuscles are large and well-developed. Their arrange- 

 ment (see fig. 12, pi. II) is the same for the hind as for the front 

 wings. Arising on or near the floor of the thorax, they pass up- 

 wards and insert on the wing-bases. The fulcrum on which eacli 

 wing moves is furnished by a pleural process, shown in fig. 13, pi. 

 II, immediately above the humeral and the second lateral sutures, 

 respectively. It may here be designated the fulcral proeesn. The 

 muscles which elevate the wing are placed nearest the middle line 

 of the thorax, and their insertions on the wing-base ihside of the 



