t 



NO. 3 INSECT HEAD SNODGKASS II7 



36. — Second dorsal dilators of the pharynx (figs. 41. 44). — Each 

 arises by a slender stalk on sulmntennal ridge of frons (fig. 41) ; in- 

 serted by spreading base on upper end of anterior pharynx. 



37. — Third dorsal dilators of the pharynx (figs. 41, 43. 44). — Each 

 arises by slender stalk on vertex near inner rim of compound eye 

 just anterior to first dorsal fibers of mandibular adductor ; inserted 

 by widely spreading base on dorsal wall of posterior pharynx. 



38. — Retractors of the mouth angles (figs. 41, 44). — These, the 

 largest muscles of the stomodeum, and the first of the lateral series, 

 arise on the subantennal ridges of the frons (fig. 38 D), and extend 

 downward and posteriorly to their insertions on the oral arms of the 

 hypopharyngeal suspensorial rods (figs. 42 A, B, 44) in the lateral 

 angles of the mouth. 



jp. — First lateral dilators of the pharynx (fig. 44). — A pair of 

 slender muscles arising laterally on frontal region ; inserted on sides 

 of anterior pharynx. 



40.- — Second lateral dilators of the pharynx (figs. 41, 44). — A slen- 

 der muscle on each side, arising on posterior face of distal end of dor- 

 sal arm of tentorium (fig. 41) ; inserted by spreading base on upper 

 end of anterior pharynx (fig. 44). 



41. — Ventral dilator of the buccal cavity (figs. 41, 44). — A median, 

 unpaired, strap-like muscle arising on ventral face of body of tentor- 

 ium ; inserted on median groove of posterior wall of mouth. 



42. — First ventral dilators of the pharynx (figs. 41, 44). — A pair 

 of fibers arising on ventral surface of tentorium ; going anteriorly to 

 insertions medially on lower end of posterior wall of anterior pharynx. 



43. — Second ventral dilators of the pharynx (figs. 41, 44). — A 

 group of diverging fibers on each side, arising on anterior edge of 

 tentorium ; inserted latero-ventrally on anterior pharynx. 



44. — Third ventral dilators of the pharynx (figs. 41, 43, 44). — A 

 large fan of fibers on each side, arising on dorsal edge of posterior 

 arm of tentorium ; the spreading fibers inserted ventro-laterally along 

 entire length of posterior pharynx. 



45. — Anterior dilators or protractors of the crop (figs. 41, 43, 44). 

 — A large group of fibers arising on each posterior tentorial arm. 

 behind origin of 44 ; spreading posteriorly to insertions ventro-later- 

 ally along anterior third of crop. These are the last of the stomodeal 

 muscles that have their origin in the head. 



46. — Posterior protractors of the crop and gastric caeca (fig. 43). — 

 A pair of long, branched muscles, each arising by a slender stalk on 

 inner surface of prothoracic tergum, just anterior to base of troch- 

 antinal muscle ; branching downward and posteriorly, one branch in- 



