NO. 2 THORACIC MECHANISM OF A GRASSHOPPER SNOD€RASS 67 



1 1 J. Tergo-sternal inusclc (fig. 34). — A large muscle, the first of 

 the inner lateral series in metathorax, attached dorsally on lateral 

 prescutal lobe, and below by a wide base on lateral part of sternum 

 before coxal cavity. This muscle corresponds with 8^ of the meso- 

 thorax, a scuto-sternal muscle (84) being absent in the metathorax. 



//-/. Plcuro-alar muscle: flexor of the hind wing (fig. 38, 114). — 

 This muscle consists of two bundles of fibers in metathorax, one ex- 

 ternal, the other internal, both arising from upper end of pleural ridge, 

 and inserted on ventral surface of third axillary sclerite of wing base. 

 The outer muscle is not visible from mesal plane until the first is 

 removed. 



i-ij. Plciiro-sternal muscle (figs. 34, 35). — A dense mass of very 

 short fibers connecting pleural apophysis with apophysis of meta- 

 sternum. 



116. Fifth ventral longitudinal muscle (figs. 34, 35). — A strong 

 fiber, apparently a sclerotized muscle, extending from posterior edge 

 of mesosternal apophysis (^'^2) to median anterior angle of meta- 

 sternal apophysis {SA^). 



iiy. Sixth ventral longitudinal muscle (figs. 34, 35). — A slender 

 muscle arising on second spina {2Spn), becoming tendinous pos- 

 teriorly ; extends posteriorly and laterally to inner extremity of pleura! 

 apophysis of metathorax. 



The ventral longitudinal muscles of the metathorax have evidently 

 lost their contractile nature because of the fusion of the mesosternum 

 and metastemum, and are converted mostly into sclerotic strands to 

 brace the pull of the mesothoracic ventral muscles {60, 8"/, 88) on the 

 sternal plates of the prothorax. 



The following thirteen muscles (118 to 130) are muscles of the 

 metacoxa and the hind wing. 



118. Tergal promotor of the coxa (figs. 34, 38 A). — Lies immedi- 

 ately behind the tergo-sternal (fig. 34, 113). Arises dorsally on lateral 

 area of scutum (fig. 38 A) ; inserted ventrally on apodemal disc of 

 anterior angle of coxa (fig. 38 D, F, 118). 



119. First tergal remoter of the coxa (figs. 34, 38 A). — A large 

 muscle arising from posterior scutal margin ; goes downward and 

 posteriorly, behind pleural arm, to aix>demal disc on posterior inner 

 angle of coxa (fig. 38 D, F, 119). 



120. Second tergal rcmotor of the coxa (figs. 34, 38 A). — A slender 

 muscle lying close behind //p, tapering ventrally to slender apodeme 

 arising from extreme posterior angle of coxa (fig. 38 B, D, F, i2o). 



