62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



86. Pleuro-sternal muscle (figs. 34, 35). — A dense mass of very 

 short fibers connecting the approximated ends of the pleural apophysis 

 and the sternal apophysis. 



Sy. Third ventral longitudinal muscle (figs. 34, 35). — Attached 

 laterally on first spina ( iSpn) ; extends posteriorly and laterally over 

 posterior end of do to anterior edge of apophysis of mesosternum 

 {SA,). 



88. Fourth ventral longitudinal muscle (figs. 34, 35). — A slender 

 muscle attached anteriorly on first spina (iSpn) and posteriorly on 

 second spina {sSpn). 



The following thirteen muscles (89-101) include the muscles of 

 the base of the leg and the principal direct muscles of the wing. 



8p. Tergal promoter of the coxa (fig. 34). — Lies close behind 84 

 in the innermost series of lateral muscles. Origin on scutum ; inser- 

 tion on stalked disc (fig. 37 A, B, C, 8p) arising from articular mem- 

 brane at anterior angle of coxa close to lower end of trochantin 

 (B, C, Tn). The representative of this muscle in the prothorax 

 (fig. 33 A, 62) is inserted on the trochantin, as it is in most insects 

 in which the trochantin is well developed. 



go. First tergal remoter of the coxa (fig. 34). — Origin on scutum ; 

 goes ventrally posterior to pleural arm to insertion on stalked disc 

 arising from inner posterior angle of coxa (fig. ;^'/ A, B, po). 



pi. Second tergal remotor of the coxa (fig. 37 A). — A slender 

 muscle arising on scutum from outer end of ridge .y (fig. 22 B) ; goes 

 obliquely ventrally and posteriorly to slender apodeme arising from 

 extreme posterior angle of coxa (fig. 2)7 A, B, 91). This muscle is 

 the last of the tergal muscles of the mesothorax ; it lies just external 

 to posterior border of po and is partially visible from median plane 

 (fig. 34) between po and 7/j. 



The group of mesothoracic muscles attached dorsally on the tergum 

 includes two segmental branches of the depressor of the trochanter 

 {lo^) which will be described later. When the tergal muscles have 

 been removed there is e5cposed a second or outer set of lateral muscles 

 having their origin on the pleuron (fig. 37 A). These muscles include 

 the abductors of the coxa, and the direct muscles of the wing. The 

 wing flexor {85) of the latter group has already been described as a 

 pleuro-alar muscle; the others are pleuro-coxal, with one pleuro- 

 sternal muscle. Ventrally there will be seen also the sterno-coxal mus- 

 cles, or rotators of the coxa, a description of which will logically fol- 

 low that of the tergo-coxal muscles. 



