NO. 8 



INSECT ABDOMEN SNODGRASS 



6i 



2. Retractors of the spermatJiecal pouch (fig. 19 A). — Origins an- 

 teriorly on seventh sternum external to i ; convergent posteriorly to 

 insertions on spermathecal pouch (t). These muscles clearly represent 

 the external ventrals of the preceding segments. (Described by Du 

 Porte, 1920, and Ford, 1923, as inserted on the median oviduct.) 



J. Tergal muscles of the first valvifers (fig. 17 A, E, F, H).— The 

 largest muscles of the ovipositor. Origins on anterior lateral apodemes 

 and anterolateral surface of eighth tergum (E) ; insertions ventrally 

 on anterior ends of first valvifers. These muscles, on the assumption 



VlllStn 



Fig. 19. — The spermatheca and associated structures of Gryllus assimilis. 



A, dorsal view of spermatheca, lateral oviducts, and base of seventh sternum. 



B, median section of genital chamber, spermathecal pouch, and median oviduct. 

 aiv, anterior intervalvula ; GC, genital chamber ; Gpr, gonopore ; /, fold of 



membrane at side of gonopore ; Ode, oviductus communis ; Odl, oviductus later- 

 alis; Spt, spermatheca; SptD, spermathecal duct; t, spermathecal pouch of geni- 

 tal chamber ; tv, transverse ventral muscle of seventh segment ; u, spermathecal 

 spout ; vi, internal ventral muscle of seventh segment ; /, muscle from seventh 

 sternum to first valvifer ; 2, muscle from seventh sternum to spermathecal pouch. 



that the first valvifers are the bases of the first gonopods, are tergo- 

 pleural muscles of the eighth segment. 



4. Ventrolateral dilators of the rectum. — A group of slender, 

 branching fibers arising on inner face of each first valvifer behind 

 articulation with ninth tergum ; inserted ventrolaterally on rectum. 

 (Not shown in figures.) 



The four following pairs of muscles arise on the lateral parts of 

 the ninth tergum. Two of them (fig. 17 E, 5, 8), inserted ventrally 

 on the intervalvulae, are anterior and posterior tergosternal muscles ; 

 the other two (6, 7), inserted on the second valvifers, are tergopleural 

 muscles. 



