NO. O INSECT ABDOMEN SNODGRASS 59 



valvifer forms a second strong process, the inferior apophysis (G, H, 

 g). The articular condyle by which the second valvifer is hinged to 

 the first is located on the inner face of the anterior margin of the 

 dorsal arm (G, h). The second valvifer of the cricket has no direct 

 connection with the ninth tergum. 



Two intervalvular sclerites are well developed in Gryllus. The first, 

 or anterior intervalvula (fig. 17 H, aiv), is a transverse bar between 

 the anterior processes (g) of the second valvifers. Medially it bears 

 a small apodeme (;'). The second, or posterior intervalvula (piv), is 

 a broad, externally convex plate exposed above the bases of the 

 dorsal valvulae (A, piv). By its produced lateral extremities it 

 articulates with the second valvifers at the deeply notched angles 

 between the dorsal arms of the latter and the bases of the dorsal val- 

 vulae (H). Medially the posterior intervalvula bears a high, plate- 

 like apodeme (E, H, ^). In a lengthwise section of the abdomen 

 (figs. 17 E, 18) it is clearly seen that the two intervalvulae {aiv, piv) 

 belong to the venter of the ninth abdominal segment, and that they 

 have the status of anterior and posterior sternal sclerites lying between 

 the second valvifers. Tergal muscles of the ninth segment are inserted 

 on each of the intervalvulae. 



The reduced eighth sternum, which forms a free subgenital plate 

 (fig. 18, VlllStn) beneath the base of the ovipositor, conceals a small 

 genital chamber {GC) above its dorsal wall, between the bases of 

 the valvulae. Into the anterior end of the genital chamber the short 

 median oviduct (Ode) opens between two membranous folds (fig. 

 19 B, /) on the dorsal surface of the subgenital plate. Dorsal to the 

 opening of the oviduct, the anterior dorsal wall of the genital chamber 

 before the anterior intervalvula {aiv) forms a deep pouch (t) pro- 

 jecting into the body cavity above the oviduct. The pouch contains a 

 strongly sclerotized, spoutlike organ (u) reflected from its anterior 

 wall, which is transversed by the terminal part of the spermathecal 

 duct (SptD). The deflected distal extremity of the spout, containing 

 the opening of the sperm duct, projects into the genital chamber a 

 little beyond the opening of the oviduct. The eggs issuing from 

 the gonopore are thus, evidently, fertilized just before entering the 

 channel of the ovipositor between the bases of the valvulae. 



The shaft of the ovipositor consists of the slender, elongate first and 

 third valvulae. The two valvulae on each side are firmly but freely 

 interlocked by a ridge with an expanded margin on the lower edge of 

 the dorsal third valvula (fig. 20) that is held in a groove on the ap- 

 posed surface of the ventral first valvula. The valvulae of opposite 

 sides are not united. The inner walls of the dorsal valvulae are 



