NO. 6 



GRASSHOPPER ABDOMEN SNODGRASS 



47 



the gonopore undergoes a posterior transposition that gives it its defi- 

 nite location behind the eighth sternum. In the early part of the first 

 instar, Nel says, the oviduct opens on the extreme anterior part of the 

 eighth sternum in the groove extending posteriorly from its aperture. 

 During this instar the lips of the groove unite ventrally, the union pro- 

 ceeding from in front backward ; the oviduct is thus extended pos- 



VmT DCr XT 



Fig. 20. — Structure and development of the female copulatory apparatus. 

 A, vertical section of end of abdomen of Dissosfcira Carolina just to left of 

 median plane, showing genital chamber (GC) invaginated between bases of 

 ventral valvulae and eighth sternum, with gonopore {Gpr) in its ventral wall 

 and spermathecal aperture {Spr) in its dorsal wall, the eighth sternum termi- 

 nating in the egg guide {eg). B, diagrammatic section of end of abdomen of 

 first instar nymph of Locustana (from Nel, 1929), showing origin of median 

 oviduct {Ode') behind seventh sternum, and spermathecal invagination {Spt) 

 at end of eighth sternum. C, ventral view of first valvulae and dorsal wall of 

 genital chamber of Mclanoplns femur-rubriun. D, spermathecal aperture of 

 Dissosfeira earolina. E, same of Melanoptus mexieonus (structure variable in 

 this species). 



teriorly, and its opening, the gonopore, migrates in the same direction, 

 until finally, in the second instar, it takes its definitive position in the 

 newly forming genital chamber behind the eighth sternum. 



The typical acridid spermatheca is a long tubular organ extending 

 forward in the ventral sinus of the body cavity beneath the ventral 

 diaphragm (figs. 17 E, 20 A, Spt) . The middle part is variously coiled, 

 and the tube ends in an enlarged bifid terminal section. The sperma- 

 theca of the grasshopper is formed as a median invagination -in a 

 4 



