48 SMITHSONIAN MISCFXLANEOUS COLLECTIONS \0L. 94 



groove of the body wall between the bases of the first valvulae (fig. 

 20 B, Spt), and, therefore, belongs to the eighth abdominal segment. 

 The usual bifid structure of the adult organ in insects suggests that 

 the spermatheca may have been paired in its origin, but one branch 

 is generally the sperm storage chamber, and the other a glandular 

 accessory. 



The opening of the spermatheca in the dorsal wall of the genital 

 chamber in adult grasshoppers lies in a median channel of the mem- 

 branous space between the anterior basivalvular sclerites of the first 

 A^alvulae (figs. 17 E, 20 C, Spr). In Dissosteira Carolina the aperture 

 is transverse above the posterior margin of a weakly sclerotic heart- 

 shaped sclerite (fig. 20 D, ;). Structural details associated with the 

 spermathecal opening, however, may be quite different in different 

 acridid species. In Melanoplus femur-rubrum, for example, the 

 spermatheca opens through a crescentic longitudinal slit in an oval 

 area or sclerite contained in a median pocket of the genital chamber 

 wall (fig. 20 C, Spr). Behind it are two small triangular sclerites {k) 

 in the wall of the pocket. In M. mcxicamis (E) the aperture is a cleft 

 between two lateral lips of a thick oval body (wi) projecting from a 

 depression in the w'all of the genital chamber. It is possible that struc- 

 tural differences in the female spermathecal opening may be found to 

 be correlated with differences in the male intromittent organ, since 

 coition is effected by way of the spermathecal duct. 



Accessory genital glands of the ninth abdominal segment are usually 

 not developed in the Acrididae. According to Nel (1929), however, a 

 small median invagination is formed betw-een the ovipositor lobes of 

 the ninth segment in young nymphs of Locustana and Colemania 

 (fig. 20 B, AcGI), which becomes a short tube, but remains vestigial 

 even in the adult. The function of the usual female accessory glands 

 is assumed in Acrididae by a long tubular diverticulum of each lateral 

 oviduct, or more strictly of the oviducal calyx, in which is secreted 

 the frothy material of which the egg pod is formed. 



DEVELOPMENT OF THE OVIPOSITOR 



It is commonly assumed that the ovipositor of pterygote insects is 

 formed from the limb appendages of the eighth and ninth abdominal 

 segments, that the valvulae are processes of the appendage bases, and 

 that the usual supporting plates, or valvifers, are derived from the limb 

 bases themselves. There is no doubt that the organ is formed from 

 ventral outgrowths and sclerites of the two genital segments, but it 

 is quite a different matter to prove that these parts represent true 



