NO. 14 



INSECT ABDOMEN SNODGRASS 



79 



tracted with the eversion of the end-sac. The ductus ejaculatorii, 

 though independent for some distance before entering the penes, are 

 united anteriorly in a ductus conjunctus (Dejcn), which takes its 

 origin in a sachke seminal reservoir (rs) that receives the two vasa 

 deferentia (Vd). 



Fig. 27. — Hexapoda-Dermaptera : three types of structure in the male genital 

 exit system and the intromittent organ. (Diagrams based on Meinert, 1864, 

 1868; Jordan, 1909; Heymons, 1912; Walker, 1922; Snodgrass, 1935.) 



A, Labiduroidca, penes separate beyond common basal apodeme. B, Hcmi- 

 mcrus talpoides, penes united, but both exit ducts retained. C, Forficuloidea, 

 penes united, only one functional duct. 



a, median lobe of penis; aa, median lobe of conjoined penes; Ap, basal 

 apodemal plate of penes or penis ; b, paramere lobe of penis ; c, eversible end- 

 sac of penis: cc, end-sac of conjoined penes; Dcj, ductus ejaculatorius ; dej, 

 nonfunctional branch of ejaculatory duct; Dejcn, ductus ejaculatorius conjunctus ; 

 Pen, penis ; rs, seminal reservoir ; Vd, vas deferens ; Vdcn, vas deferens con- 

 junctum; Vsm, vesicula seminalis ; x-x, anterior wall of genital chamber. 



In Hemimcnis and Forficuloidea the penis is a single structure 

 (fig. 27 B, C), but, since it is armed with two paramere processes 

 (b, b) arising at the sides of a median terminal lobe (aa) contain- 

 ing an eversible end-sac (cc), there can be no doubt that the organ 

 has been produced by the union of two penes having the structure of 

 the paired organs of Labiduroidca (A). Two ductus ejaculatorii tra- 

 verse the penis of Hemimcnis talpoides (B, Dej), but they fork in 



