90 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



In male insects the history of the gonopods is much more involved 

 than in the female, and the evolution of the genital appendages into 

 organs of copulation has produced many different kinds of struc- 

 tures. It is only in certain species of Machilis that both pairs of gono- 



VIII 



IX 



Ovd 



. / ; I \ \ 



Stn LB * Sty LB iGon sGon 

 jr\. 



VIIILB(Vlf) IX LB 



\ / 



sty 



D 



-Aed 



Vlf 



iVl 2VI 3VI 



Fig. 39.— Diagrams showing the morphology of the ovipositor, and the exter- 

 nal genitalia of the male. 



A, female genital segments and generalized structure of the gonopods. B, an 

 ovipositor with two pairs of valvulae formed of the gonapophyses. C, an ovi- 

 positor with three pairs of valvulae, the third pair {sVl) formed of the basal 

 plates of second pair of gonopods (A, LB). 



D, generalized structure of ventral parts of ninth abdominal segment of male, 

 showing sternum {Stn), gonopods {Gp, Gp), and penis (Pen). E, specialized 

 structure of male genitalia; basal plates of gonopods (LB, LB) united by pons 

 basalis (pnb), parameres united with penis to form an aedeagus (Aed), and 

 styli (Sty) transformed into clasping lobes. 



Aed, aedeagus; Gon, gonapophysis ; iGon, sGon, gonapophyses of first and 

 second gonopods; LB, basal plate of gonopod; Ovd, oviduct; Pm, parameres 

 (male gonapophyses); pnb, pons basalis; siiiels, muscles of stylus; Stn, ster- 

 num; Sty, stylus; T, tergum, iVl, 2VI, 3V I, first, second and third valvulae; 

 Vlj, valvifer. 



pods bear gonapophyses (fig. 33 A, B, iGon, 2Gon). In all male 

 pterygote insects gonapophyses are lacking on the eighth segment, and 

 the gonopods of the ninth segment only enter into the copulatory 

 apparatus, though accessory structures of the eighth and the tenth 

 segment may be included. 



