NO. 14 



INSECT ABDOMEN SNODGRASS 



61 



The male bursa genitalis, or genital chamber, which usually con- 

 tains the phallic organ or organs, projects into the ninth abdominal 

 segment (fig. 22 A, GC) since it is an invagination of the integument 

 behind the ninth sternum, though its dorsal wall presumably belongs 

 to the venter of the tenth segment. Appendages of the ninth segment 

 (gonopods) may be entirely absent; in Orthoptera and some related 

 insects they are small styluslike structures resembling the abdominal 

 styli of Thysanura, though unlike the latter they are not provided 



i. Dej 



' \ ^ 



A/ / \ '^"^ \ ~~ "D Phtr 



VIIINv IXNv XNv XINv(Cer) D 



Fig. 22. — Diagrams of the position and structure of the external and internal 

 genitalia of male insects. 



A, general position and relation of the male reproductive organs of orthopteroid 

 type. B, diagram of the median penis, or phallus, showing parts that commonly 

 recur, but which are not necessarily or usually present in the same species. 



AcGId, accessory genital gland; Acd, aedeagus ; Ccr, cercus ; Dej, ductus 

 ejaculatorius; Enph, endophallus : Eppt, epiproct ; GC, genital chamber, or 

 bursa genitalis; Gpr, gonopore (aperture of ejaculatory duct) ; Gtr, gonotreme 

 (opening of genital chamber) ; IXS, sternum of ninth abdominal segment (male 

 subgenital plate, hypandrium) ; Pap^t, paraproct ; Phb, phallobase ; Phi, phallus 

 (median penis); Phtr, phallotreme (distal opening of endophallus); Pmr, 

 paramere ; Tcs, testis; Til, titillator, f'J, vas deferens; Vrg, virga; VII-XI, 

 seventh to eleventh abdominal segments ; I'lIINv, IXNv, XNv, XINv, principal 

 lateral nerves of eighth, ninth, tenth, and eleventh abdominal segments issuing 

 from composite last ganglion of ventral nerve cord. 



with muscles. In many of the higher insects, however, the appendages 

 of the male genital segment take the form of large movable organs 

 of various shapes usually adapted to grasping or holding the female. 

 These genital claspers (valvae, harpes, harpagones) are always dis- 

 tinguishable from other similar but immovable or merely flexible lobes 

 or processes borne on the ninth or other segments of the genital com- 

 plex by the fact that they are independently movable by muscles in- 

 serted on or in their bases. Such appendages are most probably homo- 

 logues of the thysanuran abdominal styli. In some cases the movable 

 claspers are supported on distinct basal plates, but more commonly 



