No. 6.] STRC/CTURES OF THE AXTENNATA. 279 



as evidence of origin from the homodynamous pairs of a series 

 of metameric Nephridia and it seems to me that the argument 

 might be similarly employed to account for the ectodermal 

 portion of the sexual apparatus. Is it not probable that a 

 primarily segmental Anlage made these conditions possible .' 



The condition of the Strepsiptera in this connection is most 

 interesting. Here only the male undergoes complete meta- 

 morphosis. The female becomes sexually mature in the larval 

 condition, and the young which develop from the egg in the 

 body of the mother emerge through four median unpaired 

 funnels, which open eventually near the posterior border of the 

 second to the fifth abdominal segments, respectively. These 

 funnels are curved toward the anterior part of the body and 

 lined with chitin which is provided with outwardly directed 

 spinules. Their general appearance reminds one strongly of 

 the apodemes in some insects. 



In the male there is a single genital aperture in the posterior 

 border of the antepenultimate segment at the end of an unpaired 

 chitin-lined ductus ejaculatorius. In both sexes the chitinous 

 portions arise as unpaired ectodermal invaginations. The draw- 

 ings give an idea of the conditions as figured by Nassanow ('92) 

 for Xenos Rossii. My own study of the American Xcnos Peckii 

 gives identical results. Fig. 6 represents the three posterior 

 segments of the adult male seen from above, d.c. is the ductus 

 ejaculatorius; v.d., the vas deferens; /"., testes; in., muscles; 

 d.t., digestive tracts, with c, coeca. 



Fig. 7 is a sagittal section through a sexually mature female : 

 m., representing the mouth ; b.c, the brood canal ; b.f., brood 

 funnels; 0., ova; s.g., supra-oesophageal ganglion; s.g., sub- 

 oesophageal ganglion ; f.b., fat -body. Fig. 8 represents five 

 stages in the development of a segmental brood funnel of the 

 female, in which c. is used to designate ectoderm and m. meso- 

 derm. Stage D persists during the development of the young, 

 when the end of the funnel breaks through, giving place to 

 Stage E. 



The occurrence of funnels in four successive segments recalls, 

 the condition described by Heymons('9l) for Blatta, and Wheeler 

 ('93) for Xiphidiimi, where the beginnings of the reproductive 



