192 



MEMOIES OF THE QUEENSLAND MUSEUM. 



The atrium is surroimded by a well-marked sphincter, especially in the 

 region of the female pore (fig-. 14). There is only a slight genital papilla 

 present at sexual maturity. It lies near the middle of the segment, and, as 

 already mentioned, alternates irregularly. 



Fig. 13. — Transverse section of segment in I'egion of cirrus sac {c.s.), showing ejaculatorjr 

 duct (ej.d.) and cirrus (c.) cut across. 



Female System. — Tlie ovary is a fairly large, compact organ consisting 

 of two pyriform lobes connected by a narrow ovarian bridge which lies more 

 ventrally and rather more posteriorly than the rest of the gland. From the 

 bridge there is given off a short, fairly wide oviduct provided Avith a ' ' swallowing 

 apparatus" (fig. 18). 



Fig. 14. — T.S., showing vagina opening into the genital atrium, also the sphincter mu.scle 

 Lsp.m.) surrounding the vagina ; v.d., vas deferens. Other lettering as in preceding figures. 



The vagina leads from the female pore which generally lies in front of, 

 and ventrally to, the male aperture (fig. 11) but occasionally postero-ventrally. 

 It is a rather wide tube which travels inwards ventrally or antero-ventrally to 

 the cirrus sac very close to the ventral layer of longitudinal muscle and just 

 above the excretory canal. It then curves backwardly behind and below the 

 inner end of the cirrus sac, and below the coils of the vas deferens, becoming 

 slightly narrowed as it passes inwards, its level gradually rising until it comes 

 to be just above the uterus (figs. 13-15, 17). Its course is then practically 



