TYPES OF SPKCIKS OF CKsrODA — KREFFT. 31 



with ii maximum breadth of 014") mm. In general shape it is 

 cylindrical or pyriform, being usually of the latter form in 

 sexually mature segments. Its outer wall contains powerful 

 muscles within which there is abundance of a loose parenchy- 

 matous tissue pervaded by muscle fibres acting as retractors of 

 tlie cirrus. There are also well-defined fibres passing inwards 

 from the inner end of the sac itself, their function being that of 

 retractors of the sac. The walls of the vas deferens within the 

 sac contain well-developed "longitudinal and circular muscle fibres. 

 When everted the cirrus is seen as a relatively short (0275 mm.) 

 tube with a broad base (0 - 10 mm.) tapering considerably towards 

 the free end which measures 027 mm. in diameter. The 

 muscular fibres mentioned by Fuhrmanu" 7 as passing from the 

 cirrus sac to the cloacal wall in G. perversa were distinctly seen 

 in G. austral iensis, more especially in early sexual maturity. 



The female system lacks a vagina. The ovary is a very 

 extensive organ occupying the middle of each proglottid. At 

 maturity it forms a compact mass of about 34 mm. in breadth, 

 reniform in shape, the vitellarium and shell gland lying in the 

 posteriorly directed hilus. In younger segments one may readily 

 recognise a transverse bridge connecting the two ovarian lobes ; 

 each lobe is very greatly branched. Some of these branches or 

 tubes lie in the dorsal portion of the medulla, the uterus commonly 

 passing between them in the lateral regions of the gland. 

 Portions of the ovary maj' extend forwards to lie below the 

 anterior section of the uterus and even the testes. The bridge 

 lies ventrally. The oviduct passes backwards and slightly 

 dorsally to enter the shell gland. A receptaculum seminis was 

 not recognised though it seems reasonable to expect the presence 

 of some reservoir in which sperms may be stored. The vitelline 

 gland is a conspicuous reniform organ lying behind the ovarian 

 bridge, and dorso-posteriorly to the shell gland which may at 

 times partly overlie it. The vitellarium and the ovarian bridge 

 lie at the same dorso-ventral level, the rather large rounded 

 shell-gland being situated more dorsally than either of them. 

 The vitello-duct passes away dorsally from the hilus of the gland 

 to join the oviduct within the shell complex. 



The uterine duct leaves the shell-gland dorso-anteriorly .is a 

 narrow tube which passes forwards above the ovary until it 

 reaches the uterus, opening into it in the median line just behind 

 the testes. The uterus is a very characteristic organ resembling 

 that of other species of Gyrocailia in being ring-like. In young 



fiT Fuhrmann — hoc. cit., p. 619. 



