TYPES OF SPECIES OF CESTODA — KREFFT. U 



just above and in front of the vitellarium being situated between 

 the latter and the ovarian bridge. The complex as a whole is 

 an elongate solid gland made up of a great number of granular 

 deeply staining cells, whose inner end is narrowed and duct-like. 



Each vagina is a wide tube leading from the corresponding 

 female genital pore inwards and backwards to the middle of the 

 segment where it meets its fellow fiom the other side. It then 

 passes forward to enter into relationship with the various female- 

 glands. A more detailed account of its course may now be given. 

 Each passes inwards close beside the wall of the cirrus sac along 

 its dorsal surface. It then crosses over the lateral part of the 

 vas deferens at about the point where the latter becomes thrown 

 into a few loops or coils to lie postero-ventrally or ventrally to 

 the male duct which it accompanys inwards as far as the inner end 

 of the vesicula seminalis. In the region of the excretory canals 

 the vagina lies between these and the more dorsally placed vas 

 deferens, whilst in the neighbourhood of the vesicula, it lies on 

 the ventral limit of the medulla. In this last locality it frequent- 

 ly becomes widened to form an elongate receptaculum seminis 

 which extends still further inwards and backwards as will be 

 mentioned below. Occasionally this portion of the vagina 

 becomes swollen into a rounded reservoir of about the same thape 

 and size as the vesicula seminalis which lies immediately anter- 

 iorly to it. In a longitudinal vertical section of a segment (PI. 

 i, fig. 2), the vagina and the vas deferens are seen in trans- 

 verse sections as two adjacent tubes, the former possessing a 

 wide lumen and thin walls, the latter a narrow lumen with thick 

 walls containing longitudinal muscular fibres. The vagina now 

 travels inwards, backwards and ventrally, skirting round the 

 posterior border of the corresponding ovarian lobe, this part of 

 the duct being fairly wide. The two vagina? unite medianly 

 near the posterior margin of the segment to form a short wide 

 common transverse tube from which the fertilising canal passes 

 forwards. The oviduct and vitelline duct enter it from the 

 neighbourhood of the shell-gland complex which is now pene- 

 tiated. The duct then passes forwards to the transversely 

 placed uterus. The vaginae persist in segments in which the 

 uterus is well developed and in which the ovary has disappeared. 



The uterus consists at first of a more or less transversely 

 placed sac whose middle lies just posteriorly to the ovarian 

 bridge. The long " wings " of the sac extend outwards and back- 

 wards between the ovarian tubes, and as they develop very rapid- 

 ly they soon come to extend into the posterior corner of each 



