180 ANNALS OF THE QUEENSLAND MUSEUM. 
genital canals passi out ventrally below them. At the posterior end 
of each row there: comes off a delicate vitelloduct which travels 
inwards between the excretory vessels and downwards so as to pass 
bejow the ovarian lobes. The two ducts unite just below and 
behind the middle of the ovarian bridge to give rise to a short 
and rather wider common duct which passes directly dorsally to 
enter the shell-gland complex. 
Fi 'oni the female pore the wide vagina passes inwards parallel 
with and dorsally to the cirrus sac. As already mentioned, this 
duct rather more frequently lies in front of the male duct. In the 
outer portion of its course its walls are covered by a layer of deeply 
staining gland cells similar to those figured by Kraemer* in P. 
filicollis. It passes! round close behind the sac crossing dorsally 
above the vas deferens, which is here very narrow, and then 
trends inwards; and backwards, forming a curve which lies just 
below the niid-dorso-ventral level and below the main mass of the 
wide coiled vas deferens. On reaching the mid-line of the segment 
it travels backwards above the uterus towards the ovary, which it 
crosses dorsally. Just in front of and behind the ovarian bridge 
the vagina becomes thrown into a number of loose coils, this por- 
tion possessing a rather wider lumen than the more anterior part, 
and acting as a sperm reservoir. In mature segments there may 
be readily recognised, lying just behind the ovary, a coiled mass, 
the constituent parts of which can only be worked out by a careful 
study of serial sections. The details of the oviduct, vitelline duct, 
and shell-gland have already been mentioned. The vagina becomes 
narrowed to form the fertilising duct, which passes dorsally to 
enter the shell-gland very soon after taking up the oviduct. As 
stated previously, the common vitelline duct enters the fertilising 
canal within the shell complex. The uterus travels forwards from 
the latter as a narrow tube, rising dorsally above the ovary and the 
vagina, very soon bending ventrally, passing: to one side of the 
vagina and coming to lie just below the inner longitudinal muscula- 
ture. It then extends forwards along the mid-line, its rounded 
extremity lying near the anterior border of the segment. The 
uterus is at first a long, narrow, simple sac, but short lateral 
diverticula soon appear, these increasing in size as egg formation 
progresses. As the cavity increases the male and female glands 
* Kruemer, Zeitschr. f. wicS. Zool. liii, 1892, p. 617-722. 
