422 MR. R. C. LEWIS ON 
The vagina is a thick-walled tube with a narrow lumen. It is 
connected with a very large receptaculum seminis. With in- 
creasing age, before the ovary is functional, the vagina atrophies 
from the pore inwards, and finally, when female and male canals 
are fully developed, the vagina remains only as a small tubular 
projection from the receptaculum (figs. 9 & 11). This resembles 
the condition found in C. zschokkei von Janicki (10), and von 
Janicki concludes that the young proglottides, whose testes are 
not yet developed, function as females, and that the older pro- 
glottides with abortive vagine function as males, although the 
female organs are otherwise fully developed. The eggs must all 
be fertilized by the sperm stored up in the receptaculum seminis, 
which receives sperm through the vagina from the same worm or 
from another worm by copulation in the young state, and this is 
proved by the fact that the receptaculum of proglottides in which 
testes are not yet developed are filled with spermatozoa. 
Male Reproductive Organs. 
The first rudiments of the testes are seen about the 12th seg- 
ment. They reach maturity about the 60th segment, and are seen 
as small rounded sacs lying in the dorsal field of each segment 
between the transverse excretory canal of the preceding segment 
and the cirrus-sac (figs. 7 & 11). They do not extend in towards the 
median field as in C. kuvaria Shipley (7), but are confined to the 
dorsal region between the ventral excretory canal and the inner 
termination of the cirrus-sac. From these testicular sacs, about 
50 on each side, little ducts are given off which connect with the 
vas deferens. The vas deferens is a slender duct which runs in 
towards the median field and then loops back above the recep- 
taculum seminis to run obliquely down to the cirrus-pouch. The 
vas deferens does not extend further towards the median field 
than the inner extremity of the receptaculum seminis. Before 
entering the cirrus-pouch there is a circular swelling, the vesicula 
seminalis, with a diameter of *1 mm. anda thick wall. The cirrus- 
pouch is elongated and of uniform size and thickness in mature 
segments, 1 mm. long by -2 mm. broad (figs. 9 & 11). It has mus- 
cular walls consisting of an outer longitudinal layer and an inner 
thicker circular layer. The cirrus also has circular and longi- 
tudinal fibres. The space between the muscular wall of cirrus- 
sac and cirrus is filled with spongy tissue. The cirrus is thick- 
walled with a narrow lumen. It is often seen protruding toa 
great extent, nearly as far as the length of the cirrus-pouch. It 
is covered externally with closely set bristles. The outer end of 
the cirrus-sac discharges into a space, the genital atrium. Its 
outer end is guarded by a circular muscular sheath, the sphincter ; 
and beyond this sheath, in the genital atrium, is a circular pro- 
jection of the floor of the latter. 
Testes are not observed after the 100th segment, though the 
cirrus-sac persists to within twelve segments of the posterior 
