102 TRANSACTIONS LIVERPOOT, BIOLOGICAL SOCIETY. 
history when the vagina becomes a functional organ. 
None of those seen have been impregnated, and the 
substance contained in the lumen of the vessel is not 
semen, but a colloid of some sort, probably only mucus. 
It is difficult to believe that copulation takes place through 
the very narrow tube forming the termination of the 
uterus, though this may conceivably occur, and not per 
vaginam. It is, of course, possible that the latter struc- 
ture may not be functional in this species, but it is highly 
unlikely that this condition exists. The muscular tissue 
round the receptaculum seminis offers yet another diffi- 
culty: it is too strongly developed not to be of some use ; 
and it appears to me to be likely that the receptaculum 
may be muscular, in the functional female phase, and 
that spermatozoa received from another animal may be 
stored within it, and ejected when required into the 
oviduct. Obviously, these and other questions must await 
solution until material in other stages of sexual growth 
are obtained. 
A genito-intestinal canal does not apparently exist 1n 
this species. 
The Vitellaria 
The vitellaria are very conspicuous structures in this 
species. They vary somewhat, both in degree of develop- 
ment and distribution in the specimens examined. In the 
worm figured they are present as a single layer of rather 
large follicles, situated marginally, and mostly external 
and dorsal to the rami of the intestine. The follicles are 
pear-shaped, and the stalked portions of two or three 
adjacent ones usually fuse to form ducts of the second 
order, which open into the longitudinal collecting vessels. 
In the specimen figured (one of the larger worms collected 
in 1905 by Mr. Scott) there are only two main longitudinal 
ducts, one on each side, and these receive the ductules 
