A NEW MAMMALIAN CESTODE. 1043 
receptaculum to be full of sperm. Neither the testes nor the ova 
were ripe so early in the body. 
The testes lie posteriorly in the segment just in front of the 
transverse water-vascular vessel. They form a narrow band 
running right across each segment, but contained within the 
area bounded by the lateral water-vascular trunks. 
It may be seen in transverse and horizontal sections that the 
testes are not more than two deep and are in three or four 
rows. There are about 60-70 in each segment. I regard the 
testes as dorsal in position, because when the outer and dorsal 
water-vascular trunk moves away from its lateral position with 
reference to the inner tube, it les to the side corresponding to 
that on which lie the testes. They are therefore dorsal, and the 
ovary 1S ventral in position. 
Furthermore, since the cirrus-sac passes to the same side of the 
two water-vascular tubes as that on which the testes lie, it has a 
dorsal position with regard to them ; this point is not mentioned 
by Fuhrmann in his account of Shipleya. Moreover, as the trans- 
verse vessels arise from the ventral vessels they, too, are ventral 
in position, and therefore the female organs such as the recep- 
taculum, which is more or less level with them, must be ventral. 
Fuhrmann states that in Shipleya the ovary is ventral. JI have 
not been able to notice any ripe masses of spermatozoa in the 
testes, though there are many in the cirrus. This absence of 
sperm from the testes has already been noted by Fuhrmann in 
another genus. 
The vas deferens of this worm is very remarkable. In the 
very young proglottids the vas deferens emerges from the cirrus- 
sac asa short and curved tube which is curved backwards towards 
the testes. In rather older proglottids the vas deferens is not 
much longer but is distinctly differentiated into two regions; 
there is a ‘wider tube which emer ges from the cirrus-sac and this 
abruptly becomes narrower in the distal region, where it ulti- 
mately breaks up into three or four branches for the supply of 
the testes. This differentiation of the vas deferens is much more 
highly developed in mature proglottids. The vas deferens after it 
emerges from the cirrus-sac runs forwards and inwards obliquely 
towards the anterior end of the segment, and that is away from 
the testes, which are posterior in position ; this region of the vas 
deferens is that of the greater calibre, and the fine tube which 
issues from it is the sperm-duct proper and runs backwards 
towards the testes and thus at an acute angle with the anterior 
region. This is foreshadowed in the curved course of the entire 
vas deferens shown in the immature proglottids. To return to 
the anterior section of the vas deferens—this tube is very wide, 
relatively speaking, and often dilates at the ends, where it passes 
into the narrow section of the vas deferens, into a circular sac ; 
its width varies in parts and according to the state of develop- 
ment of the segment. 
The intimate structure of this region of the vas deferens is a 
(OTs 
