Mr Shipley , On a new species of Bothriocephalus. 211 
broad and showing no structure but an unstained granular 
contents. 
Daring the course of its twisting the uterus is so narrow that 
the eggs lie in a single row one behind the other so that in a 
transverse section but one egg is ever seen. In the uterus-sac 
however they are in considerable numbers, at least 100. The 
uterus-sac is not median as seems to be the case in other species 
of Bothriocephalus. It is pushed sometimes to the right and 
sometimes to the left by the presence of the cirrus-bulb, and 
whether it lies to the right or to the left seems to follow no 
certain law. In one series of sections through seven proglottides 
the position of the uterusrsac was R. R. L. L. R. L. R., in another 
series seven proglottides with the uterus-sac to the right were 
followed by six in which it was to the left. The opening of the 
uterus-sac to the exterior is circular, it does not seem to be 
provided with anything of the nature of a sphincter muscle, 
nevertheless it is a very definite and distinct structure. In a 
considerable number of the sections eggs were seen passing out 
of the pore. From what I have seen I think it probable that 
eggs pass out from the tape-worm into the alimentary canal of 
the host and that in B. histiophorus the eggs pass freely out from 
each ripe proglottis and do not wait until the posterior proglot- 
tides break off to make their escape from the parent. 
Unlike the other species of the genus these specimens do not 
have their uterus-opening in the middle line or nearly in the 
middle line, but this aperture is quite distinctly pushed either 
to the left or to the right according to the side to which the 
uterus has been pushed by the conspicuous cirrus-bulb. 
The yolk-glands are very numerous, in longitudinal sections 
they seem almost to run from segment to segment. In transverse 
section they run almost all round the segment but are broken by 
slight areas free from their presence at both sides and in the 
median line both dorsally and ventrally. They lie exclusively in 
the outer parenchyma outside the layer of longitudinal muscles 
which separates the central from the cortical parenchyma. Their 
four ducts unite and open by a common duct into the ootype close 
to the opening of the vagina. The brown or under a high power 
yellow yolk granules are unusually conspicuous in this form. 
The vagina is a fine tube with thin muscular walls which 
passes almost straight from the ootype to the dorsal surface. It 
lies behind the cirrus-bulb and opens close behind the opening 
of the penis. Close to its opening is a well marked sphincter 
muscle clearly shown in Figure 3. This is the “ napiform ” mus- 
cular body of Linton, who regards the opening of the reproductive 
ducts as ventral whereas, as is indicated above, Ltihe regards them 
as dorsal. There is no receptaculum seminis. 
VOL. XI. PT. III. 
16 
