Mr Shipley, On a new species of Bothriocephalus. 211 



broad and showing no structure but an unstained granular 

 contents. 



During 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 uterus,-sac 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. XL PT. III. 16 



