1008 MR. F. E. BEDDAUD ON 



commencement of the genital cloaca, perforating the muscular 

 pad. Its walls are not distinctly cellular and they stain deepjy, 

 both of which features are very common in these animals. 

 Distally, the vagina may be easil}'' followed until it opens into a 

 well-marked receptaculum seminis, which is very large and con- 

 spicuous in Anoplotcenia. In young segments its course is straight 

 across the segment ; in older ones it passes straight to the 

 middle line in an oblique course, then bends back along the middle 

 line of the segment. This sac lies almost exactly in the middle 

 of the body and is absolutely circular in transverse sections of the 

 progiottids. The vagina enters it on the ventral surface and 

 leaves it again at an exactly corresponding point further towards 

 the non-pore side of the proglottid. Thus the tube leaving the 

 receptaculum has to be followed for a short distance in sections 

 before it can be ascertained whether it is the distal or proximal 

 part of the vagina. The receptaculum was gorged with sperm. It 

 is not spherical as might be imagined from its circular contour in 

 section, but narrows to the more slender tube at one end which is 

 beyond the exit of the vagina. 



Towards its point of opening into the genital cloaca, the vagina 

 lies parallel to the cirrus sac, in some cases being less oblique 

 in its course than in other progiottids. It has a very thick 

 muscular wall, that is to say thick relatively to the size of its very 

 small lumen. This muscular coat is double, an inner longitudinal 

 and an outer cii'cular layer being present. Opposite the actual 

 point of opening into the genital cloaca, the vagina suddenly 

 widens into a very small sac lying closely adpressed to the 

 muscular pad which forms part of the wall of the genital cloaca ; 

 from this sac, a narrow tube passes at right angles to the 

 rest of the vagina and perforates the muscular pad. The terminal 

 sac of the vagina is seen to be filled with sperm. It is related 

 perhaps to the latei'al oi-ifice of the cirrus within the invaginated 

 pouch of the cirrus sac : this when protruded forms a bulbous 

 extreiriity, near to which the orifice would pour its contents 

 into, quite fill and perhaps even somewhat dilate, this terminal 

 sac of the vagina. This matter is, however, more fully dealt with 

 under my description of the cirrus sac and penis (on p. 1014). 



I am disposed to think that the i-eceptaculum seminis is no 

 more than a dilatation upon the vagina, for it could easily owe its 

 shape to mere gorging with sperm, and its walls appear to be like 

 those of the rest of the vagina and to have lost their cellular 

 character. It is at any rate greatly disguised in them as in so 

 many other tapeworms. As Gough has lately pointed oiit,* this 

 non-cellular appearance is preceded by a distinct wall of cells. If 

 the receptaculum seminis be as I suggest merely a local swelling 

 of the vagina, it is clearly quite different in its nature from the 

 receptaculum described above in Thysanotcenia lemuris. This 

 latter is most obviously a distinct and definitely specialised region 



* "Tapeworms of the subfamily AviteUina:," Quart. Jouru. Micr. Sci. vol. Ivi. 



