BY T. HARVEY JOHNSTON. 73 



passes forwards, and then laterally towards the pore-bearing 

 edge. It very soon becomes thrown into an extensive system 

 of coils, occupying a very large part of the mature segment, 

 and lying in the antero-lateral corner of the medulla. Some 

 of the coils may be seen in the middle of the anterior part of 

 the proglottid. In a section of this portion, the vas is seen 

 to fill fully one-quarter of the medulla, and to extend from 

 the dorsal almost to the ventral transverse muscle-layer. At 

 about the mid dorsoventral level of tlie convoluted mass, the 

 vas passes laterally above the excretory vessel and nerve, to 

 terminate in the weak cirrus-sac. This portion of the vas 

 deferens lies in front of, and approximately parallel to, the 

 vagina. Contrary to the condition usually met with in 

 Cestoda, the testes persist, and may be distinctly recognised 

 in segments containing hexacanth embryos, thotigh they do 

 not appear to be any longer glandular. The vasa efferentia 

 and the vas deferens also remain, the latter being very con- 

 siderable in dimensions. In fact, the persisting male struc- 

 tures occupy about one-half of the medulla in ripe pro- 

 glottids. 



The cirrus-sac is a long, thin, cylindrical or fusiform 

 structure about 007 mm. in length, and 00 16 mm. in width. 

 Its mvisculature is poorly developed. The cirrus, when 

 everted, is seen to be about 0004 mm. long, and 0-006 mm. 

 wide; and to be densely covered with minute spines. 



Female Genitalia. — The female complex is not situated in 

 the middle of the segment, but lies rather nearer to the pore- 

 bearing edge. The ovary, which is about 0-16 mm. in 

 breadth, is approximately transverse in position, lying imme- 

 diately posteriorly to the coiled mass of the vas deferens, and 

 in front of the testes and vitellarium. It is a bilobed organ, 

 each lobe or wing consisting of comparatively few ovarian 

 tubes. The lobe which lies near the pore side is situated 

 more ventrally than the other. The bridge connecting the 

 lobes lies more ventrally than these, but anteriorly and 

 slightly dorsally to the shell-gland. A narrow oviduct passes 



