68 ILLINOIS BIOLOGICAL MONOGRAPHS [68 



parenchyma. The dorsal vessel passes dorsad and the ventral vessel 

 ventrad to the cirrus-pouch and vagina. In diameter the ventral vessel 

 greatly exceeds the dorsal and its lining membrane is thin while the 

 membrane lining the dorsal vessel is thick. A posterior excretory com- 

 missure in each proglottid could not be found. Numerous secondary 

 excretory openings which are connected with the ventral vessel and less 

 frequently with the dorsal vessel have been seen. The drawing (Fig. 



91) shows rather an extraordinary case in that the duct is larger and 

 more extensive in its connections than is usual. In the end-proglottid 

 the four main excretory ducts discharge to the exterior by a common 

 pore. A bladder could not be seen. 



The common genital sinus is marginal, situated at or near the mid- 

 dle of the proglottid. While the vagina lies anterior to the cirrus-pouch, 

 the opening of the vagina, without exception, is dorsal to the opening of 

 the cirrus (Figs. 88, 90). There is no genital papilla. The testes (Fig. 



92) are numerous, 54-70. These are in a single layer in the medullary 

 parenchyma, occupying nearly the entire field between the vitellaria 

 anterior to the ovary. The testes measure as much as 0.05 mm. long by 

 0.04-0.05 mm. broad. The vasa efferentia (Fig. 90) form a network of 

 fine anastomosing tubules just dorsal to the testes and within the medul- 

 lary parenchyma. The main branches of the vasa efferentia unite to 

 form the larger vas deferens. The junction occurs at a point near the 

 median line about one-fourth the distance from the anterior to the pos- 

 terior end of the segment. From this point of juncture the vas deferens 

 forms a mass of coils extending to the cirrus-pouch. These coils function 

 as a vesicula seminalis. When the vas deferens enters the cirrus-pouch 

 it receives some additional glandular elements, the prostate cells. This 

 part of the vas deferens is called the ductus ejaculatorius. The ductus 

 in this species is very nearly straight. The cirrus which is a continua- 

 tion of the ductus ejaculatorius has a heavier musculature than is pres- 

 ent in any other part of this canal. The cirrus lies in the pouch as an 

 almost straight organ. When protruded it measures 0.07-0.08 mm. long 

 by 0.02-0.025 mm. broad. The cirrus-pouch is elongated oval in outline. 

 It is short and stout, being 0.13-0.14 mm. long by 0.05-0.06 mm. broad. 

 The ratio of its length to the proglottid breadth is 1 :4 to 1 :3. 



The vaginal pore opens into the genital sinus just dorsal to the 

 cirrus-pouch tho the greater part of the initial part of the vagina itself 

 lies anterior to the pouch. A small sphincter vaginae is situated near 

 the opening. In its course to the mid-field the vagina crosses the inner 

 end of the cirrus-sheath. When passing posteriad to enter the inter- 

 ovarial space the vagina is straight, not sinuous or coiled. Just anterior 

 to the ovary the vagina dilates slightly to form a receptaculum seminis. 

 The relations of the vagina are shown in figures 88, 90, and 92. The 

 ovary is bi-lobed . The lobes (Fig. 92) are elongated oval and smooth in 



