30 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vou 55. 



about these free fields, but they leave a fairly wide, distinct, clear 

 field about the ovaries and vitellaria and do not extend posterior of 

 these. The vas deferens is without a vesicula seminalis and arises at 

 a little distance from the median stem of the uterus on the pore side 

 of the segment. The vas deferens is narrow and is looped in com- 

 paratively open loops. It is quite commonlj^ pigmented. The cirrus 

 pouch is cylindrical, 450 \l long and 130 [i wide. 



Female genitalia. — The ovaries are approximately circular in 

 dorso-ventral view, except for a flattening on the sides nearest one 

 another, by virtue of which they bound an interovarian space of 

 rectilinear outline. The ovary on the aporal side of the segment is 

 distinctly larger than that on the pore side. The vitellarium has a 

 very distinct and regular reticular structure. It is narrow and pro- 



FiG. 35.— Taenia hydatigena. Mature segment. Enlarged. After Deffke, 1891. 



longed along the transverse axis of the worm and does not extend be- 

 yond the ovaries laterally or into the interovarian field anteriorly. 

 The shell-gland is distinctly in the interovarian field and is not in 

 apparent contact with the vitellarium. The vagina curves posteriorly 

 from the genital cloaca and then anteriorly to the level of the ex- 

 cretory canals, forming a sort of crescent, which is widely dilated. 

 From the excretory canals it extends straight in toward the median 

 portion of the segment, paralleling practically the entire extent of 

 the vas deferens, and then curving around the nearest ovary to the 

 receptaculum seminis in the interovarian field. The vagina is not in- 

 frequently pigmented. In gravid segments (fig. 36) the uterine stem 

 bears on each side few, 5 to 10, thick lateral branches, which in turn 

 send out few thick secondary branches which remain fairly distinct 



