107 
I then becomes abruptly narrower, losing- an outer layer of cells and its 
i lining- of thick cuticuia; at the point of constriction the vagina is sur- 
: rounded by a spherical bulb consisting of short thick muscle fibers, 
I longitudinally directed with ]-espect to the vagina (figs. 122, 123). 
I Beyond the muscle bulb the vagina is prolonged as a thin walled tube, 
land sooner or later widens out into an elongated seminal recej)tade^ 
about 85yw in diameter. The receptacle sem., figs. 115, 117) 
extends mediad on the anterior side of tfie two dextral testes, and on 
the posterior side of the sinistral testis, and continues past the median 
line into the sinistral third of the proglottis to empty into the oviduct. 
The ovary {ov.^ figs. 115, 117) consists of two lobes connected by a 
slender isthmus. The oviduct takes its origin from the middle of the 
isthmus (fig. 121); about midway between its origin and the point at 
which it is surrounded by the shell gland, it is joined by the seminal 
rec.sem. 
Fig. 122. — Portion of the vagina of H. lanceolafa. Longitudinal section. Enlarged. (After WolfThiigel, 
1900b, p. 53, tig. 4.) 
Fig. 123. — Transverse section of vagina of H. lanceolata through muscle bulb. Enlarged. (After 
WolfThiigel, 1900b, p. 53, fig. 5.) 
Fig. 124. — Diagramatic representation of the female canals of H. lanceolata: ov., ovary; ore?., oviduct: 
rec. sem., receptaculum seminis; s.g., shell gland; ut., uterus; y.g., yoke gland. Enlarged. (After 
WolfThiigel, 1900b, p. 54, fig. 6.) 
Fig. 125.— Egg of H. lanceolata. Enlarged. (After Railliet, 1886, p. 267, fig. 163B; also Railliet. 1893, 
p. 300, fig. 195B.) 
receptacle. The yolk gland {y. g., figs. 117, 124) is ventrally situated 
with respect to the ovaiy and has a diameter equal to about one-third 
the length of the proglottis. The yolk duct (fig. 121) joins the oviduct 
in the shell gland (^. r/., fig. 121), a rounded body about 100 y in diam- 
eter located dorsal of the isthmus of the ovary. From the shell gland 
the oviduct continues forward and ventrad to the vterus {at., figs. 
117, 121). The latter at first is a thin canal, ventrally situated near 
the anterior boundary of the proglottis, extending transversely beyond 
the excretory canals on either side. In gravid segments the uterus 
becomes a large sac with outpocketings which push between the longi- 
tudinal muscle bundles and out against the cuticuia, thus filling most 
of the segment. 
Eggs . — The egg (fig. 125) is spherical or oval and possesses an outer 
and an inner membrane. The latter closely invests the embryo and is 
