668 DAVID HILT TENNENT. 
the oviduct bends in nearly a right angle and receives the 
median vitelline duct, which has been formed by the union 
of the two lateral vitelline ducts. 
Immediately beyond the junction of the oviduct with the 
vitelline duct, the oviduct passes into a second enlargement 
which is surrounded by the shell-glands; from thence it 
emerges as the uterus, which passes through an irregular 
course to open into the genital atrium. 
The course of the uterus may be traced only in sexually 
immature animals. As previously noted, when filled with 
developing eggs, it is greatly distended, and appears as a 
large sac almost filling the body. In the living worm the 
shell-glands appear as an aggregation of rounded cells, which 
is closely applied to the oviduct. In sections, they are elon- 
gated in outline, with a deeply staining nucleus and with 
coarsely granular contents. 
The vitellaria, as a rule, thirty-two in number, sixteen on 
each side, are situated in the anterior dorsal part of the body, 
immediately behind the sucking disc. On each side of the 
body they are united by fine ducts, which may be seen in the 
living worm, with the main vitelline duct of that side. The 
two vitelline ducts pass backward, uniting into a single duct 
before passing into the oviduct (fig. 47, vit.). 
Each vitellarium consists of a rounded accumulation of 
cells, in which the nucleus is very distinct (fig. 44). Packed 
closely within the cell and surrounding its nucleus are the 
yolk granules. Before these globules pass down the vitelline 
ducts, the cellular structure breaks down, the yolk granules 
passing outward into the ducts while the nuclei remain 
behind. In sections passing through the yolk-laden ducts I 
have never found nuclei, while sections through the vitellaria, 
after the yolk has passed out, show many nuclei. 
THe Mate RepropuctivE ORGANS. 
The testes, lying one slightly behind the other, are situated 
posterior to the ovary (figs. 46, 47, 52). From each testis 
