396 
Tetrm'hynchus erinaceus 
the copulatory passage, or vagina, runs backwards Avith few convolutions 
and ends in a dilatation—the receptaculum seminis. The oviduct takes 
origin from the posterior margin of the ovary and is almost immediately 
joined by a very naiTOw duct from the receptaculum seminis—the 
canalis seminis. The oviduct now turns forward and is joined by the 
vitelline duct and it also I’eceives the efferent stalks of the cells of the 
shell gland. The compound duct so formed, which may be called the 
uterine canal, runs forward being thrown into numerous convolutions 
and opens into a thick walled sac which lies along the ventral side of 
the segment. This is the uterus. It does not open to the exterior. 
Testes 
Longitudinal 
derm a / muscles 
Vitelline 
Region of 
S ubcuticufar 
'cells 
Longitudi n a! 
^muscles 
u re rui 
retory 
Cana! 
Fig. 8. Transverse section through an immature proglottis in much the same stage of 
maturity as that represented in PI. XXI, fig. 10. The shading of the various organs 
is quite diagrammatic but their j^ositions and proportions are fairly accurate. Mag. 
70 dia. 
The male genital tract begins as the cirrus—an evaginable tube 
surrounded by a muscular apparatus—the cirrus sac. Leaving the 
cirrus sac the male duct expands to form the vesicula seminalis and is 
then continued as a wide duct—the vas deferens, which runs forward in 
close coils, and then branches to form the vasa efferentia each of which 
finally ends in a testicular follicle. 
