REPRODUCTIVE SYSTEM. 391 
it reaches this, however, the oviduct is associated with two 
structures. The first of these is a long process, as long as 
the common duct beside which it runs, in appearance 
suggesting the flagellum, but expanding at its free end into 
a globular sac—the veceptaculum seminis or spermatheca. 
In Helix aspersa a long slender diverticulum is given off 
from the duct of the receptaculum. This is also occasionally 
seen in Helix pomatia. A spermatophore from another 
Fic. 211.—Snail (He/zx pomatza) laying its eggs. — 
After Meisenheimer. 
snail passes into the receptaculum, and is there dissolved 
after some days, liberating hundreds of spermatozoa. By 
these spermatozoa the ova of the snail are fertilised. It 
seems likely that the place of fertilisation is in a small 
diverticulum at the upper end of the oviducal side of the 
common duct, whither the spermatozoa are said to find 
: their way. The second structure associated with the female 
duct is a conspicuous mucus gland, formed of two sets of 
finger-like processes. The secretion is very abundant 
during copulation, and as it contains not a little lime, it is 
possible that it may form the calcareous shells of the eggs. 
