The male ducts often have glandular walls, secreting capsules or spermatophores within which the spermatozoa are packed for transference to the female.
Fertilization is effected by the male transferring spermatophores into the genital orifice of the female by means of his proboscis.
In some species the male deposits small oval spermatophores indiscriminately on any part of the body of the female.
In Polytoreutus, also, spermatophores have been found in these spermathecal sacs.
In this duct and sac the spermatophores received in copulation from another snail are lodged.