Here is some info I got from this page
http://www.aqua-fish.net/show.php?h=mysterysnails
Breeding:
Unlike most snails these are not hermaphroditic (asexual), you will need at least 1 male and 1 female for breeding success. The male has a penal tube similar to its breathing siphon tube that is used purely for this purpose. When they pair up the male will insert the tube under the females shell and enter her body. It is quite often that you will see the female carrying the male about on the back of her shell. Eggs are normally laid at night out of the water and in a clutch averaging anywhere from 200-600 eggs at a time.
In my breeding setup I used a 10 gallon tank, filling it up halfway.
For aeration, filtration a double sponge filter was added and a temp of 26°C was set. I placed the tank in a dimly lit place adding a watertight lid to prevent any escapees.
Eggs once laid would be expected to hatch out after 2 weeks sometimes 3 weeks but the young couldn’t be easier to
feed, basically they were given the same
diet as the adults.
As a matter of habit I doubled the water changes to reduce any risk of mortalities but these were normally very few, and to be honest, a newly hatched snail is not the easiest thing to find if it does not survive.