It's either one of the physid species or one of the limnaeid species. The difference is their shells curl in different directions but I can't tell from the photos.
You can see the snail better than me, and there are diagrams in here to help you work out which one
Basic Terminology for Identification Anatomy: Foot: the bottom, muscular portion of the animal used for locomotion. Siphon: a proboscis-like appendage appearing on the side of the shell in some species. Mantle: the soft tissue inside the opening of the shell. Spire: the conical part of a...
www.fishforums.net
There are also profiles of the two types of snail in the link.