The snails you see on the pathways are land dwellers out moving around because
of all the free moisture after a rain that helps them move.
Aquatic snails come in two versions. One has to come up to the surface, take in
air and then go back down below the water's surface. The other type has a gill
of sorts and always stays underwater.
You can try a google.com search with the words
'native aquatic snails Ontario' and see what turns up.




kathy :-)
algae primer
http://hometown.aol.com/ka30p/myhomepage/garden.html