This time I'm I 'think' I've found a native. I spotted it while photographing fungi at Fern Glade by the Emu River. My amateur efforts at keying it out put it in the family Charopidae. These snails are said to feed on decaying vegetable matter and fungi. There are at least 24 Tasmanian members in this family most of which are quite small (2 - 5 mm). Based only on the relatively large size of this snail (7-8mm) and it's location, it may well be Thryasona diemenensis. This is a fairy widespread snail in Tasmania and is known to exist at the site where I found this one.
EDIT: Dr. Kevin Bonham has kindly provided a correct ID for this snail. I was way of the mark although I at least put it in the right family :-) The snail is Stenacapha ducani. It can grow to around 15mm in this area and in the far north-west reaches over 20mm.
(Click to enlarge)