This is one of the species in the widespread and speciose family Enidae. It is a snail of limestone rocks on the mountains of western Turkey.
I have never seen the snail itself. But I did photograph dormant individuals stuck on rocks in the summer of 2006.
Empty shells of Zebrina cosensis seem to quickly fade into a whitish color. The shell of the live snail in the above photo had a blue tint, while the specimen in the 1st photo, which was collected empty, has retained brownish patches.
The previous entry in this series was Helix lucorum.