I found this empty shell at Ricketts Glen State Park near the same fallen log that I found the Anguispira alternata. It measures 18.1mm in width. The books list this as 19mm to 25mm but I figure that's close enough. One interesting thing is that I can see what looks like a pupa/chrysalis inside the shell.
|Range map from Land Snails of Limestone Communities and Update of Land Snail Distributions in Pennsylvania (Pearce) with my own county added to range (in orange). Formerly unknown to Luzerne County.|