Alethopteris are quite common at Saint Clair location. But apparently there are at least 6 different species.
These are all from "Fossil Plants from the Anthracite Coal Fields of Eastern Pennsylvania."
A zip file that contains the PDF can be downloaded from http://www.dcnr.state.pa.us.
Here's a direct link.http://www.dcnr.stat...dcnr_016425.zip