Once you get to East-Central NY the Devonian rocks are less limy and more argillaceous and seem to preserve pelecypods better. Thus you get lucky and sometimes find both valves of a pelecypod laid out next to each other such as in this specimen. It's a Pseudoaviculopecten princeps and, while missing a bit of the left valve, is a nice specimen. Pseudoaviculopecten princeps can be identified by the rounded shape of the shell, whose width is greater than it's length, long hinge line with an extended ear off the posterior side as well as the crosshatching created by the raised radial ribs and concentric growth lines.
This specimen cam from the Moscow formation (Devonian, Givetian stage) and was found in a quarry off Deep Springs Rd. in Madison County, NY.