Early Pliocene to Middle Pleistocene; Extinct.
Southern Florida to Virginia.
Original Description (from Conrad, 1833, p. 341):
"Shell suborbicular, compressed, thin, a little oblique; ribs about twenty two, rounded, little elevated and smooth; inferior valve nearly flat. Length, two inches."
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- Middle Pleistocene
- Bermont Formation (S. FL)
- Early Pleistocene
- Bear Bluff Formation (SC)
- Caloosahatchee Formation (S. FL)
- Chowan River Formation (VA)
- James City Formation (NC)
- Nashua Formation (N. FL)
- Waccamaw Formation (SC, NC)
- Late Pliocene
- Croatan Formation (NC)
- Duplin Formation (NC)
- Duplin / Raysor formations (GA)
- Jackson Bluff Formation (N. FL)
- Raysor Formation (GA, SC)
- Tamiami Formation (S. FL)
- Tamiami Formation (Buckingham Limestone) (S. FL)
- Tamiami Formation (Lower) (S. FL)
- Tamiami Formation (Ochopee Limestone) (S. FL)
- Tamiami Formation (Pinecrest Beds) (S. FL)
- Yorktown Formation (NC, VA)
- Yorktown Formation (Mogarts Beach Clay) (VA)
- Early Pliocene
- Goose Creek Limestone (GA, SC)