1. Ipswich River, Middlesex Co., MA - 78 mm
2. Chartley Pond, Bristol Co., MA - 56 mm
3. Tar River, Pitt Co., NC - 96 mm
4. Ottawa River, Pontiac Co., Quebec - 92 mm
5. Scantic River, Hartford Co., CT - 90 mm
6. Dead River, Somerset Co., ME - 70 mm
Elliptio complanata (Lightfoot, 1786)
1. Ipswich River, Middlesex Co., MA - 78 mm
2. Chartley Pond, Bristol Co., MA - 56 mm
3. Tar River, Pitt Co., NC - 96 mm
4. Ottawa River, Pontiac Co., Quebec - 92 mm
5. Scantic River, Hartford Co., CT - 90 mm
6. Dead River, Somerset Co., ME - 70 mm
Type locality: Potomac River, Washington D.C.
Range: James Bay drainage, northern Great Lakes, St Lawrence to Altamaha River systems; Ochlockonee, Apalachicola, Econfina River systems.
Remarks: This is a very variable species, but not as variable as some people have tried to make it. The periostracum varies from smooth to velvety. Most specimens are not distinctly rayed, particularly as an adult. Most are quite compressed, but occasional populations are inflated. The nacre varies from purple to white. It is thinner shelled than most members of the Complanata Group.
Compare with congaraea, which is heavier, yellower, more distinctly rayed, and has a thicker hinge. Insulsa and conferta are much more inflated and box-like. Roanokensis is more elongate, particularly as juveniles.
This species may be abundant at some sites on the eastern seaboard, but is rather rare in the Gulf drainages.