The heavy shell of the southern quahog, Mercenaria campechiensis, is ovate trigonal and inflated with valves of equal size (Andrews 1994). Several concentric growth lines are present on the gray to whitish exterior. Three cardinal teeth (the middle one split) on each valve help to hold the shell together at the hinge. In empty shells, the interior color is often porcelaneous white with purple marks occurring rarely. Two muscle scars are present on the interior surface, both attached to the pallial line.
- Abbott, RT & PA Morris. 1995. Shells of the Atlantic and Gulf Coasts and the West Indies, 4th Edition. Houghton Mifflin. New York, NY. USA. 350 pp.
- Andrews, J. 1994. A Field Guide to Shells of the Florida Coast. Gulf Publishing. Houston, TX. USA. 182 pp.
- Arnold, WS, Bert, TM, Marelli, DC, Cruz-Lopez, H & PA Gill. 1996. Genotype-specific growth of hard clams (genus Mercenaria) in a hybrid zone: variation among habitats. Mar. Biol. 125: 129-139.
- Busby, D. 1986. An overview of the Indian River Clamming Industry and the Indian River Lagoon. Florida Sea Grant Extension Program. Technical Paper No. 44. Project IR-85-7. 45 pp.
- Dillon, Jr., RT. 1992. Minimal hybridization between populations of the hard clams, Mercenaria mercenaria and Mercenaria campechiensis, co-occurring in South Carolina. Bull. Mar. Sci. 50: 411-416.
- Stewart, VN. 1981. Sea-stats: a summary of information and statistics on Florida's marine organisms and the marine environment. No. 7: Clams. Florida Department of Natural Resources. 11 pp.
- Surge, D & KJ Walker. 2006. Geochemical variation in microstructural shell layers of the southern quahog (Mercenaria campechiensis): implications for reconstructing seasonality. Palaeoecol. 237: 182-190.
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