Southwest Florida Shells with Emphasis on Sanibel & Captiva
José H. Leal
Shell size to 50 mm; Shell circular, with marked, irregularly distributed commarginal (“concentric”) growth lines, and strong posterior groove. Shell whitish, sometimes with hints of light brown imparted by delicate periostracum. Periostracum consisting of fine extensions each ending in a calcified (hard) “scale”. Well-preserved periostraca are, however, difficult to observe, as beach-collected valves are usually eroded. The main illustration shows a complete shell found by Ken Piech in June 2019 at Kice Island, in Collier County. The next illustration shows a worn valve found on Sanibel (where the species is unusually rare) by Susan Hewitt, in December 2014. The additional illustration, of a shell from the Bahamas, collected by Colin Redfern, serves to show the unusual periostracum, characteristic of the species.