Shell of the Week: The Thick Lucine
At up to 60 mm (about 2.4 inch), Phacoides pectinatus (Gmelin, 1791) is one of the largest local members of the family Lucinidae. Its shell outline is circular, with a squarish, truncated posterior end (on left of the photos.) The shell surface is chalky, and the external sculpture consists of coarse, irregular ridges. The thin, brownish periostracum (external, brownish layer) is present in well-preserved shells. The color is white, and sometimes the internal surface of the shell is suffused with a delicate peach-orange tint. Not commonly found, but the Museum collection has samples from the bay area of Sanibel and Captiva.