348 American Seashells 



are finely cut on the upper edge by short radial grooves. Inner margin of 

 valves smooth. Shell dull-white. Periostracum thick, tufted, extending be- 

 yond the ventral edge of the shell. Commonly dredged in moderately shal- 

 low water. 



Fa7mly GLYCYMERIDAE 



Genus Glycymeris DaCosta 1778 



Shell heavy, usually orbicular, equivalve, porcellaneous, usually with a 

 soft, velvety periostracum. Beaks slightly curved inward. Hinge heavy, with 

 numerous, small, similar teeth. Ligament external, its area distinct and with 

 diverging grooves. The largest muscle scar is at the anterior end. Often mis- 

 spelled Gly cimerts or GHcymeris. 



Glycymeris pectinata Gmelin Comb Bittersweet 



Plate 27! 



North Carolina to both sides of Florida and the West Indies. 



% to I inch in size; characterized by 20 to 40 raised, radial ribs which 

 have no fine radial striae or scratches on them. Color grayish and commonly 

 splotched with brown. A common shallow-water species. 



Glycyjneris undata Linne Atlantic Bittersweet 



Plate 27g 



North Carolina to east Florida and the West Indies. 



2 inches in length, heavy, smoothish, except for microscopic radial 

 scratches and somewhat larger concentric scratches, giving a silky appear- 

 ance. There are numerous very weak and hardly discernible radial ribs sepa- 

 rated by lines of white. Beaks at about the middle of the ligamental area. 

 Color cream to white wdth bold splotches of nut-brown. Interior all white 

 or well-stained with brown. This is G. Hneata Reeve. 



In the region of the Carolinas, an inch-long species (spectralis Nicol 

 1952) is found which is more oval, its beaks face slightly toward the rear 

 and the color is almost a uniform light-brown. Both common. 



Glycyiiwris deciissata Linne Decussate Bittersweet 



Plate lyh 



Southeast Florida and the West Indies. 



2 inches in size, very similar to undata, but differs in the posteriorly 

 pointing beaks, and in having nearly all of the ligamental area in front of 

 the beaks. The radial scratches are stronger. This is G. pen?iacea Lamarck- 

 Moderately common. 



