Page:American Seashells (1954).djvu/430

348 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.