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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 beyond
the ventral edge of the shell. Commonly dredged in moderately shallow
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
North Carolina to both sides of Florida and the West Indies.
Plate 27!
% 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
North Carolina to east Florida and the West Indies.
Plate 27g
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
Southeast Florida and the West Indies.
Plate lyh
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.