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Rh Glycymeris americana DeFrance Giant American Bittersweet North Carolina to north Florida to Texas. Up to 5 inches in length, rather compressed, always much flatter than imdata. The dorsal or hinge side of large specimens is quite long. Beaks point toward each other and are located at the midpoint of the hinge. Color drab-gray or tan, rarely with weak mottlings. Rare. Glycymeris subobsoleta Carpenter Aleutian Islands to Lower California. West Coast Bittersweet Plate 3ie I inch in size, subtrigonal, texture chalky. Periostracum velvety, but usually worn away. Ligament area short. Radial ribs flat, with narrow inter- spaces; usually white, but may be with light- to medium-brown markings. A rather common shallow- to rather deep-water species.

Figure 74. Hinges of some genera of mussels. Suborder ANISOMYARIA Superfamily MYTILACEA Family MYTILIDAE Genus Crenella Brown 1827 Shells small, oval to oblong-oval, thin, brownish periostracum and with fine decussate radial ribs. Ligament weak, internal. Margins crenulated. In-