PLATE LXIII. 
1. Pecten Plicatus. ( Plicated Pecten.) Orbicular, oblique, convex; ears undefined; surface, 
with many, smooth, elevated stride. 
2. P. Grandis. (Great Pecten.) Sub-orbicular; convex valve, with thirteen, large, divergent 
ribs, most of which with central sulcus, containing a secondary rib; ears square, equal, longitudinally 
striated; surface of convex valve, with irregular, concentric striae; on other valve regular, close-set 
striae. 
3. P. Inaequicostatus. (Unequal-ribbed Pecten.) Orbicular, smooth; with nine, flat, unequal 
ribs; ears moderate, equal. 
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4. 5, 6, 7. P. Obsoletus. (Obsolete Pecten.) Obovate; ears unequal; surface, with many, 
divergent ribs; sometimes plain, with minute, nearly obsolete, longitudinal striae. 
8. P. Vimineus. ( Wicker Pecten.) Convex; with about twenty, prominent ribs, with close-set, 
elevated scales. 
9. P. Annulatus. (Binged Pecten.) Orbicular, convex; surface, with many, thin, concentric 
laminae, crossed by fine, longitudinal striae; ears large. 
10. P. Complanatus. (Plain Pecten.) Sub-orbicular; one valve nearly flat, concave near 
beak; ears square, equal; surface, with thirteen or fourteen, broad, flattened ribs. 
11. P. Gracilis. (Slender Pecten.) Orbicular, convex; thin, slender; with many, longitudinal 
ridges, crossed by many, close, uniform, concentric striae; ears unequal; margin entire. 
12. P. ReconditllS. (Recondite Pecten.) Orbicular, oblique; valves convex; ears unequal, 
obliquely ribbed; surface, with about twenty, longitudinal ribs; intermediate surface, with concentric 
lines of sharp scales; ribs, with three rows of scales; internal surface furrowed. 
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