PLATE LXV. 
1. P. Stutchburiensis. {Stutchbury's Pecten.) Sub-triangular, elongated, compressed, with about sixty, close-set, 
scaly ribs; intercostal sulci, obliquely striated. 
2. P. QuadPicOStatllS. {Four-ribbed Pecten.) Triangular; posterior auricle large; front semi-circular; margin 
notched ; convex valve, with six, large ribs, and three smaller ones. 
3. P. QuinquecostatllS. ( Five-ribbed Pecten.) Sub-triangular, oblique; front semi-circular, toothed; convex valve 
gibbose; with five or six, principal ribs and four, lesser ones ; upper valve flat, toothed; surface, with minute, transverse 
striae, intersected by lines of growth. 
4. Avieula Papyracea. ( Papyraceous Avicula.) V. Plate LXI.**, Pig. 11. 
5. A. Hemisphserica. {Hemispherical Avicula.) Orbicular; lower valve circular, convex; ears undefined ; hinge-line 
straight, oblique ; surface, with squamose striae. 
6. P. AJquivalvis. {Fqual-valved Pectm.) Lenticular; valves convex; ears equal, large; surface, with about twenty, 
longitudinal ribs, crossed by many, concentric striae. 
7. P. Stellaris. {Little Star Pectm.) Sub-orbicular ; with about fifteen, strong, smooth, longitudinal, divergent ribs. 
8. A, Plicata. {Plicated Avicula.) Orbicular; oblique; valves compressed ; hinge-line triangular; ears large, un¬ 
equal, w r ith divergent, distinct striae, crossed by curved strife; one ear concave on the side; surface, with many, radiating 
striae, classed by indistinct ones ; margins even. 
9. P. AbjectUS. {Abject Pecten.) Orbicular; hinge-line oblique, ears small; surface, with many, longitudinal, 
narrow ribs, crossed by indistinct, concentric striae; margin crenulated. 
10. 11. P. ArenoSUS. {Sandy Pecten.) Equal-sided; ears small, unequal, square; surface, with many, radiating 
striae, alternately large and small, crossed by many, crenulated striae. 
12. Avicula Similis. {Similar Avicula.) Orbicular ; ears large, with transverse and longitudinal, oblique striae; 
hinge-line triangular; surface smooth, with divergent striae; one side, with ear and margin straight. 
13. A. Oweni. {Owen's Avicula.) Orbicular, compressed, with large, unequal ears ; surface, with many, divergent 
strife, and a few, distinct lines of growth; sides plain. 
14. P. SublEevis. {Half-smooth Pecten.) Convex, orbicular; ears unequal, blunt; surface, with about nineteen, 
smooth, longitudinal ribs; margins crenulated. 
15. P. DemisSUS. {Humble Pecten.) Elongated; sides finely rounded ; ears equal, small. 
16. P. GrailOSUS. (Gh'anulated Pecten.) Orbicular, oblique, convex; ears unequal, undefined; surface, with about 
thirty, granulated, longitudinal ribs, with intervening smooth ones. 
17. P. DiSCPepailS. (Discrepant Pecten.) Sub-orbicular ; ears equal, with obliquely longitudinal ribs ; surface, with 
about twelve, large, longitudinal, sub-imbricated ribs; margins scalloped. 
18. P. ViPg’UilifePUS. ( Whitish Pecten.) Oblong, flatfish; ears unequal; surface, with many, longitudinal striae, 
covered with short, imbricated scales. 
19. P. Ellipticus. (j Elliptical Pecten.) Elliptical, compressed, smooth; ears unequal, short; sides not much rounded. 
20. 21. P. Dissimilis. {Dissimilar Pecten.) Sub-orbicular, elongated; lower valve, with many, longitudinal, scaly 
ribs; ears equal, ribbed; with transverse and longitudinal strife; upper valve concave, with flat, concentric ribs. 
22. P. FimbriatllS. {Fringed Pecten.) Ovate, compressed; ears small, plain; surface, with many, radiating ribs 
and sulci; margin crenulated. 
23. P. Asper. {Bough Pecten.) Orbicular, oblique ; valves convex ; ears equal; surface, with about seventeen ribs, 
roughened by a series of sub-tubular scales ; margin crenated; inside plain, with fringed margin. 
24. P. Anisotus. Oblong-oval, oblique; ears unequal, longitudinally and transversely striated ; surface, with obscure, 
divergent strife and distant lines of growth. 
25. P. DeornatllS. {Unadorned Pecten.) Orbicular, smooth; ears small, equal; surface, with equidistant, smooth, 
concentric sulci. 
26. 27. P. Simplex. {Simple Pecten.) Oblong-ovate, oblique; lower valve tumid, with strong, radiating, arched ribs ; 
upper valve flatter, with corresponding, but flatter sulci; ears of medium size; hinge-line oblique. 
28. P. Interstitialis. {Interstriate Pecten.) Oblong, oblique; ears of medium size, acute; surface, with about 
sixteen, longitudinal, sharp ribs ; intervening sulci, with three finer ribs. 
( 80 ) 
