154 



CONCH I FEE A. 



Pecten. 



9. Pecten Beaveri — Beaver's Pecten, pi. LXII. fig. 12. 

 P. Beaveri. Sowerby, II. p. 131, pi. 1.58. 



Orbicular, compressed ; general surface smooth, with irre- 

 gular longitudinal ribs, sometimes with one or two smaller 

 costa3 between the larger ones; ears nearly equal, and as wide 

 as the shell ; the substance of the shell thin. 



The Clialk, Norwich and Sussex, the Red Chalk, Hunstan- 

 ton, and the Under Greensand, Hants. 



10. Pecten corneus. — The Horny Pecten, pi. LXII. fig. 6. 

 P. cornea. Sowerby, III. p. 1, pi. 204. 



Orbicular, much compressed, smooth, and shining ; beaks 

 prominent, and well marke<l ; ears small, nearly equal ; two 

 obtuse teeth in each valve near the ears ; substance of the shell 

 thin and fragile. 



The London Clay, Stubbington. 



11. Pecten dentatcs. — The Toothed Pecten, pi. LXIV. 

 tig. 16. 



P. deniatus. Sowerby, VI. p. 143, pi. 574, fig. 1. 



Almost orbicular, convex ; ears small, unequal ; surface 

 with about twenty close, large, angular, obtuse, longitudinal 

 ribs, crossed by minute, concentric, regular strire ; margin 

 deeply toothed. 



The Inferior Oolite, Duudry. 



12. Pecten ueconditus. — The Recondite Pecten, pi. 

 LXIII. fig. 12. 



P. reconditus. Sowerby, VI. p. 14G, pi. 57a, figs. 5, G. 



Orbicular, oblique ; valves unequally convex ; ears unequal, 

 obliquely ribbed ; surface with about twenty rounded, longitu- 

 dinal ribs, the intermediate surface destitute of stride, and 

 covered with concentric lines of sharp scales ; ribs with three 

 rows of scales ; the interstices have only one ; internal surface 

 furrowed. 



The London Clay, Barton and Stubbington. 



13. Pecten ^quivalves. — The Equal-valved Pecten, pi. 

 LXV. fig. 6'. 



P. equivalns. Sowerby, II. p. 83, pi. 136, fig. 1. 



Lenticular ; valves equally convex, the lower one smoothest ; 

 ears equal, rather large ; surface with about twenty rounded 

 longitudinal ribs, crossed by numerous acute concentric strino, 

 which are more or less inconspicuous as they pass over the ribs, 

 and the intervening spaces rather concave. 



The Inferior Oolite, Ilminster and Cotswold, and the Lias, 

 Prees and Yorkshire. 



14. Pecten fibrosis. — The Fibrous Pecten, pi. LXIV. 

 fig. 21. 



P.fihrosus. Sowerby, II. p. 85, pi. 136, fig. 2. 



Orbicular, somewhat longer than broad, compressed ; ears 

 equal ; rectangular ; surface with nine or ten longitudinal, broad, 

 divergent furrows, and numerous deep concentric striae ; beak 

 rectangular ; margin internally and rather deeply undulated. 



The Middle Oolite, Yorkshire, Wiltshire, and Oxfordshire. 



15. Pecten gbanosus. — The Granulated Pecten, pi. LXV. 

 fig. 16. 



P. granosus. Sowerby, VI. p. 144, pi. 517, fig. 2. 



Nearly orbicular, somewhat wider than long ; oblique, a 

 little convex , ears unequal, undefined, extending nearly the 

 whole breadth of the shell ; surface with about thirty granu- 

 lated longitudinal ribs, with intervening smooth ones. 



The Carboniferous Limestone, BoUand, Kiidare, and Cork. 



16. Pecten plicatus. — The Plicated Pecten, pi. LXIII. 

 fig. 1. 



P. plicatus. Sowerby, VI. p. 144, pi. 574, fig. 3. 



Almost orbicular, somewhat oblique and convex ; ears un- 

 defined, extending the whole width of the shell; surface with 

 numerous irregular, smooth, elevated striae. 



The Carboniferous Limestone, Ardconnaught, Ireland, and 

 the Devonian Shales, Plymouth. 



17. Pecten duplicatus. — The Double-plaited Pecten, pi. 

 LXIV. figs. 4, 5. 



P. duplicatus. Sowerby, VI. p. 145, pi. 575, figs. 

 1, 2, 3. 



Orbicular, compressed ; ears small, defined ; surface with 

 one valve nearly smooth, the other very rough, and with 

 many distant, thin, rounded, longitudinal ribs, which become 

 more numerous towards the margin, numbering about ten 

 near the beak, and amounting to about forty at the basil mar- 

 gin ; also covered with minute sharp scales. 



The London Clay, Hamstead and Primrose Hill. 



18. Pecten carinatus. — The Keeled Pecten, pi. LXIV. 

 fig. 1. 



P. carinatus. Sowerby, VI. p. 145, pi. 575, fig. 4. 



Orbicular, somewhat elongated, convex ; ears rather large 

 and smooth, square and defined ; surface with about seven- 

 teen longitudinal, distant, rounded ribs, with a sharp keel 

 along the middle of each, and a broad, flat, smooth, interven- 

 ing space, with a sharp line along its middle. 



The London Clay, Barton. 



19. Pecten complanatus. — The Plain Pecten, pi. LXIII- 

 fig. 10. 



P. complanatus. Sowerby, VI. p. 164, pi. 586. 



Sub-orbicular ; its width exceeding its length ; one valve 

 nearly flat, concave near the beak ; ears square and equal ; 

 surface with thirteen or fourteen broad, elevated, flattened 

 ribs, with nearly perpendicular sides. 



The Coral Crag, Aldborongh. 



20. Pecten lamellosus. — The Plated Pecten, pi. LXII. 

 fig. 9. 



P. lamellosus. Sowerby, III. p. 67, pi. 239. 



Orbicular, both valves convex, the lower more so than the 

 other ; ears large, distant ; beaks rectangular ; surface with 

 concentric imbricated lamina", and divergent small striae near 

 the beaks, which are gradually lost towards the front. 



Portland Stone, Portland, Wiltshire, Oxfordshire, and 

 Buckinghamshire. 



21. Pecten oBscuRfs. — The Obscure Pecten, pi. LXII. 

 fig. 8. 



P. obscurus. Sowerby, III. p. 3, pi. 205, fig. 1. 



Nearly orbicular, a little longer than wide ; compressed ; 

 ears rather large ; nearly parallel above ; surface smooth, with 

 obsolete, longitudinal, divergent furrows ; edge thick. 



The Tipper Greensand, Hythe, Parham, and Isle of Wight ; 

 and the Great Oolite, Stonesfield. 



22. Pecten lens. — The Lens-shaped Pecten, pi. LXII. 

 fig. 11. 



P. lens. Sowerby, III. p. 3, pi. 205, figs. 2, 3. 



Orbicular, convex, and nearly lenticular, but deepest near 

 the beaks ; surface with divergent, arcuated, deeply punctured 

 striae ; substance of the shell thin. 



