154 
CONCHIFERA. 
Pecten. 
9. Pecten Beaveri.—B eaver’s Pecten, pi. LXII. fig. 12. 
P. Beaveri. Sowerby, II. p. 131, pi. 158. 
Orbicular, compressed ; general surface smooth, with irre¬ 
gular longitudinal ribs, sometimes with one or two smaller 
costae between the larger ones; ears marly equal, and as wide 
as the shell ; the substance of the shell thin. 
The Chalk, Norwich and Sussex, the Bed Chalk, Hunstan¬ 
ton, and the Under Greensand, Hants. 
10. Pecten corneus.—T he Horny Pecten, pi. LXII. fig. 6. 
P . cornea . Sowerby, III. p. 1, pi. 204. 
Orbicular, much compressed, smooth, and shining; beaks 
prominent, and well marked ; 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 dentatus.—T he Toothed Pecten, pi. LXIY. 
fig. 16. 
P. dentatus . Sowerby, YI. 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 stria); margin 
deeply toothed. 
The Inferior Oolite, Dundry. 
12. Pecten reconditus.—T he Recondite Pecten, pi. 
LXIII. fig. 12. 
P. reconditus . Sowerby, YI. p. 146, pi. 575, figs. 5, 6. 
Orbicular, oblique ; valves unequally convex ; ears unequal, 
obliquely ribbed ; surface with about twenty rounded, longitu¬ 
dinal ribs, the intermediate surface destitute of strife, 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 asquivalves.—T he Equal-valved Pecten, pi. 
LXY. fig. 6. 
P. equicalris . 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 stria), 
which are more or less inconspicuous as they pass over the ribs, 
and the intervening spaces rather concave. 
The Inferior Oolite, Uminster and Cotswold, and the Lias, 
Prees and Yorkshire. 
14. Pecten fibroses.—T he Fibrous Pecten, pi. LXIY. 
fig. 21. 
P . fibrosus. 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 strife ; beak 
rectangular ; margin internally and rather deeply undulated. 
The Middle Oolite, Yorkshire, Wiltshire, and Oxfordshire. 
15. Pecten graxosus.—T he Granulated Pecten, pi. LXY. 
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, Bolland, Kildare, and Cork. 
16. Pecten plicatus. —The Plicated Pecten, pi. LXIII. 
fig. 1. 
P. plicatus. Sowerby, YI. p. 144, pi. 574, fig. 3. 
Almost orbicular, somewhat oblique and convex ; ears un¬ 
defined, extending the wholo width of the shell; surface with 
numerous irregular, smooth, elevated strife. 
The Carboniferous Limestone, Ardconnaught, Ireland, and 
the Devonian Shales, Plymouth. 
17. Pecten duplicates. —The Double-plaited Pecten, pi. 
LXIY. figs. 4, 5. 
P. duplicatus. Sowerby, YI. 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, ITamstead and Primroso Hill. 
18. Pecten carinatcs. —The Keeled Pecten, pi. LXIY. 
fig. I. 
P. cannatus. Sowerby, YI. 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- ,f >- 
P. complanatus. Sowerby, VI. p. 1G4, pi. 586. 
Sub-orbicular ; its width exceeding its length ; one valve 
nearly fiat, concave near the beak ; ears square and equal; 
surface with thirteen or fourteen broad, elevated, flattened 
ribs, with nearly perpendicular sides. 
The Coral Crag, Aldborough. 
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 stria) near 
the beaks, which are gradually lost towards the front. 
Portland Stone, Portland, Wiltshire, Oxfordshire, and 
Buckinghamshire. 
21. Pecten obscures. —The Obscure Pecten, pi. LXII. 
fig. 8. 
P. obscurits. Sowerby, III. p. 3, pi. 205, fig. I. 
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, Stoncsfield. % 
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 
strife ; substanco of the shell thin. 
