Pecten. 
CONCIIIFERA. 
155 
Tlio KimmeridgeClay, Brick Ilill, Bedfordshire; the Middle 
Oolite, Yorkshire and Brora; the Inferior Oolite, Glaizedale 
and the Blue Wick. 
23. Pecten laminatus. —The Laminated Pecten, pi. LXII. 
fig. 14. 
P. laminata. Sowerby, III. p. 4, pi. 205, fig. 4. 
Sub-orficular, compressed; oars unequal, triangular, the 
largor plaited ; surface with arcuated, slightly undulating 
strke. 
The Cornbrash, Chatloy Lodge, Somersetshire. 
24. Pecten arcuatus. —The Arcuated Pecten, pi. LXII. 
fig. 15. 
P. arcuata. Sowerby, III. p. 4, pi. 205, figs. 5 and 7. 
Orbicular, compressed ; oars large, dissimilar, the larger 
quadrangular and punctated; side of the shell below arcuated; 
surface with arched, punctated, divergent stria?, and sometimes 
with forked furrows. 
The Kimmeridge Clay, Aylesbury, and the Coral Crag, 
Caine. 
25. Pecten obsoletus. —The Obsolcto Pecten, pi. LX III. 
figs. 4, 5, G, & 7. 
P. obsoletus. Sowerby, VI. p. 79, pi. 541. 
Obovate; ears very unequal ; surface with many divergent 
ribs, varying considerably in number and development; in 
some there are five or six broad obtuse ribs, with the interven¬ 
ing furrows longitudinally striated ; others have furrows with 
the flat parts striated ; while some are plain, with very minute, 
nearly obsolete, longitudinal stria); in some specimens the 
lower margin is considerably inflected. 
The Mammiferous Crag, Bramerton, and Red Crag, Sutton. 
20. Pecten annulatus. —The Ringed Pecten, pi. LXIII. 
fig. 9. 
P. annul at us. Sowerby, VI. p. 80, pi. 542, fig. 1. 
Orbicular, convex; surface with numerous thin, erect, con¬ 
centric lamina), about a line apart, crossed by many flue, close- 
set, longitudinal strke, also passing over the cars, which are 
rather large. 
This species has a considerable resemblance to P. cinctus , but is 
much less inflated. 
The Oxford Oolite, Osmington, Dorsetshire, and the Corn- 
brash, Felmersham Bedfordshire. 
27. Pecten gracilis. —The Slender Pecten, pi. LXIII. 
fig. 11. 
P. gracilis . Sowerby, IV. p. 129, pi. 393, fig. 2. 
Orbicular, a little longer than wide, convex ; very thin and 
slender ; with numerous small longitudinal ridges, every fourth 
one being a little more elevated than the others, and these in¬ 
ternally produce grooves which are more conspicuous than the 
rest; these are crossed by numerous close, elevated, sharp, 
uniform, concentric stria?, which are strongest near the mar¬ 
gins ; ears unequal, and the margin entire. 
The Red Crag, Sutton. 
28. Pecten vimineus. —The Wickor Pecten, pi. LXIII. 
fig. 8. 
P. rimineus. Sowerby, VI. p. 81, pi. 543, figs. 1 & 2. 
Convex, somewhat longer than wide; with about twenty 
prominent longitudinal ribs, some of which are obscurely tri¬ 
partite towards the edge, all of them provided with close-set, 
thick, elevated scales, which aro less numerous on the loft 
valve. 
Some specimens are furnished with small intervening ribs. 
The Oxford Clay, Up ware, Cambridgeshire, and in the 
Coral Crag> Malton and Brora. 
29. Pecten injsquicostatus. —The Unequal-ribbed Pecten, 
pi. LXIII. fig. 3. 
P. inwquicostatus. Phillips, Geo. York, I. p. 101, pi. 4, 
fig. 10. 
Nearly orbicular, smooth, with nine broad, flat, divergent, 
unequal ribs, the four central ones considerably larger than 
the others; ears moderate, and nearly equal. 
The Coralline Oolite, Malton. 
30. Pecten nitidi s. —The Shining Pecten, pi. LXIV. 
fig. 2. 
P. nitidus. Man tell, Goo. Sus. pi. 26, figs. 4, 9. Sowerby, 
IY. p. 130, pi. 394, fig. 1. 
Obovate, shining, one valve convex, with numerous crenula- 
ted ridges; the other nearly flat, with as many almost smooth 
ridges, with tho interstices minutely striated transversely; 
ears nearly equal, and the margins entire. 
Tho Under Chalk, Lewis and Gravesend. 
31. Pecten jacob.eus. — The Jacobean Pecten, pi. 
LXIV. fig. 3. 
P . jacobceus. Sowerby, VI. p. 164. Brown, Recent 
Conch. Brit. p. 71, ph 25, fig. 5. 
Upper valve flat, depressed towards the beak, with about 
sixteen longitudinally grooved, decussated, quadrangular, ele¬ 
vated ribs ; lower valve with sixteen rounded, grooved ribs, 
and the interstices transversely striated; ears equal, rect¬ 
angular, with decussated stria*. 
The Coral Crag, Aldborough. 
32. Pecten maxim us. —The Great Pecten, pi. LXIV. 
fig. 17. 
P. maximus . Sowerby, VI. p. 164. Brown, Recent 
Conch. Brit. p. 71, pi. 25, fig 1. 
Upper valve flat, depressed towards the beak, with from 
fourteen to seveuteon rounded longitudinally striated, or groov ¬ 
ed ribs; lower valve very convex, and longitudinally striated ; 
the interstices between the ribs of both valves striated ; ears 
rectangular, with decussated stria?. 
Tho Coral Crag, Aldborough, and Pleistocene Marine For¬ 
mation, Ayrshire. 
33. Pecten similis. —The Similar Pecten, pi. LXIV. 
fig. 11. 
P. similis. Sowerby, III. p. 5, pi. 205, fig. 6. 
Sub-orbicular, compressed, with longitudinal arched stria?; 
one ear larger than the other, with tho side straight beneath 
it; sides nearly straight. 
The Coral Crag, Shotover, Oxfordshire. 
34. Pecten rigidus. —The Rigid Pecten, pi. LXII. fig. 10. 
P. rigida. Sowerby, III. p. 5, pi. 205, fig. 8. 
Orbicular, compressed ; binge-line triangular; ears unequal, 
large ; surface with strong longitudinal stria*, and slender, ir¬ 
regular, concentric stria?. 
The Forctt Marble, Castle Combe, Wiltshire. 
35. Pecten opercu laris. —The Lid-shaped Pecten, pi. 
LXIV. fig. 15. 
