Pecten. 
CONCIIIFERA. 
153 
Genus XXII.—IIINNUS.— De/rance. 
Shell inequivalve, nearly equal sided ; valves eared ; the 
area of the hinge quadrangular ; tripartite; the cartilage sunk 
in a deep longitudinal pit in the centre; the lateral portions 
striated, supporting the ligament; sinus for the byssus small, 
provided with one large muscular impression, connected with 
the pallia] impressions. 
1. Hinnus Dubissoni.—D ubissons Ilinnus, pi. LX. fig. 18. 
H. Dubissoni. Sowerby, VI. p. 210, pi. 601, Defrance, Diet, 
dos Sci. Nat. XXI. p. 170. 
Oblong; shell rather thick ; surface with numerous, narrow, 
distant, divergent ribs, with short intervening ones towards the 
base of the valves; the whole of the ribs arc a littlo imbri¬ 
cated towards the lower part of the valves, and with remote 
irregular lines of growth ; ears nearly equal, with a few longi¬ 
tudinal shallow furrows; umbo obtuse. 
The Coral Crag, Ramshot. 
Genus XXIII. PECTEN.— Bruguicre. 
Shell inequivalve; the under valve generally more convex 
than the upper; sub-equilateral, with many grooves or ribs 
diverging from the unibones to the margins; provided with 
two ears, which are usually unequal in sizo; close below ono 
of them, in the upper valve, is a small notch for the 
passage of a byssus ; muscular impression large, placed 
somewhat to one side; pallial impressions destitute of a sinus; 
hinge linear, without teeth ; ligament consisting of three por¬ 
tions, of which the two lateral parts are elongated, and follow 
the hinge line, the third portion thick and triangular, and 
fitted into a central, triangular, shallow pit within the hinge. 
1. Pecten grandis.—T he Great Pccten, pi. LXIII. fig. 2. 
P. grandis . Sowerby, Min. Conch., VI. p. 1G3, pi. 585, 
figs. 1 & 2. 
Shell sub-orbicular, somewhat broader than long ; the convex 
valve provided with thirteen greatly elevated, rounded, more 
or less compound, divergent ribs, most of which with a cen¬ 
tral sulcus, and between each is a single secondary rib; ono 
valve rather convex, towards the umboues somewhat concave, 
and the other very convex; ears square, almost equal, and 
longitudinally striated ; whole surface of the convex valve 
covered with very irregular, slightly raised, concentric striae, 
upon the other they are regular, close-set, and elevated, ap¬ 
proaching to the form of sharp lamimu. 
Found in the Crag at Newbourn, Ram shot, and Suffolk. 
2. Pkcten quaduicostatus.—T he Four-Ribbed Pocteu, 
pi. LX V. fig. 2. 
P. quadricostata. Sowerby, I. p. 121, pi. 56, figs. 1, 2. 
Triangular; length somewhat more than the width; poste¬ 
rior auricle large; nearly even; front semicircular; margin 
notched; convex valve with six large ribs, ami three smaller 
ones intervening between each : making five series of four ribs 
each ; towards the sides the ribs are less regular and smaller. 
The Upper Greensand, Isle of Wight, Dorsetshire, and 
Wiltshire; and the Greensand, Parham and Ilaldon Hill. 
•3. Pecten q,uin q,uecost at a u .—The Five-Ribbed Pccten, 
pi. LXV. fig. 3. 
Pecten quinquecostalu. Sowerby, I. p. 122, pi. 56, figs. 5 to 8. 
Sub-triangular, somewhat oblique, length a little exceeding 
its width ; front semicircular, toothed ; convex valve gibbose ; 
with five or six principal ribs, and four lesser intervening 
ones; upper valve fiat, toothed ; whole surface with minute 
transverse stria), and intersected by deep lines of growth, 
which give the surface a fringed appearance. 
1 he Chalk, Lowes, Gravesend, and Antrim, Ireland; the 
Upper'Greensand, Petcrsfield ; the Gualt, Isle of Wight; and 
the Lower Greensand, Sandgate, Sussex, Ilaldon, and Staple 
Ilill, Devises. 
4. Pecten Fleming!. —Fleming’s Pecten, pi. LVI.* fig. 40. 
Convex, with numerous elevated, slightly undulating ribs 
between each, one or more smaller, less elevated ones; in many 
of the interstices, towards the base, the intermediate ribs are 
superseded by six or seven longitudinal striae ; base and sides 
crossed by numerous, irregular lines of growth and striae, pro¬ 
ducing a denticulated appearance. 
Found by my esteemed friend Dr Fleming of Pendleton, 
Manchester, in the Great Oolite, Melton, and in his cabinet. 
5. Pecten aspeii. —The Rough Pecten, pi. LXV. fig. 23. 
P.asper. Sowerby, IV. p. 05, pi. 370, fig. 1. 
Nearly orbicular; slightly oblique; both valves convex; 
ears nearly equal; surface with about seventeen ribs, arranged 
in series of from five to seven, which are rendered very rough 
by a series of sub-tubular, imbricated scales, the centre of each 
set being provided with larger scales; margin crenated, and 
presenting a fringed appearance; inside plain, with a fringed 
margin. 
The Uppor Greensand, Petcrsfield and Wiltshire, and the 
Greensand, Blackdown and Lyme Regis* 
6. Pecten obliquus. —The Oblique Pecten, pi. LXIV. f. 19. 
P. obliquus . Sowerby, IV. pi. 370, fig. 2. 
Obliquely oval, its breadth about two-thirds its length ; both 
valves convex, hut unequally so; ears large; surface with 
numerous ribs, roughened by semicircular imbricated scales, 
every third rib being larger than the intermediate ones, alto¬ 
gether amounting to about twenty. 
The Upper Greensand, Ilythe, Parham, and Isle of Wight; 
the Great Oolite, Stonesfield. 
7. Pecten ci notes. —The Girdled Pecten, pi. LXII. fig. 7. 
P. cinctus. Sowerby, IV. p. 06, pi. 37L 
Almost circular, gibbose, valves nearly equally convex ; ears 
small, and covered with close ridges; longitudinally striated, 
the striae covered with thin erect concentric laminae, becoming 
very numerous towards tho edges, which are entire; substance 
of the shell thick, especially towards the beaks. 
The Inferior Oolite, llorncastle. 
8. Pecten barb at us. —Tho Bearded Pecten, pi. LXIV. f. 7. 
P. barbatus . Sowerby, III. p. 53, pi. 231. 
Orbicular, compressed; the spinous valve flatter than the 
opposite; ears nearly equal; surface with about fourteen flat¬ 
tened divergent ribs ; those upon one valve beset with spines 
and transverse striic, which are sharp and considerably ele¬ 
vated upon the sides of the ribs, from whence they curve into 
the bases of the spines, there being about five on each rib ; ribs 
upon the opposite valve convex, and equal in width to the in¬ 
tervening spaces, and crossed by less elevated stria); sides of 
both valves pectinated near the ears. 
The Inferior Oolite, Dundry and llie Lias, Weston. 
2 o 
