Pecten. 



CONCHIFEIU. 



153 



Genus XXII.— IIINNUS.— Z)e/>-ance. 



Shell inequivalve, nearly equal sided ; valvea eared ; the 

 area of the binge 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 pallial impressions. 



1. Ui.vNrs DuBissoNi. — Dubisson's Ilinnus, pi. LX. fig. 18. 



H. Dulissoni. Sowerby, VI. p. 210, pi. 601, Defrance, Diet, 

 des 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 are a little 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. VEGTKS.—Bruguiere. 



Shell inequivalve ; the under valve generally more convex 

 than the upper ; sub-equilateral, with many grooves or ribs 

 diverging from the umbones to the margins ; provided with 

 two ears, which are usually unequal in size ; close belosv one 

 of them, in the upper valve, is a small notch for the 

 passage of a bj'ssus ; 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. Pecte.n grandis. — The Great Pecten, 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 ; one 

 valve rather convex, towards the umbones somewhat concave, 

 and the other very convex ; ears square, almost equal, ami 

 longitudinally striated ; whole surface of the convex valve 

 covered with very irregular, slightly raised, concentric striic, 

 upon the other they are regular, close-set, and elevated, ap- 

 proaching to the form of sharp laminie. 



Found in the Crag at Ncwbourn, Ramshot, and Suft'olk. 



2. Pecten quadricostatus. — The Four-Ribbed Pecten, 

 pi. LXV. fig. 2. 



P. quadricostata. Sowerby, I. p. 121, pi. jG, figs. 1, 2. 



Triangular ; length somewhat more than the width ; poste- 

 rior auricle large; nearly even; front stmicircular ; margin 

 notched; convex valve with six large ribs, and throe smaller 

 ones intervening between each : making five series of four ribs 

 each ; towards the sides the ribs are less regular and siiiallcr. 



The Upper Greens.and, Isle of Wight, Dorsetshire, and 

 Wiltshire; and the Greensand, Parhani and lialdon Hill. 



3. Pecten quinulecostatau. — The Five-Ribbed Pecten, 

 pi. LXV. fig. .3. 



Pecten quimptecostatu. Sowerby, I. p. 1 22, pi. 56, figs. 5 to 8. 



Sub-triangular, somewhat oblique, length a little exceeding 

 its wi<lth ; front semicircular, toothed ; convex valve gibbose ; 

 with five or six principal ribs, and four lesser intervening 

 ones ; upper valve flat, toothed ; whole surface with minute 

 transverse stria;, and intersected by deep lines of growth, 

 which give the surface a fringed aj)pcarance. 



The Chalk, Lcwcs, Gravesend, and Antrim, Ireland ; the 

 Upper Greensand, Petcrsfiold ; the Gualt, Isle of Wight; and 

 the Lower Greensand, Sandgate, Sussex, Haldon, and Staple 

 Hill, Devises. 



4. Pecten Flemingi. — Fleming's Pecten, pi. LVI.* fig. 4-0. 

 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 strice ; base and sides 

 crossed by numerous, irregular lines of growth and stria;, 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 aspeu. — The Rough Pecten, pi. LXV. fig. 23. 

 P.asper. Sowerby, IV. p. 95, 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 Upper Greensand, Petersfield and Wiltshire, and the 

 Greensand, Blackdown and Lyme Regis. 



6. Pecten oblkjuus. — The Oblique Pecten, pi. LXIV. f. 1 9. 

 P. oh/iquus. Sowerby, IV. pi. 370, fig. 2. 



Obliquely oval, its breadth about two-thirds its length ; both 

 valves convex, but 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, Hythe, Parham, and Isle of Wight ; 

 the Great Oolite, Stonesfielu. 



7. Pecten cinctus. — The Girdled Pecten, pi. LXII. fig. 7. 

 P. cinclus. Sowerby, IV. p. 96, pi. 371. 



-Almost circular, gibbose, valves nearly equally convex ; cars 

 small, and covered with close ridges ; longitudinally striated, 

 the stria; covered with thin erect concentric lamina;, becoming 

 very numerous towards the edges, which are entire ; substance 

 of the shell thick, especially towards the beaks. 



The Inferior Oolite, Horncastlc. 



8. Pecten barbatus. — The Bearded Pecten, pi. LXIV. f. 7. 

 P. harlatus. 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 stria;, 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 o' 

 both valves pectinated near the ears. 



The Inferior Oolite, Dundrv and the Lias, Weston. 

 '2 o 



