Pecten. MOLLUSCA. BIVALVIA. 387 



18. v. ohliquus^ — Obliquely oval, convex on both sides; radii very nume- 

 rous, roughened by semicircular imbricated scales ; ears large, distinct. — 

 Sower, Rlin. Conch, t. ccclxx. f. 2 — In Green Sand. 



19. P. cinctus — Orbicular, gibbose, longitudinally striated, imbricated; 



edges of the laminae thin, erect ; ears small ; edge entire Sower. Min. 



Conch, t. ccclxxi — Under Oolite 9 



20. P. sulcatus. — Obliquely orbicular, with twenty obscurely tripartite 

 rays, the intermediate spaces longitudinally striated, the whole rougli with 

 minute scales ; internally sulcated ; ears nearly equal. — Sower. Min. Conch, 

 t, cccxciii. f. !• — Suffolk Crag. 



21. P. ^raci&.— Orbicular, thin, convex, with many small longitudinal 

 ridges, concentrically striated ; strise close, elevated, sharp ; ears unequal ; 

 mai'gin entire. — Sov)er. Min. Conch, t. cccxciii. f. 2. — In Crag. 



22. P. striaius. — Oval, convex ; valves nearly equal, with numerous smooth 

 or scaly ridges ; within plain, margin entire ; ears equal, ratlier lar'ge — Sower. 

 Min. Conch, t. cccxciv. f. 2, 3, 4 — In Crag. 



23. P. nitidus — Obovate, one valve nearly flat, with numerous, nearly 

 smooth ridges, the interstices minutely striated transversely, the other valve 

 convex, with as many crenulated ridges ; margin entire ; ears nearly equal. 



. — Mant. Suss. 202. t. xxvi. f. 4-9. — Sower. Min. Conch, t. cccxciv. f. 1. In 



Chalk. 



24. T.olsoletus? — Equivalved ; ears very unequal ; surface finely striated ; 

 striae obliquely diverging. — Sower. Min. Conch, t. Dxli In Crag. 



25. P. pririceps — Orbicular, compressed ; decorated with ninety rounded 

 nearly equal radii, surmounted with erect concave scales ; ears large, un- 

 e(iuai, squamose ; valves equal. — Sower. Min. Conch, t. Dxlii. f. 2. — In Crag. 



26. p. aimulatus — Orbicular, convex ; numerous thin, ei'ect, concentric 

 laminae, and fine longitudinal striae ornament the surface, passing over the 

 large eai's -Smver. Min. Conch, t. Dxlii. f. 1. — Lower Oolite. 



27. ]P. vimineus Convex, rather longer than wide, concentrically striated 4 



ribs about twenty, prominent, close beset with thick elevated scales, which 

 are less numerous upon the left valve ; ears nearly equal. (P. varius, Geol. 



Surv. Yorksh. 223. t. ix. £ 9.)—S(noer. Min. Conch, t. Dxliii. £ 1, 2 Lower 



Oolite. 



28. P. vagans — Rather convex, a little longer than wide ; ribs eleven, 

 large, convex, decorated with large erect concave scales, that are very close 

 upon the right, but distant upon the left, valve ; ears nearly equal, crossed 

 by larger scales.— (P. sulcatus^ Geol. Surv. York. 233. t. ix. f. ^.)—Soiver. 

 Min. Conch, t. Dxliii. f 3, 4, 5 — Lower Oolite. 



29. P. triplicatus. — Subtriangular, longitudinally striated, with three deep, 

 longitudinal furrows, Vv-hich form angular plicee on the front ; margin crenu- 

 lated — Mant. Geol. Suss. 128. t. xxv. f. 9 In Grey Chalk Marl. 



30. P. laminostis — Suborbicular, much depressed, concentrically laminated, 

 ears nearly equal.— Man/?. Geol. Suss. 128. t. xxvi. f. 8. — In Grey Chalk 



Marl. 



31. P. dissifnilis — Suborbicular, slightly lengthened, the right or lower 

 valve with numerous i-ibs, slightly scaly ; ears nearly equal, ribbed trans- 

 vcrsel}' and longitudinally ; the left or upper valve concave, regularly mark- 

 ed concentrically with flat obsolete ribs, which become scaly in crossing the 

 longitudinally ribbed ears. In my cabinet, from the shale and limestone of 



the Independent Coal formation In the concavity of the left valve, it agrees 



with the recent P. marinns and P. JacobcBu.s. 



E b g 



