130 



PECTEN striatas. 

 TAB. CCCXClV.-^«^5. 2, 3 and 4. 

 Spec. Char. Oval, convex; valves nearly 

 equal ; with numerous smooth or scaly 

 ridges ; within plain ; margin entire ; ears 

 unequal, rather large. 



The width is five sixths of the length ; the ridges are 

 irregular, but nearly equal. In some specimens they 

 have rather distant obtuse crenulations, or scales upon 

 them ; in others they are wholly smooth, perhaps from 

 wear: the shell is rather thick and shews within it but 

 slight signs of the ridges. 



Found in the Crag at Holywells, by Mrs. Cobbold, and 

 at Woodbridge by the Rev. Mr. Leathes : the speci- 

 menij with scales upon the ridges, differ in no other 

 respect from the smooth ones, and both are found of 

 various sizes ; it is possible the latter may have been 

 worn before they were changed into Crag. 



PECTEN nitidus. 

 TAS. CCCXCIY.— Jig. 1. 



Spec. Char. Obovate, one valve nearly flat, 

 with numerous, nearly smooth ridges, the 

 interstices minutely striated transversely, 

 the other valve convex with as many crenu- 

 lated ridges; margin entire; ears nearly 

 equal. 

 Syn. Pecten nitida, Mantell Geol. Sussex, p, 

 202. tab. 26./. 4 and 9. 

 Pecten cretosus, and P. arachnoides, De 

 France, Brogniart and Ciivier Geo. de Paris 

 383 and 384. tub. 3./. 7 and 8. ed. 1822. 

 A rather broader shell than the last, much resembling 

 it, but Avell distinguished by the fineness of its concentric 

 st'riee, the flatness of one valve, and thinness of both 

 valves; the ridges upon the convex valve are decidedly 

 crenulated or granulated, while those of the other are 

 mostly smooth, a circumstance that has apparently led 

 Blr. De France to make two species of them. 



By no means a rare Shell in Chalk, but so excessively 

 thin that it is seldom found perfect ; the dissimilarity 

 of the two valves is proved by specimens in which they 

 still remain applied together, probably M. de France 

 never met with a pair, or he would have observed this ; 

 the flatter valve is sometimes nearly as convex as the 

 other. 



