128 GREY CHALK MARL. 



separated, the external surface was rugous, a circumstance that explains 

 the cause of its adherence to the surrounding matrix. 



The specimen figured is from Hamsey ; it shews the inner surface. 



LocaHties. Southerham, Beachy-head, Hamsey, Kingmer. 



52. Pecten tripUcata. Tab. xxv. fig. 9. 



Subtriangular, longitudinally striated, with three deep, longitudinal 

 furrows, which form angular pHcee on the front ; margin crenulated. 



Although but one valve of this elegant httle Pecten has been dis- 

 covered, its characters are sufiiciently remarkable to warrant a specific 

 appellation. The surface is furrowed by three deep sulci, that diverge 

 from the hinge towards the margin, where they terminate in acute, 

 angular pHc£e. The shell is covered with minute longitudinal striae, 

 decussated by transverse hnes of growth. The margin is thick, and de- 

 licately crenated. 



Locahty. Hamsey. The shell itself remains, and appears to have 

 undergone but Httle change. 



53. Pecten quinqiiecostata ? Tab. xxv. fig. 10. 



In many particulars, this beautiful shell resembles the flat valve of P. 

 quinquecostata * ; but it is much more elongated, and may probably belong 

 to a distinct species. 



Locality. Hamsey. 



54. Pecten laminosa. Tab. xxvi. fig. 8. (22 ?) 



Suborbicular, much depressed, concentrically laminated, ears nearly 

 equal. 



This shell so closely resembles P. orbicularis of Sowerby, {Min. Conch. 

 tab. 186.) that at first I was induced to consider it as belonging to that 

 species; a more careful examination has however detected differences 

 which appear to be specific. 



The striae in P. orbicularis, are described as elevated and sharp ; but in 

 the shell before us they are very slight, and are produced by the ter- 



* Vide Chalk Fossils, No. 64. 



