30 EOCENE MOLLUSC A. 



An oyster from Kleyn Spauwen was obligingly sent to me some years ago by the 

 Comte du Chastel, but without a name. The specimen is, I believe, identical with the 

 Brockenhurst shell ; it resembles it even in colour. 



18. Ostrea pulchra, J. Soioerby. Tab. I. 



Ostrea pulchra. J. Sow. Min. Conch., t. 279. 



— — Morris. Catal. Brit. Foss., p. 175, 1854. 



Spec. Char. 0. testa magna, orbiculato-ovatd, cr asset, depressd ; valvd inferiore 

 convexd, lamellatd, in juventute plicatd vel costatd; valvd superior e planatd ; car dine 

 brevissimd ; impressione musctdari ovato. 



Shell large, roundly ovate, thick, depressed; lower valve convex, lamellated, and 

 plicated or costated in the young state ; upper valve plain and flat, hinge very short ; 

 muscular impression ovate. 



Diameter, 7 inches. 



Localities. Reading, Clarendon {Edivards). 



Small var. Bromley, Tyler's Hill near Chesham, Old Basing {Prestwich). I 



This species differs from 0. Bellovacina in being more numerously rayed or costated 

 in the lower valve of the young shell ; these ridges become nearly obsolete as it 

 advances in age, and the upper valve is naked, or free from radiating ridges. The 

 Reading specimens are generally orbicular, those from Clarendon have the greatest diameter 

 from the umbo to the ventral margin. 



In the Reading specimens many have the two valves united, and the ligament preserved ; 

 the small shell figured Tab. IV, fig. 2, a, b, is the representation of what I imagine 

 to be the young state of the upper or right valve of this species from Clarendon ; 

 the umbo is much recurved or inflected after the manner of Gryp/iaa or Exogyra, and 

 on each side of the hinge the margin is crenulated or denticulated ; this character may 

 be seen in some of the large and full-grown specimens of this species from Clarendon. 

 Mr. Edwards' specimen of this species from Reading measures seven inches and a half 

 in the longest diameter, and I think the animal inhabitant must have attained to the 

 dimensions of at least six inches, with a depth of rather more than one inch. The shell 

 figured in ' Min. Conch.' from Bromley, above referred to, represents what I believe to 

 be a small variety of this species, and the same kind is also found at Sunning Hill. 



