30 EOCENE MOLLUSCA. 
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, 
Ostrpa putouRa, J. Sowerby. Tab. I. 
OsrReA PULCHRA. J. Sow. Min. Conch., t. 279. 
— — Morris. Catal. Brit. Foss., p. 175, 1854. 
Spec. Char. O. testd magna, orbiculato-ovatd, crassd, depressd ; valvd inferiore 
convexd, lamellatd, in juventute plicaté vel costatd; valvd superiore planatd ; cardine 
brevissimd ; tmpressione musculart 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 (Hdwards). 
Small var. Bromley, Tyler’s Hill near Chesham, Old Basing (Prestwich). 
This species differs from O. Bellovacina in bemg more nunerously 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 ab. IV, fig. 2, a, 4, 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 Gryphea or Hrogyra, 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. 
