BIVALVIA. 21 
Shell suborbicular; lower valve convex, and irregularly laminated; upper valve 
ornamented with fine, longitudinal, and divaricating striz ; margin of the valve crenulated 
above on each side of the hinge. 
Dimensions, 5 inches by 4. 
Localities. Bracklesham (Ldwards). 
France, Valmondois et Senlis (Deshayes). 
This species is not abundant, and it is confined, I believe, to Bracklesham. ‘The 
peculiarity of this shell, whence I presume it received its name, is the elevation of the 
centre of the upper valve. ‘This arises from an adherence of the animal to some cylin- 
drical body, by which a considerable indenture is given to the outside of the lower valve 
and an elevated ridge to the inside; this is communicated to the upper valve, in order to 
give room to the animal inhabitant, and thus an elevated, semi-cylindrical ridge is on the 
outside of the upper valve, corresponding with the body adhered to. Specimens sometimes 
occur which have been attached by the greater portion of the lower valve to a flat surface, 
and the upper valve in this case has no elevation, but its favorite habit was apparently to 
select a cylindrical stem for support. ‘The upper valve is covered with fine stria, and 
the interior has the margins crenulated near the hinge; but M. Deshayes figures a specimen 
(pl. 64, fig. 3) in which the crenulations have extended round the entire margin of the 
upper valve. ‘This is not so in the British specimens which have come under my inspection. 
The ligamental area is large and broad. 
8. Osrrea pLEGANS? Deshayes. 
Osrrea ELEGANS. Desh. Coq. Foss. des Env. de Par., p. 361, pl. 50, figs. 7—9. 
= — J. Sowerby, in Dixon’s Geol. of Sussex, p. 174, 1850. 
— — J. Morris. Catal. Brit. Foss., p. 174, 1854. 
“'This is intermediate in several respects between O. radiosa and O. flabellula, but has 
more plaits than the latter. I much doubt the propriety of separating it as a species.” — 
J. Sowerby. 
I am inclined to think with Mr. Sowerby that the English fossil called eZegans is only a 
variety. There is not any fossil in Mr. Edwards’s collection that deserves to be called 
elegans, in specific contradistinction to radiosa, Sow., flabellula, or cymbula; and as the 
above name is given upon the authority of Mr. Edwards’s specimens, it is introduced here 
without a figure, and with considerable doubt. 
9. Ostrea PLABELLULA, Lamarck. ab. III, fig. 4, a—d. 
Cuama eticata. Solander, in Brander, Foss. Hant., pl. viii, figs. 84, 85, 1766. 
OsTREA FLABELLULA. Lam. Ann. du Mus., t. viii, p. 164, No. 16; and t. xiv, pl. 20, 
fig. 3, a, 5, 1806. 
