BIVALVIA. 31 



19. OSTREA TABULATA, J. SoWCl'by. Tab. IV, fig. 1, (/, b. 



Ostrea tabulata. J. Sow., in Dixon's Foss. of Suss., pp. 117, 226, 1850. 

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



Spec. Char. Testa orbiculatd, depressd ; lavigatd ; valvd inferiore imbrieatd obscure 

 radiatd ; valvd superiore plana, nitidd, politd ; umbonibus parvis. 



" Shell orbicular, depressed, smooth ; upper valve slightly concave, even, its plates few, 

 with distant, scarcely raised edges ; lower valve obscurely marked by radiating undulations, 

 its plates few, in groups, with remote, deeply imbricating edges ; beaks small, pointed ; 

 muscular impression ovate, curved, of a moderate size." — Sowerby. 



Diameter, 7 inches, 



Locality. Bognor. 



This is an abundant shell at Bognor, to which locality it appears to be restricted. 



Mr. Sowerby remarks "that it was evidently a rapid growing shell; its nearly smooth 

 external laminse extend far between each period of growth, and show their fibrous 

 structure distinctly, especially upon the surface." The specimens generally have 

 adhered only in the young state by a very small portion of the surface, and are 

 solitary. I have rarely seen them in groups. A specimen in Mr. WethereH's 

 cabinet shows the muscle-mark to be rather elongate, and more curved than is the rounded 

 form of this mark in yiyantea. The lower valve in the young state is obscurely rayed, 

 and the upper is generally glossy, and the shell is flatter or more compressed than that of 

 gig ant ea. 



:20. Ostrea tenera, /. Sowerby. Tab. VI, fig. 1, a, b. 



Ostrea tener. J. Sow. Min. Conch., t. 252, figs. 2, 3, 1819. 



— tenera. Id., in Dixon's Foss. of Suss., p. 174, t. iv, figs. 2, 3, 1850. 

 _ _ jyOrbigny. Prod, de Palaeont., t. ii, p. 307, No. 199, 1850. 



— — Morris. Catal. Brit. Foss., p. 175, 1857. 



Spec. Char. Testa clongatd, attenuatd, angustd, depressd valvd inferiore sub-pland, 

 transversim latnellosd, valvd superiore striata vel inornatd ; umbonibus longis attenuatis ,- 

 fossuld ligamenti angustd. 



Shell elongate, attenuated, depressed ; lower valve very slightly convex and transversely 

 lamellated; upper valve flat, striated, or plain ; umbones attenuated, ligamental ; area long 

 and pointed. 



Height, 4£ inches. 



Localities. Woolwich, Sundridge Park, New Cross, smooth and thick var. {Prcsttcich) . 

 Bracklesham, thin and striated var. {Edwards). 



