BIVALVIA. 33 



variable. Fig. 5, c, resembles 0. Sparnacensis, Desh. (pi. G4, figs. 5 — 8.) The hinge (which 

 is peculiar) is very similar, although, if that figure be correct, the muscle-mark is not so elon- 

 gated as in our species. Fig. 5, b, is, I imagine, the lower valve of a specimen belonging to 

 this species, and its recurved umbo gives it the appearance of a Gryphaa. None of the 

 specimens in Jermyn-street possessed, that I could see, the radiations spoken of by M. 

 Deshaycs as distinguishing O. gryphina ; and there is no diagnosis or any remark by the 

 late Professor E. Forbes, on whose authority that species is introduced (Mem. Geol. 

 Survey., 185G, p. 88.) I am therefore unable to consider Gryphina as a British 

 species. 



22. Ostrea velata, S. Wood. Tab. VII, fig. 1, a, b. 



Spec. Char. Testa ovato-irigond, sub-obliqud ; area cardinali lata, incurvd ; valvd 

 inferiore lamellatd ; lamellis subregularibus, fmbriosis ; valvd superiore plamdatd, striata ; 

 striis magnis, undulatis. 



Shell ovately trigonal, somewhat oblique ; cardinal area rather broad, incurved ; inferior 

 valve lamellated, the lamellae in general regular, fimbriated, or projecting ; upper valve 

 flattened and striated, striae large and undulating. 



Diameter, 2 inches. 



Localities. Col well Bay (Edivards), Whitecliffe Bay {Prcstivich) . 



This is rather a pretty looking shell, and does not appear at all rare. Its great 

 peculiarity consists in being striated upon the upper valve. The striation in our specimens 

 exists only in the outer coating of the upper valve ; this coating is sometimes entirely 

 removed, and is seldom seen except in patches. I thought at one time it might have 

 belonged to cochlearia, and that the French specimens had lost this outer cuticle ; but 

 there are no " obscure plications" in the lower valve, which the French fossil is said to 

 possess, but it is regularly lamellated or fimbriated. I have, therefore, with reluctance 

 felt compelled to give it a new name. The upper valve of this species, much distorted, I 

 found, many years ago, in the small patch of marine shells which intervenes between the 

 fresh-water deposits on the Hampshire Coast, at Hordwell. 0. cochlear. Poli, is a recent 

 species, and is quite distinct. 0. cochlear., Nyst (p. 330, pi. 32, fig. 2), which he gives as a 

 fossil from Hoesselt and Lethen, in the Limburg, appears from figure and description, to be 

 different from any oyster that I have seen from the older Tertiaries of England. 

 Cochlearia is a name attached to several specimens of Ostrea in the Museum in Jermyn- 

 street ; but these specimens appear to me to belong either to Vectensis or to this species. 

 In the second part of ' Coq. Foss. des Env. de Paris/ t. 2, p. 114, the author considers his 

 former species of O. cochlearia as a variety of 0. cyathula. 



