308 OSTREAD^. 



particular description, the latter is a much more character- 

 istic looking shell and not very frequently ohservable, in 

 fine preservation, in the cabinets of our collectors. Whilst 

 those individuals most ordinarily met with at our tables 

 have the surface of the upper valve of an uniform drab or 

 brownish buff-colour, this variety is beautifully radiated, 

 in addition, with lines and streaks of dull purplish crim- 

 son or reddish chocolate colour, and its concentric la- 

 mellffi, which are extremely thin, and usually composed 

 of rather large plates, instead of being appressed, are more 

 or less elevated, broadly overlap each other, and are rather 

 obscurely folded in radiating fashion. The ribs, or rather 

 radiating folds, of the lower valve, which are more or 

 less numerous, and for the most part narrow or but mo- 

 derately broad, are sometimes stained with rich purplish 

 red towards the margin, and, when the concentric laminae 

 are elevated (which is generally the case when the valve 

 is attached by the apex alone), are wont to be sur- 

 mounted by vaulted, and even occasionally somewhat tu- 

 bular fimbriations. When this form is afiixed by the 

 entire surface of the lower valve, (which consequently loses 

 all traces of colouring or sculpture), the laminae of the 

 upper valve are quite devoid of folds, and the lower series 

 of them overlaps, as it were, the ventral edge of the 

 inferior valve. In ordinary circumstances, these laminse, 

 when perfect, extend as far as the extreme edge of the 

 attached valve, but the somewhat pearly substance of the 

 interior, which is white (in one variety with purple stains), 

 is never so far produced as the nacre of the other valve. 



The natural form of our undisturbed oyster, which is apt 

 to vary greatly in that respect, but is, we believe, always 

 broader than long, appears to be obovate, contracted 

 above, and dilated below ; we have seen it, however, of 



