OSTREA. 309 



almost as produced a shape as that of Virginia. The upper 

 valve is always the flatter (or, at least, the more shallow), 

 the lower the more solid. The edges of the shell, although 

 irregularly wavy, are never plicated, and are neither cre- 

 nated nor scabrous, but the vicinity of the cartilage is often 

 beset in one or both valves with closely-disposed raised 

 denticular wrinkles (not granules) or even elevated rugose 

 sulci, which run parallel to the hinge-line. These denticles 

 vary very greatly in number and distinctness, sometimes 

 becoming nearly if not quite obsolete. 



About four inches may be considered the average 

 breadth for the full-sized common rough oysters of our 

 markets, but they are occasionally found at least five 

 inches wide. 



The animal of our oyster is much compressed, yet 

 rather thick, and of a general drab colour, with darker 

 viscera, and brownish margins to its mantle. The latter, 

 except on the beaks, is freely open, with slightly pendent 

 margins, double fringed, the filaments short and rather 

 irregular; the anal orifice is sessile. The great adductor 

 muscle is very powerful, white and round ; it is esteemed 

 one of the sweetest morsels of the oyster's body. The 

 liver is of a greenish hue, and the ventral mass of a 

 creamy white. 



The Ostrea edulis may be said to have its capital in 

 Britain, for though found elsewhere on the coasts of 

 Europe, both northwards and southwards, in no part 

 of them does it attain such perfection as in our seas, 

 through which it is generally distributed, sparingly in 

 some places, abundantly and in gregarious assemblages in 

 others, chiefly inhabiting the laminarian and coralline zones. 

 The ancient Romans valued our native oysters even as we 

 do now, and must have held them in higher estimation 



