BRITISH OYSTERS : OLD AND NEW. 189 
on the lower valve, the ribs varying in number and breadth, 
the lower valve rather shallow ; the upper valve flat, having the 
concentric laminae closely appressed or but little raised; colour 
a uniform deep or brownish buff, margins of valves plain ; in¬ 
terior an opalescent white, with a white scar of the adductor 
muscle. 
The same type is present in the Aldborough marshes, and the 
Roman coast encampments, the Walton-on-the-Naze raised 
beach, the alluvial flats at Norwich, and as far back in time as 
the March Pleistocene silts. They show the original oyster 
in this area to have been of Rutupinian type (Plate xiii., fig. 7). 
Frank Buckland' defined a “ native ” as a thorough-bred 
oyster, its geographical limits extending from Harwich to Margate 
at or about the mouth of the Thames, and indigenous to the soil. 
Most of this district is under cultivation, and it is only here 
and there that a few natural freely-fished beds are found ; the 
cultivated area includes the Colne, Faversham, Whitstable, 
and Medway, but the brood has been so often replenished, that 
the original type has been nearly lost. The Milton oysters, true 
Rutupinian, are perhaps the purest of the East Coast breeds. 
The present * ‘Colchester” natives are the result of careful selection 
and do not represent the aboriginal species or variety. The 
South Coast from Dorset eastwards to Colchester has been 
virtually peopled from France and the mid-Channel, and hardly 
an aboriginal native is left, and only a few deep-sea shells, mostly 
of large size, are now to be had. 2 
The continual waste of the coast line by denudation is partly 
responsible for the scarcity of oyster beds off the Norfolk coast 
beyond Burnham and Happisburgh. Although from the recur¬ 
rence of names, such as Oysterness, on the Humber Estuary 
their former presence may be inferred, the shell is not given in 
Wood’s list of the marine Mollusca of the Yorkshire coast (Hull 
Museum Publication, No. 91, 1912), the bulk of the shells found 
at the holiday resorts on that line of country being mostly 
American Blue-points, Portugese, or importations. For many 
years before and even after 1820, the extensive oyster banks off 
Happisburgh, Norfolk, now almost exhausted, yielded a never- 
2 Solent oysters grow very large. Philpots mentions one he bought which was 
6Jin. long by 5$in. broad, and another from off Christchurch which was 7in. by 7in. f and 
weighing 3^ pounds. I have had them from off Newhaven nearly as large. 
