202 THE WORLD OF THE SEA. 
mollusks; but the fact is, that the young oysters are destroyed in 
millions by creatures which prey upon them. Moreover, being but 
feeble swimmers, they are utterly at the mercy of the currents ; 
and, unless the bank be in absolutely still water, the greater part 
of the spat is swept away, and thus destroyed. 
The favourite habitat of the oyster is the shore, in water not 
very deep, and not disturbed by currents. In such a locality their 
development is very rapid, and they accumulate in large numbers, 
forming what is technically termed an oyster bank. Many of 
these banks extend for some miles, and seem quite inexhaustible. 
In 1819, one was discovered near Zealand, which provided the 
whole of the Low Countries with oysters for a year, in such abun- 
dance that they were sold at the rate of ten for a penny; but 
as this bank was very near the level of the sea at low tide, a 
rigorous winter destroyed it. 
The species of oysters usually eaten are the common oyster 
(Ostrea edulis), and the horse-foot oyster (Ostrca hippopus), which 
are natives of our own coasts. On the French Mediterranean 
shore they also find the rose-coloured oyster (Ostrea rosacea), and 
the milky oyster (Ostrea lacteola). Two other species—the crested 
oyster (Ostrea cristata) and the Ostrea plicata—are also found, but 
not so frequently as others. The Corsican coast yields the Ostrea 
lamellosa. 
In seaports, the oysters are distinguished by the localities from 
which they are taken. Those from deep sea banks are not so 
valuable as those from the more shallow water. There are two 
principal varieties dredged up on the French coast, which differ 
in their flavour and size—these are the Cancale and the Ostend 
oyster. When the first has been fed for some time in the oyster 
park, it assumes a greenish hue, and is then called the Marenna— 
so named from the park in the Bay of Seudre. We shall again 
refer to the nature and the source of this coloration. 
The oyster bears the palm from all the dishes of the table, 
since it is the most digestible, and consists of the very element of 
all substances capable of giving nourishment. It is peculiarly fitted 
for the delicate, the sick, and the convalescent. No feast can be 
