386 THE OCEAN WORLD. 
scrapes up, detaching the oysters, and throwing them into a net 
attached to the dredge. In this process oysters, large and small, are 
torn from their native bed, some going into the net, but a larger 
number are buried in the mud. It would be difficult to imagine a 
more destructive process; and when the habits of the oyster are 
considered, it is evidently one admirably contrived to destroy the 
race. 
In France oyster dredging is conducted by fleets of thirty or 
forty boats, each carrying four or five men. At a fixed hour, and 
under the surveillance of a coast-guard in a pinnace bearing the 
national flag, the flotilla commences the fishing. In the estuary ot 
the Thames the practice is much the same, although no official 
surveillance is observed. Each bark is provided with four or five 
dredges, each resembling in shape a common clasp purse. These 
dredges are formed of network, with a strong iron frame, as repre- 
sented in Fig. 171, the iron frame serving the double purpose of 
acting as a scraper, and keeping the mouth open, while giving it a 
proper pressure as it travels over the oyster-beds. When the boat is 
over the oyster scarp, the dredge is let down, and no more attractive 
sight exists than that presented by, the well-appointed Whitstable 
boats on one side of the estuary, or the Colne boats on the other, 
as they wear and tack over the oyster-beds, bearing up from time to 
time to haul in the dredge, and empty its contents into the hold. 
The tension of the rope is the signal for hauling in, and very hetero- 
geneous are the contents of the dredge—sea-weeds, star-fishes, 
lobsters, crabs, actinia, and stones. In this manner the common 
oyster-beds on both sides of the Channel were ploughed up by the 
oyster dredger pretty much as the ploughman on shore turns up a 
field. The consequence was that, twenty years ago, the French 
beds were totally exhausted, and France had to look to foreign 
countries for its oysters. Oyster-farms which had employed 1,400 
men and 200 boats were reduced to employing 200 men and twenty 
boats. Similar results from over-dredging would have followed, no 
doubt, on this side the Channel had the mollusc not been protected 
by the companies and private proprietors who held the oyster-beds 
in the large estuaries. This state of things in France led to some 
important discoveries in the science of oyster culture, which have 
produced important changes there. 
The name of Sergius Orata has already been mentioned as a culti- 
vator of oysters. He lived in the fifth century before our era, and 
according to Pliny he first attempted parking oysters at Baia in the 
time of the orator Lucius Crassus. He was the first to recognise the 
