112 TRANSACTIONS LIVEEPOOL BIOLOGICAL SOCIETY. 



being poor and saltish in taste. Possibly these may have 

 been grown from spat derived from embryos which have 

 been drifted up on some occasion from Arcachon. 



Mabennes, &c. 



The flat district on both sides of the estuary of the 

 Seudre is the chief region for fattening up the oysters and 

 preparing them for market, and it is in this neighbourhood 

 that the celebrated green oysters, so well known and 

 highly prized in some markets, are produced. But it 

 must not be thought that all the oysters reared in these 

 claires are green, the two kinds (" huitres vertes " and 

 " huitres blanches") are cultivated in the same neigh- 

 bourhood. 



La Tremblade is on the southern side of the Seudre a 

 few miles from the estuary, and its port is La Greve. A 

 wide canal, up which small coasting vessels and fishing 

 boats can sail, leads the sea-water from La Greve to 

 Tremblade and supplies the numerous oyster "claires" 

 in the district around. The country is very flat and the 

 soil is clay or clay and marl. It is excavated in all directions 

 for miles to form claires and the branch canals supplying 

 them. The "claires" (PI. II, fig. 4) are merely shallow 

 artificial ponds of more or less rectangular form and about 

 2 feet deep on an average. The floor is simply the clayey 

 soil and is very muddy, while the sides are turf banks 

 pierced somewhere by a pipe leading from a branch canal 

 or a neighbouring claire. On the north of the estuary in 

 the neighbourhood of the little town of Marennes there are 

 also numbers of claires supplied by a canal leading inland. 



A good deal of the low-lying land is also occupied by salt 

 marshes (marais salants), shallow excavations in which 

 the sea-water is evaporated and from which the salt is 

 scraped up in heaps by great wooden rakes. The pyramids 



