OYSTER AND MUSSEL REPORT. 49 
they place their ‘‘ collectors” in position. They consider 
that it is of great importance that the collectors should 
not be put in the water unnecessarily soon as the tiles are 
liable to become coated with other things, slime and sedi- 
ment, which will prevent the oyster spat (“‘naissain,” as 
they call it) from adhering. 
The collectors are crates (called ‘‘ gabarets”’ or ‘‘ruches”’) 
of earthenware tiles coated with a lime cement (PI. I, fig. 
2). The tiles are like ordinary roofing tiles. They are 
about 14 inches in length 6 inches in breadth at one end 
and 5 at the other, and 3 an inch in thickness The clay 
they are made of is coarse and of areddish colour. Later 
on I saw the tiles being made further up the coast, north of 
the Gironde, whence they are shipped in coasting vessels. 
The tiles are prepared for use as collectors by being 
coated with a layer of imy cement which gives them a 
whitewashed appearance. The cement is made of lime 
mixed with sea-water and a certain amount of sand so as 
to form a creamy paste. Different proprietors use slightly 
different proportions of lime and sand, and in some places 
hydraulic cement is also used. This process of coating, 
known as ‘“‘chaulage,’’ adds about from ;4, to + inch in 
thickness to each side of the tile. It has to be done with 
some care so that the limy layer may be of the right nature, 
sufficiently strong and adhesive and yet readily detachable 
when the right time comes, so that the young oysters may 
be removed from the tiles without injury and without the 
necessity of breaking up the tiles as used to be the case. 
By the present method the oysters and cement can be 
scaled off and the tiles preserved for use again the follow- 
ing year. A dozen or more millions of these tiles are 
probably employed each year at Arcachon. 
The prepared tiles are arranged in rows inside cases 
(“‘ruches’’) made of sparwork or strips of wood so that the 
