ARTIFICIAL OYSTER CULTIVATION. I I 67 



SLATES, 



Arranged in parallel horizontal layers, and kept apart by 

 bricks, are used in some parts of France ; they, like tiles, 

 can be covered with cement, but their expense is against 

 them. 



STONES, 



At the He de Re, and at Oleron slabs of stones, from 18 

 inches to 2 feet long, by 9 inches or 10 broad, are placed 

 in rows canted up one against the other. Series of stones 

 ^o arranged are made about 100 feet long, and four or five 

 of them are grouped together, within a space of about 30 

 yards square. The walls of this enclosure, called a " pare," 

 are constructed of slabs of stone placed upright, and made 

 watertight by being coated with a coarse cement made from 

 mud found close by. The cost of a pare of the above 

 dimensions is about 800 francs. 



Stones are about the worst sort of collectors that can 

 be used. They are heavy to move, difficult to clean, and 

 the oysters are liable to injury when being removed from 

 them ; but as they are not expensive, entailing no cost but 

 that of manual labour, they are suited to the exigencies of 

 those districts where labour is cheap. 



Similar constructions are erected at Oleron ; but here, 

 contrary to the custom adopted at Re of laying down parent 

 oysters in the pares, they trust entirely to the spat being 

 drifted in from the natural banks outside. Like arrange- 

 ments of collectors, slightly modified according to local 

 circumstances, may be seen in work at Chatellion, and at a 

 few places on the west coast of Ireland. 



TILES. 



After long experiment it has been found that a good 

 kind of collector is the common house-tile covered with a 



