108 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



8 months although an individual oyster may only be in 

 for one month or so. Eventually all the oysters not sold 

 to eleveurs or exported get transferred from the ambu- 

 lances to the other parts of the pare. 



Mons. Daste told me that he soaked his ambulances 

 thoroughly in coal tar once a year to preserve them. 

 Although they are some little expense at first they last 

 well, and are used over and over again. 



The rest of an oyster pare is marked out into certain 

 areas like little rectangular fields having raised edges all 

 round and a sluice at one corner so that the water may 

 either be retained or allowed to run out (PI. I, fig. 6). At 

 low water the boundary banks of these are all exposed but 

 there is usually some 6 or 8 inches or so of water retained 

 over the area. This shallow water becomes warm towards 

 the last of the ebb and it is swarming with living things 

 and so no doubt supplies abundance of food to the oysters 

 lying on the floor of the enclosure. The banks bounding 

 these areas are formed of two parallel rows of closely set 

 vertical bunches of the local heath, Erica scoparia, with the 

 space between, a foot or more wide, filled in with masses 

 of a tenacious clay (PL I, fig. 6) obtained from the He 

 des Oiseaux. In some places the boundary is strength- 

 ened, or partly formed, of planks of wood and stakes. 



An objection which is urged against the use of the heath 

 is that it forms a most attractive system of "bouchots" 

 upon which young mussels settle down and flourish. The 

 mussels are not cultivated, nor desired, but they are present 

 in considerable abundance over some parts of the oyster 

 pares, hanging in clusters from the branches of the heath. 

 The men at Arcachon say that there is not enough lime 

 in the water for both the oysters and the mussels, and 

 that the latter being the stronger they get all the lime and 

 the former suffer correspondingly. This is one way of ex- 



