OYSTER AND MUSSEL REPORT. 109 



pressing the general fact that somehow in the complex 

 struggle for existence the mussels get on best. 



There are many crabs and other enemies of the oyster 

 in the pares. Every here and there one can pick up 

 empty oyster shells quite recently dead and having a neatly 

 drilled hole in one valve which shows that the oyster had 

 been attacked and killed by a carnivorous Gastropod. 

 Crabs are injurious both directly by eating young oysters 

 and also indirectly by excavating holes in the floor of the 

 pare into which oysters slip and are then smothered by 

 mud. 



The young oysters when taken from their ambulances 

 are put in these little fields or enclosures with the mud 

 banks, and there they remain thickly scattered over the 

 floor till they are required for exportation. I was informed 

 that they usually put about 1,000,000 oysters in each 

 enclosure, which is about at the rate of 125 to the square 

 metre. The oysters grow very rapidly on leaving the am- 

 bulances and may be § inch across in a couple of months. 

 When one year old they are usually from 1 inch to 1 J inches 

 in diameter, and when two years old they are usually 

 from 2J to 2J inches in diameter. During the time I was 

 there (July) some of the one and two year old oysters 

 were evidently growing very rapidly. It was easy to see 

 the annual increments by means of the lines on the shell, 

 and some of the shells had beautifully transparent exten- 

 sions of new matter from their free edges. One Ostrea 

 angulata which I was shown had evidently added an inch 

 to the edge of its shell during the past year. 



Between neighbouring oyster pares, and surrounding 

 the "concessions" of the various proprietors, run lanes of 

 water about 4 metres wide. These give ready access to 

 all parts of the pare and are traversed by the boats of the 

 oyster men (parqueurs). These boats at Arcachon are 



