OYSTER AND MUSSEL REPORT. 55 
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 parcs. 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 3 inch across in a couple of months. 
When one year old they are usually from 1 inch to 13 inches 
in diameter, and when two years old they are usually 
from 2+ to 24 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 parcs, 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 
