OYSTER AND MUSSEL REPORT. 59 
of gleaming white salt which are formed at the sides of 
the salt marshes are often a conspicuous feature in the land- 
scape. They are seen in one of the figures (PI. IIT, fig. 3). 
In spring and early summer the éleveurs prepare their 
claires for use by emptying them of water and allowing 
the floor to be exposed for some time to the sun and 
weather, they then dig over the soil on the bottom and 
break it up thoroughly so as to let air through it. They 
dig the edges more deeply so as to form a slight trench all 
round which is said to be of some importance in catching 
and retaining the fine sediment, and may also be of value 
in equalizing the temperature. In the central part of the 
claire the soil is heaped up so as to form in some cases a 
considerable convexity, so that later on, when in use, the 
water is shallower in the middle. 
About July or August they let a little water in by the 
sluices and this mixes with the clay and marl crust and 
makes a frothy scum in which many lowly organisms begin 
to grow. A little later more water is let in so as to fill up 
the claires and then the green water-weeds (Algw) make 
their appearance and soon cover the floor with a dense 
green growth. This is known to the éleveurs as ‘‘ moss” 
or “‘ verdure’’ and they recognise its very great importance 
in connection with the nutrition of the oysters. 
I collected samples of the green growth from the bottoms 
of several claires, and these specimens have been carefully 
examined for me by Mr. R. J. Harvey Gibson, the 
lecturer on Botany at University College, who finds that 
they consist of Cladophora flavescens and Cladophora 
expansa, along with Spirulina tenuissima and a Lyngbya, 
the Cladophora being however the chief constituent. A 
microscopic examination of these Algee shows that they 
are teeming with other forms of life. Small Amphipods, 
Cladocera and other kinds of Crustacea as well as lower 
