OYSTEE AED MUSSEL REPORT. 113 



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 (PL III, fig. 3). 



In spring and early summer the eleveurs 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 A^alue 

 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 

 w T ater 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 (Algse) make 

 their appearance and soon cover the floor w T ith a dense 

 green growth. This is known to the eleveurs 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. B. J. Harvey Gibson, the 

 lecturer on Botany at University College, who finds that 

 they consist of Claclophora flavescens and Claclophora 

 expansa, along with SpiruUna tenuissima and a Lyngbya, 

 the Claclophora being however the chief constituent. A 

 microscopic examination of these Algse shows that they 

 are teeming with other forms of life. Small Amphipods, 

 Cladocera and other kinds of Crustacea as well as lower 



