1 84 The Irish Naturalist, [July, 



III.— NOTES ON THE MARINE MOLLUSCA OF 



RATHUN ISLAND. 



BY GKORGE \V. CHASTER. 



Encouraged by the success of our last year's work, four of 

 our party determined to dredge again in Church Bay, Rathlin 

 Island, our special object being the discovery of the habitat 

 of Montacida donacina. Unfortunately we were almost 

 entirely becalmed, and our boatman considered that there 

 was a risk of our being carried away by the tidal current if 

 we ventured as far to the west side of the bay as our last 

 year's ground. Our operations were therefore confined to 

 the middle of the bay, and thence S.E. towards Rue Point. 

 We obtained from our several hauls a very large quantity of 

 sand, which was passed through our sieves and afterwards 

 through a sieve of special construction designed to avoid the 

 necessity of throwing away the enormous quantity of sand 

 which still contained certain small forms. Ordinary sieves of 

 wire gauze cannot conveniently be used with a smaller mesh 

 than ^-inch, as sand rapidly chokes finer gauze. Our 

 ** washer," as we styled it, served its purpose so admirably, 

 that I will briefly describe it. 



The framework consists of two rings of stout brass wire. 

 On these a broad piece of sackcloth was sewn, whilst at the 

 bottom was stitched a piece of corn-millers' silk bolting cloth, 

 with 40 meshes to the inch. To the uppermost ring were 

 fixed four cords meeting in a loop, by which was suspended 

 the washer, which, when complete, looked like a large sieve 

 with collapsible sides. It measured nine inches in depth, and 

 fourteen in diameter. The washer was hung over the side of 

 the boat from a rowlock, being half immersed in the sea and 

 constantly rotated to and fro. It was surprising to see how 

 quickly the sand was got rid of, leaving behind everything of 

 value. Instead of several hundredweights we took home 

 little more than a pint of material from our sieves and 

 " washer." 



