MASEFIELD : THE ECONOMIC USE OF SOME BRITISH MOLLUSCA. 163 



they are not of so good a colour as, and not to be compared either in 

 size or beauty with those found in U. margaritifer. The pearl fishery is 

 still carried on in the Tay and other rivers of Scotland, where this 

 mollusc is found, and during a dry season, when the rivers are low, as 

 much as £S to £\o has been made weekly. In Ireland, near Deny 

 and Waterford, and in Donegal, near Gweedore, in the Clady river, 

 pearl shell fishery is carried on to a small extent, and at the latter 

 place I have had pearls offered to me by the peasants of more or less 

 value according to the clearness of the colouring. The price asked 

 is from ios. to ^5 and more, and single pearls have been found there 

 and sold for ^20. 



In the Conway river and in other rocky streams in Wales this mus- 

 sel is also met with, and I can see no reason why a pearl fishery there 

 should not pay if systematically carried on, as besides yielding pearls 

 the empty shells of this bivalve are regularly manufactured into purses, 

 toys, fancy work, inlaid work, and ornaments of various kinds. The 

 Rev. J. G. Wood states that a pearl taken from the Conway river holds 

 a place in the crown of England. 



Another use for these shells is to pulverize them to give to poultry 

 to cure the very common trouble with poultry-keepers of hens laying 

 shell-less eggs. Shells, too, if calcined, make excellent lime, which is 

 said to be stronger than that made from limestone. The shells of 

 Anodons are also used as cream skimmers and sugar and flour scoops, 

 and the valves of Unios were formerly always used by artists for hold- 

 ing their colours, hence the specific name pictorum. I have submitted 

 thick shells of Unios found in this county to pearl button manufac- 

 turers in Birmingham, to see if they could utilize them in their trade, 

 but they state that these shells are more brittle than those obtained 

 from abroad, or else they would be available for manufacturing pur- 

 poses. Cannot some of our chemists devise some means of over- 

 coming this brittleness, and so give us a new industry ? 



I do not think it is generally known that slugs, and especially the 

 freshwater mussel, Dreissensia polymorpha, are most tempting baits for 

 Perch, Chub, Trout, Eels, and other fish. 



The shells of our larger Helices are also used for making whistles, 

 toys, ornamental pincushions, shell boxes, and ornaments, and I be- 

 lieve it is still a custom with the peasants of Bundoran and Iona to 

 make necklaces of Helix nemoralis and H acuta, and to sell them to 

 tourists for threepence and fourpence each ; bracelets may also be 

 made of these shells, or of H. itala, forming very artistic articles of 

 adornment. Another use of shells is that of making tooth powder by 

 grinding them to dust ; perhaps this may have arisen from Pliny's old 

 recipe, contained in his " Natural History " (vol. 5), where he says 



