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THE NON-MARINE MOLLUSCA OF LLANDUDNO 

 AND DISTRICT. 



By H. BEESTON. 



(Read before the Society, March T4th, 1917). 



In August, 1901, I spent three weeks at Llandudno, and occupied 

 much of my time collecting. In 19 15 I again visited the district, and 

 spent a fortnight in and around Llandudno, making some additional 

 observations. 



If these notes serve no better purpose they will at least shew that 

 molluscan life is no exception to the law of change and variation ; 

 not only do habitats alter or disappear entirely through the onward 

 march of civilization, but the animals increase or decrease very 

 perceptibly ; variation takes place ; some varieties die out or nearly 

 so, while others appear to increase and become almost permanent. 

 Species recorded by one observer as abundant at one time appar- 

 ently disappear altogether for years ; then as suddenly re-appear in 

 large numbers. 



A great deal of the interest in the study of the fauna of a district 

 is to try and discover why these changes occur. 



Some rather curious facts were the outcome of my researches. 

 When I first visited Llandudno (1901) seventeen years had elapsed 

 since Mr. W. Denison Roebuck had published a List of Mollusca of 

 Llandudno and District {Quarterly Journ. of Conch., vol. iv, p. 206), 

 which was followed two years later by a supplementary one from 

 Mr. J. R. le B. Tomlin {Quarterly Journ. of Conch., vol. v, p. 28). 



Since then practically nothing has been published, so with my own 

 notes and observations I have endeavoured to bring all the known 

 information up-to-date. I am indebted very largely to these old lists 

 for the compilation of my own, and I would like to say that so 

 thoroughly was the district worked by Messrs. Roebuck and Tomlin 

 that I have been able to add but few new species. 



In the first place I will refer to local changes in the topography 

 of Llandudno and district, which have caused either total disappear- 

 ance of some species, or the decrease in others, which I noted in 1 901, 



Mr. Roebuck says : — -" One pond in Abbey Road, close under the 

 south-west escarpment of the Great Orme, . . . yields Sphcerium 

 lacustre and Physa hyptwriim also." 



One day I decided to explore this pond, but was greatly dis- 

 appointed. I discovered a trim model yacht pond, surrounded by a 

 gravel path, the sides of the pond being carefully concreted, the 

 water weeds and snails being conspicuous by their absence. 



