I'koc. K. I. Acad., Vol. XXIX.. Sect. B. 



Plati-; VII. 



M*H,4.iH4<; 



4^ 



45 46 47 ^8 49 50 



51 



|> 



52 



53 



54 



55 "^^ 56 



R. Welch, Photo. 



Variation in form and size. 

 Stelfox. — L\ND AND Fresh-watek Mollu.sks of Ireland. 



