TO TUOMAS 13. WILSON, M. D. 



My Dear Sir : 



I offer you this volume of my contributions towards the development of one branch 

 of the Malacology of the United States. I feel the more pleasure in so doing, as it testifies my 

 sense of the great yaluc your services have been to the science of our country, by your unwearied 

 and unremitted labors to promote every kind o£ knowledge which our Academy embraces. 

 Very sincerely and truly yours, 



ISAAC LEA. 



