INTRODUCTORY LETTER. 21 



Mollusca, Mr. George W. Tryon, jr., of the Academy of Natural 

 Sciences of Philadelphia; Mr. W. G. Binney, of Burlington, N. J.; Dr. 

 James Lewis, of Mohawk, N. Y.; and Mr. -Temple Prime, of New York 

 City. 



I have the honor to be, very respectfully, your obedient servant, 



H. C. Yarrow, 

 Acting Assistant Surgeon United States Army. 

 First Lieut. George M. Wheeler, 



Corps of Engineers United States Army, in charge. 



