it< design: the imperfection of human judgment, the uncertainty arising from 

 paucity of material in some OM68, in others, perhaps, the bewilderment caused 

 by its redundancy, are fruitful sources of error which will occasionally waylay 

 and mislead the most honest, thorough and patient investigator. I cannot 

 hope to escape them : but 1 shall take note of all corrections, as well as of such 

 additional information as may hereafter become accessible to me, in order that 

 these may be incorporated in appendices, or perhaps in additional volumes, to 

 l>e published from time to time, whenever the accumulation of such material 

 may render them necessary. 



I feel that the work I propose to undertake is a worthy one : that its com- 

 pletion will enable the Concliologist for the fir xt time to identify and to learn the 

 history of all the species in his cabinet without the necessity of consulting 

 many extensive and costly monographies, besides thousands of fugitive papers. 

 Towards the completion of this task I ask the sympathy and aid of all 

 interested in Conchologioal pursuits. 



GEORGE W. TRYOX, JR. 



