its design: the imperfection of human judgment, the uncertainty arising from 



paucity of material in some rases, in others, perhaps, the bewilderment o 



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



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

 hope to escape them : but I shall take note of all corrections, aa well a* of such 



additional information as m.-iy hen-after become accessible t.. me. in order that 

 those may be incorporated in appendices, or perhaps in additional volm,, 

 be published from time to time, whenever the accumulation ,,f such material 

 may render them necessary. 



I 1V.-1 that the work T propose- to undertake is a worthy one : that its com- 

 pletion will enable the ttmchologist/or tkefirtt time to identify and to learn the 

 history of all the species in his cabinet without, the aecessity of consulting 

 many extensive and costly monographies, besides thousands of fugitive paper,"! 

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

 interested in Conchological pursuits. 



<;KOR<JK w. TRVOX, ,J K . 



