PREFACE. V 



Besides this, it had occurred to me that no conchological text- 

 book, except translations of elementary works, had been published 

 in this country; and that a work in which especial prominence 

 should be given to the description and illustration of American 

 genera would be found very useful by our students, as well as 

 by many conchologists in other countries who are interested 

 in American mollusks. 



These designs I have decided to carry out in the present 

 volumes. I have also aimed at more abundant illustration than 

 is contained in the text-books referred to. The plates of this 

 work will embrace nearly three thousand figures, mostly of good 

 size, and sufficiently well-done to insure the recognition of the 

 species. This feature has considerably increased the cost of the 

 book, but will, I believe, full}'- recompense the purchaser for its 

 necessarily increased price. Besides Woodward, I have availed 

 mj'self fully of the large amount of valuable original material 

 contained in the first parts of Dr. Fischer's " Manuel." My 

 own time has been so engrossed by the study of systematic 

 conchology, that the structural portion of mj^ book is peculiarly 

 indebted to Dr. Fischer ; who, although an accomplished syste- 

 matist, has mainly and very successfull}^ occupied himself with 

 anatomical investigations. 



These general acknowledgments made, I have not deemed it 

 necessary to designate by quotation-marks in the text all the 

 paragraphs for which I am indebted to Messrs. Woodward and 

 Fischer ; but the authorities for numerous otherwise-derived 

 statements and quotations are carefully recorded. The whole 

 bod}' of notes and references collated for my " Manual of Con- 

 cholog3%" now in course of publication, has been examined for 

 material. The " Structui'al and Systematic Conchology " may 

 be considered an introduction and companion to that work. 

 Constant and important aid in the preparation of the fossil 

 genera has been rendered by my able colleague, Prof. Angelo 



