I i 



PREFACE. 



be more rudimentary in scope than that of the Messrs. Adams, 

 many of the less important groups were insufficiently charac- 

 terized or omitted. The Supplement published by Prof. Ralph 

 Tate with the edition of 1870, included many additional genera, 

 but scarcely represented the progress of the science to that date. 

 Subsequent editions present no new features or additions. 



Practically, more than twenty years have thus elapsed since 

 the publication of an English text-book upon conchology ; and 

 for an almost similar period no treatise on the subject has 

 appeared in any other country ; yet these years have unques- 

 tionably been the most active in research and discovery of any 

 in the history of the science. Dr. Kobelt, in Germany, Dr. Paul 

 Fischer, in Paris, and myself, appear to have nearly simulta- 

 neousl}^ conceived the idea of supplying the want thus indicated. 



Of Dr. Kobelt's work, now completed, it suffices to say that 

 its elementary character makes it an introduction to, rather 

 than a text-book of conchology. Dr. Fischer and myself have 

 recognized the superiorit}^ of Woodward's Manual over every 

 similar work heretofore published; and we have not only adhered 

 generally to its plan, but largely copied from its pages. 



Dr. Fischer's " Manuel de Conchyliologie," is in every respect 

 an excellent work, well planned and abounding in original obser- 

 vations ; and it promises, when completed, to become a worthy 

 successor of " Woodward." Higher commendation could not be 

 bestowed upon it. The first number of Dr. Fischer's " Manuel " 

 appeared before I had definitely arranged the scope of my own 

 similar undertaking ; and at first I thought of abandoning the 

 latter, to issue in its stead a translation of Fischer, with notes. 

 But I had contemplated a work which, conservative as to genera, 

 should nevertheless include, in a subordinate rank, the names 

 and diagnoses of the numerous less well-marked or critical 

 groups of modern authors ; that is, these groups were to be 

 included in more comprehensive ones, yet not extinguished. 



