PREFACE. 



The admirable " Manual of the Mollusca," of the late S. P. 

 Woodward, forms the basis of the present work ; and in incor- 

 porating with it the numerous important acquisitions made by 

 conchological science during the past twenty years, care has been 

 taken to preserve its conservative spirit, as far as practicable. 



The " Genera of Recent Mollusca," published by Messrs. 

 Henry and Arthur Adams, in 1853-1858, introduced a large 

 number of new generic and subgeneric groups, which experience 

 has proved to be founded on unimportant or mutable characters. 

 This work also, under the plea of priority of date of publication, 

 substituted the vaguely-defined groups of obscure earlier writers 

 for the more accurately described genera of Lamarck and his 

 successors. The " Genera " certainly inaugurated the modern 

 progressive era of sjT^stematic conchology ; but, unfortunately, 

 its vicious antiquarianism and free multiplication of genera 

 revealed tempting opportunities to those desirous of obtaining 

 the cheap distinction of naming new groups, or of overthrowing 

 the names of old ones ; so that for awhile the aim of many 

 writers appeared to be scientific reputation, rather than the 

 advance of knowledge. During the same period appeared 

 "Woodward's " Manual of the Mollusca;" and, probably, to that 

 work, more than to any other influence, is due the gradual 

 reaction towards a more stable classification. 



An immense amount of reliable information is contained in 

 the single 18mo volume of 486 pages, forming the first edition 

 of Woodward (1851-1856)-, still, as the work was intended t-o 



<iii) 



