PREFACE. 



are mentioned by Mr. Parkinson, in his third volume of the 

 Organic Remains of a Former World, as being published in 

 some other works; either in the Journal (VHistoire Naturelle, 

 ov Memoires de la Societe (.VHisloire Naturelle de Paris, or 

 the Annales du Museum d'Histoire Naturelle, or the Suite 

 des Memoires sur les Fossiles des Environs du Paris, &c. But 

 not having an opportunity of referring to those works, the 

 descriptions of those genera, together with four or five formed 

 by Mr. Parkinson, are taken fi'om his " Organic Remains of 

 a Former World." In order to elucidate the descriptions of the 

 genera both of Linnseus and of Lamarck more perfectly than 

 can be done by verbal description, it has been judged neces- 

 sary to add some plates. The figures are generally of those 

 shells to which Lamarck refers as examples. It is hoped that 

 those parts on which the generic characters depend are di- 

 stinctly shown. In some cases where the shells were not easily 

 procured, or were very common, or the genus so small that 

 perhaps only one species is known, the figures are omitted ; 

 but in this case a reference is given to a plate in some 

 work of credit. Those which are introduced as examples 

 of the principal genera of the recent shells are intended to 

 make the Work more complete ; but if a figure of a shell of 

 every genus had been given, it would have added much to the 



