FLUYIATILE AND MARINE SHELLS 



NORTH AMERICA. 



[No. 1. The Article Conchology, from the tliird American edition of 

 Nicholson's Encyclopoedia, Philadelphia, 1819.*] 



We here introduce descriptions, illustrated by figures, of a few 

 of the land and fresh water shells of the United States, induced 

 particularly by the silence with which these productions of our 

 country are regarded in the Systema Naturse. In the extensive 

 work of Lister, entitled " Historiae sive Synopsis Methodicae Con- 

 chynorum," &c., several of our shells are figured, and, to a few of 

 them, short descriptions are annexed, not, however, designated with 

 specific names ; of this work we have availed ourselves, from quo- 

 tations and references. 



It will be readily perceived by the conchologist, that in the ar- 

 rangement we have deviated from the course pursued in this work 

 relative to the inviolability of the Linnaean system, so as to intro- 

 duce some of the more recent improvements in the construction of 

 genera, and that some considerable modifications are ventured to be 

 made in this article. 



We think it proper to state, in addition to the above remarks, 

 which were annexed to the descriptions in the first and second 

 American editions of this work, that several species and three new 

 genera are now added, which, with the exceptions of a small num- 

 ber of new species now first published, we have previously given to 

 the world, in several detached essays, in the pages of the Journal 

 of the Academy of Natural Sciences, in the collection of which 

 Academy all the specimens are preserved. 



*[The extracts are taken from the third edition. The previous editions 

 are referred to in the Index. — Ed.1 



