of research at his command. To avoid extending the size of this catalogue, syno- 

 nymes have bean omitted, except in those casesjn which varieties have been re- 

 garded by the authors of the names as distinct species. Exceptin the more obvi- 

 ous cases of specific identity, the union of varieties has not been attempted, and 

 the correctness of all the species herein named is not guaranteed. The order of 

 arrangements, in the several parts, is that of Lamarck, inverted and with a few al- 

 terations. 



Some Algerian shells have been included in Part I, and the West Indian spe- 

 cies are included in Part II, Those, which were collected by the Author in the 

 Island of Jamaica, have the letter J. annexed to their names. 



It has been an object in this collection to obtain a great number of varieties of 

 form, color, size, density, &c., the effects of age, locality, accidents, &c.j and the 

 result has been in some cases that supposed species are degraded to the rank of 

 varieties, while in others slight differences have been found to have an unexpected 

 constaiacy. Bui it is not consistent with the design of this catalogue to introduce 

 any such results here. The practice of making such collections is mentioned in 

 order to recommend it, as of much importance in determining the limits of species, 

 and especially appropriate for public institutions. 



C, E, ADAMS. 



Middlebury,Vt.,Jan. 1, 1847. 



