INTRODUCTION. g-j' 



succeeding the article on Conchology, also by Mr. Say, 

 published in the Journal of the Philadelphia Academy, 

 is dated in January, 1821. These are the two earliest 

 pubhcations relatmg to this subject ; and, although their 

 date is so recent, they anticipated all foreign pubhca- 

 tions, and secured the priority of the descriptions and 

 names contauied in them. The same good fortune has 

 attended the later pubhcations here, so that it may be 

 said, that with a few exceptions, American species 

 have been first described by American naturalists. The 

 exceptions are, descriptions by MM. Mliller, Ferussac, 

 and others, of species common to the Antilles, and some 

 parts of the shores of the Gulf of Mexico, as well as to 

 the United States ; and by ]Mr. Rackett, of a smgle 

 species from Canada, pubhshed in the Linngean Transac- 

 tions in 1822. It seems remarkable, considering the 

 frequent intercoui'se between this country and Europe, 

 and the activity that already prevailed among European 

 naturahsts in procuring new objects from foreign coun- 

 tries, that so few American species fell into their hands 

 previous to the time when the American publications 

 commenced. Indeed, they seem to have been better 

 known to JNIr. Lister in 1770, than to M. Lamarck in 

 1822, the former having given figures of nine or ten of 

 them, against descriptions of only five by the latter. 



The titles of the various papers, memoirs, catalogues, 

 and more elaborate works, relatuig to the terrestrial 

 mollusks, may be found in the catalogue of American 

 authors contained m the preceding pages. On reference 



