36 INTRODUCTION. 



application of scientific knowledge to the investigation 

 of the natural resources of the country woiild hasten 

 the discovery of new sources of prosperity, and disclose 

 the best and most economical mode of developing and 

 improving those already known, induced the Legislatures 

 of more than half the States of the Union, to establish 

 scientific Commissions for the examination of the Geology 

 and Mineralogy of those States respectively. In some 

 of them the Commissions Avere directed to collect infor- 

 mation respecting Zoology and Botany. In accordance 

 with this authority, extensive and elaborate works on the 

 Zoology of Massachusetts and of New York have been 

 given to the pubhc, at the expense of those States, and 

 catalogues of the species, with short notices of the 

 animals of other States, have also been prepared. These 

 have contributed much to elucidate the general subject, 

 and, especially, have added largely to what was before 

 known of the geographical distribution of species. 



The two classes of publications Avhich have been men- 

 tioned, are believed to comprise all the materials, of any 

 importance, relating to the particular department of 

 Zoology here treated of, except the article entitled Con- 

 cliology in the third American edition of Nicholson's 

 Encyclopedia, wliich bore the date of 1819, and con- 

 tained descriptions, by Mr. Say, of several native land- 

 shells. In this exception must also be included the 

 papers of Mr. Rafinesque, which Avill be presentl}'- 

 noticed, but which, for reasons hereafter given, are not 

 deemed worthy of any consideration. The next paper 



