3(5 INTRODUCTION. 
application of scientific knowledge to the investigation 
of the natural resources of the country -would 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 were 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 public, 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 which 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- 
chology in the third American edition of Nicholson's 
Encyclopedia, which 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. Rafinesquc, which will be presently 
noticed, but which, for reasons hereafter given, are not 
deemed worthy of any consideration. The next paper 
