170 PROCEEDINGS OF 



out the entire valley of the Mississippi. By pursuing our course still farther, we 

 eventually come to a new zoological district, where great bodies of fresh water ex- 

 pand themselves like inland seas, inhabited, in many respects, by a different suite 

 of speeies, and this may be known as the lake region. 



To effect a subdivision of these broad ranges of territory, we may cross them by 

 any number of parallel lines, equidistant, as the parallels of latitude, and thus, in a 

 rough way, assign the boundary to each smaller district. A great number of lo- 

 calities, whose natural history it were desirable fully to explore, will be created, and 

 collections made within their limits will exhibit great dissimilarity of species, and 

 frequently of entire genera. 



But in the unsettled, and, so far as science is concerned, the uncivilized state of 

 many of the indicated regions, it were impracticable entirely to accomplish so de- 

 sirable an end ; for it would be a long time before an individual, disposed to collect 

 and exchange species, could be found in each, and be placed in correspondence with 

 the National Institution ; and in its recent slate, its duplicates, although exceed- 

 ingly abundant, would scarcely afford a supply to so great a number. I have 

 arranged the surface of the territory of the United States into these numerous por- 

 tions, only to show that collections must be made from all of them, if we wish to 

 possess complete suites of its shells. 



As an illustration of these principles, applied to practice, I established a corres. 

 pondence with gentlemen in the various cities and towns on the Atlantic coast, to 

 wit : St. John's, New-Brunswick ; Portland, Maine ; Boston, Massachusetts ; a point 

 a few miles north of Chesapeake Bay; Charleston, South-Carolina; Savannah, 

 Georgia ; and Mobile, Alabama. I proposed to accomplish, by this method, a col- 

 lection of our coast shells, and have mainly succeeded. But it will strike every 

 one who runs his eye along a map of the coast, that there are, by this enumeration, 

 great gaps left unfilled. I have no station on Long-Island or the Jersey coast ; both 

 sides of the peninsula of Florida are unrepresented ; and it were desirable to havo 

 collections from the mouths of the Mississippi. For the interior, I have selected, at 

 the head of tide, corresponding points to the above ; likewise in the valley of the 

 Mississippi, and others on the Ohio, Cumberland, and Tennessee rivers. 



My experience leads me to believe that the species native to this country will be 

 more acceptable, generally, to intelligent correspondents, than such as may bo pro- 

 cured from foreign voyages, unless the latter be very rare, and in fine preservation. 



I have uniformly preferred liolding correspondence with teachers or professors in 

 vaiuous colleges, or with professional men, who, by their position in society, are 

 above the reach of the invariable cut bono interrogatory ; since many well.meaning 

 persons hold tlie study of these portions of science, without regard to their direct 

 or indirect utility, in groat contempt, and this deters many private persons from 

 their pursuit. Such correspondents likewise command an influence over many 

 persons in their respective districts, and are enabled to draw from all quarters, by a 

 little exertion, large supplies of various new and old species. Another advantage 

 still is found in procuring immediate and full returns from such, as, for the most 

 part, they havo access to either public or private cabinets, know how to collect in 

 the field, and no time is lost in tho process of initiation, which ordinarily occupies 

 one or two seasons before the haunts of all tho species become familiar. 



In adopting this system and sotting it to work in a thinly populated countrj, in 



