188 INTRODUCTION. 



tions, that these combined causes operate over an exten- 

 sive region, and there, consequently, the species proper 

 to it exist in multitudes. In the parts of the country 

 which have been long cultivated, and are nearly deprived 

 of their forests, they have mostly disappeared, and only 

 survive in places where some shelter of wood or stones is 

 still afforded to them. They everywhere avoid cultiva- 

 ted fields and open pastures, and are never found in 

 gardens/ or about or within houses or other buildings. 

 In this respect, they present a remarkable contrast to 

 the same animals in Europe, which not only are very 

 common in open and cultivated tracts, but are particu- 

 larly numerous in fields and gardens, where some of the 

 species commit much mischief, and in cellars, drains and 

 other similar situations, in immediate contiguity with 

 man. The species which have been introduced from 

 Europe, and naturalized in this country, are distinguished 

 by the same habits as the stock from which they are 

 derived, and differ as much from the native species. 

 Thus, Helix hortensis, and IT. jnilchella live in open and 

 exposed situations destitute of shelter, except that 

 afforded by grass and shrubs. Helix cellar'ia occupies 

 gardens and cellars. Limax variegatus inhabits cellars 

 and damp places about drains, and L. agrestis is com- 

 mon everywhere in gardens, fields, cellars, and houses. 

 It infests the road side, and the neighborhood of our 



' There is a single exception to this remark in Helix fallax, Say, which 

 we observed a few years since living in great numbers in gardens, in 

 Charleston, S. C. in company with Bulimiis decnllatxis. 



