I iS s 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, 1 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 H". pulchella live in open and 
exposed situations destitute of shelter, except that 
afforded by grass and shrubs. Helix cellaria 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 
1 There is a single exception t<> this remark in Helix faJtlaX) Saj , which 
we observed a few years since living in great numbers in gardens, iu 
Charleston, S. C. in company with Bulimtts decollaius. 
