88 HELICID^. 



dens and open fields, but are generally confined to 

 forests, sheltered under logs and stones, and are rarely 

 seen abroad except during twilight or on damp and dark 

 days ; indeed, they almost entirely disappear as the 

 forests are cut down, and seem to flee the approach of 

 man. The European species, on the other hand, follow 

 in the track of cultivation, and are common in gardens 

 and fields, on walls and hedges, and other places exjjosed 

 to the action of Ught. With the exception of R. alter- 

 nata and H. polychroa, there is scarcely a species hav- 

 ing bands or variegated colors inhabiting the United 

 States proper ; and even this latter species can scarcely 

 be regarded as an exception, as it is only to be found at 

 the southern part of Florida, and is more properly a 

 West India shell. In Texas, and beyond the Rocky 

 Mountains in Oregon and California, many of the spe- 

 cies have one or more bands. 



Another pecuharity of the American snails is the 

 tooth-like appendages with which the aperture of a large 

 proportion of them is armed, and which are characteiis- 

 tic of the group designated by F^russac under the name 

 Hehcodonta. More than one-half of the whole number, 

 and more than three-fourths of those with reflected lips, 

 are thus provided. In some species these appendages 

 assiune the form of folds rather than teeth ; and in 

 others we have simple threads or laminae revolving with- 

 in the aperture in the course of the spire. They are 

 not formed until the shell has attained its full growth. 



The Hehces are found in every region of the United 



