CONCHOLOGIA CESTRICA. 25 



or strings. The young appear in twenty days, or more, 

 being influenced very much by moisture, and tempera- 

 ture ; and are provided, at first, with a shell of about 

 one and a half turns. Unable to subsist without moist- 

 ure, the snails inhabit damp, and secluded, places, under 

 stones, logs, and fallen leaves ; often in pastures, lawns, 

 and gardens. Unlike the slugs, they hibernate during 

 winter, either in their summer retreats, or buried deeper 

 in the earth. On the first occurrence of frost, they retire 

 to their mural homes, close the aperture of the shell, 

 with a thin transparent membrane, the epiphragm; and 

 as the animal retreats, still farther, other epiphragms 

 are successively formed. 



DIAGRAM OF THE SUB-FAMILIES, SUB-GENERA, AND SPECIES, OF 

 THE FAMILY HELICID^. 



FAMILY. 



HELICID^E. 



