136 LAND AND FRESH-WATER MOLLUSKS. 
several but much thinner epiphragms, behind 
which it rests ina torpid state during the winter ; 
thus it remains unconscious of what is going on 
around it—sleeping through the winter months, 
until the genial showers of April call it forth. 
Its specific name pomatia is derived from the 
Greek poma, an operculum, from the thick cal- 
careous epiphragm it forms. 
This snail has been the object of numerous 
experiments, with the view of ascertaining the 
extent of the remedial power among land mol- 
lusks. The Abbé Spallanzani cut off the tenta- 
cles, which were reproduced even to the eyes at 
the end of two months; not content with sub- 
jecting the creature to such torture, he tested 
the reparative power in a greater degree, by 
removing the entire head, which was reproduced 
to perfection. The snails thus experimented 
upon, retired immediately into their shells, and 
there remained weeks or months, outwardly in 
a state of quiescence, but internally the won- 
derful power of reproduction was silently at 
work until the end was attained. 
The Helices diminish in size with their range 
in elevation; but H. pomatia, on the other hand, 
» Increases in size according to the altitude at- 
tained. Itis found on the Vaudois Alps, up to 
the very verge of the forests, 5,850 feet above 
the level of the sea. 
