CHAP. 59. (39.)—VIPERS AND SNAILS.
It is said, that the viper is the only one among the serpents that conceals itself in the earth; the others lurking either in the hollows of trees or in holes in the rocks.1866 Provided they are not destroyed by cold, they can live there, without taking food, for a whole year.1867 During the time that they are asleep in their retreat, none of them are venomous.
A similar state of torpor exists also in snails. These animals again become dormant during the summer, adhering very powerfully to stones; and even, when turned up and pulled away from the stones, they will not leave their shells. In the Balearic isles, the snails which are known as the cave-snail,1868 do not leave their holes in the ground, nor do they feed upon any green thing, but adhere to each other like so many grapes. There is another less common species also, which is closed by an operculum that adheres to the shell.1869 These animals always burrow under the earth, and were formerly never found, except in the environs of the Maritime Alps: they have, however, of late been dug up in the territory of Liternum;1870 the most valued, however, of all, are those of the island of Astypalæa.1871