Page:Natural History, Mollusca.djvu/19

Rh which in some species are placed close to this orifice.

Every one who has touched a crawling Slug or Snail, must have had a practical proof of the delicacy of its sense of touch. The whole surface of the body, invested with a soft, flexible, and mucous skin, contracts on the slightest contact with any unexpected substance, and is, doubtless, an extended organ of feeling, probably much more sensitive than the naked skin of our bodies. But, besides this, most, if not all of these animals are furnished with organs of special touch called tentacles, which serve to collect and convey impressions of the proximity, the form, the hardness, and perhaps other qualities, of those bodies which the animals may desire to investigate. The mantle, also, in many of the Gasteropoda, is fringed with a number of filaments, often curiously branched, which are probably accessary organs of touch.

The sensitiveness manifested by some of the large Gasteropoda, the great Conchs of the West Indies, for example, to the presence of other bodies, even without contact, and which the Rev. Lansdown Guilding attributed to the sense of hearing, may, perhaps, rather be considered as a modification of feeling, capable of appreciating the pulsations of the atmosphere. The experiments of this naturalist, not to be vindicated from the charge of cruelty, are thus described. "I lately suspended," he says, "a number of large Strombi by the spire, that the animal, when dead, might fall from the shell. They had remained in this situation several days, till the body, weak and emaciated, hung down nearly a foot from the aperture, and the eyes had become dim. I found that