MOLLUSCGA. i 
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 deli- 
cacy 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 ex- 
tended organ of feeling, probably much more sen- 
sitive 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 tenta- 
cles, which serve to collect and convey impressions 
of the proximity, the form, the hardness, and per- 
haps other qualities, of those bodies which the 
animals may desire to investigate. ‘The mantle, 
also, in many of the Casteropoda, 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 Casteropoda, the great Conchs of the West 
Indies, for example, to the presence of other 
bodies, even without contact, and which the Rev. 
Lansdown Guiding 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 aper- 
ture, and the eyes had become dim. I found that 
