324 SUPPLEMENT 
an elongation of the dermoid envelope, consequently some 
muscular fibres line the internal face of this hollow cylinder. 
These fibres are in a great measure annular, and of course 
their contraction suffices to elongate the organ. 
The mouth is armed above with a small arched tooth, 
adapted for cutting the leaves of the plants on which they 
feed. 
The limaces possess the sense of touch in more perfection 
probably than the helices, and especially in the anterior 
parts, and on the edges of the mantle. In taste, smell, and 
sight, there must be a strong resemblance. That they both 
taste and smell is certain, since they seek out and prefer cer- 
tain substances to others. ‘They donot seem, in reality, to 
perceive bodies, although they are provided with an organ of 
vision, and they are certainly deaf. 
Their locomotion is performed pretty nearly like that of 
snails, by the successive contraction of the muscular fibres of 
the foot, and especially of those of its middle band. But it is 
more lively and more rapid, particularly when they are en- 
deavouring to escape from a place where they have been 
detained. 
Their food essentially consists of vegetable substances. 
These are, particularly young plants, paper, rotten wood, 
fruits, mushrooms, &c. They will also feed upon some 
animal substances, as cheese, meat, and other matter of this 
kind in a state of putrefaction. They are evidently most 
voracious animals, and eat more in the evening than any 
other part of the day. Their mode of eating is a sort of 
mastication, the lingual plate being opposed to the upperjaw, 
and then pushing the substance towards the cesophagus. As 
in all the molluscous animals, digestion appears to be very 
slow in the limaces, and accordingly they can support a very 
long fast. ‘hey are less capable of this, however, than the 
helices, unless they are in very favourable circumstances for 
a a a 
