590 
SNAIL. 
observing, that as the animal increases in growth, 
it draws its tail from the bottom of the shell ; that, 
having become too little for its reception, it then 
ascends higher, and fixes its tail near the second 
or third contortion of the shell, and enlarges its 
apartment at the opening. As it makes these ad- 
vances by little and little, and ascends from point 
to point, as they lie contiguous to each other; those 
parts of its body in the aperture of the shell, that 
by the diversity of their pores cause this variation 
of colour, form one continued and regular streak : 
but when the animal, in changing its situation, 
leaves an interval between the point from whence 
the tail is removed, and the new one to which it is 
fastened, all the other parts of the body move in 
the same proportion; and those in the orifice of the 
shell, that impress the stains, being transferred to 
some distance from the preceding speck, tinge the 
shell so, as to leave a space of more or less extent 
between each spot. A thousand accidents may 
likewise intervene to heighten or diminish certain 
tints, and diversify the whole to infinity. 
Snails have four horns, which are distinctly visible 
while the animal is in motion. The eyes appear at 
the extreme ends of the two uppermost horns like 
blackish points, and their situation is admirably 
calculated to assist the animal in discovering sur- 
rounding objects, as they resemble two lenses placed 
at the end of flexible tubes, which are capable of be- 
ing moved in any direction. The mouth is seen 
beneath the lower pair of horns, and is provided 
