SNAIL. 
589 
covering, the new piece that fills the vacancy should 
exactly tally in colour with the old fragment, as well 
as with all the rest of the shell ; and yet several snails 
repair their shell in such a manner that the addi- 
tional piece will be of a different colour from the 
rest. This circumstance, as well as the streaks and 
clouds which we admire on the shells of these ani- 
mals, is supposed to proceed from the different dis- 
position of the extreme parts of the creature’s body, 
that are visible at the aperture of the shell, where 
we may frequently discover some minute lobes or 
lines of flesh, that differ from the rest in colour. 
This variety leads us to believe that they have a 
different texture from those that are contiguous, and 
consequently the juices that flow into them, passing 
through strainers, whose perforations vary from those 
of the adjoining parts, acquire a particular com- 
plexion in that place ; and as these lobes perform 
their functions and evacuations as well as the others, 
and, in the successive formation and enlargement of 
the shell, contribute their proportion with the rest of 
the shelly substance that is from time to time thrust 
out, all the points of the old shell that correspond with 
them must inevitably assume the same colour, and 
which differs from that of the surrounding parts : 
consequently these colours must be drawn out, and 
distributed into lines and rays, and continued in the 
same manner as long as the animal persists in her 
gentle motions, and makes new additions to her 
shell, by the repeated protrusions of her body. 
This process may perhaps be rendered clearer by 
