LECTURE XL 17S 
cretions have' been formed Besides those found 
in the body of the animal, several are often observ- 
ed rising from the internal surface of the shell, to 
which they are closely attached, so as not to be 
completely round, and are therefore considered as 
of little value. The largest Pearl-Shells, and such 
as are most encrusted with extraneous marine subn> 
stances, as Serpulae, Corals, &c. are in general ob- 
served to be most productive of pearls ; while the 
smaller and smoother shells afford but few, or so 
small as to be of no importance in commerce. 
In addition to what has been said relative to 
Pearls, we may add, that irregular or grape- shaped 
pearls sometimes occur, Avhich seem to be owing 
to a coalescence of several smaller ones into one 
mass. One of the noblest pearls on record is that 
which Cleopatra is absurdly said to have dissolved 
in vinegar, during an entertainment which she 
gave to Mark Antony, and afterwards to have 
drank it. We must surely suppose that she 
caused it to be well bruised first, before she put it 
into the vinegar. It was a pearl belonging to a 
* According to Cuvier pearls may be considered as formed by 
an extravasation of the calcarious matter with which the animal 
is furnished, for the augmentation of its shell. 
