My bodily infirmity and the lateness of the hour force me to end my discourse.  However, I have still many observations to make on the products of the sea, for the admiration of my attentive audience.  To speak of the sea itself, how does its water change into salt?  How is it that coral, a stone so much esteemed, is a plant in the midst of the sea, and when once exposed to the air becomes hard as a rock?  Why has nature enclosed in the meanest of animals, in an oyster, so precious an object as a pearl?  For these pearls, which are coveted by the caskets of kings, are cast upon the shores, upon the coasts, upon sharp rocks, and enclosed in oyster shells.  How can the sea pinna produce her fleece of gold, which no dye has ever imitated? The Pinna is a bivalve with a silky beard, of which several species are found in the Mediterranean.  The beard is called by modern naturalists byssus.  The shell of the giant pinna is sometimes two feet long.  How can shells give kings purple of a brilliancy not surpassed by the flowers of the field?