238 SUPPLEMENT 
astonishing that man often experiences an effect of this nature 
when he eats a considerable number of these animals; but 
it is proved that in certain circumstances, not very easily 
defined, and on certain individuals, the effect is much more 
intense, and often followed by very grievous consequences. 
But it is not merely as objects of nutriment that the mol- 
lusca may be useful to man: some of them, few in number, it 
is true, furnish him with the materials of clothing. Such are 
the pinne marine, whose filaments, which constitute their 
byssus, have been employed from time immemorial by the in- 
habitants of the coasts of the Mediterranean, and especially by 
those of Sicily, to form tissues, equally remarkable for their 
beauty and the duration of their natural colour, and also for 
their lightness, and their property of retaining heat. 
The semi-transparence presented by the valves of the genus 
placuna is the reason why the inhabitants of China and the 
Philippine Islands employ them to furnish their windows, 
where they answer as a substitute for glass. 
The property which certain parts of univalve or bivalve 
shells possess of reflecting the rays of light by decomposing 
them, which characterizes the iridescent mother-of-pearl, has 
caused them to be employed as objects of dress or ornament. 
We also remove by art from these shells portions of greater or 
less thickness of the nacre, or mother-of-pearl ; and according 
to their plane or curved form, their thickness or slenderness, 
we form the ornaments of a multitude of instruments, of 
tables, the pannels of furniture, and of personal ornaments for 
the use of women. 
We have already remarked, that the human species also | 
derives from the animals of the molluscous type many objects 
useful in the arts of painting and of dyeing. If it is not abso- 
lutely proved that the ink of China is formed of the matter 
deposited in the bladder of some species of cryptodibranchia, 
it is at least certain respecting the sepia, which has even 
