ON MOLLUSCA. 239 
received its name from the colouring matter which it yields, 
and which is so finely and so equally divided. 
It is not less doubtful that the ancients extracted the fine 
purple colour, with which they tinted the garments almost 
exclusively consecrated to princes, from a species of subcepha- 
lous mollusca, of the family of the purpure, which inhabited 
the shores of the Mediterranean, and especially towards the 
coasts of Tyre, and which no doubt it would be easy to find 
again, or to replace by some species of our own seas, as has 
been proposed by many other writers. But the small quantity 
of this colour which was derived from each individual, and 
consequently the great difficulty attached to the tincture, must 
have led to the abandonment of this employment of the mol- 
lusca, especially when means were discovered of replacing the 
purple by a colour equally fine, furnished in abundance by the 
kermes and the cochineal. . 
We shall not delay long in explaining the therapeutic pro- 
perties attributed by the ancient physicians to certain parts of 
the mollusca, because time has not respected those opinions, 
but has destroyed them in succession. The only one which 
appears to have resisted its influence is that of the calming 
and soothing virtues of the decoction, or rather broth, made of 
snails and others of the limax and helix tribe, in affections of 
the chest and lungs. This, however, is any thing but a spe- 
cific remedy. We may add the slightly purgative quality of 
oysters and pectines when eaten raw, which, most probably, 
as we have already hinted, may be attributed to the sea-water 
which they contain. 
After what has been said, it is evident that the principal 
utility of the mollusca to man consists in the article of diet ; 
but we shall also find that these animals are less injurious to 
us than useful. 
The octopi are perhaps the only species which, by their 
carnivorous instinct, may prove injurious to us, in the relation 
