INSTINCT, INTELLIGENCE, AND USES 143 
of a Bivalve shell, the vendor receiving back the 
counterpart on the completion of the transaction by 
way of receipt. 
In agriculture shells were formerly much used in 
districts where lime was scarce for dressing the soil, 
and also, it has been stated, in the manufacture of 
porcelain, but for this there appears no warranty. 
Dyes have been extracted from molluscs. The 
Tyrian purple of the ancients was obtained from 
certain species of Murex. Aplysia, the Sea-Hare, 
yields a violet fluid; so, too, does Ianthina, and an 
indelible dye is obtainable from the common Purpura 
of our coasts, but no practical use appears to have 
been made of them. 
As some measure of the part shells play in com- 
merce it may be mentioned that in rg1o £587,115 
worth of shells of all kinds were imported into this 
country, nearly one quarter being from Western 
Australia. 
While, however, man has thus profited by the 
mollusc, the latter, at times directly, but more 
frequently indirectly, has its revenge. More than 
one diver and bather has suffered from the embrace 
of the Octopus and supplied sensational material for 
the fiction writer. The Cones are capable of inflict- 
ing a poisonous bite on the hand of the unwary 
captor. .The Oyster and Cockle from sewage con- 
taminated beds, immune themselves, will convey the 
germs of typhus to the consumer, while Mussels are 
