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 1910 £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 



