THE MOLLUSCA 



211 



When injured, or even irritated, the animal exudes a 

 vast quantity of a purple fluid, which stains whatever it 

 touches very deeply. (This is a different secretion to the 



Fig. 90. Aplytsia punctata. f Natural size 



" Purple of Tyre," which is said to be the product of a 

 form allied to Purpura lapillus, although some maintain 

 it was obtained from a large species of Aplysia.) Aplysia 

 has a powerful odour of cedar oil, which is no doubt pro- 



