96 UNIVALVES. 



could be removed from that part which it is in- 

 tended to cover ; the animal therefore is furnish- 

 ed with the means, perhaps by a solvent liquid, 

 of eating away the lower part of these projections, 

 so that they become detached and fall off by the 

 time that he is ready to form his new inner lip 

 upon the space which they occupy ; thus he 

 forms a comparatively smooth and even surface 

 on which he is to spread the testaceous matter, 

 of which the addition to his building is composed.* 

 It is principally in this genus that are found 

 the shells which yielded the celebrated Tyrian 

 dye, they were thence called Purpurae. An ex- 

 pression of Virgil implies that it was extracted 

 from the animals of this genus in his time ; He 

 says, " glowing with Tyrian Murex." The Ty- 

 rians were the most successful among the ancients 

 in preparing and using this celebrated colour. 

 The Mediterranean supplied them with the mol- 

 lusks in abundance, and in order to produce the 

 tint that was in highest estimation, a bath of the 

 liquid extracted from the animal of the Murex 

 was prepared : in this they steeped the wool for 

 a certain time, and when taken out they im- 

 mersed it in another boiler, which contained an 

 extract from the Buccinum alone. Wool which 

 had been subjected to this double process was 

 so highly valued, that in the reign of Augustus 

 each pound of it sold for about j36 ; this enor- 



* Sowerby's Genera of Recent and Fossil Shells. 



