96 UNIVALVES. 



shells, unless they could be removed from that 

 part which it is intended to cover ; the animal 

 therefore is furnished 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 forming 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 

 Tyrians were the most successful among the 

 ancients in preparing and using this celebrated 

 colour. The Mediterranean supplied them with 

 the mollusks in abundance, and in order to pro- 

 duce 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 immersed it in another boiler, which con- 

 tained 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 



* Sowerby's Genera of Recent and Fossil Shells. 



