236 MOLLUSCA. 



surmounts them, but neither of these are more singu- 

 lar than these outriggers, by which the vessel of the 

 Violet Snail is kept both buoyant and steady."* 



We are not aware whether the violet coloured 

 fluid discharged by this species, is capable of appli- 

 cation to the arts, but from several species of the 

 great genus 



Murex y \ the Rock Shell, 



a liquor is obtained, which, before the discovery 

 of cochineal and other modern dyes, was held in 

 high estimation. One species of this tribe produced 

 the far-famed Tyrian purple, the brilliancy and per- 

 manence of whose hue are so highly celebrated by 

 the ancients. The genus is marked by the long 

 straight canal which terminates the mouth of their 

 shells, and the formidable array of ridges and spines 

 with which they are armed. The animal is furnish- 

 ed with a proboscis, and long tentacles, on the .outer 

 side of which are placed the eyes ; in many respects, 

 it resembles the common Whelk, (Buccinum^ but 

 has no operculum. The reservoir of its purple dye 

 is placed above the neck, by the side of the stomach; 

 it seems probable that it is intended as a protection 

 for the creature, being squirted out when alarmed, in 

 the manner of the Cephalopoda. The process by 

 which the ancients transferred the hue to silken, linen 

 or woollen stuffs, has long been lost ; Aristotle, how- 



* Kirby, Bridge-water Treatise, vol. i. p. 291. 



f Its ancient Latin name. t Bt/xav^, bukane, a trumpet. 



