M U R p. X. 95 



ought not at once to degenerate into mere specific 

 ones, but should, in subordination, collect the spe- 

 cies into natural divisions. 



The genus owes its designation to a certain 

 number of its shells, which are rough and rock- 

 like. The PunpuR-E of the ancients form the se- 

 cond section. From these shells, or rather from 

 their inhabitants, was expressed the famous Tyrian 

 dye, the costly purple which constituted an attri- 

 bute of imperial dignity. A single vein situated near 

 the head of the fish contains this colouring liquor 

 which was formerly considered so precious, but has 

 of late years yielded its claims on public estima- 

 tion to other purple dyes equally beautiful and 

 more easily attainable. 



The quality is not confined to this one family of 

 Testacea, but has been discovered in certain spe- 

 cies of Buccinum, and may very probably belong- 

 to some Limaces which inhabit other genera. 



