WHELKS, ETC. 175 
apparatus consists of two unequal plumes, the 
leaflets of which are arranged like the teeth of a 
comb. An operculum is for the most part present, 
horny in texture, marked with lines which show 
the layers of progressive growth, but varying much 
in form, according to the different genera. 
Some of the more prominent, or more interesting 
of the genera composing this important group, I 
shall slightly notice; and first of all, that fine 
series of shells which gives name to the family, 
the genus Murex. Many of the species are remark- 
able for their brilliancy of colouring, and for the 
beauty and singularity of the forms which they 
assume. ‘The siphonal canal is sometimes greatly 
lengthened, as in the species called the Wood- 
cock’s-head (J. haustellum), and is occasionally 
beset, as well as other parts of the shell, with long 
shelly spines, as the Thorny Woodcock (M. tennis- 
pina): often the progressive stages of growth are 
marked by beautiful shelly foliations, as in the 
magnificently-hued Royal Murex (J. regius) of 
South America. 
It was from various species of this family, but 
preeminently from those of the genus Murex, that 
the ancients obtained the purple dye which made 
Tyre the “ crowning city.” This rich hue was of 
great costliness ; its beauty has been celebrated by 
poets and historians, and the very finest kinds were 
reserved for the hangings of temples, and the robes 
of kings and priests. In the reign of Augustus, 
double-dyed purple wool was sold for about 36/. 
sterling per lb. But as wealth would not hesitate 
at any price to obtain that which was fashionable, 
laws were enacted, rendering it penal for any one 
but the emperor to wear cloth of this sort. 
