38 MOLLUSCA. 
composed of the black liquor of some species of 
Cuttle; and an ink is prepared in Italy from this 
liquor, which, according to Cuvier, differs from the 
genuine China ink only in being a little less black. 
Among the ancients this secretion was certainly 
the basis of the ordinary writing ink, and the soft 
blackish-brown colour, known as sepia, is at this 
day manufactured from it. 
The Tyrian purple, the most celebrated manufac- 
ture of that famous crowning city whose merchants 
were princes, was the juice of a shell-fish. Several 
species were employed to communicate various tints, 
but the principal was the Murex trunculus, one of 
the commonest shells of the Mediterranean, which 
may be compared for size and general appearance 
to our familiar Whelk. But there is a shell oc- 
curring by myriads on our own rocky shores, which 
has a like property ; it 
is the Purpura lapillus, 
a small white univalve, 
surrounded by one or 
more bands of brown 
more or less distinct. I 
have myself been en- 
tertained with making 
experiments on the 
purple dye of this shell-fish, which, perhaps, some 
of my readers may like to imitate. In order to 
this, having collected a few of the animals, which 
adhere to the rocks between tide-marks, break the 
shells with the blow of a hammer, taking care not 
to crush the animals: throw them then into a basin 
of fresh water, in which they will die in a few 
minutes. Examining them now, you will find, just 
behind the head, under the overlapping edge of the 
PURPURA. 
