The four are the _Buccinum lapillus_ of Pliny,[285] which is the _Purpura lapillus_ of modern naturalists; the _Murex trunculus_; the _Murex brandaris_; and the _Helix ianthina_.

The Buccinum derives its name from the form of the shell, which has a wide mouth, like that of a trumpet, and which after one or two twists terminates in a pointed head.[286] The _Murex trunculus_ has the same general form as the Buccinum; but the shell is more rough and spinous, being armed with a number of long thin projections which terminate in a sharp point.[287] The _Murex brandaris_ is a closely allied species, and "one of the most plentiful on the Phoenician coast."[288] It is unlikely that the ancients regarded it as a different shell from _Murex trunculus_.

The _Helix ianthina_ has a wholly different character.

It is a sort of sea-snail, as the name _helix_ implies, is perfectly smooth, "very delicate and fragile, and not more than about three-quarters of an inch in diameter."[289] All these shell-fish contain a _sac_ or bag full of colouring matter, which is capable of being used as a dye.

It is quite possible that they were all, more or less, made use of by the Phoenician dyers; but the evidence furnished by existing remains on the Tyrian coast is strongly in favour of the _Murex brandaris_ as the species principally employed.[290] The mineral treasures of Phoenicia have not, in modern times, been examined with any care.