Though several kinds of lichen produce a similar red dye, I agree in opinion with Dillenius, that _Phycos thalassion_ is our archil; for at present no species is known which communicates so excellent a colour, and which corresponds so nearly with the description of Theophrastus. Besides, it is still collected in the Grecian islands, and it appears that it has been used there since the earliest ages[71]. Tournefort[72] found this lichen in the island Amorgos, which lies on the eastern side of Naxos, and which at present is called Morgo. In his time it was sent to England and Alexandria, at the rate of ten rix-dollars per hundred weight; and he says expressly that it was common in the other islands. He shows from Suidas, Julius Pollux[73], and other ancient writers, that this island was once celebrated for a kind of red linen cloth, which in commerce had the name of the island; and he conjectures, not without probability, that it might have been dyed with this lichen. Imperati[74] says, that the _roccella_, of which he gives a figure, was procured from the Levant. This naturalist gives the figure also of a lichen from Candia, used for dyeing, which was then called _rubicula_, and which, as may be seen in Bauhinus[75], is comprehended under the name of Roccella. Dillenius and Linnæus, however, make it a distinct species; and the latter names it _Lichen fuciformis_. This distinction is, perhaps, not improper: for the _rubicula_ does not grow like a shrub or bush, as the _roccella_, but belongs rather to the foliaceous lichens. Be this as it may, it is certain, as Dillenius has remarked, and as I know from my own observation, that _L. fuciformis_ is often mixed with the real roccella, and particularly with that brought from the Canary Islands; but whether it be equally good, experience has not yet taught us. From what has been said, I think I may venture to conclude that our archil was not unknown to the ancient Grecians. But when was it first employed as a dye by the moderns, and introduced into our commerce? Some writers are of opinion that this drug was first found in the Canary Islands, and afterwards in the Levant. The use of it, therefore, is not older than the last discovery of that island. That this opinion is false, will appear from what follows.