The mosses of this order were substituted in the room of the _usnea_ in the composition of the _pulvis cyprius_. The very species, which was most frequently used for this purpose, was the channel-leaved _lichenoides_ of Dillenius[115], on account of its being easily reduced into a fine powder, of a good white colour. Nevertheless, others are undoubtedly as well adapted to the same purposes: and, if it was of importance enough to employ them to any purposes of the like nature in our own country, they might be procured in sufficient plenty. One of the plants of this order is applicable to the same uses as the Canary-weed, and is reckoned not much inferior to it; and as it is found in the same places, it is very often packed up with it in considerable quantities. Dillenius calls it _The flat dyers lichenoides with longer and sharper horns_[116]. It is truly and properly a plant of the lichen genus, tho’ the older writers of the last century called it a fucus. They were led into this mistake by its having flat ramifications, and from its growing on the rocks by the sea side. It is found in the East Indies upon trees, and is frequent on the coasts of the Mediterranean, as well as about the Canary Islands. 7. Lichenes peltati. _Such as consist of a tough or coriaceous matter, disposed into a foliaceous appearance; on the edges of which, in general, the parts of fructification are placed, in the form of flattish oblong bodies, in these mosses called_ shields _or_ pelts. This division contains the third series of the second order of Dillenius’s _lichenoides_; the _lichenes coriacei_ of Linnæus; and several of the _placodium_ of Hill. That celebrated and well-known plant, the ash-coloured ground liverwort[117] of Ray belongs to this order. It is very common all over England on dry and barren ground; and indeed almost all Europe, and America too, seems to afford it in sufficient plenty, as we find it observed by almost all the botanic writers since Ray, who was one of the first that described it.