The English flora - SeaweedAfrica

130 L1CHENES.
first plants which clothe the bare rocks and form a humus for
others of a higher organization to live and flourish in. In the
arts, in domestic economy, (scarcely in medicine,) many of them
are highly valuable, as will be mentioned under the respective
species.
The Genera of Acharius, being those in most general use, are
here adopted, with some modifications : and the arrangement
followed is founded on that of M. Fee (published in his
" Essai sur les Cryptogames des ecorces exotiques officinales"},
which arrangement appears to me to be the most natural of
any that has hitherto appeared. Eschwetter, Fries, Agardh,
Meyer, Walroth, and Chevalier, have likewise proposed new
methods ; but I have not yet had the opportunity of studying
their respective merits. It will be seen in this and the remaining
Orders of Cryptogamia, that the plant itself, independent of
the fructification or reproductive organs, by whatever name they
may be called, is essential in distinguishing the genera, as is
also the fructification.
It is to be regretted that no publication of specimens of the
Lichens of Great Britain, (which have been so successfully
ascertained and described by the labours of Dickson, Smith,
Turner, and Borrer) similar to those of 31osses by Drummond
and Hobson, and of Hepaticce by the latter, has appeared.
Such a work (including other Cryptogamic Plants,) was begun
by Mr. Baxter of Oxford, but the author died before it had
reached the 3d. Fasciculus ; and no one has undertaken the con-
tinuation. Upon the Continent many have appeared of consider-
able merit, and which have proved of great utility in the study of
Cryptogamic Botany. I may particularly mention the Stirpes
CryptogamiccB Vogeso-RJienance of Mougeot and Nestler, the
Cryptogamische Gewachse besonders des Fichtelberg of Funck,
the Lichenes Exsiccati of Reichenbach and Schubert, and above
all the Lichenes Helvetici Exsiccati of my valued .and learned
friend M. Schcerer, Minister of Lauperswyl, in the Canton of
Berne, with whom I have collected many of the specimens
contained in his work, in one of the most delightful excursions
I ever made upon the Alps of Switzerland. These publications,
however, are rare in this country, and I shall limit my
references to that of M. Schserer, than whom no one has studied
the family with more ardour and enthusiasm, nor under more
favourable circumstances ; whether his situation be considered,
surrounded as is his place of residence by lofty mountains and
the noblest forests, or his extended correspondence with the
most eminent Lichenographists of Europe. With such helps
as these now enumerated, and such figures as those of English
Botany, the difficulty of studying this extensive and intricate
tribe will be found much diminished.