louiid the World, aecompuuied hy very heautiful ]dates.
Whatever he the merits ol' these authors, they concur in
warmly advocating the opinions ol their late countiyman
Professor L amouroux, in opposition to those ol the learned
Swedish Algologist. In order, therefore, to do justice to my
subject, an examination of the rival arrangements was now
absolutely necessary ; and as this could not he doue, hy passing
under review the productions ol a single country, I had
no resource hut carefully to investigate the structure and affinities
of the orders, genera and species, of all inarticulated
Alga. I t is hardly necessary to mention, th a t my materials
for this purpose were not so complete as for my original undertaking,
h u t they were nevertheless of such a nature as to
enable me to proceed, in most instances, with considerable
confidence. Very much, however, i-emains to he done; we
are quite ignorant of the fructification of numerous species,
and that of many others is very partially understood. Systematic
relations are consequently in such cases only indicated
or conjectured hy the structure of the frond, or the
mere habit of the plant. Differing, as I find reason for doing,
both from Agardh and the French Naturalists, I still offer my
own arrangement—the result of my inquiry—as one necessarily
imperfect, and perhaps containing e rro rs to be a ttributed
to the absence of fructification in some of my specimens.
A synopsis of the known genera in the Latin tongue, with a
systematic enumeration of all the better known species, m th
authoritative references, will he found a t the end of this introduction.
The more detailed portion of the work, devoted
to the British Species, forms an iiitegi-al part of my general
arrangement.
As it is not my object, in this place, to give an historical
sketch of the progress of this department ol botanical science,
I shall allude very briefly to those who have mainly contributed
towards it. L in næ u s , it is well known, divided the
aquatic Algoe into four great genera, Tremella, Fucus, Ulva,
and Conferva. The subject was then in its veriest infancy,
and for a long time botanists were more intent upon descrihing
new species, than in classing or arranging those already
known. Any systematic division of the Algoe is in fact so
recent, that, while some have endeavoured to construct genera,
others continued, till very lately, to call them hy their
old names. Such being the case, we shall, in the first instance,
enumerate the more systematic Algologists.
The earliest attempt towards a division of the Algoe into a
greater number of genera, is one in manuscript hy D r J o h n
W a l k e r , Professor of Natural History in the University of
Edinburgh, and contained in the sixth volume of his Adversaria,
dated ITTl. He divides them into fourteen genera,
and it is remarkable, that, according to his views, the genus
Fucus is very nearly the same as restricted a t the present
moment ; while Laminaria, as defined by A g a r d h , is exactly
represented by his Phasgonon. Dr W a l k e r was followed hy
Dr R o t h and Mr S t a c k h o u s e , who wrote about the same
time. The former inserted his remarks in his Catalecta Botánica,
published at Leipsic in The latter proposed six
genera in his Nereis Britannica, a folio work, with indifferent
plates, published at Bath : these genera are. Fucus, Palmaria,
Chxmdrus, Sphoerococcus, Chorda, and Codium. By D e c a n -
D O L L E , the marine Algoe are described in the Flore Française,
under the three genera. Viva, Fucus, and Ceramium ; and it
may he remarked, that, while he rendered Fucus somewhat
more natural, hy retaining only the tuherculated and capsuli-
ferous species, Ulva became an assemblage of individuals,
without similarity in structure or reproductive function.
Up to this period, all the changes that had been proposed,
were made either upon vague, uncertain or artificial principles,
or upon local and imperfect materials. The excellent
L a m o u r o u x must therefore be considered as having, not
only laid the foundation-stone of an uniform system, hut
as having carried up the edifice to a considerable elevation.
His Essai sur les Genres de la Famille des Thalassiophytes
non-articulées, was read before the Institute of France in 1812,
and published in the twentieth volume of Mémoires du Museum
d’FIistoire Naturelle. I t may also he had in a separate
a 2