With the animal kingdom, sea-weeds are connected by F. tomentosus, and F. bursa, (Turn. t. 135, 6.) both of which resemble sponges in imbibing water, and giving it out on being pressed ; and also in emitting a peculiar dis agreeable odour a few hours after being taken from the sea. F. bursa, indeed, is classed, both by Linnxus and Pallas, as a zoophyte. F. simpliciusculus of Turner, (t. 175), and F. Iycopodium, (t. 199), approach very near to that class of beings; but, of all others, a small caulerpa, found by Mr Brown in King George's Sound, attached to mytili, and lately figured by Turner, under the title of F. peniculus, (t. 228), forms a link that most closely unites sea-weeds to the animal kingdom.
If it is a difficult task to distinguish and arrange the vegetable productions of the surface of the earth, which can be examined at all seasons, the difficulty is evidently greatly increased in regard to marine plants. In these last the organizatio. is more simple, and consequently they exhibit fewer distinctive characters ; and their place of growth almost precludes the possibility of watching their progress and reproduction. Those best able to delineate their characters are often situated at a distance, and must decribe from the examination of specimens not always judiciously selected by others ; frequently front such as are torn from the rocks, and thrown ashore in storms, when the root or means of attachment is generally wanting.
The older botanists, such as Clusius, the Bauhins, Bar relier, and Morison, contented themselves with giving very short descriptions, or a few figures of sea plants. About the year 1711, Reaumur first examined the parts of fructification in some fuci. He fell into a mistake similar to that which long prevailed concerning the seeds of ferns and mosses; in considering as seeds what are truly cap sules, or tubercles, containing seeds. The opinions of Reaumur seem to have been almost implicitly adopted by botanists down to the close of the 18th century. The cele brated Linnxus had too much to do in reforming the arrangement of phxnogamous plants, to pay very great attention to the cryptogamia. His situation at Upsala was certainly not favourable for the investigation of the sub mersed alga, and his herbarium contained but comparatIve ly a few species ; yet he described near 60 species of fuci. In 1768, Gmelin published, in 4to, his Historia generalis et specialis Fucorum, a work in which he not only collected whatever was previously known, but added very considera bly to the stock of knowledge. Indeed, considering it as the first general work on this branch of natural history, the author deserves great praise. Ile divided the plants of which lie treated into nine orders : \'esiculosi, Penicilliferi, Curallini, Mein branacei, Hadicati, Agara, Tre inella, and Ult a:. Ile described 101 specks; of which number he considered 37 as new, for he gives no sync nimes with them. 1.innaus's name is given to 27 species only. His notions, in genet al, concerning the fructifica
tion of foci, and particularly the supposition of unisexual and asexual plants, were rather et ude, and ha% e not been adopted.
The numerous foci which inhabit our own shores, have been gradually illustrated by a series of writers since the days of Ray, who enumerated a good many in his Synopsis. Those kinds of alga which Dillenius considered as enti tled to a place in his Historia Mascorum, which were chiefly Confervx, he arranged according to general habit and structure. But in the minute kinds, the want of a microscope has often led him into error; for instance, to describe as jointless, plants in which the dissepiments are obvious under an ordinary lens. Withering, in his Art ange ment of British plants, gives descriptions of a number of species. He subdivides the genus into several sections: those with bladders; with pod-like leaves; necklace-like, or jointed ; flat; cylindrical ; and capillary : the flat he farther distinguishes as either mid-ribbed or ribless; and these he still further separates, as either opake or pellucid: both the cylindrical and capillary he likewise subdivides by the same character of opake and pellucid. Hudson, in his Flora ?nglica, is remarkable for care and accuracy ; in evidence of which it may be mentioned, that his nomencla ture is seldom altered by that most scrupulously exact naturalist Mr Turner of Yarmouth, in his writings on this branch of natural history. The descriptions of Lightfoot, in his Flora Scotica, when made from specimens picked up by himself, and examined on the spot, are highly cha racteristic and luminous. The Nereis Britannica of Stack house, which appeared, in fasciculi, between 1795 and 1802, has very considerable merit. The author had good oppor tunities of examining the English sea-weeds, as he resi on the shores of Cornwall. He divided the genus Focus into several genera, chiefly according to the fructi fication ; and although he was but imperfectly acquainted with this, his arrangement deserves attention, and shall be afterwards detailed. Major Velley's figures, which are highly finished, and his dissertation on the propagation of fuci, do him great credit. In the third volume of the Transactions of the Linnean Society, the Bishop of Carlisle and Mr Woodward not only gave a most accurate summary of the state of knowledge with regard to ; but added several new species, and amended the specific cha racters of others. In the course of editing the extensive periodical work, English Botany, Sir James Edwat d Smith likewise added several new species to the list In 1802, NI:. Dawson Turner, of Yarmouth, produced his Synopsis of British Fuci, a valuable little work, which gave the most encouraging earnest of what might be expected from this writer, in his great work on fuci, then only projected, but the publication of which is now considerably advanced.