The genus Oscillate is has rigid, elastic, oscillating,. simple, continuous filaments, which are invested by a common mucous matrix. The species are very numerous, but many of them are very difficult to distinguish. They are not all found immersed in water, but always occupy damp places. The 0. tcnuissima is an inhabitant of the warm springs of Bath, occupying broad velvet-like patches of a dark green colour. Its singular appearance, Sir J. E. Smith observes, "arises from the filaments being collected together into little ascending tufts, apparently rooted in the muddy deposit of the water. Each tuft proves, on examination, to consist of simple, reniform, even filaments, crowded together, and quite pellucid and equally destitute of joints and branches ; their diameter, is not more than an 8-1000th or 10-1000th part of, an inch."' The order Nostoceteem consists of plants with elliptical or globose cells connected in gelatinous moniliform strings. The filaments are separate, or several are united together in a gelatinous frond. The cells com posing the filaments are of two kinds ; first, a set of a bright green colour, which constitute the greater part of the filaments, and secondly, solitary cells of different form and size to the rest, destitute of colour, and covered with cilia. They occur at intervals in all the filaments, and are called connecting cella,' or 'heterocysts.' They probably represent the anthcridia in the higher plants. The Nestoracee are chiefly found in fresh-water streams and damp ditches.
The l'altnelloeter are amongst the lowest forms of the Algae. They consist of globose or elliptical cells, which are mom or less distinct, and am collected together by means of a string-layer into a frond. The genus Protoeoceas has only one specie., the 1'. niralis. This little plant has gained a large share of attention on account of its being sucpcieed at one time to be the cause of red anew. Now however the animal kingdom has put in a claim for a share in the productiou of this phenomenon. [Scow, RED.) Most of the species of Ilainatocom are of a red colour, and give an appearance like that of blood to the rocks on which they grow. These appearances have often been regertled with a superstitions eye, and looked upon as warnings or omens from Heaven. One of the species of Palmetto, the P. cruenta, has a dark blood-red colour, and on that account has been called 'gory dew.' It occurs on white-washed walls, especially in damp cellars ; and in such situations has sometimes given occasion fur alarm, ou account of its having the appearance of stains of blood. The other Flocks of Palladia have various colours, as yellow, green, and black. They are found in fresh water streams and on rocks on the sea-shore.
(Harvey, British Marine Alger; Hooker, British Flora; Agardh, Ppeoist Algarwm ; Ores-file, Britannica ; Lindley, Vegetable Ringelont; Hama% Fresh-Water Algc r ; Buruett, Outlines of Botany.)