The stem of the Chylocladia kaliformis is a cylindrical tube, from four to eighteen inches high, constricted at intervals of half an inch or more into long hollow joints; branches of the very same construction but smaller spring from each constriction either opposite to one another or in whorls; these again have lesser branches, all tapering more or less to each end. The plant, which is of a pink colour fading to greenish yellow, is propagated by tetraspores imbedded in the branches, and by transparent conceptacles sessile on the branchlets, enclosing nuclei containing pyramidal spores. We neither possess the Constantinea rosa marina, nor the C. sitchensis, some of the largest and finest plants of the group, both being inhabitants of high latitudes, but there are some very pretty species on the British coasts. They are supposed to be annuals. The red dulses belong to the foliaceous and gelatinous part of this order. The Chondrus crispus, or Irish moss, sold as Carrigeen, is very common on rocky coasts in the northern seas. It is from three to eight inches high, and exceedingly varied in form. The frond is thickish, firm, and elastic, with a stratum of cellular tissue under the skin, which is probably much developed, as the plant becomes horny when dried. It is reproduced by tetraspores, in large oval groups scattered all over the surface, often prominent on one side only, and, in some rare instances, spores in prominent oval conceptacles are immersed in the lesser frond divisions. Besides these are warts composed of radiating threads, possibly antheridia, but not made out. [Illustration: Fig. 26.—A, Rhabdonia Coulteri, portion of nucleus. B, Sphærococcus coronopifolius; portion of nucleus and single spore. C, Wrangelia penicillata, spore threads. D, Cruoria pellita, tetraspores.] The Rhodymeniaceæ are sometimes filiform, but for the most part they are compressed flat cellular fronds, spreading widely from a short delicate stem. They are usually of a blood red, but Rhodymenia palmata, or common Scotch dulse, is of a dark purple. The tetraspores are variously disposed, and simple or compound globular conceptacles containing nuclei are either attached externally to the filiform fronds, or partly immersed in those that are foliaceous. The spores are produced in the joints of moniliform threads within the nuclei, which are sometimes divided into two chambers by threads running from wall to wall. Rhabdonia (fig. 26 A) belongs to this group. The Wrangeliaceæ are filiform, many species consisting of a central thread coated more or less with smaller ones, sometimes so disposed as to form a most elegant lacework. Each joint of the stem, branches, and branchlets is beset with whorls of short slender forked and jointed ramuli. They have clusters of spores in stalked capsules. The spore threads of Wrangelia penicillata (fig. 26 C) are surrounded by a whorl of ramuli composed of radiating pyriform spores arising from the endochrome of terminal cells.