^A. esculenta.^ Stem compressed, four to twelve inches long, one fourth to one half of an inch wide, and running like a midrib through the lamina; lamina one to ten feet long, two to ten inches wide, frequently torn and ragged; margin wavy; leaflets three to eight inches long and without midrib, growing on both sides of the stem, below the lamina. The spores are produced in the leaflets in the autumn. This is an edible alga and is used as food in Scotland and Ireland, where it is called henware, badderlocks, murlins, and so on. (Plate XII.) GENUS ^Agarum^ The sea-colanders. ^A. Turneri.^ Stem two to twelve inches long, round below, flattened above, and extending like a midrib through the lamina; lamina one foot to four feet long, with holes over the whole surface; margin wavy. The perforations in the lamina are produced by conical hollow papillæ which cover the young frond and which at length burst, leaving a hole which enlarges as the plant expands. This species is found from Cape Cod to Greenland. There are other species, which differ from this one in the size of the perforations, the shape of the lamina, and the prominence of the midrib. Harvey describes the plant as an arctic genus growing ten to twelve feet long. (Plate XII.) [pg070] GENUS ^Laminaria^ The plants of this genus are all large, varying from one foot to twelve feet or more in length. They are of wide geographical range, and are more numerous in species than any others of the order. They are commonly known as oarweeds, tangle, devil's-aprons, sole-leather, kelp, sea-furbelows, and so on. ^L. longicruris^ ("long-stalked"). Stem six to twelve feet long, one to two inches thick, slender and solid at base, hollow and inflated at the middle, contracted at the top; attached by a strong, branching, root-like holdfast; color light brown. The large, single, leaf-like lamina, usually shorter than the stem, is five to twenty feet long, two to three feet broad, with much waved and folded margin, outlined with two rows of depressed spots. The spores form a band in the center of the blade. Found from Cape Cod northward and on the Pacific coast. ^L. saccharina^, the sea-tangle. This species differs from /L. longicruris/ in having a short, solid stem and narrow, ribbon-like lamina. Stem three inches to four feet long; lamina three to thirty feet long, six to eighteen inches wide, with central band of depressed spots; margin much waved; color olive-green, semi-transparent. It is named from the saccharine matter, called /mannite/, which it contains. Found on northern shores of the Atlantic and the Pacific oceans. (Plate XII.)