^L. digitata^ ("fingered"). Stem one to five feet long, thick, round, and solid; lamina oval at base, leathery, smooth, brown, deeply cleft into segments of unequal breadth. It is named from the hand-like form of the lamina. This species is found in Long Island Sound, but is not common south of Cape Cod. The stem is used by fishermen for knife-handles. Pieces of it, placed on the blades while green, contract in drying and become solid. (Plate XIII.) For the genera ^Macrocystis^, ^Nereocystis^, ^Lessonia^, and ^Thalassiophyllum^, see the Introduction, pages 35, 36. ORDER =DICTYOTACEÆ= GENUS ^Dictyota^ ^D. fasciola.^ Fronds olive-brown, expanded, membranaceous, erect, flat; many times forked narrow branches; grows in tufts six to ten inches long, matted at the base. ^D. dichotoma.^ Same as /D. fasciola/, except that the divisions of the forked frond are one eighth to one half of an inch wide. Found in tide-pools in Southern waters. (Plate XIII.) [Illustration: PLATE XIII. Laminaria digitata. Dictyota dichotoma. Taonia atomaria. Padina pavonia.] [Illustration: PLATE XIV. Haliseris polypodioides. Cutleria multifida. Fucus vesiculosus.] GENUS ^Zonaria^ ^Z. lobata.^ Thallus flat, fan-shaped, but not so rounded as in /Padina pavonia/, twelve or more inches in height, cleft irregularly into many [pg071] narrow lobes, the clefts extending nearly or quite to the base; olive-green, with concentric zones of darker color; edges thin and bordered with a dark line. Found in southern California and in tropical and subtropical seas. GENUS ^Taonia^ ^T. atomaria.^ Spreading, fan-shaped frond; clefts irregular and not extending to the basal stem; spores arranged in dark wavy lines and spots on the frond, giving it a mottled appearance and beautiful gradation of color. Found in tropical seas. (Plate XIII.) GENUS ^Padina^ ^P. pavonia^, the peacock's-tail. Frond broadly fan-shaped; substance between membranaceous and leathery; powdery on the outer surface; deeply and variously cleft or entire; several laminæ emanating from a stalk-like base; each lamina fan-shaped; concentric lines numerous; variegated in zones. This beautiful alga is always regarded as a prize. It is found on stones at low-water mark, and is not uncommon south of Charleston, South Carolina, but is more luxuriant in tropical seas. (Plate XIII.) GENUS ^Haliseris^ The sea-endive. ^H. polypodioides.^ Fronds flat, forked, notched on lower part; divisions about one quarter of an inch wide; distinct midrib; olive-green; grows in tufts. It is found in North and South Carolina, and is abundant on the Florida Keys. (Plate XIV.) ORDER =CUTLERIACEÆ= GENUS ^Cutleria^ ^C. multifida.^ Frond erect, flat; branches in a forking manner; ultimate branches fine and short, and with branchlets on the tips. This species resembles /Taonia/. It is found in Southern waters. (Plate XIV.) ORDER =FUCACEÆ=