The other common green Enteromorpha is called “the compressed.” It is in the form of a branching green, delicate tube, flattened here and there; and it clothes rocks between tide-marks, being sometimes as fine as a hair. It gets narrower at its attachment and is broad at the ends. Near high-water mark it forms a short, shaggy pile of slender fronds spreading over rocks and stones, and most treacherous to the stepping of unwary feet, being most slippery. A little lower down, in the rock-pools, it is larger, tubular, branched, and thin near the root; and where fresh water runs in close to it, the fronds get larger, broader, and more inflated. Almost everything on floating timber or on stone is this kind of weed. From being more or less tubular, these Enteromorphæ have a double green membrane. Now there is a beautiful ribbon-shaped ulva which has this double formation and which is found at half-tide level. It is long, even reaching to two feet, and is only half an inch to two inches broad. Very elegant and graceful are its tapering, curling, wrinkling, and plaiting of the edges; it is called Ulva linza, and is of a bright green color. Among the commonest of the small green sea-weeds are the confervæ, hairy-like green threads, which collect in layers and fleeces and cover much surface, or wave in the rock-pools. One kind called the sandy conferva lives at half-tide level at Bantry Bay and also in Scotland at Appin. It forms fleeces a yard or more in extent, made up of thin layers placed over each other, but so slightly connected that they may be separated like gauze, for some inches, without breaking. The hairs or filaments are five or six inches long and are rather rigid; they are very long-pointed, and consist of a delicate tube membrane which incloses a series of long cells. Another conferva, found attached to other sea-weeds at Bantry Bay, Berwick, Firth of Forth, and Torquay, has its filaments forming densely interwoven layers which cling over their supporting plant. It is of a dark green color. A third frequents salt pools by the edge of the sea and rocks at half-tide level. It is a very twisted thing, and forms crisped layers from a few inches to several feet thick, which closely adhere to the inequalities of the rock, or to the plants which grow on it. It is of a glossy brilliant green color, and is called the tortuous conferva.