The waving, slender, long weed, so slimy to the touch, and which is so abundant on all British shores--the dread of the bather when it forms submarine meadows, over mud flats--is called the cord-weed (Corda filum). It is sometimes forty feet, but usually from one to twenty feet in length, and is not twice as thick as a bristle where it starts from a stone, tapering and clothed with delicate hair, getting wider in the middle, and slender and hairy at the top. There are some remarkable sea-weeds, which certainly do not look like things belonging to the sea, but rather to the land, where lichens and fungi live on stones and trees. One often is called rivularia, and is found on rocks, at half-tide level, on the southern shores of England, and in the South and west of Ireland. It incrusts the rocks, rising in short lobes, and it feels fleshy and firm. It begins with a globe-shaped substance, which sends forth ragged-looking pieces; and although it is so dense, the surface is covered with a close pile of exquisite filaments. Many a dark rock, otherwise perfectly barren at the end of summer, is clothed with the bright green patches of this singular weed. Another of these incrusting things is often as round as a half-crown, and looks like a lichen. It is leathery, and gets ragged and warty with age, and is of a coffee-brown color. It is called Ralfsia, after Mr. Ralf. A third kind looks like a flat thin clot or stain of blood; hence its name cruoria, from “cruor,” blood. It forms a scum on the smooth, exposed rocks between tide-marks, and is especially abundant in the west of Ireland and Jersey. The patches are from one to three inches in diameter, and their edges are very clearly curved; they are brown and red, and the hairs or filaments of which they are composed are purplish red. It can be removed in flakes with a knife. Many sea-weeds are found upon others; and indeed some of the most beautiful kinds are thus parasitic upon larger ones. An instance of this occurs to one of the humble crust-like weeds which is found on pebbles at half-tide mark. So small is the parasite that a slight magnifying power is required to make it distinct, and then it is found to be made up of thousands of minute forked threads, each of which consists of several long cells, one placed before the other, and some of the cells are large and egg-shaped, and contain the seeds or spores. It is called the Myrionema, from two Greek words which mean numberless thread.