This order comprises many species of branched, filamentous plants, some of which are of hair-like fineness and form beautiful feathery tufts of brownish or olive-green color. They resemble, except in their tawny color, the green alga /Cladophora/. The name is derived from Greek words meaning "outside" and "fruit," the spores of the plants being borne on the branches. The species are determined by the arrangement of the spores, according as they are in the pod-like branches, in groups, or in cases on stalks. Since these differences are not perceptible to the naked eye, it is impracticable to describe many species, or for the amateur collector to try to separate them. GENUS ^Ectocarpus^ ^E. littoralis.^ Filaments fine, in dense tufts, interwoven, six to twelve inches long; pod linear in the substance of the branches; color olive-green. This is the most common species of /Ectocarpus/, and grows abundantly everywhere, appearing like large, fine, dull-green plumes. (Plate IX.) [pg065] ^E. siliculosus.^ Tufts loosely entangled at the base, free and feathery above, of indefinite length; spores in pod-like forms at the ends of the branches. Common on the larger algæ and on wharves. ^E. viridis.^ Tufts a little more loose and expanding than in /E. siliculosus/; spores in pods at the base of the branches. (Plate IX.) ^E. tomentosus.^ Fine filaments, densely interwoven into rope-like, spongy masses, two to four inches long; yellowish-brown; pods on stalks. Found in summer growing on /Fucus/. ORDER =SPHACELARIACEÆ= GENUS ^Sphacelaria^ ^S. cirrhosa.^ Olive-brown; branched, feathery filaments, one half of an inch to two inches long. Each branch ends with an oblong, swollen cell containing a dark granular mass which gives it a withered appearance. These cells can be seen with a strong pocket-lens. It forms dense, globe-like tufts on /Fucus/. ^S. radicans.^ Filaments one half of an inch to one inch high; branches few and hairy. It forms a dense, grass-like covering, of indefinite extent, on the under side of muddy rocks. Found on the New England coast. GENUS ^Cladostephus^ ^C. verticillatus.^ Fronds bristle-like, dividing regularly; covered with whorls of branchlets set close to the stems, each whorl overlapping the previous one, giving the plant a spongy appearance. (Plate IX.) ORDER =RALFSIACEÆ= GENUS ^Ralfsia^ The species of this genus are brown, leathery, crustaceous expansions of indefinite form, one inch to six inches in diameter, resembling lichens. They appear on rocks in shallow, exposed pools. ORDER =ENCŒLIACEÆ= GENUS ^Punctaria^ Dotted-weeds. Fronds pale olive-green, membranaceous, leaf-like, with short stem; covered with spores which appear like dots.