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Growing in a small glass dish filled with water, Providence, Rhode Island.

On limestone rocks, near Gaylordsville, Connecticut.

In tide-pools, Newport, Rhode Island.

In shady pools, epiphytic on various algae, especially Gelidum, between tidemarks, La Jolla, San Diego County, California.

Portion of old frond with unilocular sporangia, washed ashore, Nahant, Massachusetts.

On flats at entrance to harbor, San Pedro, California.

Attached to rocks, in running spring water, outlet of Comal Spring, New Braunfels, Texas.

On rocks and in pools, at extreme low water mark, Nahant, Massachusetts.

San Pedro. California.

In fronds of Helminthocladia purpurea, San Pedro, California.

On wet cliff, Cascade, Melrose, Massachusetts.

Among Oedogonium, in a ditch in a cranberry bog, Norwich, Connecticut.

Ditch in Middlesex Fells, Malden, Massachusetts.

On stones at low water mark, Revere Beach, Massachusetts.

On rocks between tides, Cape Rosier, Maine.

On Ascophyllum nodosum, in tide pool, Seal Harbor, Mount Desert Island, Maine.

On Zostera, in tide pool, Spectacle Island, Penobscot Bay, Maine.

In muddy marsh pools, Bridgeport, Connecticut.

In half-tide pools, Newport, Rhode Island.

In a ditch in a cranberry bog, Norwich, Connecticut.

In cushion-like masses on upper face of a smooth rock, Pacific Beach, San Diego County, California.

On Scytosiphon lomentarius, in tide pools, Ochre Point, Newport, Rhode Island.

On Codium mucronatum, La Jolla, California.

On Rhodymenia palmata and Saccorhiza dermatoides, Nahant, Massachusetts.

Forming great floating masses, loosely tufted, in deep water, buoyed up by air bubbles, but reaching the bottom at a depth of several meters; Horn Pond, Woburn, Massachusetts.

On Laminaria etc., Nahant, Massachusetts.

On clam shells in False Bay, at half tide, San Diego, California.

Portsmouth, Rhode Island.

Magnolia, Massachusetts.

Indian River Inlet.

On rocks near low water mark, in positions exposed to the waves. Land's End, San Francisco, California.

On stones between tide marks, Carmel Bay, Monterey County, California.

La Jolla, San Diego County, California.

On shaded cliffs, Eagle Island, Penobscot Bay, Maine.

On rocks and stones, at extreme low water mark, Pyramid Point, Pacific Grove, California.

Forming an aerugineous coating on an old wooden pier in Lake Pontchartrain, Louisiana.

On ground, Spanish Point, Bermuda.

Floating in large dark aerugineous masses on the surface of Lake Hendricks, So. Dakota.

In a slow stream near Pasadena, California.

Forming a smooth black covering on smooth rocks, at high water mark in exposed places, Carmel Bay, Monterey County, California.

On sandy ground near Fresh Pond, (brackish), Stratford, Connecticut.

On algae in high rock pool, Easton's Point, Newport, Rhode Island.

Floating in stagnant marsh pool near Fresh Pond, (brackish), Stratford, Connecticut.

On Chondria flagelliformis, in tide pool, Marblehead, Massachusetts.

Floating in large, light-aerugineous masses on the surface of a pond supplied with artesian water, So. Dakota.

On sand dunes, Paget, Bermuda.

Epiphytic, mostly on Phyllitis fascia, in marsh pool, Bridgeport, Connecticut.

On various algae, chiefly on Scytosiphon lomentarius, Conanicut, Rhode Island.

On upper surface of rocks near high water mark, La Jolla, California.

In tide pools, Crowninshield's Point, Seal Harbor, Mount Desert Island, Maine.