SEAWEEDS OF THE BLACKWATER ESTUARY 325
Dumontiaceae
Dilsea carnosa (Schmeidel) Kunz. Harwich, Batters (1894) (as D.
edulis Schmitz.).
Dumontia incrassata (O. F. Mull.) Lamour Blackwater Estuary,
Batters (1894) (as D. filiformis Grev.); River Blackwater (Ray Creek,
St. Peters Flats, Osea Island, Bradwell Creek, Mersea Shore, Colne
Point), G.M.M., 1965.
Polyideaceae
Polyides rotundus (Huds.) Grev. Walton, Harwich, Clacton, Black-
water Estuary, Batters (1894); River Blackwater (Goldhanger Creek,
Stoney Point), G.M.M., 1963.
Grateloupiaceae
Grateloupia filicina (Lamour.) C. Ag. Felixstowe, Batters (1894).
Choreocolacaceae
Harveyella mirabilis (Reinsch) Reinke Clacton, Batters (1894).
Rhodymeniales
Rhodymenia palmata (L.) Grev. Harwich, Felixstowe, Clacton,
Batters (1894); River Blackwater (Sales Point), G.M.M., 1963.
Ceramiales
Ceramiaceae
Antithamnion cruciatum (C. Ag.) Nag. River Blackwater (Cocum
Hills, Mersea Shore, Colne Point), G.M.M., 1963.
Antithamnion plumula (Ellis) Thur. Estuaries of the Orwell and
Stour, Batters (1894); River Blackwater, G.M.M., 1963-64.
Calithamnion polyspermum C. Ag. Harwich, Batters (1894).
Callithamnion hookeri (Dillw.) S. F. Grey. River Blackwater,
G.M.M., 1964.
Ceramium deslongchampsii Chauv. Dovercourt, Harwich, Southend,
Batters (1894); River Blackwater (Bradwell Creek, St. Peters Flats,
St Osyth, Thirslet Spit, Stone, Cocum Hills, Colne Point, Decoy
Point, Stoney Point) Harwich, G.M.M., 1963-64.
Ceramium diaphanum (Lightf.) Roth. Felixstowe, Harwich, Dover-
court, Batters (1894); River Blackwater (Bradwell Creek), G.M.M.,
1963.
Ceramium flabelligerum J. Ag. Harwich, Felixstowe, Batters (1894).
Ceramium rubrum (Huds.) J. Ag. Maldon, Walton, Harwich, Felix-
stowe, Clacton, Batters (1894); River Blackwater (St. Peters Flats,
St. Osyth, Goldhanger Creek, Cocum Hills, Colne Point, Stoney Point,
Bradwell Creek, Mersea Shore, Decoy Point), Clacton, Harwich,
G.M.M., 1963-64.
Ceramium tenue J. Ag. River Blackwater (Cocum Hills), G.M.M.,
1963.
Ceramium tenuissimum (Roth.) J. Ag. Harwich, Batters (1894).
Griffithsia corallioides (L.) Batt. Dovercourt, Batters (1894) (as
G. Corallina Ag.).
Griffithsia devoniensis Harv. River Blackwater (St. Peters Flats),
G.M.M., 1963.
Griffithsia flosculosa (Ellis) Batt. Walton, Felixstowe, Harwich,
Clacton, Batters (1894) (as G. setacea); River Blackwater (St Peters