124 
SUPPLEMENT. 
The only American specimen I have yet seen is small and very slender, about two 
and a half inches long, and not thicker than hog’s bristle. It is abundantly in fruit ; 
otherwise it could hardly be recognised. The branches are few, opposite or alternate, 
some of the larger ones bearing a few ramuli, and all tapering to a very fine point. 
On the British coast this species varies greatly in size. Sometimes it is nearly as 
small and slender as that just noticed. Other specimens, like that figured in Phyc. 
Brit, are 8-12 inches long, and from one to two lines in diameter. The branching is 
irregular and sometimes whorled. 
Page 137, add, 
3. Sphacelaria arctica ; filaments naked at the base, erect, elongate, slender, irre- 
gularly branched, scarcely pinnate ; ramuli filiform, naked, erect. 
Hab. In tide pools, Isle of Disko, Greenland, Dr. Lyall. (v. s. in Herb. T.C.D.) 
Filaments 1-2 inches high, irregularly once or twice compounded, the main branches 
few, the secondary numerous, densely set and very erect, lateral, either naked or bearing 
few or many, long, filiform, erect, naked, slender ramuli, from half an inch to an inch 
in length. Articulations short in the stem and branches ; once and a half as long as 
broad in the ramuli. Colour a dull olive. Fruit unknown. 
Page 138, add, 
III.* MYRIOTBICHIA, Harv. 
Frond capillary, flaccid, jointed, (simple), beset with quadrifarious, simple, spinelike 
ramuli, clothed with byssoid fibres. Fructification , elliptical spores, containing dark- 
coloured endochrome. 
1. Myriotrichia filiformis , Griff. ; stem filiform, slender, often flexuous or curled, 
beset at irregular intervals with oblong clusters of short, papilliform ramuli. Harv. 
Phyc. Brit. t. 156. Wyatt , Alg. Danm. No. 213. J. Ag. Sp. Alg. 1. p. 14. Kiitz. 
Sp. Alg. p. 470. 
Hab. Parasitic on Dictyosiphon fceniculaceus at Penobscot Bay, Mr. Hooper, (v. v.) 
Fronds an inch or more in length, very slender, filiform, but thickened at intervals, as 
if nodose ; the thickening caused by the dense aggregation of short ramuli of two or three 
cells each. These ramuli emit byssoid fibres. Spores roundish, scattered. Substance 
soft. It adheres closely to paper. 
On the British Coast this parasite commonly infests Chorda Lomentaria. 
Page 139, add, 
2* Ectocarpus longifructus , Harv. ; tufts large, branching, the divisions feathery ; 
filaments robust, excessively branched, branches mostly opposite, the lesser ones set 
