MYRIOTRICHIA. 63 



On mud-covered rocks and stones, near low- water mark, and at a greater 

 depth. Annual. April and May. Rare; but found from Orkney to 

 Cornwall, and on the Irish coast. Main stems 2 5 inches long, nearly 

 simple, set throughout with opposite, or by suppression, alternate branches 

 of unequal length ; the branches linear and undivided, furnished for their 

 whole length, and at distances of every second or third joint, with slender, 

 spreading, subulate ramtili, one-third the diameter of the branch, and at 

 intervals bearing a larger pinnated ramulus; all the divisions exactly dis- 

 tichous and opposite ; the branches resembling delicate feathers. Joints 

 of the stem marked with a central, longitudinal, coloured band, those of 

 the ramuli bright green, very short. Spores imbedded in the distended 

 ramuli, containing a dark-coloured mass. Colour a fine olive-green. A 

 highly beautiful species, unlike any other of the genus, and in many re- 

 spects showing affinity with Sphacelaria, from which it is chiefly distin- 

 guished by its flaccid substance. 



IV. MYRIOTRICHIA. Harv. [Plate 9, D.] 



Filaments capillary, flaccid, jointed (simple), beset on all 

 sides with simple, spine-like ramuli, clothed with byssoid 

 fibres. Fructification : elliptical spores, containing a dark- 

 coloured, granular mass, within a transparent perispore. 

 Name, from pvpios, numberless, and fy<l, a hair. 



1. M. clavx/ormis, Harv. ; stern densely beset with quad- 

 rifarious ramuli, which gradually increase in length from the 

 base upwards, giving the frond a club-shaped figure. Harv. 

 in Hook. Journ. of Bot. Vol. i. p. 300, t. 138 ; Fl. Hib. p. 

 182; Wyatt, Alg. Damn. No. 131; Harv. Phyc. Brit. t. 

 ci. 



Parasitical on Chorda lomentaria. Annual. Summer. Fronds half an 

 inch long, tufted, flaccid, sub-gelatinous, simple, lineari-clavate, olivace- 

 ous, surrounded by colourless fibres. Primary thread running the whole 

 length of the plant, simple, attenuated at base, articulated, naked below, 

 towards the apex densely clothed with ramuli ; the young plants destitute 

 of ramuli, or merely bearing rudimentary processes. Ramuli quadrifarious, 

 whorled or irregularly scattered, obtuse, the lower ones short and naked ; 

 the upper (like the primary thread), bearing lesser ramuli, from whose tips 

 spring long, colourless, simple, long-jointed fibres, of a very thin mem- 

 branous texture and flaccid substance. Joints of the primary thread 

 very short, transversely dotted, the dots proliferous (finally becoming ra- 

 muli) ; of the ramuli oblong, with pellucid dissepiments. Spores sessile, 

 elliptical or ovate, with a pellucid limb, and containing a dense olivaceous 

 mass. Miss Hutchins appears to have been the earliest discoverer of this 

 plant, having communicated it to Dr. Mackay forty years ago, as " a cu- 

 rious new Conferva." 



2. M.Jiliformis ; stem filiform, slender, often flexuous or 

 curled, beset at irregular intervals with oblong clusters of 



