be detected in this country, is described as being effused, in the 

 manner of E. velutina. 



A. Fig. 1. Branchlet of Cystoseira ericoides infested with ElacJiistea attenuata : 

 — natural size. 2, Fragment of the same, slightly magnified. 3. Portion 

 of the Elacliistea. 4. Tubercular base of the same, in its position. 5. A 

 filament and spore : — all magnified. 



Plate XXVIII. (B). 



ELACHISTEA VELUTINA, Fries. 



Elachistea velutina ; spreading in thin, indefinite, velvetty patches ; fila- 

 ments very minute, equal in diameter throughout, dissepiments slightly 

 contracted ; joints once, to one and a half times as long as broad ; 

 spores elliptical, pedicellate, affixed to the lower part of the filaments. 



Elachistea velutina, Fries, Flor. Scan. 317. ArescJi. in Linnaa, vol. xvi. 

 p. 235. t. 8. f.9. 



Myrionema velutinum, Endl. 3rd Suppl. p. 23. 



Sphacelaria? velutina, Grev. Crypt. Fl. t. 350. Ham. in Hook. Br. Fl. vol. ii. 

 p. 325. Harv. in Mack. Fl. Hib. part 3. p. 181. Harv. Man. p. 39. 



Hab. Parasitical on Himanthalia lorea, frequent. On Fucus serratus, Dr. 



Greville. Shores of the British Islands. 

 Geogr. Distr. Atlantic coasts of Europe ; probably common. 



Descr. Forming dark olive, velvetty patches of indefinite extent on the surface 

 of the fuci affected, rooting in their substance. Filaments about a fine in 

 height, linear, obtuse, coloured, except at the very base, simple, or occa- 

 sionally forked at a joint or two above the base. Articulations once, or 

 twice as long as broad, slightly contracted at the dissepiments. Spores 

 elliptical or oblong, or somewhat obovate, dark olive, with a wide limbus, 

 supported on slender pedicels, which are evidently contracted filaments. 



ElacJiistea velutina was first observed by Dr. Greville who 

 published an excellent figure of it in the sixth volume of his 

 ' Cryptogamic Flora'. It occurs commonly on the long strap- 

 shaped receptacles of Himanthalia lorea ; but I have not seen it 

 on Fucus serratus. Mr. Ralfs, who finds it abundantly on the 

 Himantlialia, remarks that it very frequently accompanies E. 

 scutulata, and often so closely resembles that species that it 

 becomes difficult to distinguish them, except by the form of the 

 spores. Usually, however, E. scutulata is readily known by 

 occurring in raised, oval, shield-like patches. 



B. Fig. 1, Fragment of Himanthalia lorea infested with ElacJiistea velutina : — 

 natural size. 2. Lateral sectional view of a portion of the ElacJiistea, in 

 situ. 3. Portion of the same. 4. Filaments in fruit, detached : — more or 

 less magnified. 



