CHORD AKIACEiE.—ELACHISTA.—MYRIONEMA. 1 31 



VI. ELACHISTA. Duly. 



Fronds parasitical, penicillate, composed of axial and peripheric filaments. Axial 

 filaments dichotomously branched, cohering together into a tubercular common 

 base. Peripheric filaments, simple, free, penicillate, radiating from the base, coloured, 

 articulate. Fructification : pear-shaped spores attached to the axial filaments, and 

 hidden within the tubercular common basis. 



Elachista fucicola, Fries. ; tufts pencilled ; filaments elongate, flaccid, mem- 

 branaceous, attenuated upwards ; articulations once or twice as long as broad ; 

 tubercle spherical. /. Ag. Sp. Alg. 1, p. 12. Harv. Phyc. Brit., t. 240. Phy- 

 cophila fucorum, Kiitz. Sp. Alg. p. 541. (Tab. XL B.) 



Hab. Parasitical on the fronds of Fucus nodosus and F. vesiculosus. Narragan- 

 sett Pier, Mr. Olney. Halifax, W. H. H. (v. v.) 



A common parasite on littoral fuci, forming brown or foxy-coloured pencils of 

 filaments. I am acquainted only with the two American stations recorded above, 

 but most probably this parasite will be found all along the shores of the Northern 

 States. 



Plate XI. B. Fig. \. Tufts of Elachista /z<CTC0?a, growing on i^wcws noiosws, 

 the naturcd size ; fig. 2, a small portion of a tuft magnified ; fig. 3, a spore with 

 paranemata ; fig. 4, 5, portions of the pencilled filaments, the latter figures highly 

 magnified. 



VII. MYRIONEMA. Grev. 



Fronds minute, parasitical, cushion-like, composed of axial and peripheric fila- 

 ments. Axial filaments decumbent, branched, spreading as a thin expansion on 

 the surface to which the parasite adheres. Peripheric filaments short, erect, simple, 

 springing from the decumbent expansion, and united by interposed gelatine into 

 a cushion-like frond. Spores oblong, affixed either to the erect or to the decum- 

 bent filaments. 



A genus of minute parasites which annually attack the smaller red and green Algaj 

 in old age, and hasten their decay. The following is so common on old fronds of Ulva 

 latissima and Enteromorpha compressa, both common American shore plants, that I 



s2 



